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J 2. * : MEDICINE NATIONAL LIBRARY OF MEDICINE NATIONAL LIBRARY OF MEDICINE NATIONAL LIBRA RY 0 r i I IVNOUVN 3NI3IQ3W JO A » V II 8 I 1 IVNOUVN 3 N I 3 I 0 3 V* JO A II V II 8 M IVNOUVN 3N 13 Id 3W JO A » V « « yw i\ ivaa i MEDICINE NATIONAL LIBRARY OF MEDICINE NATIONAL LIBRARY OF MEDICINE NATIONAL LIBRARY C r\ i «„, A 09.^$®,°'/ Originally they are •*'i ®a*-j «*•*• VL*A® @ simple nucleated cells ^ •*$* < 'i % •> «/?*&* • inch in diameter), *\£*S?V* \JJt ha™s a rounded % * 9 form. As growth ® proceeds, they be- come elongated in their figure, and it is then perceived that each cell contains two and « Figures illustrative of the developement of bone; they are magnified 155 times, and DEVELOPEMENT OF BONE. 49 often three nucleoli round which smaller cells are in progress of formation. If we examine them nearer to the punctum ossificationis we find that the young or secondary cells have each attained the size of the parent cell (3Ifoo- of an inch), the membrane of the parent cell has disappeared, and the young cells are F,&-16* separated to a short dis- tance by freshly effused intercellular substance. Nearer still to the punctum ossificationis a more remarkable change has ensued, the energy of cellule repro- duction has augmented with proximity to the ossifying point, and each cell in place of producing two, gives birth to four, five, or six young cells, which rapidly destroy the parent membrane and attain a greater size (TJfo of an inch) than the parent cell, each cell being, as in the previous case, separated to a slight extent from its neighbour by intercellular substance. By one other repetition of the same process, each cell producing four or five, or six young cells, a cluster is formed, containing from thirty to fifty cells. These clusters lie in Flg- 17,t immediate re- lation with the punctum ossi- ficationis ; they are oval in figure (about 5fo in length by tIo in breadth), and placed in the direction of the longitudinal axis of the bone. The cells composing the cluster he drawn with the camera lucida. a. A portion of cartilage, the farthest removed from the seat of ossification, showing simple nucleated cells, having an ordinary size of 2^__ of an inch, long diameter, b. The same cartilage nearer to the seat of ossification; each simple cell has produced two, which are a little larger than the cells in figure a. * The same cartilage, still nearer the seat of ossification; each single cell of b has given birth to four, five, or six cells, which form clusters. These clusters become larger towards the right of the figure, and their cells more numerous and larger, yT^ of an inch, long diameter. t The same cartilage at the seat of ossification; the clusters of cells are arranged m columns; the intercellular spaces between the columns being ^-^ of an inch in breadth. To the right of the figure osseous fibres are seen occupying the intercellular spaces, at first bounding the clusters laterally, then splitting them longitudinally and encircling each separate cell. The greater opacity of the right hand border is due to a threefold cause, the increase of osseous fibres, the opacity of the contents of the cells, and the mul- tiplication of oil globules. In the lower part of the figure some attempt has been made to show the texture of the cells. 50 DEVELOPEMENT OF BONE. transversely with regard to its axis. In the first instance they are closely compressed, but by degrees are parted by a thin layer of inter- cellular substance, and each cluster is separated from neighbouring clusters by a broader layer G2V0- of inch) of intercellular substance. Such are the changes which occur in cartilage preparatory to the formation of bone. Ossification is accomplished by the formation of very fine and deli- cate fibres within the intercellular substance: this process commences at the punctum ossificationis and extends from that point through every part of the bone, in a longitudinal direction in long, and in a radiated manner in flat bones. Starting from the punctum ossifi- cationis, the fibres embrace each cluster of cells, and then send branches between the individual cells of each group. In this manner the network, characteristic of bone, is formed, while the cells by their conjunction constitute the permanent areolae and Haversian canals. With a high magnifying power, the delicate ossific fibres here alluded to are seen themselves to be composed of minute cells having an elliptical form and central nuclei. These cells attract into their interior the calcareous salts of the blood, and their nuclei become developed, as I believe, into the future corpuscles of Purkinje. It is possible also that s.ome of the cartilage cells become corpuscles of Purkinje in the fully developed bone. During the progress of the phenomena above described, the con- tents of the cells undergo certain changes. At .first, their contents are transparent, then they become granular, and still later opaque, from the presence of amorphous matter mingled with nuclei, nucleoli, and the remains of secondary cells. In the latter state they also contain an abundance of minute oil-globules. These latter increase in size as the ossific changes advance, and in the newly formed osseous areolae they are very numerous and have attained the ordinary size of adipose cells. Cartilaginification is complete in the human embryo at about the sixth week; and the first point of ossification is observed in the cla- vicle at about the seventh week. Ossification commences at the centre, and thence proceeds towards the surface; in flat bones the osseous tissue radiates between two membranes from a central point towards the periphery, in short bones from a centre towards the circumference, and in long bones from a central portion, diaphysis, towards a secondary centre, epiphysis, situated at each extremity. Large processes, as the trochanters, are provided with a distinct centre of developement, which is named apophysis. The growth of bone in length takes place at the extremity of the diaphysis, and in bulk by fresh deposition on the surface; while the medullary canal is formed and increased by absorption from within. The period of ossification is different in different bones; the order of succession may be thus arranged:— During the fifth week, ossification commences in the clavicle, lower jaw, and upper jaw. During the sixth week, in the femur, humerus, tibia, radius, and ulna. DEVELOPEMENT OF BONE. 51 During the seventh and eighth weeks, in the fibula, frontal, occi- pital, sphenoid, ribs, parietal, temporal, nasal, vomer, palate, vertebrae, three first pieces of sacrum, malar, metacarpus, metatarsus, third phalanges of the hands and feet, and ilium. During the third month, in the first and second phalanges of the hands and feet, lachrymal bone, and ischium. During the fifth month, in the mastoid portion of the temporal, ethmoid, inferior turbinated, sternum, os pubis, and two last pieces of sacrum. During the sixth month, in the body and odontoid process of the axis, and calcaneus. During the seventh month, in the astralagus. During the tenth month in the cuboid bone and os hyoides. During the first year, in the coracoid process of the scapula; first piece of the coccyx, inferior turbinated bone, last piece of the ster- num, anterior arch of the atlas, os magnum, os unciforme, and ex- ternal cuneiform bone. During the third year, in the cuneiform_of the carpus, internal cu- neiform, and patella. During the fourth year, in the middle cuneiform and scaphoid of the tarsus. During the fifth year, in the trapezium and os semilunare. During the seventh year, in the second piece of the coccyx. During the eighth year, in the scaphoid of the carpus. During the ninth year, in the os trapezoides. During the twelfth year, in the os pisiforme and third piece of the coccyx. During the eighteenth year, in the fourth piece of the coccyx. The ossicula auditus are the only bones completely ossified at birth; the vertebrae are not completed until the five-and-twentieth year. The entire osseous framework of the body constitutes the skeleton, which in the adult man is composed of two hundred and fourteen distinct bones. They may be thus arranged:— Head........8 Ossicula auditus......6 Face........14 Vertebral column, including sacrum and coccyx 26 Os hyoides, sternum, and ribs - - - - 26 Upper extremities......64 Lower extremities......62 Sesamoid bones......8 214 There are thirty-two teeth closely connected with the skeleton, but their structure is essentially different from bone. The skeleton is divisible into: 1. The vertebral column or central 52 VERTEBRAL COLUMN. axis. 2. The head and face, or superior developement of the central axis. 3. The hyoid arch. 4. The thoracic arch and upper extremi- ties. 5. The pelvic arch and lower extremities. VERTEBRAL COLUMN. The vertebral column is the first and only rudiment of internal skeleton in the lower Vertebrata, and constitutes the type of that great division of the animal kingdom. It is also the first developed por- tion of the skeleton in man, and the centre around which all the other parts are produced. In its earliest formation it is a simple cartilagi- nous cylinder, surrounding and protecting the primitive trace of the nervous system; but, as it advances in growth and organization, it becomes divided into distinct pieces, which constitute vertebrce. The vertebrae are divided into true and false. The true vertebrae are twenty-four in number, and are classified, according to the three regions of the trunk which they occupy, into cervical, dorsal, and lumbar. The false vertebrae consist of nine pieces, united into two bones, the sacrum and coccyx. The arrangement of the vertebrae may be better comprehended by means of the accompanying table:— ( 7 Cervical, True vertebrae 24 < 12 Dorsal, ( 5 Lumbar. False vertebrae 9 \ «> Sacrum, ( 4 Coccyx. Characters of a Vertebra.—A vertebra consists of a body, two laminae, a spinous process, two transverse processes, and four articu- lar processes. The body is the solid part of the vertebra ; and, by its articulation with adjoining vertebrae, gives strength and sup- port to the trunk. It is flattened above and below, convex in front, and slightly concave behind. Its anterior surface is constricted around the middle, and pierced by a number of small openings which give passage to nutritious vessels. Upon its posterior surface is a single irregular opening, or several, for the exit of the venae basis vertebrae. The lamina commence upon the sides of the posterior part of the body of the vertebra by two pedicles; they then expand, and, arching backwards, enclose a foramen which serves for the protection of the spinal cord. The upper and lower borders of the laminae are rough for the attachment of the ligamenta subflava. The concavities above and below the pedicles are the intervertebral notches. The spinous process stands backwards from the angle of union of the laminae of the vertebra. It is the succession of these projecting processes along the middle line of the back, that has given rise to the common desig- nation of the vertebral column, the spine. The use of the spinous process is for the attachment of muscles. The transverse processes project one at each side from the laminae of the vertebra; they are intended for the attachment of muscles. The articular 'processes CERVICAL VERTEBRAE 53 four in number, stand upwards and downwards from the laminae of the vertebra to articulate with the vertebra above and below. Cervical Vertebrce.—In a cervical ver- tebra the body is smaller than in the other Fis-18* regions; it is thicker before than behind, broad from side to side, concave on the upper surface, and convex below; so that when articulated, the vertebrae lock the one into the other. The lamina are nar- row and long, and the included spinal foramen large and triangular. The supe- rior intervertebral notches are slightly deeper than the inferior; the inferior being the broadest. The spinous process is short and bifid at the extremity, increasing in length from the fourth to the seventh. The transverse processes are also short and bifid, and deeply grooved along the upper surface for the cervical nerves. Piercing the base of the transverse process is the vertebral foramen,f which gives passage to the vertebral artery and vein, and vertebral plexus of nerves. The transverse processes in this region are formed by two small developements which proceed, the one from the side of the body, the other from the pedicle of the vertebra, and unite near their extremities to enclose the circular area of the vertebral fora- men. The anterior of these developements is the rudiment of a cervi- cal rib; and the posterior, the analogue of the transverse processes in the dorsal region. The extremities of these developements are the anterior and posterior tubercles of the transverse process. The arti- cular processes are oblique; the superior looking upwards and back- wards ; and the inferior, downwards and forwards. There are three peculiar vertebrae in the cervical region :—The first or atlas ; the second or axis ; and the seventh or vertebra promi- nens. The Atlas (named from supporting the head) is a simple ring of bone, without body and composed of arches and processes. The an- terior arch has a tubercle on its anterior surface, for the attachment of the longus colli muscle; and on its posterior aspect is a smooth surface, for the articulation of the odontoid process of the axis. The posterior arch is longer and more slender than the anterior, and flattened from above downwards; at its middle is a rudimentary spinous process; and upon its upper surface, near the articular pro- cesses, a shallow groovej at each side, which represents a superior * A central cervical vertebra, seen upon its upper surface. 1. The body, concave in the middle, and rising on each side into a sharp ridge. 2. The lamina. 3. The pedicle rendered concave by the superior intervertebral notch. 4. The bifid spinous process. 5. The bifid transverse process. The figure is placed in the concavity between the ante- rior and posterior tubercles, between the two processes which correspond with the rudi- mentary rib and the true transverse process. 6. The vertebral foramen. 7. The supe- rior articular process, looking backwards and upwards. 8. The inferior articular process. t Sometimes, as in a vertebra now before me, a small additional opening exists by the side of the vertebral foramen, in which case it is traversed by a second vein. X This groove is sometimes converted into a foramen. 5# 54 ATLAS AND AXIS. Fig. 19.* intervertebral notch, and supports the vertebral artery previously to its passage through the dura mater, and the first cervical nerve. The intervertebral notches are peculiar from being situated behind the articular processes instead of before them, as in the other verte- brae. The transverse processes are remarkably large and long, and pierced by the foramen for the ver- tebral artery. The articular pro- cesses are situated upon the most bulky and strongest part of the atlas. The superior are oval and concave, and look inwards, so as to form a kind of cup for the condyles of the occipital bone, and are adapted to the nodding movements of the head; the inferior are cir- cular, and nearly horizontal, to permit of the rotatory movements. Upon the inner face of the lateral mass which supports the articular processes, is a small tubercle at each side, to which the extremities of the transverse ligament are attached, a ligament which divides the ring of the atlas into two unequal segments; the smaller for receiving the odontoid process of the axis, and the latter to give passage to the spinal cord and its membranes. The Axis (vertebra dentata) is so named from having a process upon which the head turns as on a pivot. The body is of large size, and supports a strong process, the odontoid, which rises perpendicu- larly from its upper surface. The odontoid process presents two arti- culating surfaces; one on its anterior face, to articulate with the anterior arch of the atlas; the other on its posterior face, for the trans- verse ligament; the latter surface constricts the base of the process, which has given rise to the term neck applied to this part. Upon each side of its apex is a rough depression, for the attachment of the alar ligaments ; and running down from its base on the anterior surface of the body of the vertebra a vertical ridge, with a depression at each side for the attachment of the longus colli muscle. The lamince are large and strong, and unite poste- riorly to form a long and bifid spinous process, which is concave be- neath. The transverse processes are quite rudimentary, not bifid, * The upper surface of the atlas. 1. The anterior tubercle projecting from the ante- rior arch. 2. The articular surface for the odontoid process upon the posterior surface of the anterior arch. 3. The posterior arch, with its rudimentary spinous process. 4. The intervertebral notch. 5. The transverse process. 6. The vertebral foramen. -7. Supe- rior articular surface. 8. The tubercle for the attachment of the transverse ligament. The tubercle referred to is just above the head of the figure; the convexity below it is the margin of the inferior articulating process. t A lateral view of the axis. 1. The body. 2. The odontoid process. 3. The smooth facet on the anterior surface of the odontoid process which articulates with the anterior arch of the atlas. 4. The transverse process pierced obliquely by the vertebral foramen. 5. The spinous process. 6. The inferior articular process. 7. The superior articular surface. Fig. 20.t DORSAL VERTEBRA. 55 and project only so far as to enclose the vertebral foramen, which is directed obliquely outwards instead of perpendicularly as in the other vertebrae. The superior articulating processes are situated upon the body of the vertebra on each side of the odontoid process. They are circular and nearly horizontal, having a slight inclination outwards. The inferior articulating processes look downwards and forwards, as do the same processes in the other cervical vertebrae. The superior intervertebral notch is remarkably shallow, and lies behind the arti- cular process as in the atlas. The lower surface of the body is con- vex, and is received into the concavity upon the upper surface of the third vertebra. The Vertebra prominens, or seventh cervical, approaches in cha- racter to the upper dorsal vertebrae. It has received its designation from having a very long spinous process, which is single and termi- nated by a tubercle, and forms a considerable projection on the back part of the neck; to the extremity of this process the ligamentum nuchas is attached. The transverse processes are but slightly grooved along the upper surface, have each a small foramen for the trans- mission of the vertebral vein, and present only a rudimentary bifurca- tion at their extremity. Sometimes the anterior tubercle represents a small but distinct rib. Dorsal Vertebra.—The body of a dorsal vertebra is as long from before backwards, as from side to side, particularly in the middle of the dorsal region; it is thicker behind than before, and marked on each side by two half-articulating surfaces, for the heads of two ribs. The pedicles are strong, and the lamina broad and thick ; the spinal foramen small and round, and the inferior intervertebral notch of large size; the supe- Fi£-21-* rior can scarcely be said to exist. The spinous process is long, prismoid, directed very obliquely downwards, and terminated by a tubercle. The transverse processes are large and strong, and directed ob- liquely backwards. Upon the anterior and superior aspect of their summits is a small facet for the articulation of the tubercle of a rib. The articular processes are vertical, the superior facing directly backwards, and the inferior directly for- wards. The peculiar vertebrae in the dorsal region are the first, ninth, tenth, eleventh, and twelfth. The first dorsal vertebra approaches very closely in character to the last cervical. The body is broad from side to side, and concave above. The superior articular pro- * A lateral view of a dorsal vertebra. 1. The body. 2, 2. Articular facets for the heads of ribs. 3. The pedicle. 4. The superior intervertebral notch. 5. The inferior intervertebral notch. 6. The spinous process. 7. The extremity of the transverse process marked by an articular surface for the tubercle of a rib. 8. The two superior articular processes looking backwards. 9. The two inferior articular processes looking forwards. 56 LUMBAR VERTEBRAE. cesses are oblique, and the spinous process horizontal. It has an entire articular surface for the first rib, and a half surface for the second. The ninth dorsal vertebra has only one half articular surface at each side. The tenth has a single entire articular surface at each side. The eleventh and twelfth have each a single entire articular surface at each side; they approach in character to the lumbar vertebrae; their transverse processes are very short, trifid at their summits, and have no articulation with the corresponding ribs. The transverse processes of the twelfth dorsal vertebra are quite rudimentary, and its inferior articular processes look outwards. Lumbar Vertebra.—These are the largest pieces of the vertebral column. The body is broad and large, and thicker before than behind. The pedicles very strong; the lamina short, thick, and broad; the inferior intervertebral notches very large, and the spinal foramen large and oval. The spinous process is thick and broad. The transverse processes (costiform processes) are slender, pointed, and directed only slightly backwards. The superior articular processes are concave, and look backwards and inwards; the Fis-22* inferior, convex, and look forwards and outwards. Projecting backwards and upwards from the superior articular process is a short and flattened tubercle or posterior transverse process, and in a strongly marked vertebra there is not unfrequently at the base of this a smaller tubercle which has a direction down- wards. The last lumbar vertebra differs from the rest in having the body very much bevelled posteriorly, so as to be broad in front and narrow behind, and the transverse process thick and large. General Considerations.—Viewed as a whole, the vertebral column represents two pyramids applied base to base, the superior being formed by all the vertebrae from the second cervical to the last lum- bar, and the inferior by the sacrum and coccyx. Examined more at- tentively, it will be seen to be composed of four irregular pyramids, applied to each other by their smaller extremities and by their bases. The smaller extremity of the uppermost pyramid is formed by the axis, or second cervical vertebrae.; and its base, by the first dorsal. The second pyramid is inverted; having its base at the first dorsal, and the smaller end at the fourth. The third pyramid commences at the fourth dorsal, and gradually enlarges to the fifth lumbar. The fourth pyramid is formed by the sacrum and coccyx. The bodies of the vertebrae are broad in the cervical region, nar- rowed almost to an angle in the middle of the dorsal, and again broad in the lumbar region. The arches are broad and imbricated in the * A lateral view of a lumbar vertebra. 1. The body. 2. The pedicle 3 The supe rior intervertebral notch. 4. The inferior intervertebral notch. 5. The spinous process" 6. The transverse process. 7. The superior articular processes. 8. The inferior articular processes. 9. The posterior transverse process. VERTEBRAL COLUMN. 57 cervical and dorsal regions, the inferior border of each overlapping the superior of the next; in the lumbar region an interval is left between them. A considerable interval exists between the cranium and atlas, and another between the last lumbar vertebra and sacrum. The spinous processes are horizontal in the cervical, and become gradually oblique in the upper part of the dorsal region. In the middle of the dorsal region they are nearly vertical and imbricated, and towards its lower part assume the direction of the lumbar spines, which are quite horizontal. The transverse processes developed in their most rudimentary form in the axis, gradually increase in length to the first dorsal vertebra. In the dorsal region they project obliquely backwards, and diminish suddenly in length in the eleventh and twelfth vertebrae, where they are very small. In the lumbar region they increase to the middle transverse process, and again subside in length to the last. The transverse processes consist essentially of two parts, the ante- rior of which in the dorsal region is the rib, while the posterior retains the name of the transverse process. In the cervical region these two elements are quite apparent, both by their different points of at- tachment to the vertebra, and by the vertebral foramen which divides them at their base. In the lumbar region the so-called transverse processes are, in reality, lumbar ribs, while the transverse processes will be found behind them in a rudimentary state, developed like the true transverse processes in the cervical region, from the superior ar- ticular processes. When the anterior and posterior transverse pro- cesses are examined in relation with each other, they, will be observed to converge; and if the latter were prolonged they would unite as in the cervical region and enclose a foramen, or they would rest in con- tact as in the dorsal region, or become consolidated as in the forma- tion of the sacrum*. Moreover, the posterior transverse processes are directed upwards, and if they were prolonged, they would come into contact with a small tubercle which is found at the base of the poste- rior transverse process (in strongly marked vertebrae) in the vertebra above. This junction would form a posterior intervertebral foramen, as actually occurs in the sacrum. In brief, the lumbar vertebrae ex- hibit those transitional changes which are calculated, by an easy gra- dation, to convert separate vertebrae into a solid bone. The transverse processes of the eleventh and twelfth dorsal vertebrae are very inte- resting in a transcendental point of view, as exhibiting a tendency which exists obscurely in all the rest, namely, to trifurcate. Now, supposing these three branches to be lengthened in order to fulfil their purposes, the anterior would constitute the articulation or union with a rib, while the superior and inferior would join similar branches in the vertebra above and below, and so form the posterior intervertebral foramen. The intervertebral foramina formed by the juxtaposition of the notches, are smallest in the cervical region, and gradually increase to the last lumbar. On either side of the spinous processes, and extend- ing the whole length of the column, is the vertebral groove, which is shallow and broad in the cervical, and deeper and narrower in the V 58 DEVELOPEMENT OF VERTEBRAE. dorsal and lumbar regions. It lodges the principal muscle of the back. Viewed from the side, the vertebral column presents several curves, the principal of which is situated in the dorsal region, the concavity looking forwards. In the cervical and lumbar regions the column is convex in front; and in the pelvis an anterior concave curve is formed by the sacrum and coccyx. Besides the anteroposterior curves, a slight lateral curve exists in the dorsal region, having its convexity towards the right side. < Developement.—The vertebrae are developed by three primary and five secondary centres or epiphyses. The primary centres are, one for each lamella, and one for the body; the epiphyses, one for the apex of the spinous process, one for that of each transverse process, and one for the upper and under surface of the body. Exceptions to this mode of developement are met with in the atlas, axis, vertebra prominens, and lumbar vertebrae. The atlas has four centres: one for each lateral mass, one (sometimes two) for the anterior arch, and one for the centre of the posterior arch. The axis has five: one (sometimes two) for the body, two for the odontoid process, appearing side by side in its base, and one for each lamella. The vertebra pro- minens has two additional centres for the anterior or costal segments of the transverse processes, and the lumbar vertebra two for the pos- terior segments of the transverse processes. The primary centres of the vertebrae make their appearance during the seventh or eighth week of embryonic existence, the lamella being somewhat in advance of that for the body. From the former are produced the spinous, transverse, and articular processes, and the sides of the body; they unite, to complete the arch, one year after birth, and with the body during the fifth year. The epiphyses, for the extremities of the spinous and transverse processes, make" their appearance at fifteen or sixteen, and become united between twenty and twenty-five. The epiphyses of the body are somewhat later in appearance, and are consolidated between the periods of twenty-five and thirty years of age. The ossific centres for the lateral masses of the atlas appear at the same time with those of the other vertebrae; they unite posteriorly at the end of the second year, by the intervention of the centre for the posterior arch. The one or two centres of the anterior arch appear during the first year, and become consolidated with the lateral pieces during the fifth or sixth year. The axis developes its lateral pieces at the same time with the rest of the vertebrae; they join posteriorly soon after birth, and with the body during the fourth or fifth year. The centres for the body and odontoid process appear during the sixth month, and are consolidated during the third year. The body of the axis is more largely developed at birth than that of the other verte- brae. The costal segments of the vertebra prominens appear during the second month, and become united to the body at the fifth or sixth year. These processes sometimes remain permanently separate, and constitute a cervical rib. The transverse process of the first lumbar * SACRUM. 59 vertebra has sometimes a distinct centre, which may remain perma- nently separate, in that case forming a lumbar rib. The ossification of the arches of the vertebrae commences from above, and proceeds gradually downwards; hence arrest of develope- ment gives rise to spina bifida, generally in the loins. Ossification of the bodies, on the contrary, commences from the centre, and proceeds from that point towards the extremities of the column; hence im- perfection of the bodies occurs either in the upper or lower ver- tebrae. Attachment of muscles.—To the atlas are attached ten pairs of muscled ; the longus colli, rectus anticus minor, rectus lateralis, rectus posticus minor, obliquus superior and inferior, splenius colli, levator anguli scapulae, first interspinales, and first intertransversales. To the axis are attached twelve pairs, viz.: the longus colli, inter- transversales, obliquus inferior, rectus posticus major, supraspinalis, interspinales, semi-spinalis colli, multifidus spinae, levator anguli sca- pulae, splenius colli, transversalis colli, and scalenus posticus. To the remaining vertebra collectively, thirty-three pairs;—viz. pos- teriorly, the trapezius, latissimus dorsi, levator anguli scapulae, rhom- boideus minor and major, serratus posticus superior and inferior, sple- nius, sacro-lumbalis, longissimus dorsi, spinalis dorsi, cervicalis ascen- dens, transversalis colli, trachelo-mastoideus, complexus, semi-spinalis dorsi and colli, multifidus spinae, supraspinalis, interspinales, inter- transversales, levatores costarum;—anteriorly, the rectus anticus major, longus colli, scalenus anticus and posticus, psoas magnus, psoas parvus, quadratus lumborum, diaphragm, obliquus internus and trans- versalis. The Sacrum is a triangular bone, situated at the lower extremity of the vertebral column, and formed by the consolidation of five false vertebrae. It is divisible into an anterior and posterior surface, two lateral and a superior border, and an inferior extremity. The anterior surface is concave, and marked by four transverse lines, which indicate its original constitution of five separate pieces. At the extremities of these lines, on each side, are the four anterior sacral foramina, which diminish in size from above downwards, and transmit the anterior sacral nerves. The projection of the superior piece is the sacro-vertebral angle or promontory. The posterior surface is narrower than the anterior and convex. Upon the middle line is a rough caest formed by the rudiments of four spinous processes, the fifth remaining undeveloped and exposing the lower termination of the sacral canal. Immediately external to and parallel with the median crest, is a range of five small tubercles which represent the posterior transverse processes of the true vertebrae; beyond these is a shallow groove in which the four posterior sacral foramina open, and farther externally, a range of five tubercles corresponding with the anterior or costal transverse processes of the lumbar vertebrae. The lowest pair of the posterior transverse tubercles bound on each side the termination of the sacral canal, and send, each, a process downwards to articulate with the coccyx. The two descending pro- 60 SACRUM. cesses are the sacral cornua. The posterior sacral foramina are smaller than the anterior, and transmit the posterior sacral nerves. Of the anterior transverse tubercles the first corresponds with the angle of the superior border of the bone; the second is small, and enters into the formation of the sacro-iliac articulation; the third is Fi 23* large, and gives attachment to the oblique sacro-iliac ligament; the fourth and fifth are smaller, and serve for the attachment of the sacro-ischiatic ligaments. The la- teral border of the sacrum presents supe- riorly a broad and ear-shaped (auricular) surface to articulate with the ilium; and inferiorly a sharp-edge, to which the greater and lesser sacro-ischiatic ligaments are at- tached. On the superior border, in the middle line, is an oval articular surface, which corresponds with the under part of the body of the last lumbar vertebra; and on each side, a broad triangular surface wrhich supports the lumbo- sacral nerve and psoas magnus muscle. Immediately behind the vertebral articular surface is the triangular entrance of the sacral canal; and on each side of this opening an articular process, which looks backwards and inwards, like the superior articular processes of the lumbar vertebrae. In front of each articular process is an intervertebral notch. The inferior extremity of the bone presents a small oval surface which articulates with the coccyx; and on each side a notch, which, with a corresponding notch in the upper border of the coccyx, forms the foramen for the transmission of the fifth sacral nerve. The sacrum presents some variety in respect of curvature, and of the number of pieces which enter into its structure. The curve is often very slight, and is situated only near the lower part of the bone; while in other subjects it is considerable, and occurs at the middle of the sacrum. The sexual differences in the sacrum relate to its greater breadth, and the greater angle which it forms with the rest of the vertebral column in the female, rather than to any peculiarity in shape. It is sometimes composed of six pieces, more rarely of four, and occasionally the first and second pieces remain permanently separate. Developement.—By twenty-one points of ossification; five for each of the three first pieces,—viz.: one for the body, one for each lateral por- tion, and one for each lamina; and three for each of the two last, namely, one for the body, and one for each lateral portion. In the * The sacrum seen upon its anterior surface. 1, 1. The transverse lines marking the original constitution of the bone of four pieces. 2, 2. The anterior sacral foramina. 3. The promontory of the sacrum. 4. The ear-shaped surface which articulates with the ilium. 5. The sharp edge to which the sacro-ischiatic ligaments are attached. 6. The vertebral articular surface. 7. The broad triangular surface which supports the psoas muscle and lumbo-sacral nerve. 8. The articular process of the right side. 9. The in- ferior extremity, or apex of the sacrum. 10. One of the sacral cornua. 11. The notch which is converted into a foramen by the coccyx. COCCYX. 61 progress of growth, and after puberty, fourteen epiphysal centres are added, namely, two for the surfaces of each body, one for each au- ricular surface, and one for the thin edge of each lateral border. Ossification begins in the bodies of the sacral pieces somewhat later than in those of the true vertebrae; the first three appearing during the eighth and ninth week, and the last two at about the middle of intra-uterine existence. Ossification of the lamellae takes place during the interval between the sixth and the ninth month. The epiphyses for the upper and under surface of the bodies are developed during the interval between the fifteenth and eighteenth year; and for the auricular and marginal piece, after twenty. The two lower vertebral pieces, although the last to appear, are the first to be completed (between the fourth and fifth year), and to unite by their bodies. The union of the two bodies takes place from below upwards, and finishes between the twenty-fifth and the thirtieth year, with the first two pieces. Articulations.—With four bones; the last lumbar vertebra, ossa innominata, and coccyx. Attachment of Muscles.—To seven pairs; in front the pyriformis, on the side the coccygeus, and behind the gluteus maximus, latissimus dorsi, longissimus dorsi, sacro-lumbalis, and multifidus spinae. The Coccyx (xo'xxuf cuckoo, from resembling a cuckoo's beak) is composed of four small pieces, which form the caudal termination of the vertebral column. The superior piece is broad, and expands late- rally into two transverse processes ; it is surmounted by an oval arti- cular surface and two cornua, the former to articulate with the apex of the sacrum, and the latter with the sacral cornua. The lateral wings sometimes become connected with the sacrum, and convert the notches for the fifth pair of sacral nerves into foramina. The remain- ing three pieces diminish in size from above downwards. Developement.—By four centres, one for each piece. Ossification commences in the first piece soon after birth; in the second, between five and ten years; in the third, between ten and fifteen; and in the fourth, between fifteen and twenty. The pieces unite at an earlier period than the bodies of the sacrum, the two first pieces first, then the third and fourth, and lastly, the second and third. Between forty and sixty years, the coccyx becomes consolidated with the sacrum ; this event taking place later in the female than in the male. Articulations.—With the sacrum. Attachment of Muscles.—To three pairs and one single muscle; gluteus maximus, coccygeus, posterior fibres of the levator ani, and sphincter ani. OP THE SKULL. The skull, or superior expansion of the vertebral column, is divisible into two parts,—the cranium and the face; the former being adapted by its form, structure, and strength, to contain and protect the brain, and the latter the chief organs of sense. 6 62 coccvx. Fig. 24.* The Cranium is composed of eight separate bones; viz., the Occipital, Two temporal, Two parietal, Sphenoid, Frontal, Ethmoid. Occipital Bone.—This bone is situated at the posterior part and base of the cranium. It is trapezoid in figure, and divisible into two surfaces, four borders, and four angles. External Surface.—Crossing the middle of the bone transversely, from one lateral angle to the other, is a prominent ridge, the superior curved line. In the middle of the ridge is a projection, called the ex- ternal occipital protuberance; and descending from it a small vertical ridge, the spine. Above and below the superior curved line the surface is rough, for the attachment of muscles. About three-quarters of an inch below this line is another lifS ■ ^ transverse ridge, the inferior curved line, and, beneath the latter, the foramen magnum. On each side of the foramen magnum, nearer to its anterior than its posterior seg- ment, and encroaching somewhat upon the opening, is an oblong articular surface, the condyle, for articulation with the atlas. The condyles approach towards each other anteriorly, and their articular surfaces look downwards and outwards. Directly behind each condyle is an irregular fossa, and a small opening, the posterior condyloid foramen, for the transmission of a vein to the lateral sinus. In front of the condyle is the anterior condyloid foramen, for the hypoglossal nerve; and on the outer side of each condyle a projecting ridge, the transverse process, excavated in front by a notch which forms part of the jugular foramen. In front of the foramen magnum is a thick square mass, the basilar process, and in the centre of the basilar process a small tubercle for the attachment of the superior and middle constrictor muscles of the pharynx. Internal Surface.—Upon the internal surface is a crucial ridge, which divides the bone into four fossae; the two superior or cerebral fossae lodging the posterior lobes of the cerebrum; and the two in- ferior or cerebellar, the lateral lobes of the cerebellum. The superior arm of the crucial ridge is grooved for the superior longitudinal sinus, * The external surface of the occipital bone. 1. The superior curved line. 2. The external occipital protuberance. 3. The spine. 4. The inferior curved line. 5. The foramen magnum. 6. The condyle of the right side. 7. The posterior condyloid fossa, in which the posterior condyloid foramen is found. 8. The anterior condyloid foramen' concealed by the margin of the condyle. 9. The transverse process ; this process upon the internal surface of the bone forms the jugular eminence. 10. The notch in front of the jugular eminence which forms part of the jugular foramen. 11. The basilar process. 12, 12. The rough projections into which the odontoid ligaments are inserted. OCCIPITAL BONE. 63 and gives attachment to the falx cerebri; the inferior arm is sharp and prominent, for the attachment of the falx cerebelli, and slightly grooved, for the two occipital sinuses. The transverse ridge gives attachment to the tentorium cerebelli, and is deeply grooved, for the lateral sinuses. At the point of meeting of the four arms is a pro- jection, the internal occipital protuberance, which corresponds with the similar process situated upon the external surface of the bone. The convergence of the four grooves forms a slightly depressed fossa, upon which rests the torcular Herophili. In the centre of the basilar portion of the bone is the foramen magnum, oblong in form, and larger behind than before, transmitting the spinal cord, spinal accessory nerves, and vertebral arteries. Upon the lateral margins of the fora- men magnum are two rough eminences, which give attachment to the odontoid ligaments, and immediately above these the openings of the anterior condyloid foramina. In front of the foramen magnum is Fis-25* the basilar process, grooved on its surface, for supporting the medulla oblongata, and along each lateral border, for the inferior petrosal sinuses. On each side of the fora- men magnum is a groove, for the termination of the lateral sinus ; a smooth surface, which forms part of the jugular fossa; and a pro- jecting process which divides the two, and is called the jugular emi- nence. Into the jugular fossa will be seen opening the posterior con- dyloid foramen. The superior borders are very much serrated, and assist in form- ing the lambdoidal suture; the inferior are rough, but not serrated, and articulate with the mastoid portion of the temporal bone by means of the additamentum suturae lambdoidalis. The jugular emi- nence and the side of the basilar process articulate with the petrous portion of the temporal bone, and the intermediate space, which is irregularly notched, forms the posterior boundary of the jugular foramen, or foramen lacerum posterius. The angles of the occipital bone are the superior, inferior, and two lateral. The superior angle is received into the interval formed by the * The internal surface of the occipital bone. 1. The left cerebral fossa. 2. The left cerebellar fossa. 3. The groove for the posterior part of the superior longitudinal sinus. 4. The spine for the falx cerebelli, and groove for the occipital sinuses. 5. The groove for the left lateral sinus. 6. The internal occipital protuberance, the groove on which lodges the torcular Herophili. 7. The foramen magnum. 8. The basilar process, grooved for the medulla oblongata. 9. The termination of the groove for the lateral sinus, bounded externally by the jugular eminence. 10. The jugular fossa ; this fossa is completed by the petrous portion of the temporal bone. 11. The* superior border. 12. The inferior border. 13. The border which articulates with the petrous portion of the temporal bone, and which is grooved by the inferior petrosal sinus. 14. The anterior condyloid foramen. 64 PARIETAL BONE. union of the posterior and superior angles of the parietal bones, and corresponds with, that portion of the foetal head which is called the posterior fontanelle. The inferior angle is the articular extremity of the basilar process. The lateral angles at each side project into that interval formed by the articulation of the posterior and inferior angle of the parietal with the mastoid portion of the temporal bone. Developement.—By seven centres; four for the four parts of the ex- panded portion divided by the crucial ridge, one for each condyle, and one for the basilar process. Ossification commences in the ex- panded portion of the bone at a period anterior to the vertebrae; at birth the four pieces are distinct; they are united at about the fifth on sixth year. After twenty, the basilar process unites with the body of the sphenoid. two parietal, two temporal, sphe- Articulations.—With six bones noid, and atlas. Fig. 26/ To Attachment of Muscles, thirteen pairs; to the rough sur- face above the superior curved line, the occipito frontalis; to the superior curved line, the trapezius and sterno-mastoid; to the rough space between the curved lines, complexus, and splenius capitis; to the space between the inferior curved line and the foramen mag- num, the rectus posticus major and minor, and obliquus superior; to the transverse process, the rec- tus lateralis; and to the basilar process, the rectus anticus major and minor, and superior and middle constrictor muscles. Parietal Bone.—The parietal bone is situated at the side and ver- tex of the skull; it is quadrilateral in form, and divisible into an ex- ternal and internal surface, four borders and four angles. The su- perior border is straight, to articulate with its fellow of the opposite side. The inferior border is arched and thin, to articulate with the temporal bone. The anterior border is concave, and the posterior somewhat convex. External Surface.—Crossing the bone in a longitudinal direction from the anterior to the posterior border, is an arched line, the tem- poral ridge, to which the temporal fascia is attached. In the middle of this line, and nearly in the centre of the bone, is the projection called the parietal eminence, which marks the centre of ossification. Above the temporal ridge the surface is rough, and covered by the •Theexternal surface of the left parietal bone. 1. The superior or sagittal border 2. The inferior or squamous border. 3. The anterior or coronal border. 4. The posterior or lambdoidal border. 5. The temporal ridge ; the figure is situated immediately in front of the parietal eminence. 6. The parietal foramen, unusually large in the bone from which this figure was drawn. 7. The anterior inferior angle. 8. The posterior inferior angle. FRONTAL BONE. 65 aponeurosis of the occipito-frontalis; below the ridge the bone is smooth (planum semicircular e) for the attachment of the fleshy fibres of the temporal muscle. Near the superior border of the bone, and at about one-third from its posterior extremity, is the parietal foramen, which trans- mits a vein to the superior longi- tudinal sinus. This foramen is often absent. Internal Surface.—The inter- nal table is smooth; it is marked by numerous furrows which lodge the ramifications of the arteria meningea media, and by digital fossae which correspond with the convolutions of the brain. Along the upper border is part of a shallow groove, completed by the opposite parietal bone, which serves to contain the superior longitudinal sinus. Some slight pits are also observable near this groove, which lodge the glandulae Pac- chioni. The anterior inferior angle is thin and lengthened, and articulates with the greater wing of the sphenoid bone. Upon its inner surface it is deeply channelled by a groove for the trunk of the arteria meningea media. This groove is frequently converted into a canal. The posterior inferior angle is thick, and presents a broad and shallow groove for the lateral sinus. Developement.—By a single centre. Ossification commences at the parietal eminence at the same time with the bodies of the ver- tebrae. Articulations.—With five bones; with the opposite parietal bone, the occipital, frontal, temporal, and sphenoid. Attachment of Muscles.—To one only,—the temporal. The occi- pito-frontalis glides over its upper surface. Frontal Bone.—The frontal bone bears some resemblance in form to the under valve of a scallop shell. It is situated at the anterior part of the cranium, forming the forehead, and assists in the con- struction of the roof of the orbits and nose. Hence it is divisible into a superior or frontal portion, and an inferior or orbito-nasal portion. Each of these portions presents for examination an external and internal surface, borders, and processes. * The internal surface of the left parietal bone. 1. The superior, or sagittal border. 2. The inferior, or squamous border. 3. The anterior, or coronal border. 4. The poste- rior, or lambdoidal border. 5. Part of the groove for the superior longitudinal sinus. 6. The internal termination of the parietal foramen. 7. The anterior inferior angle of the bone, on which is seen the groove for the trunk of the arteria meningea media. 8. The posterior inferior angle, upon which is seen a portion of the groove for the lateral sinus. 6* 66 FRONTAL BONE. External Surface.—At about the middle of each lateral half of the frontal portion is a projection, the frontal eminence. Below these points are the superciliary ridges, large towards their inner termina- tion, and becoming gradually smaller as they arch outwards: they sOpport the eyebrows. Beneath the superciliary ridges are the sharp and prominent arches which form the upper margin of the orbits, the supra-orbital ridges. Externally the supra-orbital ridge terminates in the external angular process, and internally in the internal angular process; at the inner third of this ridge is a notch, sometimes con- verted into a foramen, the supra-orbital notch, which gives passage to the supra-orbital artery, veins, and nerve. Between the two super- ciliary ridges is a rough projection, the nasal tuberosity ; this portion of the bone denotes by its prominence the situation of the frontal sinuses. Extending upwards and backwards from the external angular process is a sharp ridge, the commencement of the temporal ridge, and beneath this a depressed surface that forms part of the temporal fossa. The orbito-nasal portion of the bone consists of two thin processes, the orbital plates, which form the roof of the orbits, and of an inter- vening notch which lodges the ethmoidal bone, and is called the eth- moidal fissure. The edges of the ethmoidal fissure are hollowed into cavities, which, by their union with the ethmoid bone, complete the ethmoidal cells; and, crossing these edges transversely, are two small grooves, sometimes canals, which open into the orbit by the anterior and posterior ethmoidal foramina. At the anterior termination of these edges are the irregular openings which lead into the frontal sinuses; and between the two internal angular processes is a rough excavation which receives the nasal bones, and a projecting process, the nasal spine. Upon each orbital plate, immediately beneath the external angular pro- cess, is a shallow depression which lodges the lachrymal gland; and beneath the internal angular process a small pit, sometimes a tubercle, to which the cartilaginous pulley of the superior oblique muscle is at- tached. * The external surface of the frontal bone. 1. The situation of the frontal eminence of the right side. 2. The superciliary ridge. 3. The supra-orbital ridge. 4. The ex. ternal angular process. 5. The internal angular process. 6. The supra-orbital notch for the transmission of the supra-orbital nerve and artery; in the figure it is almost con verted into a foramen by a small spiculum of bone. 7. The nasal tuberosity • the swell- ing around this point denotes the situation of the frontal sinuses. 8. The temporal ridge commencing from the external angular process (4). The depression in which the figure 8 is situated is a part of the temporal fossa. 9. The nasal spine. Fig. 28/ TEMPORAL BONE. 67 Internal Surface.—Along the middle line of this surface is a grooved ridge, the edges of the ridge giving attachment to the falx cerebri and the groove lodging the superior longitudinal sinus. At the commencement of the ridge is an opening, sometimes completed by the ethmoid bone, the foramen cacum. This opening lodges a pro- cess of the dura mater, and occasionally gives passage to a small vein which communicates with the nasal veins. On each side of the vertical ridge are some slight depressions which lodge the glandulae Pacchioni, and on the orbital plates a number of irregular pits called digital fossa, which correspond with the convolutions of the anterior lobes of the cerebrum. The superior border is thick and strongly serrated, bevelled at the expense of the internal table in the middle, where it rests upon the junction of the parietal, and at the expense Fis-29* of the external table, on each side, where it receives the lateral pres- sure of those bones. The inferior border is thin, irregular, and squa- mous, and articulates with the sphenoid bone. Developement.—By tico centres, one for each lateral half. Ossifi- cation begins in the orbital arches, somewhat before the vertebrae. The two pieces are separate at birth, and unite by suture dur- ing the first year, the suture sometimes remaining permanent through life. The frontal sinuses make their appearance during the first year, and increase in size until old age. Articulations.—With twelve bones; the two parietal, the sphenoid, ethmoid, two nasal, two superior maxillary, two lachrymal, and two malar. Attachment of muscles.—To two pairs; corrugator supercilii, and temporal. Temporal Bone.—The temporal bone is situated at the side and * The internal surface of the frontal bone ; the bone is raised in such a manner as to show the orbito-nasal portion. 1. The grooved ridge for the lodgment of the superior longitudinal sinus and attachment of the falx. 2. The foramen caecum. 3. The superior or coronal border of the bone; the figure is situated near that part which is bevelled at the expense of the internal table. 4. The inferior border of the bone. 5. The orbital plate of the left side. 6. The cellular border of the ethmoidal fissure. The foramen caecum (2) is seen through the ethmoidal fissure. 7. The anterior and posterior ethmoidal foramina; the anterior is seen leading into its canal. 8. The nasal spine. 9. The depression within the external angular process (12) for the lachrymal gland. 10. The depression for the pulley of the superior oblique muscle of the eye; immediately to the left of this number is the supra-orbital notch, and to its right the internal angular process. 11. The opening leading into the frontal sinuses. 12. The same parts are seen upon the opposite side of the figure. 68 TEMPORAL BONE. Fig. 30.* base of the skull, and is divisible into a squamous, mastoid, and pe- trous portion. The Squamous portion, forming the anterior part of the bone, is thin, translucent, and contains no diploe. Upon its external surface it is smooth, to give attachment to the fleshy fibres of the temporal mus- cle, and has projecting from it an arched and lengthened process, the zygoma. Near the commencement of the zygoma, upon its lower bor- der, is a projection called the tuber- cle, to which is attached the external lateral ligament of the lower jaw, and continued horizontally inwards from the tubercle a rounded eminence, the eminentia articularis. The process of bone which is continued from the tubercle of the zygoma into the eminentia articu- laris is the inferior root of the zygoma. The superior root is con- tinued upwards from the upper border of the zygoma, and forms the posterior part of the temporal ridge, serving by its projection to mark the division of the squamous from the mastoid portion of the bone; and the middle root is continued directly backwards, and terminates abruptly at a narrow fissure, the fissura Glaseri. The internal sur- face of the squamous portion is marked by several shallow fossae, which correspond with the convolutions of the cerebrum, and by a furrow for the posterior branch of the arteria meningea media. The superior, or squamous border, is very thin, and bevelled at the expense of the inner surface, so as to overlap the lower and arched border of the parietal bone. The inferior border is thick and dentated to arti- culate with the spinous process of the sphenoid bone. The Mastoid portion forms the posterior part of the bone; it is thick, and hollowed between its tables into a loose and cellular diploe. Upon its external surface it is rough for the attachment of muscles, and contrasts strongly with the smooth and polished-like surface of the squamous portion; every part of this surface is pierced by small fora- mina, which give passage to minute arteries and veins; one of these openings, oblique in its direction, of large size, and situated near the posterior border of the bone, the mastoid foramen, transmits a vein to the lateral sinus. This foramen is not unfrequently situated in the occipital bone. The inferior part of this portion is round and ex- * The external surface of the temporal bone of the left side. 1. The squamous por- tion. 2. The mastoid portion. 3. The extremity of the petrous portion. 4. The zygo- ma. 5. Indicates the tubercle of the zygoma, and at the same time its anterior root turn- ing inwards to form the eminentia articularis. 6. The superior root of the zygoma form- ing the posterior part of the temporal ridge. 7. The middle root of the zygoma ter- minatmg abruptly at the glenoid fissure. 8. The mastoid foramen. 9 The meatus auditorius externus, surrounded by the processus auditorius. 10. The digastric fossa situated immediately to the inner side of (2) the mastoid process. 11. The styloid process' 12. The vaginal process. 13. The glenoid or Glaserian fissure; the leading line from this number crosses the rough posterior portion of the glenoid fossa. 14. The opening and part of the groove for the Eustachian tube. TEMPORAL BONE. 69 panded, the mastoid process, and excavated in its interior into nu- merous cells, which form a part of the organ of hearing. In front of the mastoid process, and between the superior and middle roots of the zygoma, is the large oval opening of the meatus auditorius externus, surrounded by a rough lip, the processus auditorius. Directly to the inner side, and partly concealed by the mastoid process, is a deep groove, the digastric fossa; and a little more internally the occipital groove, which lodges the occipital artery. Upon its internal surface the mastoid portion presents a broad and shallow groove (fossa sigmoidea) for the lateral sinus, and terminating in this groove the internal opening of the mastoid foramen. The superior border of the mastoid portion is dentated; and its posterior border thick and less serrated, for articulation with the inferior border of the occi- pital bone. The meatus auditorius externus is a slightly curved canal, somewhat more than half an inch in length, longer along its lower than its upper wall, and directed obliquely inwards and forwards. The canal is narrower at the middle than at each extremity, is broadest in its horizontal diameter, and terminates upon the outer wall of the tympa- num by an abrupt oval border. Within the margin of this border is a groove for the insertion of the membrana tympani. The Petrous portion of the temporal bone is named from its extreme hardness and density. It is a three-sided pyramid, projecting hori- zontally forwards into the base of the skull, the base being applied against the internal surface of the squamous and mastoid portions, and the apex being received into the triangular interval between the spi- nous process of the sphenoid and the basilar process of the occipital bone. For convenience of description it is divisible into three sur- faces—anterior, posterior, and basilar; and three borders—superior, anterior, and posterior. Surfaces.—The anterior surface, forming the posterior boundary of the middle fossa of the interior of the base of the skull, presents for examination, from base to apex, first an eminence caused by the pro- jection of the perpendicular semicircular canal; next, a groove leading to an irregular oblique opening, the hiatus Fallopii, for the transmis- sion of the petrosal branch of the Vidian nerve; thirdly, another and smaller oblique foramen, immediately beneath the preceding, for the pas- sage of the nervus petrosus superfici- alis minor, a branch of Jacobson's nerve; and lastly, a large foramen near the apex of the bone, the termi- nation of the carotid canal. The posterior surface forms the front boundary of the posterior fossa of the base of the skull; near its mid- dle is the oblique entrance of the me- Fig. 31.* * The left temporal bone, seen from within. 1. The squamous portion. 2. The mas- 70 TEMPORAL BONE. atus auditorius internus. Above the meatus auditorius internus is a small oblique fissure, and a minute foramen; the former lodges a process of the dura mater, and the foramen gives passage to a small vein. Further outwards, towards the mastoid portion of the bone, is a small slit, almost hidden by a thin plate of bone; this is the aquaductus vestibuli, and transmits a small artery and vein of the vestibule and a process of dura mater. Below the meatus, and partly concealed by the margin of the posterior border of the bone, is the aquaductus cochlea, through which passes a vein from the cochlea to the internal jugular vein, and a process of dura mater. The meatus auditorius internus is about one-third of an inch in depth, and pursues a slightly oblique course in relation to the petrous portion of the temporal bone, but a course directly outwards in rela- tion to the cranium. At the bottom of the meatus, and upon its ante- rior aspect, is a reniform fossa, the concave border of which is directed towards the entrance of the meatus. The reniform fossa is divided into an upper and lower compartment by a sharp ridge, which is prolonged for some distance upon the anterior wall of the meatus, and sometimes as far as its aperture. In either case, it marks the situation of the two nerves, facial and auditory, which constitute the seventh pair, and enter the meatus. Along the convexity of the reniform fossa, and arranged in a curved line from above down- wards, are four or five openings, the two upper ones being the largest, and occupying the superior compartment of the reniform fossa, and the two or three inferior ones, smaller than the upper, the inferior compartment. Behind the latter, at the distance of a line and a half, and on the posterior wall of the meatus, is a cluster of three or four oblique openings, two of which are minute. The inferior and larger compartment of the reniform fossa presents a well-marked spiral groove, which commences on the convex border of the fossa, immediately below the line of openings above described; and, sweep- ing round the convexity of the inferior compartments, and be- coming deeper as it proceeds, terminates by a small round aperture, in the centre of the spire. The uppermost of the openings of the reniform fossa is the aperture of the aquaeductus Fallopii, and gives passage to the facial nerve. The rest are cul de sacs, pierced at the toid portion. The number is placed immediately above the inner opening of the mastoid foramen. 3. The petrous portion. 4. The groove for the posterior branch of the arteria meningea media. 5. The bevelled edge of the squamous border of the bone. 6. The zygoma. 7. The digastric fossa immediately internal to the mastoid process. 8. The occipital groove. 9. The groove for the lateral sinus. 10. The elevation upon the ante- rior surface of the petrous bone marking the situation of the perpendicular semicircular canal. 11. The opening of termination of the carotid canal. 12. The meatus audito- rius internus. 13. A dotted line leads upwards from this number to the narrow fissure which lodges a process of the dura mater. Another line leads downwards to the sharp edge which conceals the opening of the aquaeductus cochlea?, while the number itself is situated on the bony lamina which overlies the opening of the aquseductus vestibuli. 14, The styloid process. 15. The stylo-mastoid foramen. 16. The carotid foramen. 17. The jugular process. The deep excavation to the left of this process forms part of the jugular fossa, and that to the right is the groove for the eighth pair of nerves. 18. The notch for the fifth nerve upon the upper border of the petrous bone, near to its apex. 19. The extremity of the petrous bone which gives origin to the levator palati find tensor tympani muscles. TEMPORAL BONE. 71 bottom by a number of minute foramina, for the passage of filaments of the vestibular nerve, while the cluster of three openings on the pos- terior wall of the meatus are intended for single filaments of the same nerve. The spiral groove corresponds with the base of the cochlea, and being pierced by a number of minute foramina, for filaments of the cochlear nerve, is named tractus spiralis foraminulentus. The opening in the centre of the spiral impression leads into a canal which occupies the central axis of the modiolus, and is thence called tubulus centralis modioli. The basilar surface is rough and irregular, and enters into the formation of the under surface of the base of the skull. Projecting downwards, near its middle, is a long sharp spine, the styloid process, occasionally connected with the bone only by cartilage and lost during Fis- 32-* maceration, particularly in the young sub- ject. At the base of this process is a rough sheath-like ridge, into which the sty- loid process appears implanted, the vaginal process. In front of the vaginal process is a broad triangular depression, the glenoid fossa, bounded in front by the eminentia articularis, behind by the vaginal process, and externally by the rough lip of the pro- cessus auditorius. This fossa is divided transversely by the glenoid fissure (Fissura Glaseri) which lodges the extremity of the processus gracilis of the malleus, and transmits the laxator tympani muscle, chorda tympani nerve, and anterior tympanic artery. The surface of the fossa in front of this fissure is smooth, to articulate with the condyle of the lower jaw ; and that behind the fissure is rough, for the reception of a part of the parotid gland. At the extremity of the inner angle of the glenoid fossa is the foramen of the Eustachian tube; and se- parated from it by a thin lamella of bone, called processus cochleari- formis, a small canal for the transmission of the tensor tympani mus- cle. Directly behind, and at the root of the styloid process, is the stylo-mastoid foramen, the opening of exit to the facial nerve, and of entrance to the stylo-mastoid artery. Nearer, to the apex of the bone is a large oval opening, the carotid foramen, the commencement of the carotid canal, which lodges the internal carotid artery and the carotid plexus. And between the stylo-mastoid and carotid foramen, * A. The reniform fossa of the meatus auditorius internus; right temporal bone. 1. The ridge dividing the reniform fossa into two compartments. 2. The opening of the aqueeductus Fallopii. The openings following that of the aquaeductus Fallopii in a curved direction require no reference. 3. The cluster of three or four oblique openings on the posterior wall of the meatus. 4. The spirally-grooved base of the cochlea. B. A section of the temporal bone, right side, showing the curved direction of the meatus auditorius externus. 1. The edge of the processus auditorius. 2. The groove into which the membrana tympani is inserted. The obliquity of the line from 2 to 3 in- dicates the oblique termination of the meatus, and the consequent oblique direction of the membrana tympani. 4, 4. The cavity of the tympanum. 5. The opening of the Eusta- chian tube. 6. Part of the aqueeductus Fallopii. 7. Part of the carotid canal. C. The annulus membrana? tympani or tympanic bone of the foetal skull; right side. #* 72 TEMPORAL BONE. in the posterior border, is an irregular excavation forming part of the jugular fossa for the commencement of the internal jugular vein. The proportion of the jugular fossa formed by the petrous portion of the temporal bone is very different in different bones; but in all, the fossa presents a vertical ridge to its inner side, which cuts off a small por- tion of the rest. The upper part of this ridge forms a spinous projec- tion, which is called the jugular process, the groove to the inner side of the ridge lodges the eighth pair of nerves, and the lower part of the ridge is the septum of division between the jugular fossa and the ca- rotid foramen. Upon this portion of the ridge, near, the posterior margin of the carotid foramen, is a small opening leading into a canal, which transmits the tympanic branch of the glossopharyngeal nerve (Jacobson's nerve). Between the jugular fossa and the stylo-mastoid foramen is another small opening leading into the canal for the pas- sage of the tympanic branch of the pneumogastric nerve. Borders.—The superior border is sharp, and gives attachment to the tentorium cerebelli. It is grooved for the superior petrosal sinus, and near its extremity is marked by a smooth notch upon which reclines the fifth nerve. The anterior border is grooved for the Eustachian tube, and forms the posterior boundary of the foramen lacerum basis cranii; by its sharp extremity it gives attachment to the tensor tympani and levator palati muscles. The posterior border is grooved for the inferior pe- trosal sinus, and excavated for the jugular fossa; it forms the ante- rior boundary of the foramen lacerum posterius. Developement.—By five centres; one for the squamous portion, one for the mastoid process, one for the petrous portion, one for the au- ditory process, which in the foetus is a mere bony ring, incomplete superiorily, and serving for the attachment of the membrana tympani, annulus membrana tympani; and one for the styloid process. Ossi- fication occurs in these pieces in the following order: in the squamous portion immediately after the vertebrae, then in the petrous, tympanic, mastoid, and styloid. The tympanic ring is united by its extremities to the squamous portion during the last month of intrauterine life; the squamous, petrous, and mastoid portions are consolidated during the first year; and the styloid some years after birth. It not unfre^ quently happens that the latter remains permanently separate, or is prolonged by a series of pieces to the os hyoides, and so completes the hyoid arch. The subsequent changes in the bone are the increase of size of the glenoid fossa, the growth of the meatus auditorius ex- ternus, the levelling of the surfaces of the petrous portion, and the developement of mastoid cells. Traces of the union of the petrous with the squamous portion of the bone are usuallv perceptible in the adult. * r r Articulations.—-With five bones; occipital, parietal, sphenoid, in- ferior maxillary, and malar. Attachment of muscles.~To fourteen; by the squamous portion, to the temporal; by the zygoma, to the masseter; by the mastoid por- tion, to the occipito-frontalis, splenius capitis, sterno-mastoid, trachelo- mastoid, digastricus and retrahens aurem; by the styloid process, to • SPHENOID BONE. 73 the stylo-pharyngeus, stylo-hyoideus, stylo-glossus, and two ligaments, the stylo-hyoid and stylo-maxillary; and by the petrous portion to the levator palati, tensor tympani, and stapedius. Sphenoid Bone.—The sphenoid (tf

iv, a wedge) is an irregular bone situated at the base of the skull, wedged between the other bones of the cranium, and entering into the formation both of the cranium and face. It bears some resemblance in form to a bat with its wings ex- tended, and is divisible into body, wings, and processes. The body forms the central mass of the bone, from which the wings and processes are projected. From the upper and anterior part of the body extend on each side two small triangular plates,—the lesser wings; from either side and expanding laterally are the greater wings; proceeding backwards from the base of the greater wings, the spinous processes, and downwards, the pterygoid processes. The body presents for examination a superior or cerebral surface, an anteroinferior surface, and a posterior surface. Superior Surface.—At the anterior extremity of this surface is a small projecting plate, the ethmoidal spine, and spreading out on either side the lesser wings. Behind the ethmoidal spine in the middle line is a rounded elevation, the olivary process, which supports the com- missure of the optic nerves, and on either side of the posterior margin of this process is a tubercle, the middle clinoid process. Passing out- wards and forwards from the olivary process, are the optic foramina, which transmit the optic nerves and ophthalmic arteries. Behind the optic foramina are two sharp tubercles, the anterior clinoid pro- cesses, which are the inner terminations of the lesser wings. Beneath these processes, on the sides of the olivary process, are two depres- sions* for the last turn of the internal carotid arteries. Behind the olivary process is the sella turcica (ephippium), the deep fossa which lodges the pituitary gland and circular sinus; behind and somewhat overhanging the sella turcica, is a broad rough plate (dorsum ephip- pii), bounded at each angle by a tubercle, the posterior clinoid pro- cesses ; and behind this plate an inclining surface (clivus Blumenba- chii), which is continuous with the basilar process of the occipital bone. On either side of the sella turcica is a broad groove (carotid), which lodges the internal Fig. 33.t carotid artery, the cavernous sinus, and the orbital nerves. Immediately external to this groove, at the junction of*? the greater wings with the body, are four foramina: the first is a broad interval, the sphenoidal fissure, which separates the greater and lesser wings, and transmits * These depressions are occasionally, as in a skull before me, converted into foramina by the extension of a short bony pillar from the middle to the anterior clinoid process. t The superior or cerebral surface of the sphenoid bone. 1. The processus olivaris. 2. The ethmoidal spine. 3. The lesser wing of the left side. 4. The cerebral surface of 7 • 74 SPHENOID BONE. the third, fourth, the three branches of the ophthalmic division of the fifth and the sixth nerves, and the ophthalmic vein. Behind and beneath this fissure is the foramen rotundurn for the superior maxil- lary nerve; and still farther back, in the base of the spinous process, the foramen ovale for the inferior maxillary nerve, arteria meningea parva, and nervus petrosus superficialis minor. Behind the foramen ovale, near the apex of the spinous process, is the foramen spinosum for the arteria meningea media. Upon the antero-inferior surface of the sphenoid is a long flattened spine or crest, the superior part of which, crista sphenoidalis, articu- lates with the central lamella of the ethmoid, while the inferior part, longer and sharper, the rostrum sphenoidale, is intended to be inserted into the sheath formed by the upper border of the vomer. On either side of the crista sphenoidalis is an irregular opening leading into the sphenoidal cells. The sphenoidal cells, which are absent in the young subject, are divided by a median septum which is continuous with the crista, and are partially closed by two thin plates of bone (frequently broken away), the sphenoidal Fig. 34* spongy bones. On each side of the sphenoidal cells are the out- lets of the optic foramina, sphe- noidal fissures, and foramina ro- tunda, the lesser and greater wings; and below, the pterygoid processes. Upon the under sur- face of the body are two thin plates of bone (processus vagi- nales) proceeding from the base of the pterygoid process at each the greater wing of the same side. 5. The spinous process. 6. The extremity of the pterygoid process of the same side, projecting downwards from the under surface of the body of the bone. 7. The foramen opticum. 8. The anterior clinoid process. 9. The groove by the side of the sella turcica; for lodging the internal carotid artery, cavernous plexus, cavernous sinus, and orbital nerves. 10. The sella turcica; the two tubercles in front of the figure are the middle clinoid processes. 11. The posterior boundary of the sella turcica; its projecting angles are the posterior clinoid processes. 12. The basilar portion of the bone. 13. Part of the sphenoidal fissure. 14. The foramen rotundum. 15. The foramen ovale. 16. The foramen spinosum. 17. The angular interval which receives the apex of the petrous portion of the temporal bone. The posterior extremity of the Vidian canal terminates at this angle. 18. The spine of the spinous process; it affords attachment to the internal lateral ligament of the lower jaw. 19. The border of the greater wing and spinous process, which articulates with the anterior part of the squamous portion of the temporal bone. 20. The internal border of the spinous process, which assists in the formation of the foramen lacerum basis cranii. 21. That portion of the greater ala which articulates with the anterior inferior angle of the parietal bone. 22. The portion of the greater ala which articulates with the orbital process of the frontal bone. * The antero-inferior view of the sphenoid bone. 1. The ethmoid spine. 2. The ros- trum. 3. The sphenoidal spongy bone, partly closing the left opening of the sphenoidal cells. 4. The lesser wing. 5. The foramen opticum piercing the base of the lesser wing. 6. The sphenoidal fissure. 7. The foramen rotundum. 8. The orbital surface of the greater wing. 9. Its temporal surface. 10. The pterygoid ridge. 11. The pterygo- palatine canal. 12. The foramen of entrance to the Vidian canal. 13. The internal pterygoid plate. 14. The hamular process. 15. The external pterygoid plate. 16. The foramen spinosum. 17. The foramen ovale. 18. The extremity of the spinous process of the sphenoid. V SPHENOID BONE. 75 side and intended for articulation with the borders of the vomer. On each of these plates, close to the root of the pterygoid process, is a groove (sometimes a complete canal) converted into a canal by the palate bone, the pterygo-palatine canal for the pterygo-palatine ar- tery ; and traversing the roots of the pterygoid processes at their union with the body of the bone are the two pterygoid or Vidian canals which give passage to the Vidian nerve and artery at each side. The posterior surface is flat and rough, and articulates with the basilar process of the occipital bone. In the adult this union is usu- ally completed by bone; from which circumstance the sphenoid, in conjunction with the occipital, is described by Soemmering and Meckel, as a single bone, under the name of sphenooccipital. The posterior surface is continuous on each side with the spinous process, and at the angle of union is the termination of the Vidian canal. The lesser wings (processes of Ingrassias) are thin and triangular, the base being attached to the upper and anterior part of the body of the sphenoid, and the apex extended outwards, and terminating in an acute point. The anterior border is irregularly serrated, the pos- terior being free and rounded and received into the fissure of Sylvius of the cerebrum. The inner extremity of this border is the anterior clinoid process, which is supported by a short pillar of bone, giving attachment to a part of the common tendon of the muscles of the orbit. The lesser wing forms the posterior part of the roof of the orbit, and its base is traversed by the optic foramen. The greater wings present three surfaces; a superior or cerebral, which forms part of the middle fossa of the base of the skull, an an- terior surface which assists in forming the outer wall of the orbit, and an external surface divided into two parts by the pterygoid ridge. The superior part of the external surface enters into the formation of the temporal fossa, and the inferior portion forms part of the zygo- matic fossa. The pterygoid ridge, dividing the two, gives attach- ment to the upper origin of the pterygoideus externus muscle. The spinous processes project backwards at each side from the base of the greater wings of the sphenoid, and are received into the angular intervals between the squamous and petrous portions of the temporal bones. Piercing the base of each process is a large oval opening, the foramen ovale; nearer its apex a smaller opening, the foramen spinosum; and extending downwards from the apex a short spine, which gives attachment to the internal lateral liga- ment of the lower jaw and to the laxator tympani muscle. The ex- ternal border of the spinous process is rough, 1o articulate with the lower border of the squamous portion of the temporal bone; the in- ternal forms the anterior boundary of the foramen lacerum basis cra- nii, and is somewhat grooved for the reception of the Eustachian tube. The pterygoid processes descend perpendicularly from the base of the greater wings, and form in the articulated skull the lateral boun- daries of the posterior nares. Each process consists of an external and internal plate, and an anterior surface. The external plate is > 76 ETHMOID BONE. broad and thin, giving attachment, by its external surface, to the ex- ternal pterygoid muscle, and by its internal surface to the internal pterygoid. This plate is sometimes pierced by a foramen, which is not unfrequently formed by a process of communication passing be- tween it and the spinous process. The internal pterygoid plate is long and narrow, and terminated at its extremity by a curved hook, the hamular process, around which plays the tendon of the tensor pa- lati muscle. At the base of the internal pterygoid plate is a small oblong depression, the scaphoid fossa, from which arises the circum- flexus or tensor palati muscle. The interval between the two ptery- goid plates is the pterygoid fossa ; and the two plates are separated inferiorly by an angular notch (palatine) which receives the tube- rosity, or pterygoid process, of the palate bone. The anterior surface of the pterygoid process is broad near its base, and supports Meckel's ganglion. The base of the process is pierced by the Vidian canal. Developement.—By twelve centres; four for the body, viz. two for its anterior (spheno-orbital), and two for its posterior part (spbeno- temporal); four for the four wings; two for the internal pterygoid plates, and two for the sphenoidal spongy bones. Ossification com- mences in the various pieces of the sphenoid in the following order: greater alae, at about the same time with the other bones of the cranium ; lesser alae, posterior body, at the end of the second month; anterior body at the end of the third ; internal pterygoid plate, spongy bones, between the period of birth and the second year. Osseous union occurs first between the centres of the posterior body, and at about the same time between each centre of the anterior body and its corresponding (lesser) alae; the third union takes place between the internal pterygoid plate and the greater alae; the fourth between the two centres of the anterior body, and at the same time between the anterior and posterior body. This is the state of union at birth, the bone consisting of five centres, one being the body and lesser alae ; one on each side, the great ala and internal pterygoid plate ; and the remaining two the sphenoidal spongy bones. The greater alae unite with the body during the first year; the spongy bones after pu- berty ; and the body of the sphenoid with the basilar process of the occipital between eighteen and twenty-five. Articulations.—With twelve bones; all the bones of the head and five of the face, viz. the two malar, two palate, and the vomer. Attachment of Muscles.—To twelve pairs ; temporal, external, ptery- goid, internal pterygoid, superior constrictor, tensor palati, laxator tympani, levator palpebrae, obliquus superior, superior rectus, in- ternal rectus, inferior rectus, and external rectus. Ethmoid Bone.—The ethmoid (typk, a sieve) is a square-shaped cellular bone, situated between the two orbits, at the root of the nose, and perforated upon its upper surface by a number of small openings, from which peculiarity it has received its name. It consists of a perpendicular lamella and two lateral masses. The perpendicular lamella is a thin central plate, which articulates with the vomer and cartilage of the septum, and assists in forming ETHMOID BONE. 77 the septum of the nose. It is surmounted superiorly by a thick and strong process, the crista gal/i, which projects into the cavity of the skull, and gives attachment to the falx cerebri. From the base of the anterior border of this process there project forwards two small plates, alar processes, which are received into corresponding depres- sions in the frontal bone, and often complete, posteriorly, the foramen ccecum. On each side of the crista galli, upon the upper surface of the bone, is a thin and grooved plate perforated by a number of small openings, the cribriform lamella, which supports the bulb of the olfac- tory nerve, and gives passage to its filaments, and to the nasal branch of the ophthalmic nerve. In the groove of this lamella the foramina pierce the bone Fig. 35.* completely, but at either side they are the apertures of canals, which run for some dis- tance in the substance of the central lamella, inner wall of the lateral mass and spongy bones. The opening for the nasal nerve is a narrow slit in the anterior part of the cribri- form lamella, close to the crista galli. The cribriform lamella serves to connect the late- ral masses with the perpendicular plate. The lateral masses (labyrinthi) are divisible into an internal and external surface, and four borders, superior, inferior, anterior, and posterior. The internal sur- face is rough and slightly convex, and forms the external boundary of the upper part of the nasal fossae. Towards the posterior border of this surface is a narrow horizontal fissure, the superior meatus of the nose, the upper margin of which is thin, and somewhat curled in- wards ; hence it is named the superior turbinated bone (concha supe- rior). Below the meatus is the convex surface of another thin plate, which is curled outwards, and forms the lower border of the mass, the middle turbinated bone (concha media). The external surf ace is quadrilateral and smooth, hence it is named os planum, and, from its thinness, lamina papyracea; it enters into the formation of the inner wall of the orbit. The superior border is irregular and cellular, the cells being com- pleted by the edges of the ethmoidal fissure of the frontal bone. This border is crossed by two grooves, sometimes complete canals, open- ing into the orbit by the anterior and posterior ethmoidal foramina. The inferior border is formed internally by the lower border of the middle turbinated bone, and externally by a concave irregular fossa, * The ethmoid bone seen from above and behind. 1. The central lamella. 2, 2. The lateral masses; the numbers are placed on the posterior border of the lateral mass at each side. 3. The crista galli process. 4. The cribriform plate of the left side, pierced by the cribriform foramina. 5. The hollow space immediately above and to the left of this number is the superior meatus. 6. The superior turbinated bone. 7. The middle turbinated bone; the numbers 5, 6, 7, are situated upon the internal surface of the left lateral mass, near its posterior part. The interval between these parts is the superior meatus. 8. The external surface of the lateral mass, or os planum. 9. The superior or frontal border of the lateral mass, grooved by the anterior and posterior ethmoidal canals. 10. Refers to the concavity of the middle turbinated bone, which is the upper boundary of the middle meatus. 7* 78 NASAL BONES. the upper boundary of the middle meatus. The anterior border pre- sents a number of incomplete cells, which are closed by the superior maxillary and lachrymal bone; and the posterior border is irregularly cellular, to articulate with the sphenoid and palate bones.* The lateral masses are composed of cells, which are divided by a thin partition into anterior and posterior ethmoidal cells. The ante- rior, the most numerous, communicate with the frontal sinuses, and open by means of an irregular and incomplete tubular canal, the infundibulum, into the middle meatus. The posterior cells, fewer in number, open into the superior meatus. Developement.—By three centres; one for each lateral mass, and one for the perpendicular lamella. Ossification commences in the lateral masses at about the beginning of the fifth month, appearing first in the os planum and then in the spongy bones. During the latter half of the first year after birth, the central lamella and lamina cribrosa begin to ossify, and are united to the lateral masses by the beginning of the second. The cells of the ethmoid are developed in the course of the fourth and fifth year. Articulations.—With thirteen bones; two of the cranium,—the frontal and sphenoid; the rest of the face, viz. the nasal, superior maxillary, lachrymal, palate, the inferior turbinated, and the vomer. No muscles are attached to this bone. BONES OF THE FACE. The face is composed of fourteen bones; viz. the Two nasal, Two palate, Two superior maxillary, Two inferior turbinated, Two lachrymal, Vomer, Two malar, Inferior maxillary. Nasal Bones.—The nasal (fig. 41) are two small quadrangular bones, forming by their union the bridge and base of the nose. Upon the upper surface they are convex, and pierced by a foramen for a small artery; on the under surface they are somewhat concave, and marked by a groove, which lodges the nasal branch of the ophthalmic nerve. The superior border is narrow and thick, the inferior broad, thin, and irregular. Developement—By a single centre for each bone, the first ossific deposition making its appearance at the same time as in the vertebrae. Articulations.—With four bones; frontal, ethmoidal, nasal, and superior maxillary. Attachment of Muscles.—It has in relation with it the pyramidalis nasi, and compressor nasi; but neither of these muscles is inserted into it. * Mr. Wilson has entirely omitted the description of the pyramids of Wistar which in their early stage project as thin triangular lamina? from the posterior borders' of the lateral masses. As they become developed, the edges of the lamina? fold over so as to form an imperfect triangular pyramid, encroaching upon the body of the sphenoid bone on its under surface, and finally coalescing with it so as to perfect the sphenoidal cells The remains of these pyramids may be seen on the adult bone, and are called bv Wilson the sphenoidal spongy bones. They were first studied by Professor Wistar and are called after him.—G. ' SUPERIOR MAXILLARY BONES. 79 Fig. 36.' Superior Maxillary Bones.—The superior maxillary are the largest bones ol the face, with the exception of the lower jaw ; they form, by their union, the whole of the upper jaw, and assist in the construction of the nose, the orbit, the cheek, and the palate. Each bone is divi- sible into a body and four processes. The body is triangular in form, and hollowed in its interior into a large cavity, the antrum maxillare (the antrum of Highmore). It pre- sents for examination four surfaces, external or facial, internal or nasal, posterior or zygo- matic, and superior or orbital. The external, or facial surface, forms the anterior part of the bone; it is irregularly concave, and presents a deep depression to- wards its centre, the canine fossa, which gives attachment to two muscles, the compressor nasi and levator anguli oris. Immediately above this fossa is the infra-orbital foramen, the termination of the infra-orbital canal, trans- mitting the superior maxillary nerve, and infra-orbital artery; and above the infra-orbital foramen, the lower margin of the orbit, con- tinuous externally with the rough articular surface of the malar process, and internally with a thick ascending plate, the nasal process. Towards the middle line of the face this surface is bounded by the concave border of the opening of the nose, which is projected for- wards at its inferior termination into a sharp process, forming, with a similar process of the opposite bone, the nasal spine. Beneath the nasal spine, and above the two superior incisor teeth, is a slight depression, the incisive, or myrtiform fossa, which gives origin to the depressor labii superioris alaeque nasi muscle. The myrtiform fossa is divided from the canine fossa by a perpendicular ridge, corre- sponding with the direction of the root of the canine tooth. The inferior boundary of the facial surface is the alveolar process which contains the teeth of the upper jaw; and it is separated from the zygomatic surface by a strong projecting eminence, the malar process. The internal, or nasal surface, presents a large irregular opening, leading into the antrum maxillare; this opening is nearly closed in the articulated skull by the ethmoid, palate, lachrymal, and inferior turbinated bones. The cavity of the antrum is somewhat triangular, * The superior maxillary bone of the right side, as seen from the lateral aspect 1. The external, or facial surface; the depression in which the figure is placed is the canine fossa. 2. The posterior, or zygomatic surface. 3. The superior, or orbital surface. 4. The infra-orbital foramen; it is situated immediately below the number. 5. The infra. orbital canal, leading to the infraorbital foramen. 6. The inferior border of the orbit. 7. The malar process. 8. The nasal process. 9. The concavity forming the lateral boundary of the anterior nares. 10. The nasal spine. 11. The incisive, or myrtiform fossa. 12. The alveolar process. 13. The internal border of the orbital surface, which articulates with the ethmoid and palate bone. 14. The concavity which articulates with the lachrymal bone, and forms the commencement of the nasal duct. 15. The crista nasalis of the palate process, i. The two incisor teeth, c. The canine. 6. The two bicuspidati. m. The three molares. 80 SUPERIOR MAXILLARY BONES. corresponding in shape with the form of the body of the bone. Upon its inner wall are numerous grooves, lodging branches of the superior maxillary nerve, and projecting into its floor several conical processes, corresponding with the roots of the first and second molar teeth. In front of the opening of the antrum is the strong ascending plate of the nasal process, marked inferiorly by a rough horizontal ridge (crista turbinalis inferior), which gives attachment to the inferior turbinated bone. The concave depression immediately above this ridge corresponds with the middle meatus of the nose, and that below the ridge with the inferior meatus. Between the nasal process and the opening of the antrum, is a deep groove (sulcus lachrymalis) which is converted into a canal by the lachrymal and inferior turbi- nated bone, and constitutes the nasal duct. The superior border of the nasal surface is irregularly cellular, and articulates with the lachrymal and ethmoid bone; the posterior border is rough, and articulates with the palate bone; the anterior border is sharp, and forms the free margin of the opening of the nose; and from the inferior border projects inwards a strong horizontal plate, the palate process. The posterior surface may be called zygomatic, from forming part of the zygomatic fossa ; it is bounded externally by the malar pro- cess, and internally by a rough and rounded border, the tuberosity, which is pierced by a number of small foramina (foramina alveo- laria posteriora), giving passage to the posterior dental nerves and branches of the superior dental artery. The lower part of this tube- rosity presents a rough oval surface, to articulate with the palate bone, and immediately above and to the inner side of this articular surface a smooth groove, which forms part of the posterior palatine canal. The superior border is smooth and rounded to form the lower boundary of the spheno-maxillary fissure, and is marked by a notch, the commencement of the infra-orbital canal. The inferior boundary is the alveolar process, containing the two last molar teeth. The orbital surface is triangular and thin, and constitutes the floor of the orbit. It is bounded internally by an irregular edge, which articulates with the palate, ethmoid, and lachrymal bone; posteri- orly, by the smooth border which enters- into the formation of the spheno-maxillary fissure; and, anteriorly, by a convex margin, partly smooth and partly rough, the smooth portion forming part of the lower margin of the orbit, and the rough articulating with the malar bone. The middle of this surface is channelled by a deep o-roove and canal, the infra-orbital, which terminates at the infra-orbital foramen; and near to the root of the nasal process is a slight depres- sion, marking the origin of the inferior oblique muscle of the eyeball. The four processes of the superior maxillary bone are the "nasal malar, alveolar, and palate. The nasal process ascends by the side of the nose, to which it forms the lateral boundary, and articulates with the frontal and nasal bone. By its external surface it gives attachment to the levator labii superioris alaeque nasi, and to the orbicularis palpebrarum SUPERIOR MAXILLARY BONES. 81 muscle. Its internal surface contributes to form the inner wall of the nares, and is marked transversely by a horizontal ridge (crista turbinalis superior) which divides it into two portions, one above the ridge irregular and uneven, for giving attachment to and completing the cells of the lateral mass of the ethmoid; the other below, smooth and concave, corresponding with the middle meatus. The posterior border is thick and hollowed into a groove for the nasal duct. The margin of the nasal process, which is continuous with the lower border of the orbit, is sharp and marked by a small tubercle which serves as a guide to the introduction of the knife in the operation for fistula lachrymalis. The malar process, large and irregular, is situated at the angle of separation between the facial and zygomatic surfaces, and presents a triangular surface for articulation with the malar bone. The alveolar process forms the lower margin of the bone; it is spongy and cellular in texture, and excavated into deep holes for the reception of eight teeth. The palate process is thick and strong, and projects horizontally inwards from the inner surface of the body of the bone. Superiorly, it is concave and smooth, and forms the floor of the nares; inferi- orly, it is also concave but uneven, and assists in the formation of the roof of the palate. This surface is marked by a deep groove, which lodges the posterior palatine nerve and artery. Its internal edge is raised into a ridge (crista nasalis), which, with a correspond- ing ridge in the opposite bone, forms a groove for the reception of the vomer. The prolongation of this ridge forwards beyond the level of the facial surface of the bone is the nasal spine. At the anterior extremity of its nasal surface is a foramen, which leads into a canal formed conjointly by the two superior maxillary bones, the anterior palatine canal. The termination of this canal is situated immediately behind the incisor teeth, hence it is also named the incisive foramen, and contains the ganglion of Cloquet. Associated with the incisive openings and canal are two smaller canals, the naso-palatine, which transmit the naso-palatine nerves. These canals are situated in the walls of the incisive canal, and terminate inferiorly in that canal, either by separate openings or conjoined. Developement.—By four centres ; one for the anterior part of the palate, and incisive portion of the alveolar process (the permanence of this piece constitutes the intermaxillary bone of animals); one for that portion of the bone lying internally to the infra-orbital canal and foramen; one for that portion lying externally to the groove and canal; and one for the palate process. The superior maxillary bone is one of the earliest to show signs of ossification, this process beginning in the alveolar process, and being associated with the early developement of teeth. The early developement of the alveolar process, and the consequent fusion at this point of the original pieces, explains the difficulties which have been felt by anatomists in deter- mining the precise number of the ossifying centres. Articulations.—With nine bones, viz.; with two of the cranium and with all the bones of the face, excepting the inferior maxillary. 82 LACHRYMAL AND MALAR BONES. These are, the frontal and ethmoid, nasal, lachrymal, malar, inferior turbinated, palate, vomer, and its fellow of the opposite side. Attachment of Muscles.—To nine ; orbicularis palpebrarum, obli- quus inferior oculi, levator labii superioris alaeque nasi, levator labii superioris proprius, levator anguli oris, compressor nasi, depressor labii superioris alaeque nasi, buccinator, masseter. Lachrymal Bones—(os unguis, from an imagined resemblance to a finger-nail). The lachrymal is a thin oval-shaped plate of bone, situated at the anterior and inner edge of the orbit. It may be divided into an external and internal surface and #four borders. The external surface is smooth and marked by a vertical ridge, the lachrymal crest, into two por- tions, one of which is flat and enters into the formation 7 of the orbit, hence may be called the orbital portion ; the j other is concave, and lodges the lachrymal sac, hence the lachrymal portion. The crest is expanded inferiorly into a hook-shaped process (hamulus lachrymalis) which forms part of the outer boundary of the fossa lachrymalis. The in- ternal surface is uneven and completes the anterior ethmoid cells, it assists also in forming the wall of the nasal fossae and nasal duct. The four borders articulate with the adjoining bones. Developement.—By a single centre appearing in the early part of the third month. Articulations.—With four bones; two of the cranium, frontal and ethmoid ; and two of the face, superior maxillary, and inferior tur- binated bone. Attachment of Muscles.—To one muscle, the tensor tarsi, and to an expansion of the tendo oculi, the former arising from the orbital sur- face, the other being attached to the lachrymal crest. Malar Bones—(mala, the cheek). The malar (fig. 41) is the strong quadrangular bone which forms the prominence of the cheek. It is divisible into an external and internal surface and four pro- cesses, the frontal, orbital, maxillary, and zygomatic. The external surface is smooth and convex, and pierced by several small openings which give passage to filaments of the temporo-malar nerve and minute arteries. The internal surface is concave, partly smooth and partly rough ; smooth where it forms part of the temporal fossa, and rough where it articulates with the superior maxillary bone. The frontal process ascends perpendicularly to form the outer bor- der of the orbit, and to articulate with the external angular process of the frontal bone. The orbital process is a thick plate, which pro- jects inwards from the frontal process, and unites with the great ala of the sphenoid to constitute the outer wall of the orbit. It is pierced * The lachrymal bone of the right side, viewed upon its external or orbital surface. 1. The orbital portion of the bone. 2. The lachrymal portion ; the prominent ridge be- tween these two portions is the crest. 3. The lower termination of the crest the hamu- lus lachrymalis. 4. The superior border which articulates with the frontal bone. 5. The posterior border which articulates with the ethmoid bone. 6. The anterior border which articulates with the superior maxillary bone. 7. The border which articulates with the in- ferior turbinated bone. PALATE BONES. 83 by several small foramina for the passage of temporo-malar filaments of the superior maxillary nerve. The maxillary process is broad, and articulates with the superior maxillary bone. The zygomatic process, narrower than the rest, projects backwards to unite with the zygoma of the temporal bone. Developement.—By a single centre; rarely by two or three. In many animals the malar bone is permanently divided into two por- tions, orbital and malar. Ossification commences in the malar bone soon after the vertebrae. Articulations.—With four bones; three of the cranium, frontal, temporal, and sphenoid ; and one of the face, the superior maxillary bone. Attachment of Muscles.—Ho five ; levator labii superioris proprius, zygomaticus minor and major, masseter, and temporal. Palate Bones.—The palate bones are situated at the posterior part of the nares, where they Fis-38* enter into the formation of the palate, the side of the nose, and the posterior part of the floor of the orbit; hence they might with great propriety be named the palato-naso-orbital bones. Each bone resembles in general form the letter L, and is divisible into a horizontal plate, a perpendicu- lar plate, and a pterygoid process or tuberosity. The horizontal plate is quadrilateral; and pre- sents two surfaces, one superior, which enters into the formation of the floor of the nares, the other inferior, forming the posterior part of the hard palate. The superior surface is concave and rises towards the middle line, where it unites with its fellow of the opposite side and forms a part of a crest (crista nasalis), which articulates with the vomer. The inferior surface is uneven, and marked by a slight transverse ridge, to which is attached the tendinous expansion of the tensor palati muscle. Near to its external border are two openings, one large and one small, the posterior palatine foramina ; the former transmits the posterior pala- tine nerve and artery, and the latter the middle palatine nerve. The posterior border is concave, and presents at its inner extremity a sharp point, which with a corresponding point in the opposite bone constitutes the palate spine for the attachment of the azygos uvulae muscle. * A posterior view of the right palate bone in its natural position; it is slightly turned to one side to obtain a sight of the internal surface of the perpendicular plate (2). 1. The horizontal plate of the bone ; its upper or nasal surface. 2. The perpendicular plate ; its internal or nasal surface. 3, 10, 11. The pterygoid process or tuberosity. 4. The thick internal border of the horizontal plate, which, articulating with the similar border of the opposite bone, forms the crista nasalis for the reception of the vomer. 5. The pointed process, which with a similar process of the opposite bone forms the palate spine. 6. The horizontal ridge which gives attachment to the inferior turbinated bone; the concavity below this ridge enters into the formation of the inferior meatus, and the concavity (2) above the ridge into that of the middle meatus. 7. The spheno-palatine notch. 8. The orbital portion. 9. The crista turbinalis superior for the middle turbinated bone. 10. The middle facet of the tuberosity, which enters into the formation of the pterygoid fossa. The facets 11 and 3 articulate with the two pterygoid plates, 11 with the internal, and 3 with the external. 84 PALATE BONES. The perpendicular plate is also quadrilateral; and presents two surfaces, one internal or nasal, forming a part of the wall of the nares; the other external, bounding the spheno-maxillary fossa and antrum. The internal surface is marked near its middle by a hori- zontal ridge (crista turbinalis inferior), to which is united the inferior turbinated bone, and at about half an inch above this by another ridge (crista turbinalis superior) for the attachment of the middle turbinated bone. The concave surface below the inferior ridge is the lateral boundary of the inferior meatus of the nose ; that between the two ridges corresponds with the middle meatus, and the surface above the superior ridge with the superior meatus. The external surface, extremely irregular, is rough on each side for articulation with neighbouring bones, and smooth in the middle to constitute the inner boundary of the spheno-maxillary fossa. This smooth surface terminates inferiorly in a deep groove, which being completed by the tuberosity of the superior maxillary bone and pterygoid process of the sphenoid, forms the posterior palatine canal. Near the upper part of the- perpendicular plate is a large oval notch completed by the sphenoid, the spheno-palatine foramen, which transmits the spheno-palatine nerves and artery, and serves to divide the upper extremity of the bone into two portions, an anterior or orbital, and a posterior or sphenoidal portion. The orbital portion is hollow within, and presents five surfaces externally: three articular, and two free ; the three articular are the anterior, which looks for- ward and articulates with the superior maxil- lary bone, internal with the ethmoid, and poste- rior with the sphenoid. The free surfaces are the posterior or orbital, which forms the pos- terior part of the floor of the orbit, and the exter- nal, which looks into the spheno-maxillary fossa. The sphenoidal portion, much smaller than the orbital, has three surfaces, two lateral and one superior. The external lateral surface enters into the formation of the spheno-maxil- lary fossa; the internal lateral forms part of the lateral boundary of the nares; and the superior surface articulates with the under part of the body of the sphenoid bone, and assists the sphenoidal spongy bones in closing the sphenoi- dal sinuses. This portion takes part in the formation of the pterygo- palatine canal. The pterygoid process or tuberosity of the palate bone is the thick and rough process which stands backwards from the angle of union * The perpendicular plate of the palate bone seen upon its external or spheno-maxillary surface. 1. The rough surface of this plate, which articulates with the superior maxil- lary bone and bounds the antrum. 2. The posterior palatine canal, completed by the tuberosity of the superior maxillary bone and pterygoid process. The rough surface to the left of the canal (2) articulates with the internal pterygoid plate. 3 The spheno palatine notch. 4, 5, 6. The orbital portion of the perpendicular plate 4 The spheno maxillary facet of this portion; 5, its orbital facet; 6, its maxillary facet' to articulate with the superior maxillary bone. 7. The sphenoidal portion of the perpendicular plate. 8. The pterygoid process or tuberosity of the bone. VOMER. 85 of the horizontal with the perpendicular portion of the bone. It is received into the angular fissure, which exists between the two plates of the pterygoid process at their inferior extremity, and presents three surfaces: one concave and smooth, which forms part of the pterygoid fossa; and one at each side to articulate with the ptery- goid plates. The anterior face of this process is rough, and articu- lates with the superior maxillary bone. Developement.—By a single centre, which appears in the angle of union between the horizontal and perpendicular portion, at the same time with ossification in the vertebrae. Articulations.—With six bones; two of the cranium, the sphenoid and ethmoid; and four of the face, the superior maxillary, inferior turbinated bone, vomer, and the palate bone of the opposite side. Attachment of Muscles.—To four; the tensor palati, azygos uvulae, internal and external pterygoid. Inferior Turbinated Bones.—The inferior turbinated or spongy bone is a thin layer of light and porous bone, attached to the crista tur- binalis inferior of the inner wall of the nares, and projecting inwards towards the septum narium. The inferior turbinated bone is broad in front, narrow and tapering behind, and slightly curled upon itself, so as to bear some resemblance to one valve of a bivalve shell, hence its designation concha inferior. The bone presents for examination a convex and concave surface, and a superior and inferior border. The convex surface looks inwards and upwards, and forms the infe- rior boundary of the middle meatus naris; it is marked by several longitudinal grooves for branches of the sphenopalatine nerve and artery. The concave surface looks downwards and outwards, and constitutes the roof of the inferior meatus. The superior border is irregular; it is attached to the crista turbinalis inferior of the supe- rior maxillary bone in front, to the same crest on the palate bone be- hind, and between those attachments gives off two, and sometimes three, thin and laminated processes. The most anterior of these processes, processus lachrymalis, articulates with the lachrymal bone, and assists in completing the nasal duct. The middle process, pro- cessus maxillaris, descends and assists in closing the antrum maxil- lare ; while the posterior, processus ethmoidalis, which is often want- ing, ascends towards the ethmoid bone, and also takes part in the closure of the antrum maxillare. The inferior border is rounded, and thicker than the rest of the bone. Developement.—By a single centre, which appears at about the middle of the first year. It affords no attachment to muscles. Articulations.—With four bones; the ethmoid, superior maxillary, lachrymal, and palate. Vomer.—The vomer is a thin quadrilateral plate of bone, forming the posterior and inferior part of the septum of the nares. The superior border is broad and expanded to articulate, in the middle, with the under surface of the body of the sphenoid, and on 8 86 INFERIOR MAXILLARY BONE. each side with the processus vaginalis of the pterygoid process. The anterior part of this border is hollowed into a sheath for the recep- tion of the rostrum of the sphenoid. The inferior border is thin and irregular, and is received into the grooved summit of the crista nasalis. The posterior border is sharp and free, and forms the poste- rior division of the two nares. The anterior border is more or less deeply grooved for the reception of the central lamella of the ethmoid and cartilage of the septum. This groove is an indication of the early constitution of the bone of two lamellae, united at the inferior border. The vomer not unfrequently presents a convexity to one or the other side, generally it is said, to the left. Developement.—By a single centre, which makes its appearance at the same time with those of the vertebrae. Ossification begins from below and proceeds upwards. At birth the vomer presents the form of a trough in the concavity of which the cartilage of the septum nasi is placed; it is this disposition which subsequently enables the bone to embrace the rostrum of the •sphenoid. The vomer has no muscles attached to it. Articulations.—With six bones; the sphenoid, ethmoid, two supe- rior maxillary, and two palate bones, and with the cartilage of the septum. Inferior Maxillary Bone.—The lower jaw is the arch of bone which contains the inferior teeth; it is divisible into a horizontal por- tion or body, and a perpendicular portion, the ramus, at each side. Upon the external surface of the body of the bone, at the middle line, and extending from between the two first incisor teeth to the chin, is a slight ridge, crista mentalis, which indicates the point of conjunction of the lateral halves of the bone in the young subject, the symphysis. Immediately external to this ridge is a depression which gives origin to the depressor labii inferioris muscle; and correspond- ing with the root of the lateral incisor tooth, another depression, the incisive fossa, for the levator labii inferioris. Further outwards is an oblique opening, the mental foramen, for the exit of the inferior dental nerve and artery, and below this foramen, the commence- ment of an oblique ridge which runs upwards and outwards to the base of the coronoid process and gives attachment to the depressor anguli oris, platysma myoides, and buccinator muscles. Near to the posterior part of this surface is a rough impression made by the mas- seter muscle; and immediately in front of this impression, a groove may occasionally be seen for the facial artery. The projecting tube- rosity at the posterior extremity of the lower'jaw, at the point where the body and ramus meet, is the angle. Upon the internal surface of the body of the bone at the symphy- sis, are two small pointed tubercles; immediately beneath these, two other tubercles less marked and pointed, beneath them a ridge, and beneath the ridge two rough depressions of some size. These'four points give attachment from above downwards to the genio-hyo- glossi, genio-hyoidei, part of the mylo-hyoidei, and to the digastric muscles. Running outwards into the body of the bone from the INFERIOR MAXILLARY BONE. 87 above ridge is a prominent line, the mylo-hyoidean ridge, which gives attachment to the mylo-hyoideus muscle, and by its extremity to the pterygo-maxillary ligament and superior constrictor muscle. Imme- diately above the ridge, and by the side of the symphysis, is a smooth concave surface, which corresponds with the sublingual gland; and below the ridge, and more externally, a deeper fossa for the submax- illary gland. The superior border of the body of the bone is the alveolar pro- cess, furnished in the adult with alveoli for sixteen teeth. The infe- rior border or base is rounded and smooth ; thick and everted in front to form the chin, and thin behind where it merges in the angle of the bone. The ramus is a strong square-shaped process, differing in direction at various periods of life; thus, in the foetus and infant, it is almost parallel with the body; in youth it is oblique, and gradually in- creases in the vertical direction until manhood; in old age, after the loss of the teeth, it again declines and assumes the oblique direction. Upon its external surface it is rough, for the attachment of the mas- seter muscle ; and at the junction of its posterior border with the body of the bone, is a rough tuberosity, the angle of the lower jaw, which gives attachment by its inner margin to the stylo-maxillary ligament. The upper extremity of the ramus presents two processes, sepa- rated by a concave sweep, the sigmoid, notch. The anterior is the coronoid process; it is' sharp and pointed, and gives attachment by its inner surface to the temporal muscle. The anterior border of the coronoid process is grooved at its lower part for the buccinator muscle. The pos- terior process is the condyle of the lower jaw, which is flattened from be- fore backwards, oblique in direction, and smooth upon its upper surface, to articulate with the glenoid cavity of the temporal bone. The constriction around the base of the condyle is its neck, into which is inserted the external pterygoid muscle. The sig- moid notch is crossed by the masseteric artery and nerve. The internal surface of the ramus is marked near its centre by a large oblique foramen, the inferior dental, for the entrance of the in- ferior dental artery and nerve into the dental canal. Bounding this opening is a sharp margin, to which is attached the internal lateral * The lower jaw. 1. The body. 2. The ramus. 3. The symphysis. 4. The fossa for the depressor labii inferioris muscle. 5. The mental foramen. 6. The external ob- lique ridge. 7. The groove for the facial artery ; the situation of the groove is marked by a notch in the bone a little in front of the number. 8. The angle. 9. The extremity of the mylo-hyoidean ridge. 10. The coronoid process. 11. The condyle. 12. The sigmoid notch. 13. The inferior dental foramen. 14. The mylo-hyoidean groove. 15. The al- veolar process, i. The middle and lateral incisor tooth of one side. c. The canine tooth. b. The bicuspides. m. The three molares. 88 TABLE OF DEVELOPEMENTS, ARTICULATIONS, ETC. ligament, and passing downwards from the opening a narrow groove, which lodges the mylo-hyoidean nerve with a small artery and vein. To the uneven surface above, and in front of the inferior dental fora- men, is attached the temporal muscle, and to that below it the internal pterygoid. The internal surface of the neck of the condyle gives at- tachment to the external pterygoid muscle; and the angle to the stylo- maxillary ligament. Developement.—By two centres; one for each lateral half, the two sides meeting at the symphysis, where they become united. The lower jaw is the earliest of the bones of the skeleton to exhibit ossi- fication, with the exception of the clavicle; ossific union of the sym- physis takes place during the first year. Articulations.—With the glenoid fossae of the two temporal bones, through the medium of a fibro-cartilage. Attachment of Muscles.—To fourteen pairs ; by the external sur- face commencing at the symphysis, and proceeding outwards,—le- vator labii inferioris, depressor labii inferioris, depressor anguli oris, platysma myoides, buccinator, and masseter ; by the internal surface also commencing at the symphysis, the genio-hyo-glossus, genio-hyoi- deus, mylo-hyoideus, digastricus, superior constrictor, temporal, ex- ternal pterygoid, and interna] pterygoid. Table showing the different points of Developement, Articulations, and Attachment of Muscles of the Bones of the Head. Developement. Articulations . Attachment of muscl Occipital - - 7 - - 6 13 pairs. Parietal - - 1 - - 5 1 muscle. Frontal - - 2 - . 12 3 pairs. Temporal - - 5 - - 5 14 muscles. Sphenoid - - 12 - - 12 12 pairs. Ethmoid • - 3 - - 13 none. Nasal - - 1 - . 4 none. Superior maxillary 6 - - 9 9 muscles Lachrymal - - - 4 1 ib. Malar - - - . 4 5 ib. Palate - - . . 6 4 ib. Inferior turbinated - . 4 none. Vomer - - - - 6 none. Lower jaw - - 2 - - 2 14 pairs. SUTURES. The bones of the craniurh and face are connected with each other by means of sutures (sutura, a seam), of which there are four principal varieties,—serrated, squamous, harmonia, and schindylesis. The serrated suture is formed by the union of two borders pos- sessing serrated edges, as in the coronal, sagittal, and lambdoid su- tures. In these sutures the serrations are formed almost wholly by the external table, the edges of the internal table lyino- merely in ap- position. J ^ The squamous suture (squama, a scale) is formed by the over-lap- SUTURES-OSSA TRIQUETRA. 89 ping of the bevelled edges of two contiguous bones, as in the articu- lation between the temporal and lower border of the parietal. In this suture the approximated surfaces are roughened, so as to adhere me- chanically with each other. The harmonia suture (apen/, to adapt) is the simple apposition of contiguous surfaces, the surfaces being more or less rough and reten- tive. This suture is seen in the connexion between the superior maxillary bones, or of the palate processes of the palate bones with each other. The schindylesis suture (tf^iv^uXrio'ij, a fissure) is the reception of one bone into a sheath or fissure of another, as occurs in the articula- tion of the rostrum of the sphenoid with the vomer, or of the latter with the perpendicular lamella of the ethmoid, and with the crista nasalis of the superior maxillary and palate bones. The serrated suture is formed by the interlocking of the radiating fibres along the edges of the flat bones of the cranium during growth. When this process is retarded in the infant by over-distention of the head, as in hydrocephalus, and sometimes without any such apparent cause, distinct ossific centres are developed in the interval between the edges; and, being surrounded by the suture, form independent pieces, which are called ossa triquetra, or ossa Wormiana. In the lambdoid suture there is generally one or more of these bones; and, in a beautiful adult hydrocephalic skeleton in the possession of Mr. Liston, there are upwards of one hundred. The coronal suture (fig. 41) extends transversely across the vertex of the skull, from the upper part of the greater wing of the sphenoid to the same point on the opposite side; it connects the frontal with the parietal bones. In the formation of this suture the edges of the articulating bones are bevelled, so that the parietal rest upon the frontal at each side, and in the middle the frontal rests upon the parietal bones; they thus afford each other mutual support in the consolidation of the skull. The sagittal suture (fig. 41) extends longitudinally backwards along the vertex of the skull, from the middle of the coronal to the apex of the lambdoid suture. It is very much serrated, and serves to unite the two parietal bones. In the young subject, and sometimes in the adult, this suture is continued through the middle of the frontal bone to the root of the nose, under the name of the frontal suture. Ossa triquetra are sometimes found in the sagittal suture. The lambdoid suture is named from some resemblance to the Greek letter A, consisting of two branches, which diverge at an acute angle from the extremity of the sagittal suture. This suture connects the occipital with the parietal bones. At the posterior and inferior angle of the parietal bones, the lambdoid suture is continued onwards in a curved direction into the base of the skull, and serves to unite the occipital bone with the mastoid portion of the temporal, under the name of the additamentum sutura lambdoidalis. It is in the lambdoid suture that ossa triquetra occur most frequently. The squamous suture (fig. 41) unites the squamous portion of the 8* 90 REGIONS OF THE SKULL. temporal bone with the greater ala of the sphenoid and with the parietal, overlapping the lower border of the latter. The portion of the suture which is continued backwards from the squamous portion of the bone to the lambdoid suture, and connects the mastoid portion with the posterior inferior angle of the parietal, is the additamentum sutura squamosa. The additamentum suturae lambdoidalis and additamentum suturas squamosae, constitute together the mastoid suture. Across the upper part of the face is an irregular suture, the trans- verse, which connects the frontal bone with the nasal, superior max- illary, lachrymal, ethmoid, sphenoid, and malar bones. The other sutures are too unimportant to deserve particular names or description. REGIONS OF THE SKULL. The skull, considered as a whole, is divisible into four regions,—a superior region, or vertex; a lateral region; an inferior region, or base; and an anterior region, the face. The Superior Region, or vertex of the skull, is bounded anteriorly by the frontal eminences; on each side by the temporal ridges and parietal eminences; and behind by the superior curved line of the occipital bone and occipital protuberance. It is crossed transversely by the coronal suture, and marked from before backwards by the sagittal, which terminates posteriorly in the lambdoid suture. Near the posterior extremity of the region, and on each side of the sagittal suture, is the parietal foramen. Upon the inner, or cerebral surface of this region is a shallow groove, extending along the middle line from before backwards, for the superior longitudinal sinus; on either side of this groove are several small fossae for the Pacchionian bodies, and further outwards digital fossae corresponding with the convexities of the convolutions and numerous ramified markings for lodging the branches of the arteria meningea media. The Lateral Region of the skull is divisible into three portions; temporal, mastoid, and zygomatic. The temporal portion, or temporal fossa, is bounded above and behind by the temporal ridge, in front by the external angular pro- cess of the frontal bone and by the malar bone, and below by the zygoma. It is formed by part of the frontal, great wing of the sphenoid, parietal, squamous portion of the temporal, malar bone and zygoma, and lodges the temporal muscle with the deep temporal arteries and nerves. The mastoid portion is rough, for the attachment of muscles. Upon its posterior part is the mastoid foramen, and below, the mastoid pro- cess. In front of the mastoid process is the external auditory foramen, surrounded by the external auditory process; and in front of this foramen the glenoid cavity, bounded above by the middle root of the zygoma and in front by its tubercle. The zygomatic portion, or fossa, is the irregular cavity below the zygoma, bounded in front by the superior maxillary bone, internally SUPERIOR REGION OF THE SKULL. 91 by the external pterygoid plate, above by part of the great wing of the sphenoid and squamous portion of the temporal bone, and by the temporal fossa, and externally by the zygomatic arch and ramus of the lower jaw. It contains the external pterygoid, with part of the temporal and internal pterygoid muscle, and the internal maxillary artery and inferior maxillary nerve, with their branches. At the bottom of the zygomatic fossa are two fissures, the spheno-maxillary and the ptery go-maxillary. The spheno-maxillary fissure is horizontal in direction, opens into the orbit, and is situated between the great Fig. 41.* Fig- 42.t * A front view of the skull. 1. The frontal portion of the frontal bone. The 2, imme- diately over the root of the nose, refers to the nasal tuberosity ; the 3, over the orbit, to the supraorbital ridge. 4. The optic foramen. 5. The sphenoidal fissure. 6. The spheno maxillary fissure. 7. The lachrymal fossa in the lachrymal bone, the commence- ment of the nasal duct. The figures 4, 5, 6, 7, are within the orbit. 8. The opening of the anterior nares, divided into two parts by the vomer ; the number is placed upon the latter. 9. The infra-orbital foramen. 10. The malar bone. 11. The symphysis of the lower jaw. 12. The mental foramen. 13. The ramus of the lower jaw. 14. The parietal bone. 15. The coronal suture. 16. The temporal bone. 17. The squamous suture. 18. The upper part of the greit ala of the sphenoid bone. 19. The commencement of the temporal ridge. 20. The zygoma of the temporal bone, assisting to form the zygomatic arch. 21. The mastoid process. t The cerebral surface of the base of the skull. 1. One side of the anterior fossa : the number is placed on the roof of the orbit, formed by the orbital plate of the frontal bone. 2. The lesser wing of the sphenoid. 3. The crista galli. 4. The foramen ccecum. 5. The cribriform lamella of the ethmoid. 6. The processus olivaris. 7. The foramen opticum. 8. The anterior clinoid process. 9. The carotid groove upon the side of the sella turcica, for the internal carotid artery and cavernous sinus. 10, 11, 12. The middle fossa of the base of the skull. 10. Marks the great ala of the sphenoid. 11. The squa- mous portion of the temporal bone. 12. The petrous portion of the temporal. 13. The sella turcica. 14. The basilar portion of the sphenoid and occipital bone (clivus Blumen- bacliii). The uneven ridge between Nos. 13,14, is the dorsum ephippii, and the prominent angles of this process the posterior clinoid processes. 15. The foramen rotundum. 16. The foramen ovale. 17. The foramen spinosum; the small irregular opening between 17 and 12 is the hiatus Fallopii. 18. The posterior fossa of the base of the skull. 19, 19. The groove for the lateral sinus. 20. The ridge upon the occipital bone, which gives attachment to the falx cerebelli. 21. The foramen magnum. 22. The meatus auditorius internus. 23. The jugular foramen. 92 BASE OF THE SKULL. ala of the sphenoid and the superior maxillary bone. It is completed externally by the malar bone. The pterygo-maxillary fissure is verti- cal, and descends at right angles from the extremity of the preceding. It is situated between the pterygoid process and the tuberosity of the superior maxillary bone, and transmits the internal maxillary artery. At the angle of junction of these two fissures is a small cavity, the spheno-maxillary fossa, bounded by the sphenoid, palate, and superior maxillary bones, in which are seen the openings of five foramina,— the foramen rotundum, spheno-palatine, pterygo-palatine, posterior palatine, and Vidian. It lodges Meckel's ganglion and the termina- tion of the internal maxillary artery. The Base of the Skull presents an internal or cerebral, and an external or basilar surface. The cerebral surface is divisible into three parts, which are named the anterior, middle, and posterior fossa of the base of the cranium. The anterior fossa is somewhat convex on each side, where it cor- responds with the roofs of the orbits; and concave in the middle, in the situation of the ethmoid bone and the anterior part of the body of the sphenoid. The latter and the lesser wings constitute its posterior boundary. It supports the anterior lobes of the cerebrum. In the middle line of this fossa, at its anterior part, is the crista galli, im- mediately in front of this process, the foramen cacum, and on each side the cribriform plate, with its foramina, for the transmission of the filaments of the olfactory and nasal branch of the ophthalmic nerve. Farther back in the middle line is the processus olivaris, and on the sides of this process the optic foramina, anterior and middle clinoid processes and vertical grooves for the internal carotid arteries. The middle fossa of the base, deeper than the preceding, is bounded in front by the lesser wing of the sphenoid; behind, by the petrous portion of the temporal bone; and is divided into two lateral parts by the sella turcica. It is formed by the posterior part of the body, great ala, and spinous process of the sphenoid, and by the petrous and squamous portion of the temporal bones. In the centre of this fossa is the sella turcica which lodges the pituitary gland, bounded in front by the anterior and middle and behind by the posterior clinoid processes. On each side of the sella turcica is the carotid groove for the internal carotid artery, the cavernous plexus of nerves, the cavernous sinus, and the orbital nerves, and a little farther outwards the following foramina from before backwards, sphenoidal fissure (foramen lacerum anterius) for the transmission of the third, fourth, three branches of the ophthalmic division of the fifth, and the sixth nerve, and ophthalmic vein; foramen rotundum, for the superior maxillary nerve; foramen ovale, for the inferior maxillary nerve, arteria meningea parva, and nervus petrosus superficialis* minor; foramen spinosum, for the arteria meningea media; foramen lacerum basis cranii, which gives passage to the internal carotid artery, carotid plexus, and petrosal branch of the Vidian nerve. On the anterior surface of the petrous portion of the temporal bone is a BASE OF THE SKULL. 93 groove, leading to a fissured opening, the hiatus Fallopii, for the petrosal branch of the Vidian nerve; and immediately beneath this a smaller foramen, for the nervus petrosus superficialis minor. Towards the apex of this portion of bone is the notch for the fifth nerve, and below it a slight depression for the Casserian ganglion. Farther outwards is the eminence which marks the position of the perpendicular semicircular canal. Proceeding from the foramen spinosum are two grooves which indicate the course of the trunks of the arteria meningea media. The whole fossa lodges the middle lobes of the cerebrum. The posterior fossa, larger than the other two, is formed by the occipital bone, by the petrous and mastoid portion of the temporals, and by a small part of the sphenoid and parietals. It is bounded in front by the upper border of the petrous portion and dorsum ephippii, and along its posterior circumference by the groove for the lateral sinuses: it gives support to the pons Varolii, medulla oblongata, and cerebellum. In the centre of this fossa is the foramen magnum, bounded on each side by a rough tubercle, which gives attachment to the odon- toid ligament, and by the anterior condyloid foramen. In front of the foramen magnum is the concave sur- face (clivus Blumenbachii) which supports the medulla oblongata and pons Varolii, and on each side the following foramina from before back- wards. The internal auditory fora- men, for the auditory and facial nerve and auditory artery; behind, and ex- ternal to this is a small foramen lead- ing into the aquaductus vestibuli; and below it, partly concealed by the edge of the petrous bone, the aqua- ductus cochlea; next, a long fissure, the foramen lacerum posterius, or jugular foramen, giving passage externally to the commencement of * The external or basilar surface of the base of the skull. 1,1. The hard palate. The figures are placed upon the palate processes of the superior maxillary bones. 2. The incisive, or anterior palatine foramen. 3. The palate process of the palate bone. The large opening near the figure is the posterior palatine foramen. 4. The palate spine; the curved line upon which the number rests, is the transverse ridge. 5. The vomer, dividing the openings of the posterior nares. 6. The internal pterygoid plate. 7. The scaphoid fossa. 8. The external pterygoid plate. The interval between 6 and 8 (right side of the figure), is the pterygoid fossa. 9. The zygomatic fossa. 10. The basilar process of the occipital bone. 11. The foramen magnum. 12. The foramen ovale. 13. The foramen spinosum. 14. The glenoid fossa. 15. The meatus auditorius externus. 16. The fora- men lacerum anterius basis cranii. 17. The carotid foramen of the left side. 18. The foramen lacerum posterius, or jugular foramen. 19. The styloid process. 20. The stylo- mastoid foramen. 21. The mastoid process. 22. One of the condyles of the occipital bone. 23. The posterior condyloid fossa. 94 BASE OF THE SKULL. the internal jugular vein and internally to the eighth pair of nerves. Converging towards this foramen from behind is the deep groove for the lateral sinus, and from the front the groove for the inferior petrosal sinus. Behind the foramen magnum is a longitudinal ridge, which gives attachment to the falx cerebelli, and divides the two inferior fossae of the occipital bone; and above the ridge is the internal occipital pro- tuberance and the transverse groove lodging the lateral sinus. The external surface of the base of the skull is extremely irregu- lar. From before backwards it is formed by the palate processes of the superior maxillary and palate bones; the vomer; pterygoid, spi- nous processes, and part of the body of the sphenoid; under surface of the squamous, petrous, and mastoid portion of the temporals; and by the occipital bone. The palate processes of the superior maxil- lary and palate bones constitute the hard palate, which is raised above the level of the rest of the base, and is surrounded by the alve- olar processes containing the teeth of the upper jaw. At the ante- rior extremity of the hard palate, and directly behind the front inci- sor teeth, is the anterior palatine or incisive foramen, the termination of the anterior palat'ne canal, which contains the naso-palatine gan- glion, and transmits the anterior palatine nerves. At the posterior angles of the palate are the posterior palatine foramina, for the pos- terior palatine nerves and arteries. Passing inwards from these foramina are the transverse ridges to which are attached the expan- sions of the tensor palati muscles, and at the middle line of the pos- terior border the palate spine which gives origin to the azygos uvulae. The hard palate is marked by a crucial suture, which dis- tinguishes the four processes of which it is composed. Behind, and above the hard palate, are the posterior nares, separated by the vomer, and bounded on each side by the pterygoid processes. At the base of the pterygoid processes are the pterygo-palatine canals. The internal pterygoid plate is long and narrow, terminated at its apex by the hamular process, and at its base by the scaphoid fossa. The external plate is broad; the space between the two is the pterygoid fossa ; it contains part of the internal pterygoid muscle, and the tensor palati. Externally to the external pterygoid plate is the zygomatic fossa. Behind the nasal fossae, in the middle line, is the under sur- face of the body of the sphenoid, and the basilar process of the occi- pital bone, and, still further back, the foramen magnum. At the base of the external pterygoid plate, on each side, is the foramen ovale, and behind this the foramen spinosum with the prominent spine which gives attachment to the internal lateral ligament of the lower jaw and the laxator tympani muscle. Running outwards from the apex of the spinous process of the sphenoid bone, is the fissura Glaseri, which crosses the glenoid fossa transversely, and divides it into an anterior smooth surface, bounded by the eminentia articularis, for the condyle of the lower jaw, and a posterior rough surface for a part of the parotid gland. Behind the foramen ovale and spinosum, is the irregular fissure between the spinous process of the sphenoid bone REGION OF THE FACE. 95 and the petrous portion of the temporal, the foramen lacerum ante- rius basis cranii, which lodges the internal carotid artery and Eusta- chian tube, and in which the carotid branch of the Vidian nerve joins the carotid plexus. Following the direction of this fissure out- wards is the foramen for the Eustachian tube, and that for the tensor tympani muscle, separated from each other by the processus cochlea- riformis. Behind the fissure is the pointed process of the petrous bone which gives origin to the levator palati muscle, and, externally to this process, the carotid foramen for the transmission of the inter- nal carotid artery and the ascending branch of the superior cervical ganglion of the sympathetic; and behind the carotid foramen, the foramen lacerum posterius and jugular fossa. Externally, and some- what in front of the latter, is the styloid process, and at its base the vaginal process. Behind and at the root of the styloid process is the stylo-mastoid foramen, for the facial nerve and stylo-mastoid artery, and further outwards the mastoid process. Upon the inner side of the root of the mastoid process is the digastric fossa; and a little farther internally, the occipital groove. On either side of the fora- men magnum, and near its anterior circumference, are the condyles of the occipital bone. In front of each condyle, and piercing its base, is the anterior condyloid foramen for the hypoglossal nerve, and directly behind the condyle the irregular fossa in which the pos- terior condyloid foramen is situated. Behind the foramen magnum are the two curved lines of the occipital bone, the spine, and protu- berance, with the rough surfaces for the attachment of muscles. The Face is somewhat oval in contour, uneven in surface, and excavated for the reception of two principal organs of sense,—the eye and the nose. It is formed by part of the frontal bone and by the bones of the face. Superiorly it is bounded by the frontal emi- nences ; beneath these are the superciliary ridges, converging towards the nasal tuberosity; beneath the superciliary ridges are the supra-orbital ridges, terminating externally in the external border of the orbit, and internally in the internal border, and presenting towards their inner third the supra-orbital notch, for the supra-orbital nerve and artery. Beneath the supra-orbital ridges are the openings of the orbits. Between the orbits is the bridge of the nose, overarching the anterior nares; and on each side of this opening the canine fossa of the superior maxillary bone, the infra-orbital foramen, and still far- ther outwards the prominence of the malar bone; at the lower margin of the anterior nares is the nasal spine, and beneath this the superior alveolar arch containing the teeth of the upper jaw. Form- ing the lower boundary of the face is the lower jaw, containing in its alveolar process the lower teeth, and projecting inferiorly to form the chin; on either side of the chin is the mental foramen. If a per- pendicular line be drawn from the inner third of the supra-orbital ridge to the inner third of the body of the lower jaw, it will be found to intersect three openings;—the supra-orbital, infra-orbital, and mental, each giving passage to a facial branch of the fifth nerve. 96 NASAL FOSSAE. ORBITS. The orbits are two quadrilateral hollow cones, situated in the upper part of the face, and intended for the reception of the eyeballs, with their muscles, vessels, and nerves, and the lachrymal glands. The central axis of each orbit is directed outwards, so that the axes of the two continued into the skull through the optic foramina, would inter- sect at a right angle over the middle of the sella turcica. The supe- rior boundary of the orbit is formed by the orbital plate of the frontal bone, and by part of the lesser wing of the sphenoid; the inferior, by part of the malar bone and by the orbital processes of the superior maxillary and palate bone; the internal by the lachrymal bone, the os planum of the ethmoid and part of the body of the sphenoid; and the external, by the orbital process of the malar bone and the great ala of the sphenoid ; these may be expressed more clearly in a tabular form:— Frontal. Sphenoid (lesser wing). ^ . Lachrymal. * i. Malar- . N Orbit. Ethmoid (os planum). Sphenoid (greater wing). Sphenoid (body). Malar. Superior maxillary. Palate. There are nine openings communicating with the orbit:—the optic, for the admission of the optic nerve and ophthalmic artery; the sphe- noidal fissure, for the transmission of the third, fourth, the three branches of the ophthalmic division of the fifth and the sixth nerve, and the ophthalmic vein; the spheno-maxillary fissure, for the passage of the superior maxillary nerve and artery to the opening of entrance of the infra-orbital canal; temporo-malar foramina—two or three small openings in the orbital process of the malar bone, for the pas- sage of filaments of the orbital branch of the superior maxillary nerve ; anterior and posterior ethmoidal foramina in the suture be- tween the os planum and frontal bone, the former transmitting the nasal nerve and anterior ethmoidal artery, and the latter the poste- rior ethmoidal artery and vein; the opening of the nasal duct; and the supra-orbital notch or foramen, for the supra-orbital nerve and artery. NASAL FOSSjE. The nasal fossae are two irregular cavities situate in the middle of the face, and extending from before backwards. They are bounded above by the nasal bones, ethmoid, and sphenoid; beloiv by the palate processes of the superior maxillary and palate bones; externally by the superior maxillary, lachrymal, inferior turbinated, ethmoid, palate, and internal pterygoid plate of the sphenoid ; and the two fossae are separated by the vomer and the perpendicular lamella of the ethmoid. These may be more clearly expressed in a tabular form :— NASAL FOSSAE. 97 Nasal bones. Ethmoid. Sphenoid. ~ - fa E Nasal fossa. Fig. 44* Palate processes of superior maxillary. Palate processes of palate bone. Each nasal fossa is divided into three irregular longitudinal pas- sages, or meatuses, by three processes of bone, which project from its outer wall, the superior, middle, and inferior turbinated bones; the superior and middle turbinated bones being processes of the ethmoid, and the inferior a distinct bone of the face. The superior meatus occupies the superior and posterior part of each fossa; it is situated between the superior and middle turbinated bones, and has opening into it three foramina, viz. the opening of the posterior ethmoid cells, the opening of the sphenoid cells, and the sphe- no-palatine foramen. The middle meatus is the space between the middle and inferior turbinated bones; it also presents three foramina, the opening of the frontal sinuses, of the * A longitudinal section of the nasal fossae made immediately to the right of the middle line, and the bony septum removed in order to show the external wall of the left fossa. 1. The frontal bone. 2. The nasal bone. 3. The crista galli process of the ethmoid. The groove between 1 and 3 is the lateral boundary of the foramen caecum. 4. The crib- riform plate of the ethmoid. 5. Part of the sphenoidal cells. 6. The basilar portion of the sphenoid bone. Bones 2, 4, and 5, form the superior boundary of the nasal fossa. 7, 7. The articulating surface of the palatine process of the superior maxillary bone. The groove between 7, 7, is the lateral half of the incisive canal, and the dark aperture in the groove the inferior termination of the left naso-palatine canal. 8. The nasal spine. 9. The palatine process of the palate bone. a. The superior turbinated bone, marked by grooves and apertures for filaments ef the olfactory nerve, b. The superior meatus, c. A probe passed into the posterior ethmoidal cells, d. The opening of the sphenoidal cells into the superior meatus, e. The spheno-palatine foramen. /. The middle turbinated bone, g, g. The middle meatus, h. A prdfce passed into the infundibular canal, leading from the frontal sinuses and anterior ethmoid cells ; the triangular aperture immediately above the letter is the opening of the maxillary sinus, i. The inferior turbinated bone. k, k. The inferior meatus. I, I. A probe passed up the nasal duct, showing the direction of that canal. The anterior letters g, k, are placed on the superior maxillary bone, the posterior on the palate bone. m. The internal pterygoid plate, n. Its hamular process. o. The external pterygoid plate, p. The situation of the opening of the Eustachian tube. q. The posterior palatine foramina, the letter is placed on the hard palate, r. The roof 9 98 TEETH—CLASSIFICATION. anterior ethmoid cells, and of the antrum. The largest of the three passages is the inferior meatus, which is the space between the infe- rior turbinated bone and the floor of the fossa ; in it there are two foramina, the termination of the nasal duct, and one opening of the anterior palatine canal. The nasal fossae commence upon the face by a large irregular opening, the anterior nares, and terminate poste- riorly in the two posterior nares. TEETH. Man is provided with two successions of teeth; the first are the teeth of childhood, they are called temporary, deciduous, or milk teeth; the second continue until old age, and are named permanent. Fig. 45 * abode f g h The permanent teeth are thirty-two in number, sixteen in each jaw; they are divisible into four classes,—incisors, of which there are four in each jaw, two central and two lateral; canine, two above and two below; bicuspid, four above and four below; and molars, six above and six below. The temporary teeth are twenty in number (fig. 46); eight inci- sors, four canine, and eight molars. The temporary molars have four tubercles, and are succeeded by the permanent bicuspides, which have only two tubercles. Each tooth is divisible into a crown, which is the part apparent above the gum; a constricted portion around the base of the crown, the neck; and a root or fang, which is contained within the alveolus. The root is invested by periosteum, which lines the alveolus, and is then reflected upon the root of the tooth as far as its neck. The incisor teeth (cutting teeth) are named from presenting a sharp and cutting edge, formed *t the expense of the posterior sur- of the left orbit, s. The optic foramen, t. The groove for the last turn of the internal carotid artery converted into a foramen by the developement of an osseous communica- tion between the anterior and middle clinoid processes, v. The sella Turcica, z. The posterior clinoid process. » Permanent teeth, a. Central incisor, b. Lateral incisor, c. Cuspid or canine. d. First bicuspid, e. Second bicuspid. /. First molar, g. Second molar. A. Third molar or dens sapientia. STRUCTURE OF TEETH. 99 face. The crown is flattened from before backwards, being some- what convex in front and concave behind; the neck is considerably constricted, and the root compressed from side to side; at its apex is a small opening for the passage of the nerve and artery of the tooth. Fig. 46.* The canine teeth (cuspidati) follow the incisors in order from before backwards; two are situated in the upper jaw, one on each side, and two in the lower. The crown is larger than that of the incisors, convex before and concave behind, and tapering to a blunted point. The root is longer than that of all the other teeth, compressed at each side, and marked by a slight groove. The bicuspid teeth (bicuspidati, small molars), two on each side in each jaw, follow the canine, and are intermediate in size between them and the molars. The crown is compressed from before back- wards, and surmounted by two tubercles, one internal, the other ex- ternal ; the neck is oval; the root compressed, marked on each side by a deep groove, and bifid near its apex. The teeth of the upper jaw have a greater tendency to the division of their roots than those of the lower, and the posterior than the anterior pair. The molar teeth (multicuspidati, grinders), three on each side in each jaw, are the largest of the permanent set. The crown is quadri- lateral, and surmounted by four tubercles, the neck large and round, and the root divided into several fangs. In the upper jaw the first and second molar teeth have three roots, sometimes four, which are more or less widely separated from each other, two of the roots being external, the other internal. In the lower there are but two roots, which are anterior and posterior; they are flattened from behind forwards, and grooved so as to mark a tendency to division. The third molars, or dentes sapientiae, are smaller than the other two; they present three tubercles on the surface of the crown; and the root is single and grooved, appearing to be made up of four or five fangs compressed together, or partially divided. In the lower jaw the fangs are frequently separated to some distance from each * Temporary teeth, a. Central incisor, b. Lateral incisor, c. Canine, d. First molar. e. Second molar. 100 STRUCTURE OF TEETH. Fig. 47.+ other, and much curved, so as to offer considerable resistance in the operation of extraction.* Structure.—The base of the crown of each tooth is hollowed in its interior into a small cavity which is continuous with a canal passing through the middle of each fang. The cavity and canal, or canals, constitute the cavitas pulpae, and contain a soft cellulo-vascular organ, the pulp, which receives its supply of vessels and nerves through the small opening at the apex of each root. Mr. Nasmyth, to whose investigations science is so much indebted for our present knowledge of the intimate structure and developement of the teeth, has observed with regard to the pulp, that it is composed of two different tissues, vascular and reticular; the former being an intricate wreb of minute vessels terminating in simple capillary loops, the latter a network of nucleated cells in which calcareous salts are gradually deposited, and which by a systematic continuance of that process are gradually converted into ivory. This process naturally takes place at the surface of the pulp, and as the pulp is thus robbed of its cells, new cells are produced by the capillary plexus to supply their place, and be in their turn similarly transformed. A tooth is composed of three distinct structures, ivory or tooth- bone, enamel, and a cortical substance or cementum. The ivory con- sists of very minute, tapering, and branching fibres embedded in a dense homogeneous, in- terfibrous substance. The fibres commence by their larger ends at the walls of the cavitas pulpae and pursue a radiating and serpentine course towards the periphery of the tooth, where they terminate in ramifications of ex- treme minuteness. These fibres, heretofore considered to be hollow tubuli, have been shown by Mr. Nasmyth to be rows of minute opaque bodies, arranged in a linear series (bac- cated fibres, Nasmyth), to be, in fact, the nu- clei of the ivory cells, the interfibrous substance being the rest of the cell filled with calcareous matter. In the natural state of the tooth all trace of the parietes or mode of connexion of the cells is lost, but after steeping in weak acid the cellular network is perfectly distinct. The enamel forms a crust over the whole exposed surface of the crown of the tooth to the commencement of its root; it is thickest over the upper part of the crown, and becomes gradually thinner as it approaches the neck. It is composed of minute hexagonal crystalline fibres, resting by one extremity against the surface of the ivory, and * See an excellent practical work, " On the Structure, Economy, and Pathology of the Teeth," by Mr. Lintott. t Microscopic section of a molar tooth. 1. Enamel with its columns and laminated structure. 2. Cortical substance or cementum on the outside of the fang. 3. Ivory, showing tubuli. 4. Foramen entering the dental cavity from the end of the fang. This fang has a bulbous enlargement in consequence of a hypertrophy of the cementum. 5. Dental cavity. 6. A few osseous corpuscles in the ivory just under the enamel. i!y DEVELOPEMENT OF TEETH. 101 constituting by the other the free surface of the crown. The fibres examined on the face of a longitudinal section have a waving arrange- ment, and consist, like those of ivory, of cells connected by their sur- faces and ends and filled with calcareous substance. When the latter is removed by weak acid, the enamel presents a delicate cellular net- work of animal matter. The cortical substance, or cementum, (substantia ostoidea,) forms a thin coating over the root of the tooth, from the termination of the enamel to the opening in the apex of the fang. In structure it is analogous to bone, and is characterized by the presence of numerous calcigerous cells and tubuli. The cementum increases in thickness with the advance of age, and gives rise to those exostosed appear- ances occasionally seen in the teeth of very old persons, or in those who have taken much mercury. In old age the cavitas pulpae is often found filled up and obliterated by osseous substance analogous to the cementum. Mr. Nasmyth has shown that this, like the other struc- tures composing a tooth, is formed of cells having a reticular arrange- ment. Developement.—The developement of the teeth in the human sub- ject has been successfully investigated by Mr. Goodsir, to whose in- teresting researches I am indebted for the following narrative:—* The inquiries of Mr. Goodsir commenced as early as the sixth week after conception, in an embryo, which measured seven lines and a half in length and weighed fifteen grains. At this early period each upper jaw presents two semicircular folds around its circumference; the most external is the true lip; the internal, the rudiment of the palate; and between these is a deep groove, lined by the common mucous membrane of the mouth. A little later, a ridge is developed from the floor of this groove in a direction from behind forwards, this is the rudiment of the external alveolus; and the arrangement of the appear- ances from without inwards at this period is the following:—Most externally and forming the boundary of the mouth, is the lip; next we find a deep groove, which separates the lip from the future jaw; then comes the external alveolar ridge ; fourthly, another groove, in which the germs of the teeth are developed, the primitive dental groove; fifthly, a rudiment of the internal alveolar ridge; and, sixthly, the rudiment of the future palate bounding the whole inter- nally. At the seventh week the germ of the first deciduous molar of the upper jaw has made its appearance, in the form of a " simple, free, granular papilla" of the mucous membrane, projecting from the floor of the primitive dental groove; at the eighth week, the papilla of the canine tooth is developed ; at the ninth week, the papillae of the four incisors (the middle preceding the lateral) appear; and at the tenth week the papilla of the second molar is seen behind the anterior molar in the primitive dental groove. So that at this early period, viz. the tenth week, the papillae or germs of the whole ten deciduous teeth of the upper jaw are quite distinct. Those of the lower jaw are a little more tardy; the papilla of the first molar is merely a slight • " On the Origin and Developement of the Pulps and'Sacs of the Human Teeth," by John Goodsir, jun. in the Edinburgh Medical and Surgical Journal, January, 1839. 9* 102 DEVELOPEMENT OF TEETH. bulging at the seventh week, and the tenth papilla is not apparent until the eleventh week. From about the eighth week the primitive dental groove becomes contracted before and behind the first deciduous molar, and laminae of the mucous membrane are developed around the other papillae, which increase in growth and enclose the papillae in follicles with open mouths. At the tenth week the follicle of the first molar is com- pleted, then that of the canine; during the eleventh and twelfth weeks the follicles of the incisors succeed, and at the thirteenth week the follicle of the posterior deciduous molar. During the thirteenth week the papillae undergo an alteration of form, and assume the shape of the teeth they are intended to repre- sent. And at the same time small membranous processes are de- veloped from the mouths of the follicles; these processes are intended to serve the purpose of opercula to the follicles, and they correspond in shape with the form of the crowns of the appertaining teeth. To the follicles of the incisor teeth there are two opercula ; to the canine, three; and to the molars a number relative to the number of their tubercles, either four or five. During the fourteenth and fifteenth weeks the opercula have completely closed the follicles, so as to convert them into dental sacs, and at the same time the papillae have become pulps. The deep portion of the primitive dental groove, viz. that which contains the dental sacs of the deciduous teeth, being thus closed in, the remaining portion, that which is nearer the surface of the gum, is still left open, and to this Mr. Goodsir has given the title of secondary dental groove; as it serves for the developement of all the permanent teeth, with the exception of the anterior molars. During the fourteenth and fifteenth weeks small lunated inflections of the mucous membrane are formed, immediately to the inner side of the closing opercula of the deciduous dental follicles, commencing behind the incisors and proceeding onwards through the rest; these are the rudiments of the follicles or cavities of reserve of the four permanent incisors, two permanent canines, and the four bicuspides. As the secondary dental groove gradually closes, these follicular inflections of the mucous membrane are converted into closed cavities of reserve, which recede from the surface of the gum and lie immediately to the inner side and in close contact with the dental sacs of the deciduous teeth, being enclosed in their submucous cellular tissue. At about the fifth month the anterior of these cavities of reserve dilate at their distal extremities, and a fold or papilla projects into their fundus, constituting the rudiment of the germ of the permanent tooth; at the same time two small opercular folds are produced at their proximal or small extremities, and convert them into true dental sacs. During the fifth month the posterior part of the primitive dental groove behind the sac of the last deciduous tooth has remained open, and in it has developed the papilla and follicle of the first permanent molar. Upon the closure of this follicle by its opercula, the secondary dental groove upon the summit of its crown forms a large cavity of reserve, lying in contact with the dental sac upon the one side and DEVELOPEMENT OF TEETH. 103 with the gum on the superficial side. At this period the deciduous teeth, and the sacs of the ten anterior permanent teeth, increase so much in size, without a corresponding lengthening of the jaws, that the first permanent molars are gradually pressed backwards and upwards into the maxillary tuberosity' in the upper jaw, and into the base of the coronoid process of the lower jaw; a position which they occupy at the eighth and ninth months of foetal life. In the infant of seven or eight months the jaws have grown in length, and the first permanent molar returns to its proper position in the dental range. The cavity of reserve, which has been previously elongated by the upward movement of the first permanent molar, now dilates into the cavity which that tooth has just quitted; a papilla is developed from its fundus, the cavity becomes constricted, and the dental sac of the second molar tooth is formed, still leaving a portion of the great cavity of reserve in connexion with the superficial side of the sac. As the jaws continue to grow in length, the second permanent dental sac descends from its elevated position and advances forwards into the dental range, following the same curve with the first permanent molar. The remainder of the cavity of reserve, already lengthened backwards by the previous position of the second molar, again dilates for the last time, developes a papilla and sac in the same manner with the preceding, and forms the third permanent molar or wisdom tooth, which at the age of nineteen or twenty, upon the increased growth of the jaw, follows the course of the first and second molars into the dental range. From a consideration of the foregoing phenomena, Mr. Goodsir has divided the process of dentition into three natural stages:— 1. follicular; 2. saccular; 3. eruptive. The first, or follicular stage, he makes to include all the changes which take place from the first appearance of the dental groove and papillae to the closure of their follicles; occupying a period which extends from the sixth week to the fourth or fifth month of intra-uterine existence. The second, or saccular stage, comprises the period when the follicles are shut sacs, and the included papillae pulps: it commences at the fourth and fifth months of intra-uterine existence, and terminates for the median in- cisors, at the seventh or eighth month of infantile life, and for the wisdom teeth at about the twenty-first year. The third, or eruptive stase, includes the completion of the teeth, the eruption and shedding of the temporary set, the eruption of the permanent, and the neces- sary changes in the alveolar processes. It extends from the seventh month till the twenty-first year. " The anterior permanent molar," says Mr. Goodsir, " is the most remarkable tooth in man, as it forms a transition between the milk and the permanent set." If considered anatomically, i. e. in its developement from the primitive dental groove, by a papilla and follicle, " it is decidedly a milk tooth;" if physiologically, " as the most efficient grinder in the adult mouth, we must consider it a per- manent tooth." " It is a curious circumstance, and one which will readilv suggest itself to the surgeon, that laying out of view the wisdom teeth, which sometimes decay at an early period from other 104 GROWTH OF TEETH. causes, the anterior molars are the permanent teeth which most fre- quently give way first, and in the most symmetrical manner and at the same time, and frequently before the milk set." Growth of Teeth.—Immediately that the dental follicles have been closed by their opercula, the pulps become moulded into the form of the future teeth: and the bases of the molars divided into two or three portions representing the future fangs. The dental sac is com- posed of two layers, an internal or vascular layer, which was origi- nally a part of the mucous surface of the mouth, and a cellulo-fibrous layer, analogous to the corium of the mucous membrane. Upon the formation of this sac by the closure of the follicle, the mucous mem- brane resembles a serous membrane in being a shut sac, and may be considered as consisting of a tunica propria, which invests the pulp; and a tunica reflexa, which is adherent by its outer surface with the structures in the jaw, and by the inner surface is free, being separated from the pulp by an intervening cavity. As soon as the moulding of the pulp has commenced, this cavity increases and becomes filled with a gelatinous granular substance, the enamel organ, which is adherent to the whole internal surface of the tunica reflexa, but not to the tunica propria and pulp. At the same period, viz. during the fourth or fifth month, a thin lamina of ivory is formed by the pulp, and occupies its most prominent point; if the tooth be incisor or Fig. 48.* canine, the newly formed layer has the b figure of a small hollow cone; if molar, there will be four or five small cones corresponding with the number of tu- bercles in its crown. These cones are united by the formation of additional layers, the pulp becomes gradually sur- rounded and diminishes in size, evolving fresh layers during its retreat into the jaws until the entire tooth with its fangs is com- pleted, and the small cavitas pulpae of the perfect tooth alone remains, communicating through the opening in the apex of each fang with the dental vessels and nerves. The number of roots appears to depend upon the number of nervous filaments sent to each pulp. When the formation of the ivory has commenced, the enamel organ becomes transformed into a laminated tissue, corresponding with the direction of the fibres of the enamel, and the crystalline substance of the enamel is secreted into its meshes by the vascular lining of the sac. The cementum appears to be formed at a later period of life, either by a deposition of osseous substance by that portion of the dental sac, which continues to enclose the fang, and acts as its periosteum, or by the conversion of that membrane itself into bone; the former sup- position is the more probable. The formation of ivory commences in the first permanent molar previously to birth. * a. Capsule of a temporary incisor with the rudiment of the corresponding permanent tooth attached, b. Capsule of a molar in the same state. A part of the gu:n is seen above it and in contact. TEETH—ERUPTION. 105 Eruption.—When the crown of the tooth has been formed and coated with enamel, and the fang has grown to the bottom of its socket by the progressive lengthening of the pulp, the formation of ivory, and the adhesion of the ivory to the contiguous portion of the sac, the pressure of the socket causes the reflected portion of the sac and the edge of the tooth to approach, and the latter to pass through the gum. The sac has thereby resumed* its original follicular con- dition, and has become continuous with the mucous membrane of the mouth. The opened sac now begins to shorten more rapidly than the fang lengthens, and the tooth is quickly drawn upwards by the contraction, leaving a space between the extremity of the unfinished root and the bottom of the socket, in which the growth and comple- tion of the fang is more speedily effected. During the changes which have here been described as taking place among the dental sacs contained within the jaws, the septa be- tween the sacs, which at first were composed of spongy tissue, soon became fibrous, and were afterwards formed of bone, which was developed from the surface and proceeded by degrees more deeply into the jaws, to constitute the alveoli. The sacs of the ten anterior permanent teeth, at first enclosed in the submucous cellular tissue of the deciduous dental sacs, and received during their growth into crypts situated behind the deciduous teeth, advanced by degrees be- neath the fangs of those teeth, and became separated from them by distinct osseous alveoli. The necks of the sacs of the permanent teeth, by which they originally communicated with the mucous lining of the secondary groove, still exist, in the form of minute obli- terated cords, separated from the deciduous teeth by their alveolus, but communicating through a minute osseous canal with the fibrous tissue of the palate, immediately behind the corresponding deciduous teeth. " These cords and fora- mina are not obliterated in the child," says Mr. Goodsir, " either because the cords are to become useful as ' guber- naculd' and the canals as ' itinera dentium;' or, much more probably, in virtue of a law, which appears to be a general one in the developement of animal bodies, viz. that parts, or organs, which have once acted an important part, however atrophied they may afterwards become, yet never altogether disappear, so long as they do not interfere with other parts or functions." Succession.—The periods of appearance of the teeth are extremely irregular; it is necessary, therefore, to have recourse to an average, which, for the temporary teeth, may be stated as follows, the teeth of the lower jaw preceding those of the upper by a short interval:— 7th month, two middle incisors. 18th month, canine. 9th month, two lateral incisors. 24th month, two last molares. 12th month, first molares. * Mr. Nasmyth is of opinion that it is " by a process of absorption, and not of disrup- tion, that the tooth is emancipated." Medico-chirurgical Transactions. 1839. t Temporary tooth with the capsule of its permanent successor attached to it by ths gubernaculum dentis. 106 OS HYOIDES—STERNUM. The periods for the permanent teeth are, 6| year, first molares. 10th year, second bicuspides. 7th year, two middle incisors. 11th to 12th year, canine. 8th year, two lateral incisors. 12th to 13th year, second molares. 9th year, first bicuspides. 17th to 21st year, last molares. os HYOIDES. The os hyoides forms the second arch developed from the cranium, and gives support to the tongue, and attachment to numerous muscles in the neck. It is named from its resemblance to the Greek letter u, and consists of a central portion or body, of two larger cornua, which project backwards from the body; and two lesser cornua, which ascend from the angles of union between the body and the greater cornua. Fig 50i* The body is somewhat quadrilateral, rough and convex on its antero-superior surface, by which it gives attachment to muscles; con- cave and smooth on the postero-inferior sur- face, by which it lies in contact with the thyro-hyoidean membrane. The greater cor- nua are flattened from above downwards, and terminated posteriorly by a tubercle; and the lesser cornua, conical in form, give attachment to the stylo-hyoid ligaments. In early age and in the adult, the cornua are connected with the body by cartilaginous surfaces and ligamentous fibres; but in old age they become united by bone. Developement.—By five centres, one for the body, and one for each cornu. Ossification commences in the greater cornua during the last month of foetal life, and in the lesser cornua and body soon after birth. Attachment of Muscles.—To eleven pairs ; sterno-hyoid, thyro-hyoid, omo-hyoid, pulley of the digastricus, stylo-hyoid, mylo-hyoid, genio- hyoid, genio-hyo-glossus, hyo-glossus, lingualis, and middle constrictor of the pharynx. It also gives attachment to the stylo-hyoid, thyro- hyoid, and hyo-epiglottic ligaments, and to the thyro-hyoidean mem- brane. THORAX AND UPPER EXTREMITY. The bones of the thorax are the sternum and ribs; and, of the upper extremity, the clavicle, scapula, humerus, ulna and radius, bones of the carpus, metacarpus, and phalanges. Sternum.—The sternum (fig. 51) is situated in the middle line of the front of the chest, and is oblique in direction, the superior end lying within a few inches of the vertebral column, and the inferior being projected forwards so as to be placed at a considerable distance from the spine. The bone is flat or slightly concave in front, and * The os hyoides seen from before. 1. The antero-superior, or convex side of the body. 2. The great cornu of the left side. 3. The lesser cornu of the same side. The cornua were ossified to the body of the bone in the specimen from which this figure was drawn. STERNUM. 107 marked by five transverse lines which indicate its original subdivision into six pieces. It is convex behind, broad and thick above, flattened and pointed below, and is divisible in the adult into three pieces, su- perior, middle, and inferior. The superior piece, or manubrium, is nearly quadrilateral; it is broad and thick above, where it presents a concave border (incisura semi- lunaris), and narrow at its junction with the middle piece. At each superior angle is a deep articular depression (incisura clavicularis) for the clavicle, and on either side two notches, for the articulation of the cartilage of the first rib, and one half of the second. The middle piece or body, considerably longer than the superior, is broad in the middle, and somewhat narrower at each extremity. It presents at either side six articular notches, for the lower half of the second rib, the four next ribs, and the upper half of the seventh. This piece is sometimes perforated by an opening of various magni- tude resulting from arrest of developement. The inferior piece (ensiform or xiphoid cartilage) is the smallest of the three, often merely cartilaginous, and very various in appearance, being sometimes pointed, at other times broad and thin, and at other times again, perforated by a round hole, or bifid. It presents a notch at each side for the articulation of the lower half of the cartilage of the seventh rib. Developement.—By a variable number of centres, generally ten, namely, two for the manubrium; one (sometimes two) for the first piece of the body, two for each of the remaining pieces, and one for the ensiform cartilage. Ossification commences towards the end of the fifth month in the manubrium, the two pieces for this part being placed one above the other. At about the same time the centres for the first and second pieces of the body are apparent; the centres for the third piece of the body appear a few months later, and those for the fourth piece soon after birth. The osseous centre for the ensiform cartilage, is so variable in its advent, that it may be present at any period between the third and eighteenth year. The double centres for the body of the sternum are disposed side by side in pairs, and it is the irregular union of these pairs in the last three pieces of the body that gives rise to the large aperture occasionally seen in the sternum towards its lower part. Union of the pieces of the sternum com- mences from below and proceeds upwards; the fourth and the third unite at about puberty, the third and the second between twenty and twenty-five, and the second and the first between twenty-five and thirty. The ensiform appendix becomes joined to the body of the sternum at forty or fifty years; and the manubrium to the body only in very old age. Two small pisiform pieces have been described by Beclard and Breschet, as being situated upon and somewhat behind each extremity of the incisura semilunaris of the upper border of the manubrium. These pre-sternal or supra-sternal pieces, which are by no means constant, appear at about the thirty-fifth year. Beclard considers them to be the analogue of the fourchette of birds, and Breschet as the sternal ends of the cervical rib. 108 RIBS—TRUE AND FALSE. Articulations.—"With sixteen bones; viz. with the clavicle and the seven true ribs, at each side. Attachment of Muscles.—To nine pairs and one single muscle; viz. to the pectoralis major, sterno-mastoid, sterno-hyoid, sterno-thyroid, triangularis sterni, aponeurosis of the obliquus externus, internus, and transversalis muscles, rectus, and diaphragm. Ribs.—The ribs are twelve in number at each side; the first seven are connected with the sternum, and hence named sternal or true ribs; the remaining five are the asternal or false ribs; and the last two shorter than the rest, and free at their extremities, are the floating ribs. The ribs increase in length from the first to the eighth, whence they again diminish to the twelfth; in breadth they diminish gradually from the first to the last, and with Fig. 51.* the exception of the last two are broader at the anterior than at the posterior end. The first rib is horizontal in its direction; all the rest are oblique, so that the ante- rior extremity falls considerably below the posterior. Each rib presents an external and internal surface, a superior and inferior border, and two extremities; it is curved to correspond with the arch of the thorax, and twisted upon it- self, so that, when laid on its side, one end is tilted up, while the other rests upon the surface. The external surface is convex, and marked by the attachment of muscles; the internal is flat, and corresponds with the pleura; the superior border is rounded; and the inferior sharp and grooved upon its inner side, for the attachment of the intercostal muscles.f Near its vertebral extremity, the rib is suddenly bent upon itself; and opposite the bend, upon the external surface, is a rough oblique ridge, which gives attachment to a tendon of the sacro-lumbalis muscle, and is called the angle. The distance between the vertebral extremity and the angle increases gradually, from the second to the eleventh rib. Beyond the angle is a rough elevation, the tubercle; and immediately at the base and under side of the tubercle a smooth surface for articulation with the extremity of the transverse process of the corresponding vertebra. The verte- * An anterior view of the thorax. 1. The superior piece of the sternum. 2. The middle piece. 3. The inferior piece, or ensiform cartilage. 4. The first dorsal vertebra. 5. The last dorsal vertebra. 6. The first rib. 7. Its head. 8. Its neck, resting against the transverse process of the first dorsal vertebra. 9. Its tubercle. 10. The seventh or last true rib. 11. The costal cartilages of the true ribs. 12. The last two false ribs or floating ribs. 13. The groove along the lower border of the rib. t This groove is commonly described as supporting the intercostal artery vein and nerve, but this is not the case. ' ' COSTAL CARTILAGES. 109 bral end of the rib is somewhat expanded, and is termed the head, and that portion between the head and the tubercle is the neck. On the extremity of the head is an oval smooth surface divided by a transverse ridge into two facets for articulation with two contiguous vertebrae. The posterior surface of the neck is rough, for the attach- ment of the middle costo-transverse ligament; and upon its upper border is a crest, which gives attachment to the anterior costo-trans- verse ligament. The sternal extremity is flattened, and presents an oval depression, into which the costal cartilage is received. The ribs that demand especial consideration are the first, tenth, eleventh, and twelfth. The first is the shortest rib; it is broad and flat, and placed horizon- tally at the upper part of the thorax, the surfaces looking upwards and downwards, in place of forwards and backwards as in the other ribs. At about the anterior third of the upper surface of the bone, and near its internal border, is a tubercle which gives attachment to the sca- lenus anticus muscle, and immediately before and behind this tubercle, a shallow oblique groove, the former for the subclavian vein, and the latter for the subclavian artery. Near the posterior extremity of the bone is a thick and prominent tubercle, with a smooth articular sur- face for the transverse process of the first dorsal vertebra. There is no angle. Beyond the tuberosity is a narrow constricted neck; and at the extremity, a head, presenting a single articular surface. The second rib approaches in some of its characters to the first. The tenth rib has a single articular surface on its head. The eleventh and twelfth have each a single articular surface on the head, no neck or tubercle, and are pointed at the free extremity. The eleventh has a slight ridge, representing the angle, and a shallow groove on the lower border; the twelfth has neither. Costal Cartilages.—The costal cartilages serve to prolong the ribs forwards to the anterior part of the chest, and contribute mainly to the elasticity of the thorax. They are broad at their attachment to the ribs, and taper slightly towards.the opposite extremity; they diminish gradually in breadth from the first to the last; in length they increase from the first to the seventh, and then decrease to the last. The cartilages of the first two ribs are horizontal in direction, the rest incline more and more upwards. In advanced age the costal cartilages are more or less converted into bone, this change taking place earlier in the male than in the female. The first seven cartilages articulate with the sternum; the three next with the lower border of the cartilage immediately preceding, while the last two lie free between the abdominal muscles. All the cartilages of the false ribs terminate by pointed extremities. Developement.—The ribs are developed by three centres; one for the central part, one for the head, and one for the turbercle. The last two have no centre for the tubercle. Ossification commences in the body somewhat before its appearance in the vertebrae; the epiphysal centres for the head and tubercle appear between sixteen and twenty, and are consolidated with the rest of the bone at twenty-five. 10 110 CLAVICLE—SCAPULA. Articulations.—Each rib articulates with two vertebrae, and one costal cartilage, with the exception of the first, tenth, eleventh, and twelfth, which articulate each with a single vertebra only. Attachment of Muscles.—To the ribs and their cartilages are at- tached twenty-two pairs, and one single muscle. To the cartilages, the subclavius, sterno-thyroid, pectoralis major, internal oblique, rectus, transversalis, diaphragm, triangularis sterni, internal and external in- tercostals. To the ribs, the intercostal muscles, scalenus anticus, scalenus posticus, pectoralis minor, serratus magnus, obliquus exter- nus, obliquus internus, latissimus dorsi, quadratus lumborum, serratus posticus superior, serratus posticus inferior, sacro-lumbalis, longissimus dorsi, cervicalis ascendens, levatores costarum, transversalis, and diaphragm. Clavicle.—The clavicle is a long bone shaped like the italic letter /, and extended across the upper part of the side of the chest from the upper piece of the sternum to the point of the shoulder, where it arti- culates with the scapula. In position it is very slightly oblique, the sternal end being somewhat lower and more anterior than the scapular, and the curves are so disposed that at the sternal end the convexity, and at the scapular the concavity, is directed forwards. The sternal half of the bone is rounded or irregularly quadrilateral, and terminates in a broad articular surface. The scapular half is flattened from above downwards, and broad at its extremity, the articular surface occupy- ing only part of its extent. The upper surface is smooth and convex, and partly subcutaneous; while the under surface is rough and de- pressed, for the insertion of the subclavius muscle. At the sternal extremity of the under surface is a very rough prominence, which gives attachment to the rhomboid ligament; and at the other ex- tremity a rough tubercle and ridge, for the coraco-clavicular liga- ment. The opening for the nutritious vessels is seen upon the under surface of the bone. Developement.—By two centres; one for the shaft and one for the sternal extremity; the former appearing before any other bone of the skeleton, the latter between fifteen and eighteen. Articulations.—With the sternum and scapula. Attachment of Muscles.—To six; the sterno-mastoid, trapezius, pec- toralis major, deltoid, subclavius, and sterno-hyoid. Scapula.—The scapula is a flat triangular bone, situated upon the posterior aspect and side of the thorax occupying the space from the second to the seventh rib. It is divisible into an anterior and poste- rior surface, superior, inferior, and posterior border, anterior, superior, and inferior angle, and processes. The anterior surface or subscapular fossa, is concave and irregular, and marked by several oblique ridges which have a direction upwards and outwards. The whole concavity is occupied by the subscapu- laris muscle, with the exception of a small triangular portion near the superior angle. The posterior surface or dorsum is convex, and unequally divided into two portions by the spine; that portion above the spine is the supra-spinous fossa; and that below, the infra-spinous fossa. SCAPULA. Ill The superior border is the shortest of the three : it is thin and con- cave, and. terminated at one extremity by the superior angle, and at the other by the coracoid process. At its inner termination, and formed partly by the base of the coracoid process, is the supra-sca- pular notch, for the transmission of the supra-scapular nerve. The inferior or axillary border is thick, and marked by several grooves and depressions; it terminates superiorly at the glenoid cavity, and inferiorly at the inferior angle. Immediately below the glenoid cavity is a rough ridge, which gives origin to the long head of the triceps muscle. Upon the posterior surface of the border is a depression for the teres minor; and upon its anterior surface a deeper groove for the teres major; near the inferior angle is a pro- jecting lip, which increases the surface of origin of the latter muscle. The posterior border or base, the longest of the three, is turned to- wards the vertebral column. It is intermediate in thickness between the superior and inferior, and convex, being considerably inflected outwards towards the superior angle. The anterior angle is the thickest part of the bone, and forms the head of the scapula; it is immediately surrounded by a constricted portion, the neck. The head presents a shallow pyriform articular surface, the glenoid cavity, having the pointed extremity upwards; and at its apex is a rough depression, which gives attachment to the long tendon of the biceps. The superior angle is thin and pointed. The inferior angle is thick, and smooth upon the external surface for the origin of the teres major and for a large bursa over which the upper border of the latissimus dorsi muscle plays. The spine of the scapula, triangular in form, crosses the upper part of its dor- FiS-52* sum; it commences at the posterior bor- der by a smooth triangular surface over which the trapezius glides upon a bursa, and terminates at the point of the shoul- der in the acromion process. The upper border of the spine is rough and subcu- taneous, and gives attachment by two projecting lips to the trapezius and del- toid muscles; the surfaces of the spine enter into the formation of the supra and infra-spinous fossae. The nutritious foramina of the scapula are situated in the base of the spine. The acromion is somewhat triangular and flattened from above downwards; it overhangs the glenoid cavity, the upper surface being rough and subcutaneous, * A posterior view of the scapula. 1. The supra-spinous fossa. 2. The infra-spinous fossa. 3. The superior border. 4. The supra-scapular notch. 5. The anterior or ax- illary border. 6. The head of the scapula and glenoid cavity. 7. The inferior angle. 8. The neck of the scapula, the ridge opposite the number gives origin to the long head of the triceps. 9. The posterior border or base of the scapula. 10. The spine. 11. The triangular smooth surface, over which the tendon of the trapezius glides. 12. The acro- mion process. 13. One of the nutritious foramina. 14. The coracoid process. 112 HUMERUS. the lower smooth and corresponding with the shoulder-joint. Near its extremity, upon the anterior border, is an oval articular surface, for the end of the clavicle. The coracoid process is a thick, round, and curved process of bone, arising from the upper part of the neck of the scapula, and over- arching the glenoid cavity. It is about two inches in length and very strong ; it gives attachment to several ligaments and muscles. Developement.—By six centres; one for the body, one for the cora- coid process, two for the acromion, one for the inferior angle, and one for the posterior border. The ossific centre for the body appears in the infra-spinous fossa at about the same time with the ossification of the vertebrae; for the coracoid process during the first year; the acromion process at puberty; the inferior angle in the fifteenth year; and the posterior border at seventeen or eighteen. Union between the coracoid process and body takes place during the fifteenth year; the bone is not complete till manhood. Articulations.—With the clavicle and humerus. Attachment of Muscles.—To sixteen; by its anterior surface to the subscapularis; posterior surface, supra-spinatus and infra-spinatus; superior border, omo-hyoid ; posterior border, levator anguli scapulae, rhomboideus minor, rhomboideus major, and serratus magnus; an- terior border, long head of the triceps, teres minor, and teres major; upper angle of the glenoid cavity, to the long tendon of the biceps; spine and acromion to the trapezius and deltoid; coracoid process, to the pectoralis minor, short head of the biceps, and coraco-brachi- alis. The ligaments attached to the coracoid process are, the cora- coid, coraco-clavicular, and coraco-humeral, and the costo-coracoid membrane. Humerus.—The humerus is a long bone divisible into a shaft and two extremities. The superior extremity presents a rounded head; a constriction immediately around the base of the head, the neck; a greater and a lesser tuberosity. The greater tuberosity is situated most externally, and is separated from the lesser by a vertical furrows the bicipital groove, which lodges the long tendon of the biceps. The edges of this groove below the head of the bone are raised and rough, and are called the anterior and posterior bicipital ridge; the former serves for the insertion of the pectoralis major muscle, and the latter of the latissimus dorsi and teres major. The constriction of the bone below the tuberosities is the surgical neck, and is so named, in contradistinction to the true neck, from being the seat of the accident called by surgical writers/ractore of the neck of the humerus. The shaft of the bone is prismoid at its upper part, and flattened from before backwards below. Upon its outer side, at about its mid- dle, is a rough triangular eminence, which gives insertion to the deltoid; and immediately on each side of this eminence is a smooth depression, corresponding with the two heads of the brachialis anticus. Upon the inner side of the middle of the shaft is a ridge, for th© at- HUMERUS. 113 Fig. 53.: tachment of the coraco-brachialis muscle; and behind, an oblique and shallow groove, which lodges the musculo-spiral nerve and superior profunda artery. The foramen for the medullary vessels is situated upon the inner surface of the shaft of the bone a little below the coraco-brachial ridge; it is directed downwards. The lower extremity is flattened from before backwards, and is ter- minated inferiorly by a long articular surface, divided into two parts by an elevated ridge. The external portion of the articular surface is a rounded protube- rance, eminentia capitata, which articulates with the cup-shaped depression on the head of the radius; the internal portion is a concave and pulley-like surface, trochlea, which articulates with the ulna. Projecting beyond the articular surface on each side are the ex- ternal and internal condyle, the latter being consider- ably the longer; and running upwards from the con- dyles upon the borders of the bone are the condyloid ridges, of which the external is the most prominent. Immediately in front of the trochlea is a small depres- sion for receiving the coronoid process of the ulna during flexion of the fore-arm; and immediately be- hind it a large and deep fossa, for containing the olecranon process in extension. Developement.—By seven centres; one for the shaft, one for the head, one for the tuberosities, one for the eminentia capitata, one for the trochlea, and one for each condyle, the internal preceding the external. Ossification commences in the diaphysis of the humerus «| soon after the clavicle; in the head and tuberosities, during the second and third years of infantile life ; in the eminentia capitata and trochlea during the third and sixth years; and in the condyles during the twelfth and fifteenth. The entire bone is consolidated at twenty. Articulations.—With the glenoid cavity of the scapula, and with the ulna and radius. Attachment of Muscles.—To twenty-four; by the greater tuberosity to the supra-spinatus, infra-spinatus, and teres minor; lesser tube- rosity, subscapularis ; anterior bicipital ridge, pectoralis major; pos- terior bicipital ridge and groove, teres major and latissimus dorsi; shaft, external and internal heads of the triceps, deltoid, coraco- brachialis, and brachialis anticus; external condyloid ridge and con- dyle (condylus extensotnus), extensors and supinators of the fore-arm, viz. supinator longus, extensor carpi radialis longior, extensor carpi radialis brevior, extensor communis digitorum, extensor minimi digiti, * The humerus of the right side; its anterior surface. 1. The shaft of the bone. 2. The head. 3. The anatomical neck. 4. The greater tuberosity. 5. The lesser tuberosity. 6. The bicipital groove. 7. The anterior bicipital ridge. 8. The posterior bicipital ridge. 9. The rough surface into which the deltoid is inserted. 10. The nutritious foramen. 11. The eminentia capitata. 12. The trochlea. 13. The external condyle. 14. The internal condyle. 15. The external condyloid ridge. 16. The internal condyloid ridge. 17. The fossa for the coronoid process of the ulna. 10* ;m 114 ULNA. extensor carpi ulnaris, anconeus, and supinator brevis ; internal con- dyle (condylusflexorius), flexors and one pronator, viz. pronator radii teres, flexor carpi radialis, palmaris longus, flexor sublimis digitorum, and flexor carpi ulnaris. Ulna.—The ulna is a long bone, divisible into a shaft and two ex- tremities. The upper extremity is large, and forms principally the articulation of the elbow; wrhile the lower extremity is small, and excluded from the wrist-joint by an inter-articular fibro-cartilage. The superior extremity presents a semilunar concavity of large size, the greater sigmoid notch, for articulation with the humerus; and upon the outer side a lesser sigmoid notch, which articulates with the head of the radius. Bounding the greater sigmoid notch poste- riorly is the olecranon process; and overhanging it in front, a pointed eminence with a rough triangular base, the coronoid process. Behind the lesser sigmoid notch, and extending downwards on the side of the olecranon, is a triangular uneven surface, for the anconeus muscle; and upon the posterior surface of the olecranon a smooth triangular surface, which is subcutaneous. The shaft is prismoid in form, and presents three surfaces, anterior, posterior, and internal; and three borders. The anterior surface is occupied by the flexor profundis digitorum for the upper three- fourths of its extent; and below by a depression, for the pronator quadratus muscle. A little above its middle is the nutritious foramen, which is directed upwards. Upon the posterior surface at the upper part of the bone is the triangular uneven depression for the anconeus muscle, bounded inferiorly by an oblique ridge which runs downwards from the posterior extremity of the lesser sigmoid notch. Below the ridge the surface is marked into several grooves, for the attachment of the extensor ossis metacarpi, extensor secundi internodii, and ex- tensor indicis muscle. The internal surface is covered in for the greater part of its extent by the flexor profundis digitorum. The anterior border is rounded, and gives origin by its lower fourth to the pronator quadratus; the posterior is more prominent, and affords at- tachment to the flexor carpi ulnaris and extensor carpi ulnaris. At its upper extremity it expands into the triangular subcutaneous sur- face of the olecranon. The external or radial border is sharp and prominent, for the attachment of the interosseous membrane. The lower extremity terminates in a small rounded head, capitulum ulna, from the side of which projects the styloid process. The latter presents a deep notch at its base for the attachment of the apex of the triangular interarticular cartilage, and by its point gives attach- ment to the internal lateral ligament. Upon the posterior surface of the head is a groove, for the tendon of the extensor carpi ulnaris; and upon the side opposite to the styloid process a smooth surface, for articulation with the side of the radius. Developement.—By three centres; one for the shaft, one for the in- ferior extremity, and one for the olecranon. Ossification commences in the ulna shortly after the humerus and radius: the two ends of the bone are cartilaginous at birth. The centre for the lower end appears RADIUS. 115 « at about the fifth, and that for the olecranon about the seventh year. The bone is completed at about the twentieth year. Articulations.—With two bones; the humerus and radius; it is se- parated from the cuneiform bone of the carpus by the triangular inter- articular cartilage. Attachment of Muscles.—To twelve; by the olecranon, to the triceps extensor cubiti, one head of the flexor carpi ulnaris, and the anco- neus ; by the coronoid process, to the brachialis anticus, pronator radii teres, flexor sublimis digitorum, and flexor pro- fundus digitorum; by the shaft, to the flexor profundus Fi8-54-* digitorum, flexor carpi ulnaris, pronator quadratus, * anconeus, extensor carpi ulnaris, extensor ossis meta- carpi pollicis, extensor secundi internodii pollicis, and extensor indicis. Radius.—The radius is the rotatory bone of the fore- arm ; it is divisible into a shaft and two extremities: unlike the ulna, its upper extremity is small, and merely accessory to the formation of the elbow-joint; while the lower extremity is large, and forms almost .solely the joint of the wrist. The superior extremity presents a rounded head, depressed upon its upper surface into a shallow cup. Around the margin of the head is a smooth articular surface, which is broad on the inner side, where it articulates with the lesser sigmoid notch of the ulna, and narrow in the rest of its circumference, to play in the orbicular ligament. Beneath the head is a round constricted neck; and beneath the neck, on its internal aspect, a prominent process, the tuberosity. The sur- ' face of the tuberosity is partly smooth, and partly rough; rough below, where it receives the attachment of the tendon of the biceps ; and smooth above, where a bursa is interposed between the tendon and the bone. The shaft of the bone is prismoid, and presents three surfaces. The anterior surface is somewhat concave superiorly, where it lodges the flexor longus pollicis; and flat below, where it supports the pronator quadratus. At about the upper third of this surface is the nutritious foramen, which is directed upwards. The posterior surface is round above, where it supports the supinator brevis muscle, and marked by several shallow oblique grooves below, which afford attachment to the extensor muscles of the thumb. The external sur- face is rounded and convex, and marked by an oblique ridge, which * The two bones of the fore-arm seen from the front. 1. The shaft of the ulna. 2. The greater sigmoid notch. 3. The lesser sigmoid notch, with which the head of the radius is articulated. 4. The olecranon process., 5. The coronoid process. 6. The nutritious foramen. 7. The sharp ridges upon the two bones to which the interosseous membrane is attached. 8. The capitulum ulnce. 9. The styloid process. 10. The shaft of the radius. 11. Its head surrounded by the smooth border for articulation with the orbicular ligament. 12. The neck of the radius. 13. Its tuberosity. 14. The oblique line. 15. The lower extremity of the bone. 16. Its styloid process. jjg CARPUS—SCAPHOID BONE. * extends from the tuberosity to the styloid process at the lower extre- mity of the bone. Upon the inner margin of the bone is a sharp and prominent crest, which gives attachment to the interosseous mem- brane. The lower extremity of the radius is broad and triangular, and provided with two articular surfaces; one at the side of the bone, which is concave to receive the rounded head of the ulna; the other at the extremity, and marked by a slight ridge into two facets, one external and triangular, corresponding with the scaphoid; the other square, with the semilunar bone. Upon the outer side of the extremity is a strong conical projection, the styloid process, which gives attachment by its base to the tendon of the supinator longus, and by its apex to the external lateral ligament of the wrist joint. The inner edge of the articular surface affords attachment to the base of the inter-articular cartilage of the ulna. Immediately in front of the styloid process is a groove, which lodges the tendons of the extensor ossis metacarpi pollicis, and exten- sor primi internodii; and behind the process a broader groove, for the tendons of the extensor carpi radialis longior and brevior, and ex- tensor secundi internodii; behind this is a prominent ridge, and a deep and narrow groove, for the tendon of the extensor indicis; and still farther back part of a broad groove, completed by the ulna, for the tendons of the extensor communis digitorum. Developement.—By three centres; one for the shaft, and one for each extremity. Ossification commences in the shaft soon after the humerus, and before that in the ulna. The inferior centre appears during the second year, and the superior about the seventh. The bone is perfected at twenty. Articulations.—With four bones; humerus, ulna, scaphoid, and semilunar. Attachment of Muscles.—To nine; by the tuberosity to the biceps; by the oblique ridge to the supinator brevis, pronator radii teres, flexor sublimis digitorum and pronator quadratus; by the anterior surface, to the flexor longus pollicis and pronator quadratus; by the posterior surface, to the extensor ossis metacarpi pollicis, and exten- sor primi internodii; and by the styloid process, to the supinator longus. Carpus.—The bones of the carpus are eight in number; they are arranged in two rows. In the first row, commencing from the radial side, are the os scaphoides, semilunare, cuneiforme, pisiforme; and in the second row, in the same order, the os trapezium, trapezoides, os magnum, and unciforme. The Scaphoid bone is named from bearing some resemblance to the shape of a boat, being broad at one end, and narrowed like a prow at the opposite, concave on one side, and convex upon the other. It is, however, more similar in form to a cashew nut, flattened and concave upon one side. If carefully examined, it will be found to present a convex and a concave surface, a convex and a concave border, a broad end, and a narrow and pointed extremity, the tube- rosity. SEMILUNARE. 117 Fig. 55.* To ascertain to which hand the bone belongs, let the student hold it horizontally, so that the convex surface may look backwards [i. e. towards himself), and the convex border upwards : the broad extre- mity will indicate its appropriate hand; if it be directed to the rignt, the bone belongs to the right; and if to the left, to the left carpus. Articulations.—With five bones; by its convex surface with the radius; by its con- cave surface, with the os magnum and semilunare; and by the extremity of its upper or dorsal border, with the trapezium and trapezoides. Attachments.—By its tuberosity to the abductor pollicis, and anterior annular liga- ment. The Semilunar bone may be known by having a crescentic concavity, and a some- what crescentic outline. It presents for examination four articular surfaces and two extremities; the articular surfaces are, one concave, one convex, and two lateral, one lateral surface being crescentic, the other nearly circular, and divided generally into two facets. The extre- mities are, one dorsal, which is quadilateral, flat, and indented, for the attachment of ligaments; the other palmar, which is convex, rounded, and of larger size. To determine to which hand it belongs, let the bone be held per- pendicularly, so that the dorsal or flat extremity look upwards, and the convex side backwards (towards the holder). The circular la- teral surface will point to the side corresponding with the hand to which the bone belongs. Articulations.—With five bones, but occasionally with only four: by its convex surface, with the radius; by its concave surface, with the os magnum; by its crescentic lateral facet, with the scaphoid; and by the circular surface, with the cuneiform bone and with the point of the unciform. This surface is divided into two parts by a ridge when it articulates with the unciform as well as with the cunei- form bone. - The Cuneiform bone, although somewhat wedge-shaped in form,may be best distinguished by a circular and isolated facet, which articulates with the pisiform bone. It presents for examination three surfaces, a base, and an apex. One surface is very rough and irregular; the oppo- site forms a concave articular surface, while the third is partly rough * A diagram showing the dorsal surface of the bones of the carpus, with their articu- lations.—The right hand. 2. The lower end of the radius. 1. The lower extremity of the ulna 3. The intcr-articular fibro-cartilage attached to the styloid process of the ulna, and to the margin of the articular surface of the radius. S. The scaphoid bone. L. The semilunare articulating with five bones. C. The cuneiforme, articulating with three bones. P. The pisiforme, articulating with the cuneiforme only. T. The first bone of the second row,—the trapezium, articulating with four boaes. T. The second bone,-the trapezoides, articulating also with four bones. M. The os magnum, articulating with seven. U. I he unciforme, articulating with five. 118 TRAPEZIUM—TRAPEZOIDES. and partly smooth, and presents that circular facet which is character- pistic of the bone. The base is an articular surfacea, end the apex is rough andpointed. To distinguish its appropriate hand, let the base be directed back- wards and the pisiform facet upwards; the concave articular surface will point to the hand to which the bone belongs. Articulations.—With three bones, and with the triangular fibro- cartilage. By the base, with the semilunare; by the concave surface, with the unciforme; by the circular facet, with the pisiforme; and by the superior angle of the rough surface, with the fibro-cartilage. The Pisiform bone may be recognised by its small size, and by possessing a singular articular facet. If it be examined carefully it will be observed to present four sides and two extremities; one side is articular, the smooth facet approaching nearer to the su- perior than the inferior extremity. The side opposite to this is rounded, and the remaining sides are, one slightly concave, the other slightly convex. If the bone be held so that the articular facet shall look downwards and the extremity which overhangs the articular facet forwards, the concave side will point to the hand to which it belongs. Articulations.—With the cuneiform bone only. Attachments.—To two muscles, the flexor carpi ulnaris, and abduc- tor minimi digiti; and to the anterior annular ligament. The Trapezium (os multangulum majus) is loo irrregular in form to be compared to any known object; it may be distinguished by a deep groove, for the tendon of the flexor carpi radialis muscle. It is somewhat compressed, and may be divided into two surfaces which are smooth and articular, and three rough borders. One of the arti- cular surfaces is oval, concave in one direction, and convex in the other (saddle-seat shaped); the other is marked into three facets. One of the borders presents the groove for the tendon of the flexor carpi radialis, which is surmounted by a prominent tubercle for the attach- ment of the annular ligament; the other two borders are rough and form the outer side of the carpus. The grooved border is narrow at one extremity and broad at the other, where it presents the groove and tubercle. If the bone be held so that the grooved border look upwards while the»apex of this border be directed forwards, and the base with the tubercle backwards, the concavo-convex surface will point to the hand to which the bone belongs. Articulations.—With four bones; by the concavo-convex surface, with the metacarpal bone of the thumb; and by the three facets of the other articular surface, with the scaphoid, trapezoid, and second metacarpal bone. Attachments.—To two muscles, abductor pollicis and flexor ossis metacarpi; and by the tubercle, to the annular ligament. The Trapezoides (os multangulum minus) is a small, oblono-, and quadrilateral.bone, bent near its middle upon itself (bean-shaped). It presents four articular surfaces arid two extremities. One of the sur- faces is concavo-convex, i. e. concave in one direction, and convex in OS MAGNUM-UNCIFORME. 119 the other; another, contiguous to the preceding, is concave, so as to be almost angular in the middle, and is often marked by a small rough depression, for an interosseous ligament; the two remaining sides are flat, and present nothing remarkable. One of the two extremities is broad and of large size, the dorsal; the other, or palmar, is small and rough. If the bone be held perpendicularly, so that the broad extremity be upwards, and the concavo-convex surface forwards, the angular con- cave surface will point to the hand to which the bone belongs. Articulations.—With four bones; by the concavo-convex surface, with the second metacarpal bone; by the angular concave surface, with the os magnum; and by the other two surfaces, with the trape- zium and scaphoid. Attachments.—To the flexor brevis pollicis muscle. The Os Magnum (capitatum) is the largest bone of the carpus, and is divisible into a body and head. The head is round for the greater part of its extent, but is flattened on one side. The body is irregularly quadrilateral, and presents four sides and a smooth extremity. Two of the sides are rough, the one being square and flat, the dorsal; the other rounded and prominent, the palmar; the other two sides are articular, the one being concave, the other convex. The extremity is a triangular articular surface, divided into three facets. If the bone be held perpendicularly, so that the articular extremity look upwards and the broad dorsal surface backwards (towards the holder), the con- cave articular surface will point to the hand to which the bone belongs. Articulations.—With seven bones; by the rounded head, with the cup formed by the scaphoid and semilunar bone; by the side of the convex surface, with the trapezoides; by the concave surface, with the unciforme; and by the extremity, with the second, third, and fourth metacarpal bones. Attachments.—To the flexor brevis pol- licis muscle. The Unciforme is a triangular-shaped bone, remarkable for a long and curved pro- cess, which projects from its palmar aspect. It presents five surfaces;—three articular, and two free. One of the articular surfaces is divided by a slight ridge into two facets; the other two converge, and meet at a flattened angle.f One of the Fig. 56.* * The hand viewed upon its anterior or palmar aspect. 1. The scaphoid bone. 2. The semilunare. 3. The cuneiforme. 4. The pisiforme. 5. The trapezium. 6. The groove in the trapezium that lodges the tendon of the flexor carpi radialis. 7. The trapezoides. 8. The os magnum. 9. The unciforme. 10, 10. The five metacarpal bones. 11, 11. The first row of phalanges. 12, 12. The second row. 13, 13. The third row, or ungual phalanges. 14. The first phalanx of the thumb. 15. The second and last phalanx ofthe thumb. t When the unciforme does not articulate with the semilunare, this angle is sharp. 120 METACARPUS. free surfaces, the dorsal, is rough and triangular; the other, palmar, also triangular, but somewhat smaller, gives origin to the unciform process. If the bone be held perpendicularly, so that the articular surface with two facets look upwards, and the unciform process backwards (towards the holder), the concavity of the unciform process will point to the hand to which the bone belongs. Articulations.—With five bones; by the two facets on its base, with the fourth and fifth metacarpal bones; by the two lateral articu- lating surfaces, with the os magnum and cuneiforme; and by the flat- tened angle of its apex, with the semilunare. Attachments.—To two muscles, abductor minimi digiti, and flexor brevis minimi digiti; and by the hook-shaped process to the annular ligament. Developement.—The bones of the carpus are each developed by a single centre; they are cartilaginous at birth. Ossification commences towards the end of the first year in the os magnum and unciforme; at the end of the third year in the cuneiforme; during the fifth year in the trapezium and semilunare; during the eighth, in the scaphoides; the ninth, in the trapezoides; and the twelfth in the pisiforme. The latter bone is the last in the skeleton to ossify; it is, in reality, a sesamoid bone of the tendon of the flexor carpi ulnaris. The number of articulations which each bone of the carpus pre- sents with surrounding bones, may be expressed in figures, which will materially facilitate their recollection; the number for the first row is 5531, and for the second 4475. Metacarpus.—The bones of the metacarpus are five in number. They are long bones, divisible into a head, shaft, and base. The head is rounded at the extremity, and flattened at each side, for the insertion of strong ligaments; the shaft is prismoid, and marked deeply on each side, for the attachment of the interossei muscles; and the base is irregularly quadrilateral and rough, for the insertion of tendons and ligaments. The base presents three arti- cular surfaces, one at each side, for the adjoining metacarpal bones; and one at the extremity for the carpus. The metacarpal bone of the thumb is one-third shorter than the rest, flattened and broad on its dorsal aspect, and convex on its palmar side; the articular surface of the head is not so round as that of the other metacarpal bones; and the base has a single concavo- convex surface, to articulate with the similar surface of the tra- pezium. The metacarpal bones of the different fingers may be distinguished by certain obvious characters. The base of the metacarpal bone of the index finger is the largest of the four, and presents four articular surfaces. That of the middle finger may be distinguished by a rounded projecting process upon the radial side of its base, and two small circular facets upon its ulnar lateral surface. The base of the metacarpal bone of the ring-finger is small and square, and has two small circular facets to correspond with those of the middle meta- PHALANGES. 121 carpal. The metacarpal bone of the little finger has only one lateral articular surface. Developement.—By two centres; one for the shaft, and one for the digital extremity, with the exception of the metacarpal bone of the thumb, the epiphysis of which, like that of the phalanges, occupies the carpal end of the bone. Ossification of the metacarpal bones commences in the embryo between the tenth and twelfth week, that is, soon after the bones of the fore-arm. The epiphyses make their appearance at the end of the second, or early in the third year, and the bones are completed at twenty. Articulations.—The first with the trapezium ; second, with the tra- pezium, trapezoides, and os magnum, and with the middle metacarpal bone; third, or middle, with the os magnum, and adjoining meta- carpal bones; fourth, with the os magnum and unciforme, and with the adjoining metacarpal bones; and, fifth, with the unciforme, and with the metacarpal bone of the ring-finger. The figures resulting from the number of articulations which each metacarpal bone possesses, taken from the radial to the ulnar side, are 13121. Attachment of Muscles. — To the metacarpal bone of the thumb, three, the flexor ossis metacarpi, extensor ossis metacarpi, and first dorsal interosseous; of the index finger, five, the extensor carpi radialis longior, flexor carpi radialis, first and second dorsal interosseous, and first palmar interosseous; of the middle finger, four, the extensor carpi radialis brevior, adductor pollicis, and second and third dorsal interosseous; of the ring finger, three, the third and fourth dorsal interosseous, and second palmar; and of the little finger, four, ex- tensor carpi ulnaris, adductor minimi digiti, fourth dorsal, and third palmar interosseous. Phalanges.—The phalanges are the bones of the fingers; they are named from their arrangement in rows, and are fourteen in number, three to each finger, and two to the thumb. In conformation they are long bones, divisible into a shaft, and two extremities. The shaft is compressed from before backwards, convex on its posterior surface, and flat with raised edges in front. The meta- carpal extremity, or base, in the first row, is a simple concave arti- cular surface, that in the other two rows a double concavity, sepa- rated by a slight ridge. The digital extremities of the first and second row present a f>ulley-like surface, concave in the middle, and convex on each side. The ungual extremity of the last phalanx is broad, rough, and expanded into a semilunar crest. Developement.—By two centres; one for the shaft, and one for the base. Ossification commences first in the third phalanges, then in the first, and lastly in the second. The period of commencement corresponds with that of the metacarpal bones. The epiphyses of the first row appear during the third or fourth year, those of the second row during the fourth or fifth, and of the last during the sixth or seventh. The phalanges are perfected by the twentieth year. Articulations.—The first row, with the metacarpal bones and 11 122 OS 1NNOMINATUM—ILIUM. second row of phalanges; the second row, with the first and third; and the third, with the second row. Attachment of Muscles. — To the base of the first phalanx of the thumb four muscles, abductor pollicis, flexor brevis pollicis, adductor pollicis, and extensor primi internodii; and to the second phalanx, two, the flexor longus pollicis, and extensor secundi internodii. To the first phalanx of the second, third, and fourth fingers, one dorsal and ^>ne palmar interosseous, and to the first phalanx of the little finger, the abductor minimi digiti, flexor brevis minimi digiti, and one palmar interosseous. To the second phalanges, the flexor sub- limis and extensor communis digitorum ; and to the last phalanges, the flexor profundus and extensor communis digitorum. PELVIS AND LOWER EXTREMITY. The bones of the pelvis are the two ossa innominata, the sacrum, and the coccyx; and of the lower extremity, the femur, patella, tibia and fibula, tarsus, metatarsus, and phalanges. Os Innominatum. Fig. 57.* -The os innominatum (os coxae) is an irregular flat bone, consisting in the young subject of three parts, which meet at the acetabulum. Hence it is usually described in the adult as divisible into three portions, ilium, ischium, and pubes. The ilium is the superior, broad, and expanded portion which forms the promi- nence of the hip, and articulates with the sacrum. The ischium is the inferior and strong part of the bone on which we sit. The os pubis is that portion which forms the front of the pelvis, and gives support to the external organs of generation. The Ilium may be described as divisible into an internal and ex- ternal surface, a crest, and an an- terior and posterior border. The internal surface is bounded above by. the crest, below by a prominent line, the linea ilio-pectinea, and before and behind by the anterior and posterior borders; it is concave and smooth for the an- terior two-thirds of its extent, and lodges the iliacus muscle. The * The os innominatum of the right side. 1. The ilium; its external surface. 2. The T'T- c ■ os Pubis- 4. The crest of the ilium. 5. The superior curved line. 6. The inferior curved line. 7. The surface for the gluteus maximus. 8 The anterior superior spinous process. 9. The anterior inferior spinous process. 10. The posterior superior spinous process. 11. The posterior inferior spinous process. 12 The spine of the ischium. 13 The great sacro-ischiatic notch. 14. The lesser sacro-'ischiatic notch. 15. Ihe tuberosity of the ischium, showing its three facets. 16. The ramus of the is chium 17 The body of the os pubis. 18. The ramus of the pubis. 19. The acetabu" lum. 20. The foramen thyroideum. ISCHIUM. 123 posterior third is rough, for articulation with the sacrum, and is divided by a deep groove into two parts; an anterior or auricu- lar portion, which is shaped like the pinna, and coated by cartilage in the fresh bone; and a posterior portion, which is very rough and uneven for the attachment of interosseous ligaments. The external surface is uneven, partly convex, and partly concave; it is bounded above by the crest; below by a prominent arch, which forms the upper segment of the acetabulum ; and before and behind, by the anterior and posterior borders. Crossing this surface in an arched direction, from the anterior extremity of the crest to a notch upon the lower part of the posterior border, is a groove, which lodges the gluteal vessels and nerve, the superior curved line; and below this, at a short distance, a rough ridge, the inferior curved line. The surface included between the superior curved line and the crest, gives origin to the gluteus medius muscle; that between the curved lines, to the gluteus minimus; and the rough interval between the inferior curved line and the arch of the acetabulum, to one head of the rectus. The posterior sixth of this surface is rough and raised, and gives origin to part of the gluteus maximus. The crest of the ilium is arched and curved in its direction like the italic letter/, being bent inwards at its anterior termination, and out- wards towards the posterior. It is broad for the attachment of three planes of muscles, which are connected with its external and internal borders or lips, and with the intermediate space. The anterior border is marked by two projections, the anterior su- perior spinous process, which is the anterior termination of the crest, and the anterior inferior spinous process; the two processes being separated by a notch for the attachment of the sartorius muscle. This border terminates inferiorly in the lip of the acetabulum. The poste- rior border also presents two projections, the posterior superior and the posterior inferior spinous process, separated by a notch. Inferiorly this border is broad and arched, and forms the upper part of the great sacro-ischiatic notch. The Ischium is divisible into a thick and solid portion, the body, and into a thin and ascending part, the ramus; it may be considered also, for convenience of description, as presenting an external and internal surface, and three borders, posterior, inferior, and superior. The external surface is rough and uneven, for the attachment of muscles; and broad and smooth above, where it enters into the for- mation of the acetabulum. Below the inferior lip of the acetabulum is a notch, which lodges the obturator externus muscle in its passage outwards to the trochanteric fossa of the femur. The internal sur- face is smooth, and somewhat encroached upon at its posterior border by the spine. The posterior border of the ischium presents towards its middle a remarkable projection, the spine. Immediately above the spine is a notch of large size, the great sacro-ischiatic, and below the spine the lesser sacro-ischiatic notch; the former being converted into a foramen by the lesser sacro-ischiatic ligament, gives passage to the pyriformis muscle, the gluteal vessels and nerve, pudic vessels and nerve, and 124 OS PUBIS. ischiatic vessels and nerve; and the lesser, completed by the great sacro-ischiatic ligament, to the obturator internus muscle, and to the internal pudic vessels and nerve. The inferior border is thick and broad, and is called the tuberosity. The surface of the tuberosity is divided into three facets; one anterior, which is rough for the origin of the semi-membranosus; and two posterior, which are smooth, and separated by a slight ridge for the semi-tendinosus and biceps muscle. The inner margin of the tuberosity is bounded by a sharp ridge, which gives attachment to a prolongation of the great sacro-ischiatic ligament, and the outer margin by a prominent ridge, from which the quadratus femoris muscle arises. The superior border of the ischium is thin, and forms the lower circumference of the obturator foramen. The ramus of the ischium is continuous with the ramus of the pubis, and is slightly everted. The Os Pubis is divided into a horizontal portion or body (horizontal ramus of Albinus), and a descending portion or ramus; it presents for examination an external and internal surface, a superior and in- ferior border, and symphysis. The external surface is rough, for the attachment of muscles; and prominent at its outer extremity, where it forms part of the acetabu- lum. The internal surface is smooth and enters into the formation of the cavity of the pelvis. The superior border is marked by a rough ridge, the crest; the inner termination of the crest is the angle; and the outer end, the spine or tubercle. Running outwards from the spine is a sharp ridge, the pectineal line, or linea ilio-pectinea, which marks the brim of the true pelvis. In front of the pectineal line is a smooth depression, which supports the femoral artery and vein, and a little more externally an elevated prominence, the ilio-pectineal emi- nence, which divides the surface for the femoral vessels, from another depression which overhangs the acetabulum, and lodges the psoas and iliacus muscles. The ilio-pectineal eminence moreover marks the junction of the pubes with the ilium. The inferior border is broad and deeply grooved, for the passage of the obturator vessels and nerve; and sharp upon the side of the ramus, to form part of the boundary of the obturator foramen. The symphysis is the inner ex- tremity of the body of the bone; it is oval and rough, for the attach- ment of a ligamentous structure analogous to the intervertebral sub- stance. The ramus of the pubes descends obliquely outwards, and is continuous with the ramus of the ischium. The inner border of the ramus forms with the corresponding bone the arch of the pubes, and at its inferior part is considerably everted, to afford attachment to the crus penis. The acetabulum (cavitas cotyloidea) is a deep cup-shaped cavity, situated at the point of union between the ilium, ischium, and pubes; a little less than two-fifths being formed by the ilium, a little more than two-fifths by the ischium, and the remaining fifth by the pubes. It is bounded by a deep rim or lip, which is broad and strong above, where most resistance is required, and marked in front by a deep notch, which is arched over in the fresh subject by a strong ligament, and transmits the nutrient vessels into the joint. At the bottom of the cup and communicating with the notch, is a deep and circular pit PELVIS. 125 (fundus acetabuli), which lodges a mass of fat and gives attachment to the broad extremity of the ligamentum teres. The obturator or thyroid foramen is a large oval interval between the ischium and pubes, bounded by a narrow rough margin, to which a ligamentous membrane is attached. The upper part of the fora- men is increased in depth by the groove in the under surface of the os pubis which lodges the obturator vessels and nerve. Developement.—By eight centres; three principal, one for the ilium, one for the ischium, and one for the pubes; and five secondary, one, the Y-shaped piece for the interval between the primitive pieces in the acetabulum, one for the crest of the ilium, one (not constant) for the anterior and inferior spinous process of the ilium, one for the tu- berosity of the ischium, and one (not constant) for the angle of the os pubis. Ossification commences in the primitive pieces, immediately after that in the vertebrae, firstly in the ilium, then in the ischium, and lastly in the pubes; the first ossific deposits being situated near to the future acetabulum. At birth the acetabu- lum, the crest of the ilium, and the ramus of the pubes and ischium, are cartilaginous. The secondary centres appear at puberty, and the entire bone is not completed until the twenty-fifth year. Articulations.—With three bones; sacrum, opposite innominatum, and femur. Attachments of Muscles and Ligaments.—To thirty-five muscles ; to the ilium, thirteen; by the outer lip of the crest, to the obliquus ex- ternus for two-thirds, and to the latissimus dorsi for one-third its length, and to the tensor vaginae femoris by its anterior fourth ; by the middle crest, to the internal oblique for three-fourths its length, by the remaining fourth to the erector spinae; by the internal lip, to the transversalis for three-fourths, and to the quadratus lumborum by the posterior part of its middle third. By the external surface, to the gluteus medius, minimus and maximus, and to one head of the rectus; by the internal surface, to the iliacus; and by the anterior border to the sartorius, and the other head of the rectus. To the ischium, sixteen; by its external surface, the adductor magnus and obturator externus; by the internal surface, the obturator internus and levator ani; by the spine, the gemellus superior, levator ani, coccygeus, and lesser sacro-ischiatic ligament; by the tuberosity, the biceps, semi- tendinosus, semi-membranosus, gemellus inferior, quadratus femoris, erector penis, transversus perinei, and sreat sacro-ischiatic ligament; and by the ramus, the gracilis, accelerator urinae, and compressor urethrae. To the os pubis,fifteen; by its upper border the obliquus externus, obliquus internus, transversalis, rectus, pyramidalis, pecti- neus, and psoas parvus; by its external surface the adductor longus, adductor brevis, and gracilis ; by its internal surface, the levator ani, compressor urethras* and obturator internus; and by the ramus, the adductor magnus, and accelerator urinae. pelvi s. The pelvis considered as a whole is divisible into a. false and true pelvis; the former is the expanded portion, bounded on each side by 11* 126 PELVIS. the ossa ilii, and sepa- Fig. 58.* rated from the true pelvis by the linea ilio- pectinea. The true pelvis is all that por- tion which is situated beneath the linea ilio- pectinea. This line forms the margin or brim of the true pelvis, while the included area is called the inlet. The form of the inlet is heart-shaped, obtusely pointed in front at the symphysis pubis, ex- panded on each side, and encroached upon behind by a projection of the upper part of the sacrum, which is named the promontory. The cavity is somewhat encroached upon at each side by a smooth quadrangular plane of bone, corresponding with the internal surface of the acetabulum, and leading to the spine of the ischium. In front are two fossae around the obturator foramina, for lodging the obtu- rator internus muscle, at each side. The inferior termination of the pelvis is very irregular, and is termed the outlet. It is bounded in front by the convergence of the rami of the ischium and pubes, which constitute the arch of the pubes ; on each side by the tuberosity of the ischium, and by two irregular fissures formed by the greater and lesser sacro-ischiatic notches; and behind by the lateral borders.of the sacrum, and by the coccyx. The pelvis is placed obliquely with regard to the trunk of the body, so that the inner surface of the ossa pubis is directed upwards, and would support the superincumbent weight of the viscera. The base of the sacrum rises nearly four inches above the level of the upper border of the symphysis pubis and the apex of the coccyx, somewhat more than half an inch above its lower border. If a line were car- ried through the central axis of the inlet, it would impinge by one * A female pelvis. 1. The last lumbar vertebra. 2, 2. The intervertebral substance con- necting the last lumbar vertebra with the fourth and sacrum. 3. The promontory of the sacrum. 4. The anterior surface of the sacrum, on which its transverse lines and fora- mina are seen. 5. The tip of the coccyx. 6, 6. The iliac fossas, forming the lateral boundaries of the false pelvis. 7. The anterior superior spinous process of the ilium; left side. 8. The anterior inferior spinous process. 9. The acetabulum, a. The notch of the acetabulum, b. The body of the ischium, c. Its tuberosity, d. The spine of the ischium seen through the obturator foramen, e. The os pubis, f. The symphysis pubis. g. The arch of the pubes. h. The angle of the os pubis, i. The spine of the pubes; the prominent ridge between h and i is the crest of the pubes. k, k. The pectineal line of the pubes. I, 1. The ilio-pectineal line; m, m. the prolongation of this line to the promontory of the sacrum. The line represented by h, i. k, k. I, 1. and m, m. is the brim of the true pelvis, n. The ilio-pectineal eminence, o. The smooth surface which supports the femoral vessels, p, p. The great sacro-ischiatic notch. PELVIS-FEMUR. 127 extremity against the umbilicus, and by the other against the middle of the coccyx. The axis of the inlet is therefore directed downwards and backwards, while that of the outlet points downwards and for- wards, and corresponds with a line drawn from the upper part of the sacrum, through the centre of the outlet. The axis of the cavity represents a curve, which corresponds very nearly with the curve of the sacrum, the extremities being indicated by the central points of the inlet and outlet. A knowledge of the direction of these axes is most important to the surgeon, as indicating the line in which instru- ments should be used in operations upon the viscera of the pelvis, and the direction of force in the removal of calculi from the bladder; and to the accoucheur, as explaining the course taken by the foetus during parturition. There are certain striking differences between the male and female pelvis. In the male the bones are thicker, stronger, and more solid, and the cavity deeper and narrower. In the female the bones are lighter and more delicate, the iliac fossae are large, and the ilia ex- panded ; the inlet, the outlet, and the cavity, are large, and the ace- tabula farther removed from each other; the cavity is shallow, the tuberosities widely separated, the obturator foramina triangular, and the span of the pubic arch greater. The precise diameter of the inlet and outlet, and the depth of the cavity, are important considera- tions to the accoucheur. The diameters of the inlet or brim are three: 1. Antero-posterior, sacro-pubic or conjugate; 2. transverse ; and 3. oblique. The antero- posterior extends from the symphysis pubis to the middle of the pro- montory of the sacrum, and measures four inches. The transverse extends from the middle of the brim on one side to the same point on the opposite, and measures five inches. The oblique extends from the sacro-iliac symphysis on one side, to the margin of the brim cor- responding with the acetabulum on the opposite, and also measures five inches. The diameters of the outlet are two, antero-posterior, and transverse. The antero-posterior diameter extends from the lower part of the sym- physis pubis to the apex of the coccyx ; and the transverse, from the posterior part of one tuberosity to the same point on the opposite side; they both measure four inches. The cavity of the pelvis measures in depth four inches and a half, posteriorly; three inches and a half in the middle ; and one and a half at the symphisis pubis. Femur. The femur, the longest bone of the skeleton, is situated obliquely in the upper part of the lower limb, articulating by means of its head with the acetabulum, and inclining inwards as it descends, until it almost meets its fellow of the opposite side at the knee. In the female this obliquity is greater than in the male, in consequence of the greater breadth of the pelvis. The femur is divisible into a shaft, a superior, and an inferior extremity. At the superior extremity is a rounded head, directed upwards and inwards, and marked just below its centre by an oval depression for the ligamentum teres. The head is supported by a neck, which varies in length and obliquity according to sex and at various periods of life, 128 FEMUR. being long and oblique in the adult male, shorter and more horizontal in the female and in old age. Externally to the neck is a large pro- cess, the trochanter major, which presents upon its anterior surface an oval facet, for the attachment of the tendon of the gluteus minimus muscle; and above, a double facet, for the insertion of the gluteus medius. On its posterior side is a vertical ridge, the linea quadrati, for the attachment of the quadratus femoris muscle. Upon the inner side of the trochanter major is a deep pit, the trochanteric or digital fossa, in which are inserted the tendons of the pyriformis, gemellus superior and inferior, and obturator externus and internus muscles. Passing downwards from the trochanter major in front of the bone is an oblique ridge, which forms the inferior boundary of the neck, the anterior intertrochanteric line ; and, behind another oblique ridge, the posterior intertrochanteric line, which terminates in a rounded tu- bercle upon the posterior and inner side of the bone, the trochanter minor. The shaft of the femur is convex and rounded in Fig.59.* front, and covered with muscles; and somewhat concave and raised into a rough prominent ridge behind, the linea aspera. The linea aspera near the upper extremity of the bone divides into three branches. The anterior branch is continued for- wards in front of the lesser trochanter, and is con- tinuous with the anterior intertrochanteric line; the middle is continued directly upwards into the linea quadrati; and the posterior, broad and strongly marked, ascends to the base of the trochanter major. Towards the lower extremity of the bone, the linea aspera divides into two ridges, which descend to the two condyles, and enclose a trian- gular space upon which rests the popliteal artery. The internal condyloid ridge is less marked than the external, and presents a broad and shallow groove, for the passage of the femoral artery. The nutritious foramen is situated in or near the linea aspera, at about one-third from its upper extremity, and is directed obliquely from below upwards. The lower extremity of the femur is broad and porous, and divided by a smooth depression in front, and by a large fossa (fossa intercondyloidea) behind into two condyles. The external condyle is the broadest and most prominent, and the internal the narrowest and longest; the difference in length depending upon the obliquity of the *«The right femur, seen upon the anterior aspect. 1. The shaft. 2. The head. 3. The neck. 4. The great trochanter. 5. The anterior intertrochanteric line. 6. The lesser trochanter. 7. The external condyle. 8. The internal condyle. 9. The tuberosity for the attachment of the external lateral ligament. 10. The fossa for the tendon of origin of the popliteus muscle. 11. The tuberosity for the attachment of the internal lateral ligament. FEMUR. 129 femur, in consequence of the separation of the two bones at their upper extremities by the breadth of the pelvis. The external condyle is marked upon its outer side by a prominent tuberosity, which gives attachment to the external lateral ligament; and immediately beneath this is the fossa, which lodges the tendon of origin of the popliteus. By the internal surface it gives attachment to the anterior crucial ligament of the knee-joint; and by its upper and posterior part, to the external head of the gastrocnemius and to the plantaris. The internal condyle projects upon its inner side into a tuberosity, to which is attached the internal lateral ligament; above this tuberosity, at the extremity of the internal condyloid ridge, is a tubercle, for the insertion of the tendon of the adductor magnus; and beneath the tubercle, upon the upper sur- face of the condyle, a depression, from which the internal head of the gastrocnemius arises. The outer side of the internal condyle is rough and concave, for the attachment of the posterior crucial ligament. Developement.—By five centres; one for the shaft, one for each extremity, and one for each trochanter. Fis-60-* The femur is the first of the long bones to show signs of ossification. In it, ossific matter is found immediately after the maxillae before the termination of the second month of embryonic life. The se- condary deposits take place in the following order, in the condyloid extremity during the last month of foetal life ;f in the head towards the end of the first year; in the greater trochanter between the third and the fourth year ; in the lesser trochanter between the thirteenth and fourteenth. The epiphyses and apophyses are joined to the diaphysis in the reverse order of their appearance, the junction commencing after puberty and not being completed for the con- dyloid epiphysis until after the twentieth year. Articulations.—With three bones; with the os in- nominatum, tibia, and patella. Attachment of Muscles.—To twenty-three; by the greater trochanter, to the gluteus medius and mini- mus, pyriformis, gemellus superior, obturator inter- nus, gemellus inferior, obturator externus, and quad- ratus femoris; by the lesser trochanter, to the com- mon tendon of the psoas and iliacus. By the linea asj^ra, its outer lip, to the vastus externus, gluteus maximus, and short head of the biceps ; by its inner lip, to the vastus internus, pectineus, adductor brevis, and adductor longus; by its middle to the adductor magnus; by the * A diagram of the posterior aspect of the right femur, showing the lines of attachment of the muscles. The muscles attached to the inner lip are,—p, the pectineus; a b, the adductor brevis; and a I, the adductor longus. The middle portion is occupied for its whole extent by a m, the adductor magnus; and is continuous superiorly with qf, the linea quadrati, into which the quadratus femoris is inserted. The outer lip is occupied by gm, the gluteus maximus ; and b, the short head of the biceps. t Cruvcilhicr remarks that this centre is so constant in the last fortnight of ftetal life, that it may be regarded as an important proof of the foetus having reached its full term. 130 PATELLA—TIBIA. anterior part of the bone, to the cruraeus and subcruraeus ; by its con- dyles, to the gastrocnemius, plantaris, and popliteus. Patella.—The patella is a sesamoid bone, developed in the tendon of the quadriceps extensor muscle, and usually described as a bone of the lower extremity. It is heart-shaped in figure, the broad side being directed upwards and the apex downwards, the external surface convex, and the internal divided by a ridge into two smooth surfaces, to articulate with the condyles of the femur. The external articular surface corresponding with the external condyle is the larger of the two, and serves to indicate the leg to which the bone belongs. Developement.—By a single centre, at about the middle of the third year. Articulations.—With the two condyles of the femur. Attachment of Muscles.—To four; the rectus, cruraeus, vastus in- ternus, and vastus externus, and to the ligamentum patellae. Fig. 61.* Tibia.—The tibia is the inner and larger bone of the leg; it is prismoid in form, and divisible into a shaft, an upper and lower extremity. The upper extremity, or head, is large, and expanded on each side into two tuberosities. Upon their upper surface the tuberosities are smooth, to articulate with the condyles of the femur ; the internal articular sur- face being oval and oblong, to correspond with the internal condyle; and the external broad and nearly circular. Between the two articular surfaces is a spinous process; and in front and behind the spinous process a rough depression, giving attachment to the anterior and posterior crucial ligaments. Between the two tubeirosties, on the front aspect of the bone, is a prominent elevation, the tubercle, for the inser- tion of the ligamentum patellae, and immediately above the tubercle a smooth facet, corresponding with the bursa. Upon the outer side of the external tuberosity is an articular surface, for the head of the fibula; and upon the posterior part of the internal tuberosity a depression, for the insertion of the tendon of the se- mimembranosus muscle. The shaft of the tibia presents three surfaces; in- ternal, which is subcutaneous and superficial; exter- nal, which is concave and marked by a sharp ridge, for the insertion of the interosseous membrane; and posterior, grooved, for the attach- ment of muscles. Near the upper extremity of the posterior surface •The tibia and fibula of the right leg, articulated and seen from the front. 1. The shaft of the tibia. 2. The inner tuberosity. 3. The outer tuberosity. 4 The sninous process. 5. The tubercle. 6. The internal or subcutaneous surface of the shaft 7 The lower extremity of the tibia. 8. The internal malleolus. 9. The shaft of the fibula 10. Its upper extremity 11. Its lower extremity, the external malleolus. The sharp border between 1 and 6 is the crest of the tibia. V FIBULA. 131 is an oblique ridge, the popliteal line, for the attachment of the fascia of the popliteus muscle; and immediately below the oblique line, the nutritious canal, which is directed downwards. The inferior extremity of the bone is somewhat quadrilateral, and prolonged on its inner side into a large process, the internal malleolus. Behind the internal malleolus, is a broad and shallow groove, for lodging the tendons of the tibialis posticus and flexor longus digi- torum ; and farther outwards another groove, for the tendon of the flexor longus pollicis. Upon the outer side the surface is concave and triangular, rough above, for the attachment of the interosseous ligament; and smooth below, to articulate with the fibula. Upon the extremity of the bone is a triangular smooth surface, for articu- lating with the astragalus. Developement. — By three centres; one for the shaft, and one for each extremity. Ossification commences in the tibia, immediately after the femur; the centre for the head of the bone appears soon after birth, and that for the lower extremity during the second year; the latter is the first to join the diaphysis. The bone is not complete until near the twenty-fifth year. Two occasional centres have some- times been found in the tibia, one in the tubercle, the other in the in- ternal malleolus. Articulations.—With three bones; femur, fibula, and astragalus. Attachment of Muscles.—To ten; by the internal tuberosity, to the sartorius, gracilis, semitendinosus, and semimembranosus; by the external tuberosity, to the tibialis anticus and extensor longus digi- torum ; by the tubercle, to the ligamentum patellae; by the external surface of the shaft, to the tibialis anticus; and by the posterior sur- face, to the popliteus, soleus, flexor longus digitorum, and tibialis posticus. Fibula.—The fibula (*s|ov»j, a brooch, from its resemblance, in con- junction with the tibia, to the pin of an ancient brooch) is the outer and smaller bone of the leg; it is long and slender in figure, prismoid in shape, and, like other long bones, is divisible into a shaft and two extremities. The superior extremity or head is thick and large, and depressed upon the upper part by a concave surface, which articulates with the external tuberosity of the tibia. Externally to this surface is a thick and rough prominence, for the attachment of the external lateral ligament of the knee-joint, terminated behind by a styloid process, for the insertion of the tendon of the biceps. The lower extremity is flattened from without inwards, and pro- longed downwards beyond the articular surface of the tibia, forming the external malleolus. Its external side presents a rough and tri- angular surface, which is subcutaneous. Upon the internal surface is a smooth triangular facet, to articulate with the astragalus; and a rough depression, for the attachment of the interosseous ligament. The anterior border is thin and sharp; and the posterior, broad and grooved, for the tendons of the peronei muscles. 132 FIBULA. Fig. 62.* To place the bone in its proper position, and ascer- tain to which leg it belongs, let the inferior or flat- tened extremity be directed downwards, and the narrow border of the malleolus forwards; the tri- angular subcutaneous surface will then point to the side corresponding with the limb of which the bone should form a part. The shaft of the fibula is prismoid, and presents three surfaces; external, internal, and posterior; and three borders. The external surface is the broadest of the three; it commences upon the anterior part of the bone above, and curves around it so as to ter- minate upon its posterior side below. This surface is completely occupied by the two peronei muscles. The internal surface commences on the side of the superior articular surface, and terminates below, by narrowing to a ridge, which is continuous with the anterior border of the malleolus. It is marked along its middle by the interosseous ridge, which is lost above and below in the inner border of the bone. The posterior surface is twisted like the external; it commences above on the posterior side of the bone, and terminates below on its internal side; at about the middle of this surface is the nutritious foramen, which is directed downwards. The internal border commences superiorly in common with the interosseous ridge, and bifurcates inferiorly into two lines, which bound the triangular subcutaneous surface of the external malleolus. The external border begins at the base of the styloid process upon the head of the fibula, and winds around the bone, following the direction of the corresponding surface. The posterior border is sharp and prominent, and is lost inferiorly in the interosseous ridge. Developement.—By three centres; one for the shaft, and one for each extremity. Ossification commences in the shaft soon after its appearance in the tibia; at birth the extremities are cartilaginous, an ossific deposit taking place in the inferior epiphysis during the second year, and in the superior during the fourth or fifth. The inferior * The tibia and fibula of the right leg articulated and seen from behind. 1. The arti- cular depression for the external condyle of the femur. 2. The articular depression for the internal condyle; the prominence between the two numbers is the spinous process. 3. The fossa and groove for the insertion of the tendon of the semimembranosus muscle. 4. The popliteal plane, for the support of the popliteus muscle. 5. The popliteal line. 6. The nutritious foramen. 7. The surface of the shaft upon which the flexor longus digitorum muscle rests. 8. The broad groove on the back part of the inner malleolus, for the tendons of the flexor longus digitorum and tibialis posticus. 9. The s-&G^ sification.* Reticular cartilage is composed of cells (jj^ of an inch in diameter) separated from each other by an opaque, subfibrous, intercellular network, the breadth of the cells being considerably greater than that of the intercellular structure. The cells are parent cells, containing others of secondary formation, together with nuclei, nucleoli, granular matter, and oil-globules in greater number than those of true carti- lage. The fibres are short, imperfect, loose in texture, and yel- lowish. The instances of reticular cartilage are, the pinna, epiglot- tis, and Eusta- chian tube. : Fie- 67-i Fibrous carti- lage is composed of a network of white glistening fibres collected into fasciculi of various size, and containing in its meshes cells and * Page 48. t A portion of reticular cartilage. The section is taken from the pinna, and magnified 155 times. t A portion of fibrous cartilage. The section is taken from the symphysis pubis, and magnified 155 times. Ill h 144 WHITE FIBROUS TISSUE. a subfibrous tissue resembling that of reticular cartilage. The fibres of fibrous cartilages are identical with those of fibrous tissue, the cells are large (about T2Totn °f an incn) as m reticular cartilage, and the areolae are variable in dimensions. It is this latter charac- ter that constitutes the difference between different fibrous carti- lages, some being composed almost entirely of fibres with few and small interstices, as the interarticular cartilages, while others exhibit large spaces filled with an imperfect fibrous tissue and cells, as the intervertebral substance. The fibrous cartilages admit of arrangement into four groups, namely, interarticular, stratiform, interosseous, and free. The in- stances of interarticular fibrous cartilages (menisci) are those of the lower jaw, sternal and acromial end of the clavicle, wrist, carpus, knee, to which may be added the fibrous cartilages of circumference, glenoid and cotyloid. The stratiform fibrous cartilages are such as form a thin coating to the grooves on bone through which tendons play. The interosseous fibrous cartilages are the intervertebral sub- stance and symphysis pubis. The free fibrous cartilages are the tarsal cartilages of the eyelids. The developement of cartilage is the same with that of cartilage of bone (page 48), the different forms of cartilage resulting from subse- quent changes in the intercellular substance and cells. Thus, for ex- ample, in articular cartilage the cells undergo the lowest degree of developement, are very disproportionate to the intercellular substance, and the latter remains permanently structureless. In reticular carti- lage the cells possess a more active growth, and surpass in bulk the intercellular substance, while the latter is composed also of cells, which assume a fibrous disposition. In fibrous cartilage develope- ment is most energetic in the intercellular substance ; this is converted into fasciculi of fibrous tissue while the interspaces are filled with cells and imperfect fibrous tissue in every stage of developement. Fibrous Tissue is one of the most generally distributed of all the animal tissues; it is composed of fibres of extreme minuteness, and presents itself under three elementary forms ; namely, white fibrous tissue, yellow fibrous tissue, and red fibrous tissue. In white fibrous tissue the fibres are cylindrical, exceedingly minute, (about T5^5- of an inch in diameter), transparent and undulating; they are collected into small fasciculi (from 7^ above. Posterior, ) Interosseous membrane, Interosseous inferior, * A longitudinal section of the left knee-joint, showing the reflection of its synovial membrane. 1. The cancellous structure of the lower part of the femur. 2. The tendon of the extensor muscles of the leg. 3. The patella. 4. The ligamentum patellae. 5. The cancellous structure of the head of the tibia. 6. A bursa situated between the ligamen- tum patellee and the head of the tibia. 7. The mass of fat projecting into the cavity of the joint below the patella. * * The synovial membrane. 8. The pouch of synovial mem- brane which ascends between the tendon of the extensor muscles of the leg, and the front of the lower extremity of the femur. 9. One of the alar ligaments; the other has been removed with the opposite section. 10. The ligamentum mucosum left entire; the sec tion being made to its inner side. 11. The anterior or external crucial ligament. 12. The posterior ligament. The scheme of the synovial membrane, which is here presented to the student, is divested of all unnecessary complications. It may be traced from the sac cuius (at 8), along the inner surface of the patella; then over the adipose mass (7), from which it throws off the mucous ligament (10); then over the head of the tibia, forming a shea'h to the crucial ligaments; then upwards along the posterior ligament and condyles of the femur to the sacculus, whence its examination commenced. ANKLE JOINT. 175 Anterior, ) , , t>^ . • below. Posterior, ) Transverse. The anterior superior ligament is a strong fasciculus of parallel fibres, passing obliquely downwards and outwards from the inner tuberosity of the tibia, to the anterior surface of the head of the fibula. The posterior superior ligament is disposed in a similar manner upon the posterior surface of the joint. Within the articulation there is a distinct synovial membrane which is sometimes continuous with that of the knee-joint. The interosseous membrane or superior interosseous ligament is a broad layer of aponeurotic fibres which pass obliquely downwards and outwards, from the sharp ridge on the tibia to the inner edge of the fibula, and are crossed at an acute angle by a few fibres passing in the opposite direction. The ligament is deficient above, leaving a considerable interval between the bones, through which the ante- rior tibial artery takes its course forwards to the anterior aspect of the leg, and near its lower third there is an opening for the anterior peroneal artery and vein. The interosseous membrane is in relation, in front, with the tibialis anticus, extensor longus digitorum, and extensor proprius pollicis muscle, with the anterior tibial vessels and nerve, and with the ante- rior peroneal artery; and behind, with the tibialis posticus, and flexor longus digitorum muscle, and with the posterior peroneal artery. The inferior interosseous ligament consists of short and strong fibres, which hold the bones firmly together inferiorly, where they are nearly in contact. This articulation is so firm that the fibula is likely to be broken in the attempt to rupture the ligament. The anterior inferior ligament is a broad band, consisting of two fasciculi of parallel fibres which pass obliquely across the anterior aspect of the articulation of the two bones at their inferior extremity, from the tibia to the fibula. The posterior inferior ligament (fig. 94, 2) is a similar band upon the posterior surface of the articulation. Both ligaments project somewhat below the margin of the bones, and serve to deepen the cavity of articulation for the astragalus. The transverse ligament (fig. 94, 3) is a narrow band of ligamen- tous fibres, continuous with the preceding, and passing transversely across the back of the ankle joint between the two malleoli. The synovial membrane of the inferior tibio-fibular articulation, is a duplicative of the synovial membrane of the ankle joint reflected up- wards for a short distance between the two bones. Actions.—An obscure degree of movement exists between the tibia and fibula, which is principally calculated to enable the latter to resist injury by yielding for a trifling extent to the pressure exerted. 4. Ankle-joint.—The ankle is a ginglymoid articulation; the surfaces entering into its formation are the under surface of the tibia with its malleolus and the malleolus of the fibula, above, and the surface of the astragalus with its two lateral facets, below. The ligaments are three in number: 176 ANKLE JOINT. Fig. 92.* Anterior, Internal lateral, External lateral. The anterior ligament is a thin membra- nous layer, passing from the margin of the tibia, to the astragalus in front of the articu- lar surface. It is in relation, in front, with the extensor tendons of the great and lesser toes, with the tendons of the tibialis anticus and peroneus tertius, and with the anterior tibial vessels and nerve. Posteriorly it lies in contact with the extra-synovial adipose tissue and with the synovial membrane. The internal lateral or deltoid ligament is a triangular layer of fibres, attached superiorly by its apex to the internal malleolus, and inferiorly by an expanded base to the astragalus, os calcis, and sca- phoid bone. Beneath the superficial layer of this ligament is a much stronger and thicker fasciculus which connects the apex of the internal malleolus with the side of the astragalus. This internal lateral ligament is covered in and partly concealed by the tendon of the tibialis posticus, and at its posterior part is in rela- tion with the tendon of the flexor longus digitorum, and with that of the flexor longus pollicis. The external lateral ligament consists of three strong fasciculi, which proceed from the inner side of the external malleolus, and diverge in three different directions. The anterior fasciculus passes forwards, and is attached to the astragalus; the posterior, backwards, and is connected with the astragalus posteriorly; and the middle, longer than the other two, descends to be inserted into the outer side of the os calcis. " It is the strong union of this bone," says Sir Astley Cooper, with the tarsal bones by means of the external lateral ligaments, " which leads to its being more frequently fractured than dislocated." The transverse ligament of the tibia and fibula occupies the place of a posterior liga- ment. It is in relation, behind, with the posterior tibial vessels and nerve, and with the tendon of the tibialis posticus muscle; and in front, with the extra-synovial adipose tissue, and synovial membrane. * An internal view of the ankle joint. 1. The internal malleolus of the tibia. 2, 2. Part of the astragalus: the rest is concealed by the ligaments. 3. The os calcis. 4. The scaphoid bone. 5. The internal cuneiform bone. 6. The internal lateral or deltoid liga- ment. 7. The anterior ligament. 8. The tendo Achillis; a small bursa is seen interposed between the tendon and the tuberosity of the os calcis. t An external view of the ankle joint. 1. The tibia. 2. The external malleolus of the fibula. 3, 3. The astragalus. 4. The os calcis. 5. The cuboid bone. 6. The anterior fasciculus of the external lateral ligament attached to the astragalus. 7. Its middle fasci- culus, attached to the os calcis. 8. Its posterior fasciculus, attached to the astragalus. 9. The anterior ligament of the ankle. TARSAL ARTICULATIONS. 177 The Synovial membrane invests the cartilaginous surfaces of the tibia and fibula (sending a duplicature upwards between their lower ends), and the upper surface and two sides of the astragalus. It is then reflected upon the anterior and lateral ligaments, and upon the transverse ligament posteriorly. Actions.—The movements of the ankle joint are flexion and exten- sion only, without lateral motion. 5. Articulations of the Tarsal Bones.—-The ligaments which connect the seven bones of the tarsus to each other are of three kinds,— Dorsal, Plantar, Interosseous. The dorsal ligaments are small fasciculi of parallel fibres, which pass from each bone to all the neighbouring bones with which it ar- ticulates. The only dorsal ligaments deserving of particular men- tion are, the external and posterior calcaneo-astragaloid, which with the interosseous ligament complete the articulation of the astragalus with the os calcis; the superior and internal calcaneocuboid ligament. The internal calcaneocuboid and the superior calcaneo-scaphoid ligament, which are closely united posteriorly in the deep groove which intervenes between the astragalus and os calcis, separate an- teriorly to reach their respective bones ; they form the principal bond of connexion between the first and second range of the bones of the foot. It is the division of this portion of these ligaments that de- mands the especial attention of the surgeon in performing Chopart's operation. The plantar ligaments have the same disposition on the plantar sur- face of the foot; three of them, however, are of a large size and have especial names, viz. the Calcaneo-scaphoid, Long calcaneo-cuboid, Short calcaneo-cuboid. The inferior calcaneo-scaphoid ligament is a broad and fibro-cartilaginous band of ligament, which passes forwards from the anterior and inner border of the os calcis and scaphoid bone. In addition to con- necting the os calcis and scaphoid, it supports the as- tragalus, and forms part of the cavity in which the rounded head of the latter bone is received. It is lined upon its upper surface by the synovial membrane of the astragalo-scaphoid articulation. The firm connexion of the os calcis with the sca- phoid bone, and the feebleness of the astragalo-sca- phoid articulation are conditions favourable to the oc- casional dislocation of the head of the astragalus. The long calcaneo-cuboid, or ligamentum longum planta, is a long band of ligamentous fibres, which proceeds from the under surface of the os calcis to the rough surface on the under part * A posterior view of the ankle joint. 1. The lower part of the interosseous membrane. 2. The posterior inferior ligament connecting the tibia and fibula. 3. The transverse liga- ment. 4. The internal lateral ligament. 5. The posterior fasciculus of the internal late- ral ligament. 6. The middle fasciculus of the external lateral ligament. 7. The syno- vial membrane of the ankle joint. 8. The os calcis. 178 TARSOMETATARSAL ARTICULATION. of the cuboid bone, its fibres being continued onwards to the bases of the third and fourth metatarsal bones. This ligament forms the inferior boundary of a canal in the cuboid bone, through which the tendon of the peroneus longus passes to its insertion in the base of the metatarsal bone of the great toe. The short calcaneo-cuboid, or ligamentum breve planta, is situated nearer to the bones than the long plantar ligament, from which it is separated by adipose tissue; it is broad and extensive, and ties the under surfaces of the os calcis and cuboid bone firmly together. The interosseous ligaments are five in number; they are short and strong ligamentous fibres situated between adjoining bones, and firmly attached to their rough surfaces. One of these, the calcaneo-astraga- loid, is lodged in the groove between the upper surface of the os calcis, and the lower of the astragalus. It is large and very strong, consists of vertical and oblique fibres, and serves to unite the os cal- cis and astragalus solidly together. The second interosseous ligament, also very strong, is situated between the sides of the scaphoid and cuboid bone; while the three remaining interosseous ligaments con- nect strongly together the three cuneiform bones and the cuboid. The synovial membranes of the tarsus are four in number; one for the posterior calcaneo-astragaloid articulation; a second, for the an- terior calcaneo-astragaloid and astragalo-scaphoid articulation. Oc- casionally an additional small synovial membrane is found in the anterior calcaneo-astragaloid joint; a third, for the calcaneo-cuboid articulation; and a fourth, the large tarsal synovial membrane, for the articulations between the scaphoid and three cuneiform bones, the cuneiform bones with each other, the external cuneiform bone with the cuboid, and the two external cuneiform bones with the bases of the second and third metatarsal bones. The prolongation which reaches the metatarsal bones passes forwards between the internal and middle cuneiform bones. A small synovial membrane is sometimes met with between the contiguous surfaces of the scaphoid and cuboid bone. Actions.—The movements permitted by the articulation between the astragalus and os calcis, are a slight degree of gliding, in the di- rections forwards and backwards and laterally from side to side. The movements of the second range of tarsal bones is very trifling, being greater between the scaphoid and three cuneiform bones than in the other articulations. The movements occurring between the first and second range are the most considerable; they are adduction and abduction, and, in a minor degree, flexion, which increases the arch of the foot, and extension which flattens the arch. 6. Tarso-metatarsal Articulation.—The ligaments of this articula- tion are, Dorsal, Plantar, Interosseous. The dorsal ligaments connect the metatarsal to the tarsal bones, and the metatarsal bones with each other. The precise arrancement of these ligaments is of little importance, but it may be remarked, that the base of the second metatarsal bone, articulating with the METATARSOPHALANGEAL ARTICULATION. 179 Fig. 95." three cuneiform bones receives a ligamentous slip from each, while the rest articulating with a single tarsal bone receive only a single tarsal slip. The plantar ligaments have the same disposition on the plantar surface. The interosseous ligaments are situated between the bases of the metatarsal bones of the four lesser toes; and also between the bases of the second and third metatarsal bones, and the internal and external cuneiform bones. The metatarsal bone of the second toe is implant- ed by its base between the internal and external cuneiform bones, and is the most strongly articulated of all the metatarsal bones. This disposition must be recollected in amputation at the tarso-metatarsal „ articulation. ^ The synovial membranes of this articulation are three in number: one for the metatarsal bone of the great toe; one for the second and third metatarsal bones, which is continuous with the great tarsal synovial membrane; and one for the fourth and fifth metatarsal bones. Actions.—The movements of the metatarsal bones upon the tarsal, and upon each other, are very slight; they are such only as contribute to the strength of the foot by permitting of a cer- tain degree of yielding to opposing forces. 7. Metatarsal-phalangeal Articulation.—The ligaments of this arti- culation, like those of the articulation between the first phalanges and metacarpal bones of the hand, are, Anterior or plantar, Two lateral, Transverse. The anterior or plantar ligaments are thick and fibrocartilaginous, and form part of the articulating surface of the joint. The lateral ligaments are short and very strong, and situated on each side of the joints. The transverse ligaments are strong bands, which pass transversely between the anterior ligaments. The expansion of the extensor tendon supplies the place of a dorsal ligament. Actions.—The movements of the first phalanges upon the rounded heads of the metatarsal bones, are flexion, extension, adduction and abduction. 8. Articulation of the Phalanges.—The ligaments of the phalanges *The ligaments of the sole of the foot. 1. The os calcis. 2. The astragalus. 3. The tuberosity of the scaphoid bone. 4. The long calcaneo-cuboid ligament. 5. Part of the short calcaneo-cuboid ligament. 6. The calcaneo-scaphoid ligament. 7. The plantar tarsal ligaments. 8, 8. The tendon of the peroneus longus muscle. 9, 9. Plantar tarso- metatarsal ligaments. 10. Plantar ligament of the metatarso-phalangeal articulation of the great toe ; the same ligament is seen upon the other toes. 11. Lateral ligaments of the metatarso-phalangeal articulation. 12. Transverse ligament. 13. The lateral liga- ments of the phalanges of the great toe; the same ligaments are seen upon the other toes. 180 STRUCTURE OF MUSCLE. are the same as those of the fingers, and have the same disposition; their actions are also similar. They are, Anterior or plantar, Two lateral. CHAPTER IV. ON THE MUSCLES. Muscles are the moving organs of the animal frame; they consti- tute by their size and number the great bulk of the body, upon which they oestow form and symmetry. In the limbs they are situated around the bones, which they invest and defend, while they form to some of the joints a principal protection. In the trunk they are spread out to enclose cavities, and constitute a defensive wall capa- ble of yielding to internal pressure, and again returning to its original position. Their colour presents the deep red which is characteristic of flesh, and their form is variously modified, to execute the varied range of movements which they are required to effect. Muscle is composed of a number of parallel fibres placed side by side, and supported and held together by a delicate web of areolar tissue; so that, if it were possible to remove the muscular substance, we should have remaining a beautiful reticular framework, possessing the exact form and size of the muscle without its colour and solidity. Towards the extremity of the organ the muscular fibre ceases, and the areolar structure becomes aggregated and modified, so as to con- stitute those glistening fibres and cords by which the muscle is tied to the surface of bone, and which are called tendons. Almost every muscle in the body is connected with bone, either by tendinous fibres, or by an aggregation of those fibres constituting a tendon; and the union is so firm, that, under extreme violence, the bone itself rather breaks than permits of the separation of the tendon from its attach- ment. In the broad muscles the tendon is spread so as to form an expansion, called aponeurosis (<*iro, longe; vsfeov,* nervus—a nerve widely spread out). Muscles present various modifications in the arrangement of their fibres in relation to their tendinous structure. Sometimes they are completely longitudinal, and terminate at each extremity in tendon, the entire muscle being fusiform in its shape; in other situations they are disposed like the rays of a fan, converging to a tendinous point, as the temporal, pectoral, glutei, &c, and constitute a radiate muscle. Again, they are penniform, converging like the plumes of a pen to one side of a tendon, which runs the whole length of the muscle as in the peronei; or bipenniform, converging to both sides of the tendon. * The ancients named all the white fibres of the body veugd; the term has since been limited to the nerves. STRUCTURE OF MUSCLE. 181 In other muscles the fibres pass obliquely from the surface of a ten- dinous expansion spread out on one side, to that of another extended on the opposite side, as in the semi-membranosus; or, they are com- posed of penniform or bipenniform fasciculi as in the deltoid, and constitute a compound muscle. The nomenclature of the muscles is defective and confused, and is generally derived from some prominent character which each muscle presents; thus, some are named from their situation, as the tibialis, peroneus; others from their uses, as the flexors, extensors, adductors, abductors, levators, tensors, &c. Some again from their form, as the trapezius, triangularis, deltoid, &c.; and others from their direction, as the rectus, obliquus, transversalis, &c. Certain muscles have re- ceived names expressive of their attachments, as the sterno-mastoid, sterno-hyoid, &c.; and others, of their divisions, as the biceps, triceps, digastricus, complexus, &c. In the description of a muscle we express its attachment by the words " origin" and " insertion;" the term origin is generally applied to the more fixed or central attachment, or to the point towards which the motion is directed, while insertion is assigned to the more mova- ble point, or to that most distant from the centre; but there are many exceptions to this principle, and as many muscles pull equally by both extremities, the use of such terms must be regarded as purely arbitrary. In structure, muscle is composed of bundles of fibres of variable size called fasciculi, which are enclosed in a cellular membranous in- vestment or sheath, and the latter is continuous with the cellular framework of the fibres. Each fasciculus is composed of a number of smaller bundles, and these of single fibres, which, from their minute size and independent appearance, have been distinguished by the name of ultimate fibres. The ultimate fibre is found by microscopic inves- tigation to be itself a fasciculus (ultimate fasciculus), made up of a number of ultimate fibrils enclosed in a delicate sheath or myolemma.* Two kinds of ultimate muscular fibre exist in the animal economy; viz., that of voluntary or animal life, and that of involuntary or or- ganic life. The ultimate fibre of animal life is known by its size, by its uni- formity of calibre, and especially by the very beautiful transverse markings which occur at short and regular distances throughout its whole extent. It also presents other markings or striae, having a lon- gitudinal direction, which indicate the existence of fibrillae within its myolemma. The myolemma, or investing sheath of the ultimate fibre is thin, structureless and transparent. * In the summer of 1836, while engaged with Dr. Jones Quain in the examination of the animal tissues wilh a simple dissecting microscope, constructed by Powell, I first saw that the ultimate fibre of muscle was invested by a proper sheath, for which I proposed the term " Myolemma;" a term which was adopted by Dr. Quain in the fourth edition of his " Elements of Anatomy." We at that time believed that the transverse folding of that sheath gave rise to the appearance of transverse striae, an opinion which subsequent ex- animations proved to be incorrect. Mr. Bowman employs the term " Sarcolemma," as synonymous with Myolemma. 16 182 STRUCTURE OF MUSCLE. Fig. 96.T According to Mr. Bowman* the ulti- mate fibres are polygonal in shape [fig. 96] from mutual pressure. They are also variable in their size, not merely in differ- ent classes and genera of animals and dif- y'-Sifeg?^ ferent sexes, but even in the same muscle. Mflflll^- For example, the average diameter of the ultimate fibre in the human female is ^, while that of the male is 3^, the average of both being ^3. The largest fibres are met with in fishes, in which animals they average 225 ; the next largest are found in man, while in other classes they range in the following order:—insects Z±T; reptiles j^; mam- malia jJ-T; birds slf. The ultimate fibrils of animal life, according to Mr. Bowman, are beaded filaments consisting of a regular succession of segments and constrictions, the latter being narrower than the former, and the component substance probably less dense. An ultimate fibre consists of a bundle of these fibrils, which are so disposed that all the segments and all the constrictions correspond, and in this manner give rise to the alternate light and dark lines of the transverse striae. The fibrils are connected together with very different degrees of closeness in different animals; in man they are but slightly adherent, and distinct longitudinal lines of junction may be observed between them; they also separate very easily when macerated for some time. Besides the more usual separation of the ultimate fibre into fibrils, it breaks when stretched, into transverse sections [fig. 97,] corresponding with the dark line of the striae, and consequently with the constrictions of the fibrillae. When this divi- sion occurs with the greatest facility, the lon- gitudinal lines are indistinct, or scarcely per- ceptible. " In fact," says Mr. Bowman, " the primitive fasciculus seems to consist of primitive component segments or particles, arranged so as to form, in one sense, fibrillae, and in another sense, discs; and which of these two may happen to present itself to the observer, will depend on the amount of adhesion, endways or side- ways, existing between the segments. Generally, in a recent fasci- culus, there are transverse striae, showing divisions into discs, and longitudinal striae, marking its composition by fibrillae." Mr. Bowman has observed that in the substance of the ultimate * On the Minute Structure and Movements of Voluntary Muscle. By Wm. Bowman, Esq. From the Philosophical Transactions for 1840. t Transverse section of ultimate fibres of the biceps, copied from the illustrations to Mr. Bowman's paper. In this figure the polygonal form of the fibres is seen, and their composition of ultimate fibrils. t An ultimate fibre, in which the transverse splitting into discs, in the direction of the constrictions of the ultimate fibrils is seen. From Mr. Bowman's paper. Fig. 97.| STRUCTURE OF MUSCLE. 183 t fibre there exist minute " oval or circular discs, frequently concave on one or both surfaces, and containing, somewhere near the centre, one, two, or three minute dots or granules." Occasionally they are seen to present irregularities of form, which Mr. Bowman is in- clined to regard as accidental. They are situated between, and are connected with the fibrils, and are distributed in pretty equal numbers through the fibre. These corpuscles are the nuclei of the nucleated cells from which the muscular fibre was originally developed. From observing, however, that their " absolute number is far greater in the adult than in the foetus, Fls- "•* while their number, relatively to the bulk of the fasciculi, at these two epochs, remains nearly the same," Mr. Bowman regards it as certain, that " during developement, and subsequently, a fur- ther and successive deposit of corpuscles" takes place. The corpuscles are brought into view only when the muscular fibre is acted upon by a solution of " one of the milder acids, as the citric." According to my own investigations,! the ultimate fibril of animal life is cylindrical when isolated, and probably polygonal from pres- sure when forming part of an ultimate fibre or fasciculus. It measures in diameter 555110 of an Fig'99 + inch, and is composed of a succession of cells connected by their flat surfaces. The cells are filled with a transparent substance, which I have termed myoline. The myoline differs in density in different cells, and from this circumstance be- stows a peculiarity of character on certain of the cells; for example, when a fibril in its passive state is examined, there will be seen a series of dark oblong bodies separated by light spaces of 0 ^ equal length; now the dark bodies are each com- ? ^ posed of a pair of cells containing the densest § - form of myoline, and are hence highly refractive B * Mass of ultimate fibres from the pectoralis major of the human foetus, at nine months. These fibres have be?n immersed in a solution of tartaric acid, and their "nume- rous corpuscles, turned in various directions, some presenting nucleoli," are shown. From Mr. Row man's paper. + These were made on dissections of fresh human muscle, prepared with great care by Mr. Lcaland, partner of the eminent optician, Mr. Powell. t Structure of the ultimate muscular fibril and fibre of animal life. A. An ultimate muscular fibril in the state of partial contraction. b. A similar fibril in the state of ordinary relaxation. This fibril measured j^^ of an inch in diameter. c. A similar fibril put upon the stretch, and measuring ^^ of an inch in diameter. d. Plan of a portion of an ultimate fibre, showing the manner in which the transverse strioe are produced by the collocation of the fibrils. Nos. 1,1. The pair of highly-refractive cells; they form the dark parts of the single fibrils, but the bright parts of the fibre d. In the stretched fibril c, each cell has the appearance of being double. 2, 2. The pair of less refractive cells, light in the single fibrils, but forming the shaded stria in u. The transverse septum between these cells is very conspicuous ; and in c two other septa are seen to exist, making the number of trans- parent cells four. In p, the tier of cells immediately above the dark tier is partially illu- mined from the obliquity of the light. iQ «fi Fi H u 0 0 □ B EJ U a H 184 STRUCTURE OF MUSCLE. while the transparent spaces are constituted by a pair of cells contain- ing a more fluid myoline. When the fibrils are collected together so as to form an ultimate fibre or fasciculus, the appearance of the cell is altered ; those which look dark in the single fibril, that is, the most refractive, being ranged side by side, constitute the bright band; while the transparent cells of the single fibril are the shaded stria of the fibre. When the ultimate fibril is very much stretched, the two highly refractive cells appear each to be double, while the transparent space is evidently composed of four cells. The ultimate fibre of organic life (fig. 100, 4, 5) is a simple homo- geneous filament, much smaller than the fibre of animal life, flat, and without transverse markings. Besides these characters, there may generally be seen a dark line or several dark points in its interior, and not unfrequently the entire fibre appears enlarged at irregular distances. These appearances are due to the presence of the unob- literated nuclei of cells from which the fibre was originally developed. The fibres of organic life are collected into fasciculi of various size, and are held together by dark nuclear fibres, similar to those which bind the fasciculi of fibrous tissue (p. 144.) The developement of muscular fibre is effected by means of the formation of nucleated cells out of an.original blastema, and the con- version of those cells, by a process already described (p. 47), into the tubuli of ultimate fibres, while their contents, by a subsequent develope- mental action, are transformed into ultimate fibrils. According to this view the cell membranes constitute the myolemma, and the contents of the cell are a blastema out of which new cells are formed. The disposition of these latter cells, in the production of fibrillae, is probably much more simple than has hitherto been conceived. In the muscular fibre of organic life, the process would seem to stop short of the formation of fibrillae, the cells being accumulated with- out apparent order. The corpuscles, observed by Mr. Bowman, in foetal muscle (fig. 98), and the nodosities of organic fibre, are ob- viously undeveloped cells and nuclei. * 1. A muscular fibre of animal life enclosed in its myolemma; the transverse and longitudinal stria are seen. 2. An ultimate fibril of muscular fibre of animal life, according to Mr. Bowman. 3. A muscular fibre of animal life, similar to 1, but more highly magnified. Its myo- lemma is so thin and transparent, as to permit the ultimate fibrils to be seen through. The true nature of the longitudinal striae is seen in this fibre, as well as the mode of for- mation of the transverse striae. 4. A muscular fibre of organic life, from the urinary bladder, magnified 600 times linear measure. Two of the nuclei are seen. 5. A muscular fibre of organic life, from the stomach, magnified 600 times. The dia. meter of this and of the preceding fibre, midway between the nuclei, was J__0f an inch. Fig. 100.* MUSCLES OF THE HEAD AND NECK. 185 Muscles are divided into two great classes, voluntary and involun- tary, to which may be added, as an intermediate and connecting link, the muscle of the vascular system, the heart. The voluntary, or system of animal life, is developed from the ex- ternal or serous layer of the germinal membrane, and comprehends the whole of the muscles of the limbs and of the trunk. The involun- tary, or organic system, is developed from the internal or mucous layer, and constitutes the thin muscular structure of the intestinal canal, bladder, and internal organs of generation. At the com- mencement of the alimentary canal in the oesophagus, and near its termination in the rectum, the muscular coat is formed by a blending of the fibres of both classes. The heart is developed from the middle, or vascular layer of the germinal membrane; and although involun- tary in its action, is composed of ultimate fibres, having the trans- verse striae of the muscle of animal life. The muscles may be, arranged in conformity with the general divi- sion of the body into,—1. Those of the head and neck. 2. Those of the trunk. 3. Those of the upper extremity. 4. Those of the lower extremity. MUSCLES OF THE HEAD AND NECK. The muscles of the head and neck admit of a subdivision into those of the head and face, and those of the neck. Muscles of the Head and Face.—These muscles may be divided into groups, corresponding with the natural regions of the head and face; the groups are eight in number, viz.— 1. Cranial group. 5 Superior labial group. 2. Orbital group. 6. Inferior labial group. 3. Ocular group. 7. Maxillary group. 4. Nasal group. 8. Auricular group. The muscles of each of these groups may be thus arranged— 1. Cranial group. 4. JVasal group. Occipito-frontalis. Pyramidalis nasi, 2. Orbital group. Compressor nasi, r\ u- i ■ i u...,..,,™ Dilatator naris. Orbicularis palpebrarum, Corrugator supercilii, 5 Superior labial group. Tensor tarsi. (Orbicularis oris), 3. Ocular group. Levator labii superioris alaeque Levator palpebrae, nasi, Rectus superior, Levator labii superioris proprius, Rectus inferior, Levator anguli oris, Rectus internus, Zygomatics major, Rectus externus, Zygomaticus minor, Obliquus superior, Depressor labii superioris alaeque Obliquus inferior. nasi. 16* 186 CRANIAL GROUP. 6. Inferior labial group. (Orbicularis oris),* Depressor labii inferioris, Depressor anguli oris, Levator labii inferioris. Buccinator, Pterygoideus externus, Pterygoideus internus. 8. Auricular group. Attollens aurem, Attrahens aurem, Retrahens aurem. 7. Maxillary group. Masseter, Temporalis, 1. Cranial group.—Occipito-frontalis. Dissection.—The occipito-frontalis is to be dissected by making a longitudinal incision along the ver- Fig- 101,+ tex of the head, from the tubercle on the occipital bone to the root of the nose; and a second incision along the forehead and around the side of the head, to join the two extremities of the preceding. Dissect the in- tegument and superficial fascia care- fully outwards, beginning at the an- terior angle of the flap, where the muscular fibres are thickest, and re- move it altogether. This dissection requires care; for the muscle is very thin, and without attention, would be raised with the integument. There is no deep fascia on the face and head, nor is it required; for here the muscles are closely applied against the bones upon which they depend for support, whilst in the extremities the support is derived from the dense layer of fascia by which they are invested, and which forms for each a distinct sheath. The Occipito-frontalis is a broad musculo-aponeurotic layer, which covers the whole of the side of the vertex of the skull, from the occiput to the eyebrow. It arises by tendinous fibres from the outer two-thirds of the superior curved line of the occipital, and from * The orbicularis oris, from encircling the mouth, belongs necessarily to both the supe- rior and inferior labial regions; it is therefore enclosed within parentheses in both. t The muscles of the head and face. 1. The frontal portion of the occipito-frontalis. 2. Its occipital portion. 3. Its aponeurosis. 4. The orbicularis palpebrarum, which con- ceals the corrugator supercilii and tensor tarsi. 5. The pyramidalis nasi. 6. The com- pressor nasi. 7. The orbicularis oris. 8. The levator labii superioris alaeque nasi; the adjoining fasciculus between numbers 8 and 9 is the labial portion of the muscle. 9. The levator labii superioris proprius; the lower part of the levator anguli oris is seen between the muscles 10 and 11. 10. The zygomaticus minor. 11. The zygomaticus major. 12, The depressor labii inferioris. 13. The depressor anguli oris. 14. The levator labii in- ferioris. 15. The superficial portion of the masseter. 16. Its deep portion. 17. The attrahens aurem. 18. The buccinator. 19. The attollens aurem. 20. The temporal fascia which covers in the temporal muscle. 21. The retrahens aurem. 22. The ante- rior belly of the digastricus muscle; the tendon is seen passing through its aponeurotic pulley. 23. The stylo-hyoid muscle pierced by the posterior belly of the digastricus. 24. The mylo-hyoideus muscle. 25. The upper part of the sterno-mastoid. 26. The upper pirt of the trapezius. The muscle between 25 and 26 is the splenius. ORBITAL GROUP. 187 the mastoid portion of the temporal bone. Its insertion takes place by means of the blending of the fibres of its anterior portion with those of the orbicularis palpebrarum, corrugator supercilii, levator labii superioris alaeque nasi, and pyramidahs nasi. The muscle is fleshy in front over the frontal bone and behind over the occipital, the two portions being connected by a broad aponeurosis. The two muscles together with their aponeurosis cover the whole of the vertex of the skull, hence their designation galea capitis; they are loosely adherent to the pericranium, but very closely to the integument, par- ticularly over the forehead. Relations.—This muscle is in relation by its external surface from before backwards, with the frontal and supra-orbital vessels, the supra- orbital and facial nerve, the temporal vessels and nerve, the occipital vessels and nerves, and with the integument, to which it is very closely adherent. Its under surface is attached to the pericranium by a loose areolar tissue which admits of considerable movement. Action.—To raise the eyebrows, thereby throwing the integument of the forehead into transverse wrinkles. Some persons have the power of moving the entire scalp upon the pericranium by means of these muscles. 2. Orbital group.—Orbicularis palpebrarum, Corrugator supercilii, Tensor tarsi. Dissection.—The dissection of the face is to be effected by con- tinuing the longitudinal incision of the vertex of the previous dissec- tion onwards to the tip of the nose, and thence downwards to the margin of the upper lip; then carry an incision along the margin of the lip to the angle of the mouth, and transversely across the face to the angle of the lower jaw. Lastly, divide the integument in front of the external ear upwards to the transverse incision which was made for exposing the occipito-frontalis. Dissect the integument and super- ficial fascia carefully from the whole of the region included by these incisions, and the present with the two following groups of muscles will be brought into view. The Orbicularis Palpebrarum is a sphincter muscle, surrounding the orbit and eyelids. It arises from the internal angular process of the frontal bone, from the nasal process of the superior maxillary, and from a short tendon (tendo oculi) which extends between the nasal process of the superior maxillary bone, and the inner extremi- ties of the tarsal cartilages of the eyelids. The fibres encircle the orbit and eyelids, forming a broad and thin muscular plane, which is inserted into the lower border of the tendo oculi and into the nasal process of the superior maxillary bone. Upon the eyelids the fibres are thin and pale, and possess an involuntary action. The tendo oculi, in addition to its insertion into the nasal process of the superior maxillary bone, sends a process inwards which expands over the lachrymal sac, and is attached to the ridge of the lachrymal bone: this is the reflected aponeurosis of the tendo oculi. 188 TENSOR TARSI. Relations.—By its superficial surface it is closely adherent to the integument from which it is separated over the eyelids by a loose areolar tissue. By its deep surface it lies in contact above with the upper border of the orbit, with the corrugator supercilii muscle, and with the frontal and supra-orbital vessels and supra-orbital nerve; below, with the lachrymal sac, with the origins of the levator labii superioris alaeque nasi, levator labii superioris proprius, zygomaticus major and minor muscles, and malar bone; and externally with the temporal fascia. Upon the eyelids it is in relation with the broad tarsal ligament and tarsal cartilages, and by its upper border gives attachment to the occipito-frontalis muscle. The Corrugator Supercilii is a small narrow and pointed muscle, situated immediately above the orbit and beneath the upper segment of the orbicularis palpebrarum muscle. It arises from the inner ex- tremity of the superciliary ridge, and is inserted into the under sur- face of the orbicularis palpebrarum at a point corresponding with the middle of the superciliary arch. Relations.—By its superficial surface with the pyramidalis nasi, occipito-frontalis and orbicularis palpebrarum muscle ; and by its deep surface, with the supra-orbital vessels and nerve. The Tensor Tarsi (Horner's* muscle) is a thin plane of muscular fibres, about three lines in breadth Fis-102-+ and six in length. It is best dis- ^7] sected by separating the eyelids from the eye, and turning them over the 1 nose without disturbing the tendo oculi; then dissect away the small fold of mucous membrane called plica semilunaris, and some loose cellular tissue under which the mus- J cle is concealed. It arises from the -^ orbital surface of the lachrymal bone, and passing across the lachrymal sac divides into two slips, which are inserted into the lachrymal canals as far as the puncta. Actions.—The palpebral portion of the orbicularis acts involuntarily in closing the lids, and from the greater curve of the upper lid, upon that principally. The entire muscle acts as a sphincter, drawing at the same time, by means of its osseous attachment, the integument and lids inwards towards the nose. The corrugatores superciliorum draw the eyebrows downwards and inwards, and produce the vertical wrinkles of the forehead. The tensor tarsi, or lachrymal muscle, draws the extremities of the lachrymal canals inwards, so as to place »the puncta in the best position for receiving the tears. It serves also to keep the lids in relation with the surface of the eye, and com- * W. E. Horner, M. D., Professor of Anatomy in the University of Pennsylvania. The notice of this muscle is contained in a work published in Philadelphia in 1827, entitled " Lessons in Practical Anatomy." t A view of the tensor tarsi muscle. 1,1. Bony margins of the orbit. 2. Opening be- tween the eyelids. 3. Internal face of the orbit. 4. Origin of the tensor tarsi. 5, 5. In sertion into the neighbourhood of the puncta lachrymalia. LEVATOR PALPEBRAE. 169 presses the lachrymal sac. Dr. Horner is acquainted with two per- sons who have the voluntary power of drawing the lids inwards by these muscles so as to bury the puncta in the angle of the eye. 3. Ocular group.—Levator palpebrae, Rectus superior, Rectus inferior, Rectus internus, Rectus externus, Obliquus superior, Obliquus inferior. Dissection.—To open the orbit (the calvarium and brain having been removed) the frontal bone must be sawn through at the inner extremity of the orbital ridge, and, externally, at its outer extremity. Fis-103-* The roof of the orbit may then be comminuted by a few light blows with the hammer; a process easily accomplished, on account of the thinness of the orbital plate of the frontal bone and lesser wing of the sphenoid. The superciliary por- tion of the orbit may now be driven forwards by a smart blow, and the external angular process and external wall of the orbit outwards in the same manner; the broken fragments of the roof of the orbit should then be removed. By this means the periosteum will be exposed un- broken and undisturbed. Remove the periosteum from the whole of the upper surface of the exposed orbit, and examine the parts beneath. The Levator Palpebrae is a long, thin, and triangular muscle; situated in the upper part of the orbit on the middle line; it arises from the upper margin of the optic foramen, and from the fibrous sheath of the optic nerve, and is inserted into the upper border of the superior tarsal cartilage. Relations.—By its upper surface with the fourth nerve, the supra- orbital nerve and artery, the periosteum of the orbit, and in front with the inner surface of the broad tarsal ligament. By its under surface it rests upon the superior rectus muscle, and the globe of the eye ; it receives its nerve and artery by this aspect, and in front is covered for a short distance by the conjunctiva. The Rectus Superior (attollens) arises from the upper margin of the optic foramen, and from the fibrous sheath of the optic nerve, and * The muscles of the eyeball; the view is taken from the outer side of the right orbit. 1. A small fragment of the sphenoid bone around the entrance of the optic nerve into the orbit. 2. The optic nerve. 3. The globe of the eye. 4. The levator palpebrae muscle. 5. The superior oblique muscle. 6. Its cartilaginous pulley. 7. Its reflected tendon. 8. The inferior oblique muscle; the small square knob at its commencement is a piece of its bony origin broken off. 9. The superior rectus. 10. The internal rectus almost concealed by the optic nerve. 11. Part of the external rectus, showing its two heads of origin. 12. The extremity of the external rectus at its insertion; the intermediate portion of the mus- cle having been removed. 13. The inferior rectus. 14. The tunica albuginea, formed by the expansion of the tendons of the four recti. 190 RECTUS EXTERNUS. is inserted into the upper surface of the globe of the eye at a point somewhat more than three lines from the margin of the cornea. Relations.—By its upper surface with the levator palpebrae muscle; by the under surface with the optic nerve, the ophthalmic artery and nasal nerve, from which it is separated by a layer of fascia and by the adipose tissue of the orbit, and in front with the globe of the eye, the tendon of the superior oblique muscle being interposed. The Rectus Inferior (depressor) arises from the inferior margin of the optic foramen by a tendon (ligament of Zinn) which is common to it, the internal and the external rectus, and from the fibrous sheath of the optic nerve; it is inserted into the inferior surface of the globe of the eye at a little more than two lines from the margin of the cornea. Relations.—By its upper surface with the optic nerve, the inferior oblique branch of the third nerve, the adipose tissue of the orbit, and the under surface of the globe of the eye. By its under surface with the periosteum of the floor of the orbit, and with the inferior oblique muscle. The Rectus Internus (adductor), the thickest and shortest of the straight muscles, arises from the common tendon, and from the fibrous sheath of the optic nerve; and is inserted into the inner sur- face of the globe of the eye at two lines from the margin of the cornea. Relations.—By its internal surface with the optic nerve, the adipose tissue of the orbit and the eyeball. By its outer surface with the pe- riosteum of the orbit; and by its upper border with the anterior and posterior ethmoidal vessels, the nasal and supra-trochlear nerve. The Rectus Externus (abductor), the longest of the straight mus- cles, arises by two distinct heads, one from the common tendon, the other with the origin of the superior rectus from the margin of the optic foramen ; the nasal, third and sixth nerves passing between its heads. It is inserted into the outer surface of the globe of the eye at a little more than two lines from the margin of the cornea. Relations.—By its internal surface with the third, the nasal, the sixth, and the optic nerve, the ciliary ganglion and nerves, the oph- thalmic artery and vein, the adipose tissue of the orbit, the inferior oblibue muscle and the eyeball. By its external surface with the pe- riosteum of the orbit; and by the upper border with the lachrymal vessels and nerve and the lachrymal gland. The recti muscles present several characters which are common to all; thus they are thin, have each the form of an isosceles triangle, bear the same relation to the globe of the eye, and are inserted in a similar manner into the sclerotica, at about two lines from the circum- ference of the cornea. The points of difference relate to thickness and length; the internal rectus is the thickest and shortest, the ex- ternal rectus the longest of the four, and the superior rectus the most thin. The insertion of the four recti muscles into the globe of the eye forms a tendinous expansion, which is continued as far as the margin of the cornea, and is called the tunica albuginea. The Obliquus Superior (trochlearis) is a fusiform muscle arising from the margin of the optic foramen, and from the fibrous sheath of OBLIQUUS INFERIOR. 191 the optic nerve; it passes forwards to the pulley beneath the internal angular process of the frontal bone; lis tendon is then reflected be- neath the superior rectus muscle, to the outer and posterior part of the globe of the eye, where it is inserted into the sclerotic coat, near the entrance of the optic nerve. The tendon is surrounded by a synovial membrane, while passing through the cartilaginous pulley. Relations.—By its superior surface with the fourth nerve, the supra- trochlear nerve, and with the periosteum of the orbit. By the inferior surface with the adipose tissue of the orbit, the upper border of the internal rectus and the vessels and nerves in relation with that border. The Obliquus Inferior, a thin and narrow muscle, arises from the inner margin of the superior maxillary bone, immediately external to the lachrymal groove, and passes beneath the inferior rectus, to be inserted into the outer and posterior part of the eyeball, at about two lines from the entrance of the optic nerve. Relations.—By its superior surface with the inferior rectus muscle and with the eyeball; and by the inferior surface with the periosteum of the floor of the orbit, and the external rectus muscle. According to Mr. Ferrall* the muscles of the orbit are separated from the globe of the eyeball and from the structures immediately surrounding the optic nerve, by a distinct fascia, which is continuous with the broad tarsal ligament and with the tarsal cartilages. This fascia the author terms the tunica vaginalis oculi,] it is pierced an- teriorly for the passage of the six orbital muscles, by six openings through which the tendons of the muscles play as through pulleys. The use assigned to it by Mr. Ferrall is to protect the eyeball from the pressure of its muscles during their action. By means of this structure the recti muscles are enabled to impress a rotatory movement upon the eyeball; and in animals provided with a retractor muscle, they also act as antagonists to its action. Actions.—The levator palpebrae raises the upper eyelid. The four recti, acting singly, pull the eyeball in the four directions; upwards, downwards, inwards, and outwards. Acting by pairs, they carry the eyeball in the diagonal of these directions, viz. upwards and inwards, upwards and outwards, downwards and inwards, or downwards and outwards. Acting all together, they directly retract the globe within the orbit. The superior oblique muscle, acting alone, rolls the globe inwards and forwards, and carries the pupil outwards and downwards to the lower and outer angle of the orbit. The inferior oblique, acting alone, rolls the globe outwards and backwards, and carries the pupil outwards and upwards to the upper and outer angle of the eye. Both muscles acting together, draw the eyeball forwards, and give the pupil that slight degree of eversion which enables it to admit the largest field of vision. 4. Nasal Group.—Pyramidalis nasi, Compressor nasi, Dilatator naris. * In a paper read before the Royal Society, on the 10th of June, 1841. t This fascia was first described by Mr. Dalrymple in his work on the " Anatomy of the Human Eye." 1834. 192 ORBICULARIS ORIS. The Pyramidalis Nasi is a small pyramidal slip of muscular fibres sent downwards upon the bridge of the nose by the occipito-frontalis. It is inserted into the tendinous expansion of the compressores nasi. Relations.—By its upper surface with the integument; by its under surface with the periosteum of the frontal and nasal bone. Its outer border corresponds with the edge of the orbicularis palpebrarum, and its inner border with its fellow, from which it is separated by a slight interval. The Compressor Nasi is a thin and triangular muscle ; it arises by its apex from the canine fossa of the superior maxillary bone, and spreads out upon the side of the nose into a thin tendinous expansion, which is continuous across its ridge with the muscle of the opposite side. Relations.—By its superficial surface with the levator labii superi- oris proprius, the levator labii superioris alaeque nasi, and the integu- ment ; by its deep surface with the superior maxillary and nasal bone, and with the alar and lateral cartilages of the nose. The Dilatator Naris is a thin and indistinct muscular apparatus expanded upon the ala of the nostril, and consisting of an anterior and a posterior slip. The anterior slip (levator proprius alae nasi anterior) extends between the lateral and alar cartilage at about mid- way between the tip and the attached margin of the nose. The posterior slip (levator proprius alae nasi posterior) is attached above to the margin of the nasal process of the superior maxillary bone, and below to the small cartilages of the ala nasi. These muscles are difficult of dissection from the close adherence of the integument to the nasal cartilages. Actions.—The pyramidalis nasi, as a point of attachment of the occipito-frontalis, assists that muscle in its action : it also draws down the inner angle of the eyebrow, and by its insertion fixes the aponeu- rosis of the compressores nasi. The compressores nasi appear to act in expanding rather than in compressing the nares; hence probably the compressed state of the nares from paralysis of these muscles in the last moments of life, or in compression of the brain. The use of the dilatator naris is expressed in its name. 5. Superior Labial Group.—Orbicularis oris, Levator labii superioris alaeque nasi, Levator labii superioris proprius, Levator anguli oris, Zygomaticus major, Zygomaticus minor, Depressor labii superioris alaeque nasi. The Orbicularis Oris is a sphincter muscle, completely surround- ing the mouth, and possessing consequently neither origin nor inser- tion. It is composed of two thick semicircular planes of fibres, which embrace the rima of the mouth, and interlace at their extremities, where they are continuous with the fibres of the buccinator, and of the other muscles connected with the angle of the mouth. The upper segment is attached by means of a small muscular fasciculus (naso- LEVATOR LABII SUPERIORIS. 193 labialis) to the columna of the nose; and other fasciculi connected with both segments and attached to the maxillary bones are termed " accessorii." Relations.—By its superficial surface with the integument of the lips with which it is closely connected. By its deep surface with the mucous membrane of the mouth, the labial glands and coronary ar- teries being interposed. By its circumference with the numerous muscles which move the lips, and by the inner border with the mucous membrane of the rima of the mouth. The Levator Labii Superioris Alaeque Nasi is a thin triangular muscle : it arises from the upper-part of the nasal process of the su- perior maxillary bone; and becoming broader as it descends, is in- serted by two distinct portions into the ala of the nose and upper lip. Relations.—By its superficial surface with part of the orbicularis palpebrarum muscle, the facial artery, and the integument. By its deep surface with the superior maxillary bone, compressor nasi, alar cartilage, and with a muscular fasciculus attached only to the bone, and thence called musculus anomalus. The Levator Labii Superioris Proprius is a thin quadrilateral muscle: it arises from the lower border of the orbit, and passing ob- liquely downwards and inwards, is inserted into the integument of the upper lip; its deep fibres being blended with those of the orbicularis. Relations.—By its superficial surface with the lower segment of the orbicularis palpebrarum, with the facial artery, and with the integu- ment. By its deep surface with the origins of the compressor nasi and levator anguli oris muscle, and with the infra-orbital artery and nerve. The Levator Anguli Oris arises from the canine fossa of the su- perior maxillary bone,( and passes outwards to be inserted into the angle of the mouth, intermingling its fibres with those of the orbicu- laris, zygomatici, and depressor anguli oris. Relations.—By its superficial surface with the levator labii supe- rioris proprius, the branches of the infra-orbital artery and nerve, and inferiorly with the integument. By its deep surface with the superior maxillary bone and buccinator muscle. The Zygomatic muscles are two slender fasciculi of fibres which arise from the malar bone, and are inserted into the angle of the mouth, where they are continuous with the other muscles attached to this part. The zygomaticus minor is situated in front of the major, and is con- tinuous at its insertion with the levator labii superioris proprius ; it is not unfrequently wanting. Relations.—The zygomaticus major muscle is in relation by its super- ficial surface with the lower segment of the orbicularis palpebrarum above, and the fat of the cheek and integument for the rest of its ex- tent. By its deep surface with the malar bone, the masseter, and buc- cinator muscle, and the facial vessels. The zygomaticus minor being in front of the major, has no relation with the masseter muscle, while inferiorly it rests upon the levator anguli oris. The Depressor Labii Superioris Alaeque Nasi (myrtiformis) is seen by drawing upwards the upper lip, and raising the mucous membrane. 17 194 INFERIOR LABIAL GROUP. It is a small oval slip of muscle, situated on each side of the fraenum, arising from the incisive fossa, and passing upwards to be inserted into the upper lip and into the ala and columna of the nose. This muscle is continuous by its outer border with the edge of the com- pressor nasi. Relations.—By its superficial surface with the mucous membrane of the mouth, the orbicularis oris and levator labii superioris alaeque nasi muscle; and by its deep surface with the superior maxillary bone. Actions.—The orbicularis oris produces the direct closure of the lips by means of its continuity at the angles of the mouth, with the fibres of the buccinator. When acting singly in the forcible closure of the mouth, the integument is thrown into wrinkles in consequence of its firm connexion with the surface of the muscle. The levator labii su- perioris alaeque nasi lifts the upper lip with the ala of the nose, and ex- pands the opening of the nares. The depressor labii superioris alaeque nasi is the antagonist to this muscle, drawing the upper lip and ala of the nose downwards, and contracting the opening of the nares. The levator labii superioris proprius is the proper elevator of the upper lip; acting singly it draws the lip a little to one side. The levator anguli oris lifts the angle of the mouth and draws it inwards, while the zy- gomatic pull it upwards and outwards, as in laughing. 6. Inferior Labial Group.—Depressor labii inferioris, Depressor anguli oris, Levator labii inferioris. Dissection.—To cUssect the inferior labial region continue the vertical section from the margin of the lower lip to the point of the chin. Then carry an incision along the margin of the lower jaw to its angle. Dissect off the integument and superficial fascia from the whole of this surface, and the muscles of the inferior labial region will be exposed. The Depressor Labii Inferioris (quadratus menti) arises from the oblique line by the side of the symphysis of the lower jaw, and pass- ing upwards and inwards is inserted into the orbicularis muscle and integument of the lower lip. Relations.—By its superficial surface with the platysma myoides, part of the depressor anguli oris, and with the integument of the chin, with which it is closely connected. By the deep surface with the le- vator labii inferioris, the labial glands and mucous membrane of the lower lip, and with the mental nerve and artery. The Depressor Anguli Oris (triangularis oris) is a triangular plane of muscle arising by a broad base from the external oblique ridge of the lower jaw, and inserted by its apex into the angle of the mouth, where it is continuous with the levator anguli oris and zygomaticus major. Relations.—By its superficial surface with the integument; and by its deep surface with the depressor labii inferioris, the buccinator, and the branches of the mental nerve and artery. The Levator Labii Inferioris (levator menti) is a small conical slip of muscle arising from the incisive fossa of the lower jaw, and in- MAXILLARY GROUP. 195 serted into the integument of the chin. It is in relation with the mu- cous membrane of the mouth, with its fellow, and with the depressor labii inferioris. Actions.—The depressor labii inferioris draws the lower lip directly downwards, and at the same time a little outwards. The depressor anguli oris, from the radiate direction of its fibres, will pull the angle of the mouth either downwards and inwards, or downwards and out- wards, and be expressive of grief; or acting with the levator anguli oris and zygomaticus major, it will draw the angle of the mouth directly backwards. The levator labii inferioris raises and protrudes the integument of the chin. 7. Maxillary group.—Masseter, Temporalis, Buccinator, Pterygoideus externus, Pterygoideus internus. Dissection.—The masseter has been already exposed by the pre- ceding dissection. The Masseter (f/.octfd'aou.ai, to chew,) is a short, thick, and sometimes quadrilateral muscle, composed of two planes of fibres, superficial and deep. The superficial layer arises by a strong aponeurosis from the tuberosity of the superior maxillary bone, the lower border of the malar bone and zygoma, and passes backwards to be inserted into the ramus and angle of the inferior maxilla. The deep layer arises from the posterior part of the zygoma, and* passes forwards, to be inserted into the upper half of the ramus. This muscle is tendinous and mus- cular in its structure. Relations.—By its external surface with the zygomaticus major and risorius Santorini muscle, the parotid gland and Stenon's duct, the transverse facial artery, the pes anserinus and the integument. By its internal surface with the temporal muscle, the buccinator, from which it is separated by a mass of fat, and with the ramus of the lower jaw. By its posterior border with the parotid gland; and by the anterior border with the facial artery and vein. Dissection.—Make an incision along the upper border of the zygoma, for the purpose of separating the temporal fascia from its attachment. Then saw through the zygomatic process of the malar bone, and through the root of the zygoma, near to the meatus audi- torius. Draw down the zygoma, and with it the origin of the mas- seter, and dissect the latter muscle away from the ramus and angle of the inferior maxilla. Now remove the temporal fascia from the rest of its attachment, and the whole of the temporal muscle will be exposed. The Temporal is a broad and radiating muscle occupying a consi- derable extent of the side of the head and filling the temporal fossa. It is covered in by a very dense fascia (temporal fascia) which is attached along the temporal ridge on the side of the skull, extending from the external angular process of the frontal bone to the mastoid portion of the temporal; inferiorly, it is connected to the upper border 196 BUCC IN ATOR—PTERYGOIDEI. of the zygoma. The muscle arises by tendinous fibres from the whole length of the temporal ridge, and by muscular fibres from the temporal fascia and entire surface of the temporal fossa. Its fibres converge to a strong and narrow tendon, which is inserted into the apex of the coronoid process, and for some way down upon its inner surface. Relations.—By its external surface with the temporal fascia, which separates it from the attollens and attrahens aurem muscle, the tem- poral vessels and nerves; and with the zygoma and masseter. By its internal surface with the bones forming the temporal fossa, the exter- nal pterygoid muscle, a part of the buccinator, and the internal max- illary artery with its deep temporal branches. By sawing through the coronoid process near to its base, and pull- ing it upwards, together with the temporal muscle, which may be dissected from the fossa, we obtain a view of the entire extent of the buccinator and of the external pterygoid muscle. The Buccinator (buccina, a trumpet), the trumpeter's muscle, arises from the alveolar process of the superior maxillary and from the external oblique line of the inferior maxillary bone, as far forward as the second bicuspid tooth, and from the pterygo-maxillary liga- ment. This ligament is the raphe of union between the buccinator and superior constrictor muscle, and is attached by one extremity to the hamular process of the internal pterygoid plate, and by the other to the extremity of the molar ridge. The fibres of the muscle con- verge towards the angle of the mouth where they cross each other, the superior being continuous with the inferior segment of the orbi- cularis oris, and the inferior with the superior segment. The muscle is invested externally by a thin fascia. Relations.—By its external surface, posteriorly with a large and rounded mass of fat, which separates the muscle from the ramus of the lower jaw, the temporal, and the masseter; anteriorly with the risorius Santorini, the zygomatici, the levator anguli oris, and the depressor anguli oris. It is also in relation with a part of Stenon's duct, which pierces it opposite the second molar tooth of the upper jaw, with the transverse facial artery, the branches of the facial and buccal nerve, and the facial artery and vein. By its internal surface with the buccal glands and mucous membrane of the mouth. The External Pterygoid is a short and thick muscle, broader at its origin than at its insertion. It arises by two heads, one from the pterygoid ridge on the greater ala of the sphenoid; the other from the external pterygoid plate and tuberosity of the palate bone. The fibres pass backwards, to be inserted into the neck of the lower jaw and the interarticular fibro-cartilage. The internal maxillary artery frequently passes between the two heads of this muscle. Relations.—By its external surface, with the ramus of the lower jaw, the temporal muscle, and the internal maxillary artery; by its internal surface, with the internal pterygoid muscle, internal lateral ligament of the lower jaw, arteria meningea media, and inferior maxillary nerve; and by its upper border, with the muscular branches of the inferior maxillary nerve; the internal maxillary artery passes AURICULAR GROUP. 197 between the two heads of this muscle, and its lower origin is pierced by the buccal nerve. The external pterygoid muscle must now be removed, the ramus of the lower jaw sawn through its lower third, and the head of the bone dislocated from its socket and withdrawn, for the purpose of seeing the pterygoideus internus. The Internal Pterygoid is a thick quadrangular muscle. It arises from the pterygoid fossa, and descends obliquely backwards, to be inserted into the ramus and angle of the lower jaw: it resembles the masseter in appearance and direction, and was named by Winslow the internal masseter. Relations. — By its external surface, with the external pterygoid, the inferior maxillary nerve and its branches, the internal maxillary artery and branches, the internal lateral ligament, and the ramus of the lower jaw. By its internal surface, with the tensor palati, supe- rior constrictor and fascia of the pharynx; and by its posterior bor- der, with the parotid gland. Actions. — The maxillary muscles are the active agents in mastication, and form an apparatus beautifully fitted for that office. The buccinator circumscribes the cavity of the mouth, and with the aid of the tongue, keeps the food under the immediate pressure of the teeth. By means of its connexion with the superior constrictor, it shortens the cavity of the pharynx, from before backwards, and becomes an important auxiliary in deglu- tition. The temporal, the masseter, and the internal pterygoid, are the bruising muscles, drawing the lower jaw against the upper with great force. The two latter, by the ob- liquity of their direction, assist the external pterygoid in grinding the food, by carrying the lower jaw forward upon the upper; the jaw being brought back again by the deep portion of the masseter and posterior fibres of the temporal. The whole of these muscles, acting in succession, produce a rotatory movement of the teeth upon each other, which, with the direct action of the lower jaw against the upper, effects the proper mastication of the food. 8. Auricular Group.—Attollens aurem, Attrahens aurem, Retrahens aurem. Dissection.—The three small muscles of the ear may be exposed by removing a square of integument from around the auricula. This operation must be performed with care, otherwise the muscles, which are extremely thin, will be raised with the superficial fascia. They * The two pterygoid muscles. The zygomatic arch and the greater part of the ramus of the lower jaw have been removed, in order to bring these muscles into view. 1. The sphenoid origin of the external pterygoid muscle. 2. Its pterygoid origin. 3. The in- ternal pterygoid muscle. 17* Fig. 104.* 198 MUSCLES OF THE NECK. are best dissected by commencing with their tendons, and thence pro- ceeding in the course of their radiating fibres. The Attollens Aurem (superior auris), the largest of the three, is a thin triangular plane of muscular fibres arising from the edge of the aponeurosis of the occipito-frontalis, and inserted into the upper part of the concha. It is in relation by its external surface with the integument, and by the internal with the temporal aponeurosis. The Attrahens Aurem (anterior auris), also triangular, arises from the edge of the aponeurosis of the occipito-frontalis, and is inserted into the anterior part of the helix, covering in the anterior and poste- rior temporal arteries. It is in relation by its external sUfrface with the integument; and by the internal with the temporal aponeurosis and with the temporal artery and veins. The Retrahens Aurem (posterior auris), arises by three or four muscular slips from the mastoid process. They are inserted into the posterior surface of the concha. It is in relation by its external surface with the integument, and by its internal surface with the mastoid portion of the temporal bone. Actions.—The muscles of the auricular region possess but little action in man; they are the analogues of important muscles in brutes. Their use is sufficiently explained in their names. MUSCLES OF THE NECK. The muscles of the neck may be arranged into eight groups cor- responding with the natural divisions of the region; they are the— 1. Superficial group. 2. Depressors of the os hyoides and larynx. 3. Elevators of the os hyoides and larynx. 4. Lingual group. 5. Pharyngeal group. 6. Soft palate group. 7. Praevertebral group. 8. Proper muscles of the larynx. And each of these groups consist of the following muscles:—viz. 1. Superficial Group. Stylo-hyoideus, Platysma-myoides, Mylo-hyoideus, Sterno-cleido-mastoideus. Genio-hyoideus, 2. Depressors of the os hyoides * ° and larynx. 4. Muscles of the Tongue. Sterno-hyoideus, Genio-hyo-glossus, Sterno-thyroideus, Hyo-glossus, Thyro-hyoideus, Lingualis, Omo-hyoideus. Styfo-glossus, Palato-glossus. 5. Muscles of Digastricus, Constrictor inferior, 3. Elevators of the os hyoides and larynx. 5. Muscles of the Pharynx. PLATYSMA MYOIDES. 199 Constrictor medius, Constrictor superior, Stylo-pharyngeus, Palato-pharyngeus. 6. Muscles of the soft Palate. Levator palati, Tensor palati, Azygos uvulae, Palato-glossus, Palato-pharyngeus. 7. Pravertebral Group. Rectus anticus major. Dissection.—The dissection of the neck should be commenced by making an incision along the middle line of its fore part from the chin to the sternum, and bounding it superiorly and inferiorly by two transverse incisions; the superior one being carried along the margin of the lower jaw, and across the mastoid process to the tubercle on the occipital bone, the inferior one along the clavicle to the acromion process. The square flap of integument thus included should be turned back from the entire side of the neck, which brings into view the superficial fascia, and on the removal of a thin layer of superfi- cial fascia the platysma myoides will be exposed. The Platysma Myoides (VX« 4th, and 5th transverse processes. t ) 2d and 3d bodies ( 3 lower cervical vertebrae, bodies, • > 4th and 5th trans- } * ' ) verse processes. ( 3 upper dorsal, bodies. In general terms, the muscle is attached to the bodies and trans- verse processes of the five superior cervic'ai vertebrae above, and to the bodies of the last three cervical and first three dorsal below. Relations.—By its anterior surface, with the pharynx, oesophagus, the sheath of the common carotid, internal jugular vein and pneumo- gastric nerve, the sympathetic nerve, inferior laryngeal nerve, and inferior thyroid artery. By its posterior surface it rests upon the cervical and upper dorsal vertebrae. Actions.—The rectus anticus major and minor preserve the equi- librium of the head upon the atlas; and, acting conjointly with the longus colli, flex and rotate the head and the cervical portion of the vertebral column. The scaleni muscles, taking their fixed point from below, are flexors of the vertebral column; and, from above, elevators of the ribs, and therefore inspiratory muscles. Eighth Group.—Muscles of the Larynx. These muscles are described with the anatomy of the larynx, in Chapter XI. J * MUSCLES OP THE TRUNK. The muscles of the trunk may be subdivided into four natural groups; viz. 1. Muscles of the back. 3. Muscles of the abdomen. 2. Muscles of the thorax. 4. Muscles of the perineum. 1. Muscles of the Back.—The region of the back, in consequence of its extent, is common to the neck, the upper extremities, and the abdomen. The muscles of which it is composed are numerous, and may be arranged into six layers. First Layer. Third Layer. Trapezius, ^ Serratus posticus superior, Latissimus dorsi. Serratus posticus inferior, Second Layer. Splenius capitis, T t , Splenius colli. Levator anguli scapulae, Rhomboideus minor, Fourth Layer. Rhomboideus major. (Dorsal Group.) MUSCLES OF THE BACK. 213 Sacro-lumbalis, (Cervical Group.) Longissimus dorsi, Rectus anticus major, Spinalis dorsi. Rectus anticus minor, (Cervical Group.) Rectus lateralis, Cervicalis ascendens, Obliquus inferior, Transversalis colli, Obliquus superior. Trachelo-mastoideus, „. . T Complexus. Sixth Layer. jp-ri j Multifidus spinae, tijth Layer. Levatores costarum, (Dorsal Group.) Supra-spinalis, Semi-spinalis dorsi, Inter-spinales, Semi-spinalis colli, Inter-transversales. First Layer. Dissection.—The muscles of this layer are to be dissected by making an incision along the middle line of the back, from the tubercle on the occipital bone to the coccyx. From the upper point of this incision carry a second along the side of the neck, to the middle of the clavicle. Inferiorly, an incision must be made from the extremity of the sacrum, along the crest of the ilium, to about its middle. For the convenience of dissection, a fourth may be car- ried from the middle of the spine to the acromion process. The in- tegument and superficial fascia, together, are to be dissected off the muscles, in the course of their fibres, over the whole of this region. The Trapezius muscle (trapezium, a quadrangle with unequal sides) arises from the superior curved line of the occipital bone, from the ligamentum nuchae, supra-spinous ligament, and spinous processes of the last cervical and all the dorsal vertebrae. The fibres converge from these various points, and are inserted into the scapular third of the clavicle, the acromion process, and the whole length of the upper border of the spine of the scapula. The inferior fibres become ten- dinous near the scapula, and glide over the triangular surface at the posterior extremity of its spine, upon a bursa mucosa. When the trapezius is dissected on both sides, the two muscles resemble a tra- pezium, or diamond-shaped quadrangle, on the posterior part of the shoulders: hence the muscle was formerly named cucullaris (cucullus, a monk's cowl). The cervical and upper part of the dorsal portion of the muscle is tendinous at its origin, and forms, with the muscle of the opposite side, a kind of tendinous ellipse. Relations—By its superficial surface with the integument and superficial fascia, to which it is closely adherent by its cervical por- tion, loosely by its dorsal portion. By its deep surface, from above downwards, with the complexus, splenius, levator anguli scapulae, supra-spinatus, a small portion of the serratus posticus superior, rhom- boideus minor, rhomboideus major, intervertebral aponeurosis which separates it from the erector spinae, and with the latissimus dorsi. The anterior border of the cervical portion of this muscle forms the posterior boundary of the posterior triangle of the neck. The clavi- cular insertion of the muscle sometimes advances to the middle of the 214 MUSCLES OF THE BACK. clavicle, or as far as the outer border of the sterno-mastoid, and occa- sionally it has been seen to overlap the latter. This is a point of much importance to be borne in mind in the operation for ligature of the subclavian artery. The spinal accessory nerve passes beneath the anterior border, near to the clavicle, previously to its distribution to the muscle. The ligamentum nucha is a thin cellulo-fibrous layer extended from Fig. no.* * The first and second and part of the third layer of muscles of the back; the first layer being shown upon the right, and the second on the left side. 1. The trapezius muscle. 2. The tendinous portion which, with a corresponding portion in the opposite muscle, forma the tendinous ellipse on the back of the neck. 3. The acromion process and spine of the scapula. 4. The latissimus dorsi muscle. 5. The deltoid. 6. The muscles of the dorsum of the scapula, infra-spinatus, teres minor, and teres major. 7. The external oblique muscle. 8. The gluteus medius. 9. The glutei maximi. 10. The levator anguli scapulffi. 11. The rhomboideus minor. 12. The rhomboideus major. 13. The splenius capitis; the muscle immediately above, and overlaid by the splenius, is the complexus. 14. The splenius colli, only partially seen; the common origin of the splenius is seen attached to the spinous processes below the lower border of the rhomboideus major. 15. The vertebral aponeurosis. 16. The serratus posticus inferior. 17. The supra-spinatus mus- cle. 18. The infra-spinatus. 19. The teres minor muscle. 20. The teres major. 21. The long head of the triceps, passing between the teres minor and major to the upper arm. 22. The serratus magnus, proceeding forwards from its origin at the base of the scapula. 23. The internal oblique muscle. RHOMBOIDEI. 215 the tubercle and spine of the occipital bone, to the spinous process of the seventh cervical vertebra, where it is continuous with the supra- spinous ligament. It is connected with the spinous processes of the rest of the cervical vertebrae, with the exception of the atlas, by means of a small fibrous slip which is sent off by each. It is the analogue of an important elastic ligament in animals. The Latissimus Dorsi muscle covers the whole of the lower part of the back and loins. It arises from the spinous processes of the seven in- ferior dorsal vertebrae, from all the lumbar and sacral spinous processes, from the posterior third of the crest of the ilium, and from the three lower ribs; the latter origin takes place by muscular slips, which in- digitate with the external oblique muscle of the abdomen. The fibres from this extensive origin converge as they ascend, and cross the inferior angle of the scapula ; they then curve around the lower bor- der of the teres major muscle, and terminate in a short quadrilateral tendon,* which lies in front of the tendon of the teres, and is inserted into the bicipital groove. A synovial bursa is interposed between the muscle and the lower angle of the scapula, and another between its tendon and that of the teres major. The muscle frequently receives a small fasciculus from the scapula as it crosses its inferior angle. Relations.—By its superficial surface with the integument and superficial fascia; the latter is very dense and fibrous in the lumbar region; and with the trapezius. By its deep surface from below up- wards, with the erector spinae, serratus posticus inferior, intercostal muscles and ribs, rhomboideus major, inferior angle of the scapula and teres major. The latissimus dorsi, with the teres major, forms the posterior border of the axilla. Second Layer. Dissection.—This layer is brought into view by dividing the two preceding muscles near their insertion, and turning them to the oppo- site side. The Levator Anguli Scapulae arises by distinct slips, from the posterior tubercles of the transverse processes of the four upper cervical vertebra1, and is inserted into the upper angle and posterior border of the scapula, as far as the triangular smooth surface at the root of its spine. Relations.—By its superficial surface with the trapezius, sterno- mastoid and integument. By its deep surface with the splenius colli, transversalis colli, cervicalis ascendens, scalenus posticus, and ser- ratus posticus superior. The tendons of origin are interposed be- tween the attachments of the scalenus posticus in front, and the sple- nius colli behind. The Rhomboideus Minor (rhombus, a parallelogram with four equal sides) is a narrow slip of muscle, detached from the rhomboi- deus major by a slight cellular interspace. It arises from the spinous process of the two last cervical vertebrae and ligamentum nuchae, and • A small muscular fasciculus from the pectoralis major is sometimes found connected with this tendon. 216 MUSCLES OF THE BACK. is inserted into the edge of the triangular surface, on the posterior border of the scapula. The Rhomboideus Major arises from the spinous processes of the last cervical and four upper dorsal vertebrae and from the inter-spi- nous ligaments; it is inserted into the posterior border of the scapula as far as its inferior angle. The upper and middle portion of the insertion is effected by means of a tendinous band which is attached in a longitudinal direction to the posterior border of the scapula. Relations.—By their superficial surface the two rhomboid muscles are in relation with the trapezius, and the rhomboideus major with the latissimus dorsi and integument. By their deep surface they cover in the serratus posticus superior, part of the erector spinae, the inter- costal muscles and ribs. Third Layer. • Dissection.—The third layer consists of muscles which arise from the spinous processes of the vertebral column, and pass outwards. It is brought into view by dividing the levator anguli scapulae near its insertion, and reflecting the two rhomboid muscles upwards from their insertion into the scapula. The latter muscles should now be removed. The Serratus Posticus Superior is situated at the upper part of the thorax; it arises by the ligamentum nuchae, from the spinous pro- cesses of the three last cervical and those of the two upper dorsal vertebrae. The muscle passes obliquely downwards, and outwards, and is inserted by four serrations into the upper border of the second, third, fourth, and fifth ribs. Relations.—By its superficial surface with the trapezius, rhomboi- deus major and minor, and serratus magnus. By its deep surface with the splenius, the upper part of the erector spinae, the intercostal muscles and ribs. The Serratus Posticus Inferior arises from the processes and in- terspinous ligaments of the two last dorsal and three upper lumbar vertebrae, and passing obliquely upwards is inserted by four serrations into the lower border of the four lower ribs. Both muscles are con- stituted by a thin aponeurosis for about half their extent. Relations.—By its superficial surface with the latissimus dorsi, its tendinous origin being inseparably connected with the aponeurosis of that muscle. By its deep surface with the aponeurosis of the obliquus internus, with which it is also closely adherent; with the erector spinae, the intercostal muscles and lower ribs. The upper border is continuous with a thin tendinous layer, the vertebral aponeurosis. The Vertebral aponeurosis is a thin membranous expansion composed of longitudinal and transverse fibres, and extending the whole length of the thoracic region. It is attached mesially to the spinous pro- cesses of the dorsal vertebrae, and externally to the angles of the ribs; superiorly it is continued upwards beneath the serratus posticus supe- rior, with the lower border of which it is sometimes connected. It serves to bind down the erector spinae, and separate it from the superficial muscles. FOURTH LAYER. 217 The serratus posticus superior must be removed from its origin and turned outwards, to bring into view the whole extent of the splenius muscle. The Splenius Muscle is single at its origin, but divides soon after into two portions, which are destined to distinct insertions. It arises by the lower half of the ligamentum nuchae, from the spinous pro- cesses of the five last cervical, and from the spinous processes and interspinous ligaments of the six upper dorsal vertebrae; it divides as it ascends the neck into the splenius capitis and colli. The splenius capitis is inserted into the rough surface of the occipital bone between the two curved lines, and into the mastoid portion of the temporal bone. The splenius colli is inserted into the posterior tubercles of the transverse processes of the three or four upper cervical vertebrae. Relations.—By its superficial surface with the trapezius, sterno- mastoid, levator anguli scapulae, rhomboideus minor and major, and serratus posticus superior. By its deep surface with the spinalis dorsi, longissimus dorsi, semi-spinalis colli, complexus, trachelo-mas- toid, and transversalis colli. The tendons of insertion of the splenius colli are interposed between the insertions of the levator anguli scapulae in front, and the transversalis colli behind. The splenii of opposite sides of the neck leave between them a tri- angular interval, in which the complexus is seen. Fourth Layer. Dissection.—The two serrati and two splenii muscles must be re- moved by cutting them away from their origins and insertions, to bring the fourth layer into view. Three of these muscles, viz. sacro-lumbalis, longissimus dorsi, and spinalis dorsi, are associated under the name of erector spinae. They occupy the lumbar and dorsal portion of the back. The remaining four are situated in the cervical region. The Sacro-lumbalis and Longissimus Dorsi arise by a common origin from the posterior third of the crest of the ilium, from the pos- terior surface of the sacrum, and from the lumbar vertebrae ; opposite the last rib a line of separation begins to be perceptible between the two muscles. The sacro-lumbalis is inserted by separate tendons into the angles of the six lower ribs. On turning the muscle a little out- wards, a number of tendinous slips will be seen taking their origin from the ribs, and terminating in a muscular fasciculus, by which the sacro-lumbalis is prolonged to the upper part of the thorax. This is the musculus acccssorius ad sacro-lumbalem: it arises from the angles of the six lower ribs, and is inserted by separate tendons into the angles of the six upper ribs. The longissimus dorsi is inserted into all the ribs, between their tubercles and angles. The Spinalis Dorsi arises from the spinous processes of the two upper lumbar and three lower dorsal vertebrae, and is inserted into the spinous processes of all the upper dorsal vertebrae; the two 19 218 MUSCLF.S OF THE BACK. Fig. 111.* muscles form an ellipse, which appears to enclose the spinous pro- cesses of all the dorsal vertebrae. Relations.—The erector spinae muscle is in relation by its superfi- cial surface (in the lumbar region) with the conjoined aponeurosis of the transver- salis and internal oblique muscle, which separates it from the aponeurosis of the serratus posticus inferior, and longissimus dorsi; (in the dorsal region) with the ver- tebral aponeurosis, which separates it from the latissimus dorsi, trapezius, and serratus posticus superior, and with the splenius. By its deep surface (in the lumbar region) with the multifidus spinae, transverse pro- cesses of the lumbar vertebrae, and with the middle layer of the aponeurosis of the transversalis abdominis, which separates it from the quadratus lumborum; (in the dorsal region) with the multifidus spinae, semi-spinalis dorsi, levatores costarum, in- tercostal muscles, and ribs as far as their angles. Internally or mesially with the multifidus spinae, and semi-spinalis dorsi, which separate it from the spinous pro- cesses and arches of the vertebrae. The two layers of aponeurosis of the transversalis abdominis, together with the spinal column in the lumbar region, and the vertebral aponeurosis with the ribs and spinal column in the dorsal region, form a complete osseo-aponeurotic sheath for the erector spinae. The Cervicalis Ascendens is the continuation of the sacro-lumbalis upwards into the neck. It arises from the angles of the four upper ribs, and is inserted by slender tendons into the posterior tubercles of the transverse processes of the four lower cervical vertebrae. Relations.—By its superficial surface with the levator anguli sca- pulae ; by its deep surface with the upper intercostal muscles and ribs, and with the intertransverse muscles; externally with the scalenus posticus; and internally with the transversalis colli. The tendons of insertion are interposed between the attachments of the scalenus pos- ticus and transversalis colli. The Transversalis Colli would appear to be the continuation * The fourth and fifth, and part of the sixth layer of the muscles of the back. 1. The 3ommon origin of the erector spinse muscle. 2. The sacro-lumbalis. 3. The longissimus dorsi. 4. The spinalis dorsi. 5. The cervicalis ascendens. 6. The transversalis colli. 7. The trachelo-mastoideus. 8. The complexus. 9. The tranversalis colli, showing its origin. 10. The semispinalis dorsi. 11. The semispinalis colli. 12. The rectus posticus minor. 13. The rectus posticus major. 14. The obliquus superior. 15. The obliquus inferior. 16. The multifidus spina?. 17. The levatores costarum. 18. Intertransver- sales. 19. The quadratus lumborum. FIFTH LAYER. 219 upwards into the neck of the longissimus dorsi; it arises from the transverse processes of the five upper dorsal vertebrae, and is inserted into the posterior tubercles of the transverse processes of the five middle cervical vertebrae. Relations.—By its superficial surface with the levator anguli sca- pulae, splenius and longissimus dorsi. By its deep surface with the complexus, trachelo-rnastoideus and vertebrae; externally with the musculus accessorius ad sacro-lumbalem, and cervicalis ascendens; internally with the trachelo-rnastoideus and complexus. The tendons of insertion of this muscle are interposed between the tendons of in- sertion of the cervicalis ascendens on the outer side, and of origin of the trachtlo mastoid on the inner side. The Traciielo-mastoid is likewise a continuation upwards from the longissimus dorsi. It is a very slender and delicate muscle, arising from the transverse processes of the four upper dorsal and four lower cervical vertebrae, and inserted into the mastoid process to the inner side of the digastric fossa. Relations.—The same as those of the preceding muscle, excepting that it is interposed between the transversalis colli and the complexus. Its tendons of attachment are the most posterior of those which are connected with the posterior tubercles of the transverse processes of the cervical vertebrae. The Complexus is a large muscle, and with the splenius forms the , great bulk of the back of the neck. It crosses the direction of the splenius, arising from the transverse processes of the four upper dor- sal, and from the transverse and articular processes of the four lower cervical vertebrae, and is inserted into the rough surface on the occi- pital bone between the two curved lines, near the occipital spine. A large fasciculus of the complexus is so distinct, from the principal mass of the muscle as to have led to its description as a separate muscle under the name of biventer cervicis. This appellation is not inappro- priate, for the muscle consists of a central tendon, with two fleshy bellies. The complexus is crossed in the upper part of the neck by a tendinous intersection. Relations.—By its superficial surface with the trapezius, splenius, trachelo-mastoid, transversalis colli, and longissimus dorsi. By its deep surface with the semi-spinalis dorsi and colli, the recti and obliqui. It is separated from its fellow of the opposite side by the ligamentum nuchae, and from the semi-spinalis colli by the profunda cervicis artery and princeps cervicis branch of the occipital, and by the posterior cervical plexus of nerves. Fifth Layer. Dissection.—The muscles of the preceding layer are to be removed by dividing them transversely through the middle, and turning one extremity upwards, the other downwards. In this way the whole of the muscles of the fourth layer may be got rid of, and the remaining muscles of the spine brought into a state to be examined. The Semi-spinales Muscles are connected with the transverse and 220 MUSCLES OF THE BACK. spinous processes of the vertebrae, spanning one half of the vertebral column ; hence their name semi-spinales. The Semi-spinalis Dorsi arises from the transverse processes of the six lower dorsal vertebrae, and is inserted into the spinous processes of the four upper dorsal, and two lower cervical vertebrae. The Semi-spinalis Colli arises from the transverse processes of the four upper dorsal vertebrae, and is inserted into the spinous processes of the four upper cervical vertebrae, commencing with the axis. Relations.—By their superficial surface the semi-spinales are in re- lation from below upwards with the spinalis dorsi, longissimus dorsi, complexus, splenius, with the profunda cervicis and princeps cervicis artery, and posterior cervical plexus of nerves. By their dSep surface with the multifidus spinae muscle. Occipital Group.—This group of small muscles is intended for the varied movements of the cranium on the atlas, and the atlas on the axis. They are extremely pretty in appearance. The Rectus Posticus Major arises from the spinous process of the axis, and is inserted into the inferior curved line of the occipital bone. The Rectus Posticus Minor arises from the spinous tubercle of the atlas, and is inserted into the rough surface on the occipital bone, beneath the inferior curved line. The Rectus Lateralis is extended between the transverse process of the atlas and the occipital bone; it arises from the transverse pro- • cess of the atlas, and is inserted into the rough surface of the occipi- tal bone, external to the condyle. The Obliquus Inferior arises from the spinous process of the axis, I and passes obliquely outwards to be inserted into the extremity of the transverse process of the atlas. The Obliquus Superior arises from the extremity of the transverse process of the atlas, and passes obliquely inwards to be inserted into the rough surface of the occipital bone, between the curved lines. Relations.—By their superficial surface the recti and obliqui are in relation with a strong aponeurosis which separates them from the complexus. By their deep surface with the atlas and axis, and their articulations. The rectus posticus major partly covers in the rectus minor. The rectus lateralis is in relation by its anterior surface with the internal jugular vein, and by its posterior surface with* the vertebral artery. Sixth Layer. Dissection.—The semi-spinales muscles must both be removed to obtain a good view of the multifidus spinae which lies beneath them, and fills up the concavity between the spinous and transverse pro- cesses, the whole length of the vertebral column. The Multifidus Spinae* consists of a great number of fleshy fas- * Professor Theile of Berlin has examined this muscle very closely and describes a portion of it under the name of Rotatorks spin.f, which seems to be an unnecessary complication.—G. SIXTH LAYER. 221 ciculi extending between the transverse and spinous processes of the vertebrae, from the sacrum to the axis. Each fasciculus arises from a transverse process, and is inserted into the spinous process of the first or second vertebra above. Some deep fasciculi of the multifidus spinae have recently been described by Professor Theile under the name of rotatores spina. Relations.—By its superficial surface with the longissimus dorsi, semi-spinalis dorsi, and semi-spinalis colli. By its deep surface with the arches and spinous processes of the vertebral column, and in the cervical region with the ligamentum nuchae. The Levatores Costarum, twelve in number on each side, arise from the transverse processes of the dorsal vertebrae, and pass ob- liquely outwards and downwards to be inserted into the rough surface between the tubercle and angle of the rib below them. The first of these muscles arises from the transverse process of the last cervical vertebra, and the last from that of the eleventh dorsal. The levatores of the inferior ribs, besides the distribution here described, send a fasciculus downwards to the second rib below their origin, and conse- quently are inserted into two ribs. Relations.—By their superficial surface with the longissimus dorsi and sacro-lumbalis. By their deep surface with the intercostal mus- cles and ribs. The Supra-spinalis is a small and irregular muscle lying upon the spinous processes in the cervical region and composed of several fas- ciculi. The fasciculi arise from the inferior cervical and superior dorsal vertebrae, and are inserted into the spinous process of the axis. From its analogy to the spinalis dorsi this muscle has been named spinalis colli. It is sometimes wanting. The Interspinales are small muscular slips arranged in pairs and situated between the spinous processes of the vertebrae. In the cer- vical region there are six pairs of these muscles, the first being placed between the axis and third vertebra, and the sixth between the last cervical and first dorsal. In the dorsal region, rudiments of these muscles are occasionally met with between the upper and lower ver- tebrae, but are absent in the rest. In the lumbar region there are six pairs of interspinales, the first pair occupying the interspinous space between the last dorsal and first lumbar vertebra, and the last the space between the fifth lumbar and sacrum. They are thin and imperfectly developed. Rudimentary interspinales are occasionally met with between the lower part of the sacrum and the coccyx; these are the analogues of the caudal muscles of brutes; in man they have been named collectively the extensor coccygis. The Intertransversales are small quadrilateral muscles situated between the transverse processes of the vertebrae. In the cervical region they are arranged in pairs corresponding with the double con- formation of the transverse processes, the vertebral artery and ante- rior division of the cervical nerves lying between them. The rectus anticus minor and, rectus lateralis represent the intertransversales be- tween the atlas and cranium. In the dorsal region the anterior inter- transversales are represented by the intercostal muscles, while the 19* 222 MUSCLKS OF THE BACK. posterior are mere tendinous bands, muscular only between the first and last vertebrae. In the lumbar region, the anterior intertransver- sales are thin and occupy only part of the space between the trans- verse processes. Analogues of posterior intertransversales exist in the form of small muscular fasciculi (interobliqui) extended between the rudimentary posterior transverse processes of the lumbar vertebrae. With regard to the origin and insertion of the muscles of the back, the student should be informed, that no regularity attends their attach- ments. At the best, a knowledge of their exact connexions, even were it possible to retain it, would be but a barren information, if not absolutely injurious, as tending to exclude more valuable learning. I have therefore endeavoured to arrange a plan, by which they may be more easily recollected, by placing them in a tabular form (p. 224), that the student may see, at a single glance, the origin and insertion of each, and compare the natural grouping and similarity of attach- ments of the various layers. In this manner also their actions will be better comprehended, and learnt with greater facility. Actions.—The upper fibres of the trapezius draw the shoulder up- wards and backwards; the middle fibres, directly backwards; and the lower downwards and backwards. The lower fibres also act by producing rotation of the scapula upon the chest. If the shoulder be fixed the upper fibres will flex the spine towards the corresponding side. The latissimus dorsi is a muscle of the arm, drawing it back- wards and downwards, and at the same time rotating it inwards; if the arm be fixed, the latissimus dorsi will draw the spine to that side, and, raising the lower ribs, be an inspiratory muscle; and if both arms be fixed, the two muscles will draw the whole trunk forwards, as in climbing or walking on crutches. The levator anguli scapulae lifts the upper angle of the scapula, and with it the entire shoulder, and the rhomboidei carry the scapula and shoulder upwards and backwards. In examining the following table, the student will observe the constant recurrence of the number four in the origin and insertion of the muscles. Sometimes the four occurs at the top or bottom of a region of the spine, and frequently includes a part of two regions, and takes two from each, as in the case of the serrati. AgaTn, he will perceive that the muscles of the upper half of the table take their origin from spinous processes, and pass outwards to transverse, where- as the lower half arise mostly from transverse processes. To the student, then, we commit these reflections, and leave it to the pecu- liar tenor of his own mind to make such arrangements as will be best retained by his memory. The serrati are respiratory muscles acting in opposition to each other, the serratus posticus superior drawing the ribs upwards, and thereby expanding the chest; and the inferior drawinc the lower ribs downwards and diminishing the cavity of the chest. °The former is an inspiratory, the latter an expiratory muscle. The splenii mus- cles of one side draw the vertebral column backwards and to one side, and rotate the head towards the corresponding shoulder. The muscles of opposite sides, acting together, will draw the head directly SIXTH LAYER. 223 backwards. They are the natural antagonists of the sterno-mastoid muscles. The sacro-lumbalis with its accessory muscle, the longissimus dorsi, and spinalis dorsi, are known by the general term of erectores spina, which sufficiently expresses their action. They keep the spine sup- ported in the vertical position by their broad origin from below, and by means of their insertion, by distinct tendons, into the ribs and spinous processes. Being made up of a number of distinct fasciculi, which alternate in their actions, the spine is kept erect without fatigue, even when they have to counterbalance a corpulent abdominal deve- lopement. The continuations upwards of these muscles into the neck preserve the steadiness and uprightness of that region. When the muscles of one side act alone, the neck is rotated upon its axis. The complexus, by being attached to the occipital bone, draws the head backwards, and counteracts the muscles on the anterior part of the neck. It assists also in the rotation of the head. The semi-spinales and multifidus spina muscles act directly on the vertebrae, and contribute to the general action of supporting the ver- tebral column erect. The four little muscles situated between the occiput and the two first vertebrae, effect the various movements between these bones; the recti producing the antero-posterior actions, and the obliqui the rota- tory motions of the atlas on the axis. The actions of the remaining muscles of the spine, the supra and interspinales and inter-transversales, are expressed in their names. They approximate their attachments and assist the more powerful muscles in preserving the erect position of the body. The levatores costarum raise the posterior parts of the ribs, and are probably more serviceable in preserving the articulation of the ribs from dislocation, than in raising them in inspiration. 224 TABLE OF ORIGIN AND INSERTION ORIGIN. Layers. 1st Layer. Trapezius . . j Latissimus dorsi \ 2d Layer. Spinous Processes. last, cervical, 12 dorsal 7 lower dorsal, 5 lumbar Levator anguli scapula? . . i i * ' Rhomboideus min. I 2 last cervical Rhomboideus ) 4 upper dorsal and major . . . ) 3d Layer. Serratus posticus ) superior . . ) Serrauis posticus > inferior . . ) Splenius capitis ) Splenius colli . $ 1th Layer. Sacro-lumbalis ----aocessoriusad ) sacro-lumbalem ) Longissimus dorsi Spinalis dorsi . 1 Cervicalis ascendens Transversalis colli Trachelo-rnas- toideus. . . Complexus . . . last cervical 3 last cervical, 2 upper dorsal 2 lower dorsal, 3 upper lumbar 5 last cervical, 6 upper dorsal Transverse Processes. 4 upper cervical 3 lower dorsal, 2 upper lumbar 5th Layer. Semi-spinalis dorsi Semi-spinalis colli Reel us posticus maj Rectus posticus mill Rectus lateralis . Obliquus inferior . Obliquus superior 6lh Layer. Multifidus spin® . Levatores costarum Supra spinalis . . Inter-spinalis . . < Inter-transversales j axis atlas Ribs. occipital bone and "( j ligamentum nuchse 3 lower sacrum and ilium angles of 6 lower 5 upper dorsal 4 upper dorsal, 4lowercervical 4 upper dorsal, 4 lower cervical 6 lower dorsal 4 upper dorsal [angles of 4 upper sacrum and ilium sacrum and lumbar j vertebra? . . ' atlas axis cervical . . . cervical and > lumbar . . \ from sacrum to 3d cervical last cervical and eleven dorsal cervical and lumbar OF THE MUSCLES OF THE BACK. 225 INSERTION. Spinous Processes. Transverse Processes. 8 upper dorsal. ( 4 upper dorsal, ( 2 lower cervical. 4 middle cervical. 3 upper cervical 4 lower cervical. 5 middle cervical 2d, 3d, 4th, and 5th. 4 lower ribs. angles of 6 lower. angles of 6 upper. all the ribs between the tubercles and angles. atlas, from last lumbar to axis. cervical. cervical and lumbar. cervical and lumbar. all the ribs between the tubercles and angles. clavicle and spine of the scapula. posterior bicipital ridge of the humerus. angle and base of the scapula. base of the scapula. base of the scapula. occipital and mastoid portion of temporal bone. mastoid process. occipital bone between the curved lines. occipital bone. occipital bone. occipital bone. occipital bone. 226 MUSCLES OF THE THORAX. MUSCLES OF THE THORAX. The principal muscles situated upon the thorax belong in their ac- tions to the upper extremity, with which they will be described. They are the pectoralis major and minor, subclavius and serratus magnus. The true thoracic muscles are few in number, and appertain exclu- sively to the actions of the ribs; they are, the— Intercostales externi, Intercostales interni, Triangularis sterni. The intercostal muscles are two planes of muscular and tendinous fibres directed obliquely between the adjacent ribs and closing the in- tercostal spaces. They are seen partially upon the removal of the pectoral muscles, or upon the inner surface of the chest. The trian- gularis sterni is within the chest, and requires the removal of the an- terior part of the thorax to bring it into view. The Intercostales Externi, eleven on each side, commence poste- riorly at the tubercles of the ribs, and advance forwards to the costal cartilages where they terminate in a thin aponeurosis which is con- tinued onwards to the sternum. Their fibres are directed obliquely downwards and inwards, pursuing the same line with those of the external oblique muscle of the abdomen. They are thicker than the internal intercostals. The Intercostales Interni, also eleven on each side, commence anteriorly at the sternum, and extend backwards as far as the angles of the ribs, whence they are prolonged to the vertebral column by a thin aponeurosis. Their fibres are directed obliquely downwards and backwards, and correspond in direction with those of the internal oblique muscle of the abdomen. The two muscles cross each other in the direction of their fibres. In structure the intercostal muscles consist of an admixture of muscular and tendinous fibres. They arise from the two lips of the lower border of the ribs, the external from the outer lip, the internal from the inner, and are inserted into the upper border. Relations.—The external intercostals, by their external surface, with the muscles which immediately invest the chest, viz. the pecto- ralis major and minor, the serratus magnus, serratus posticus superior and inferior, scalenus posticus; sacro-lumbalis, and longissimus dorsi, with their continuations, the cervicalis ascendens and transversalis colli; the levatores costarum, and the obliquus externus abdominis. By their internal surface with the internal intercostals, the intercostal vessels and nerves, and a thin aponeurosis, and posteriorly with the pleura. The internal intercostals, by their external surface with the external intercostals, and intercostal vessels and nerves'; by their in- ternal surface with the pleura costalis, the triangularis sterni and dia- phragm. Connected with the internal intercostals are a variable number of muscular fasciculi which pass from the inner surface of one rib near its middle to the next or next but one below; these are the subcostal or more correctly the intracostal muscles. Ml'SCLES OF THE ABDOMEN. 227 The Triangularis Sterni, situated upon the inner wall of the front of the chest, arises by a thin aponeurosis from the side of the sternum, ensiform cartilage, and sternal extremities of the costal cartilages; and is inserted by fleshy digitations into the cartilages of the third, fourth, fifth and sixth ribs, and often into that of the second. Relations.—By its external surface with the sternum, the ensiform cartilage, the costal cartilages, internal intercostal muscles, and in- ternal mammary vessels. By its internal surface with the pleura costalis, the areolar tissue of the anterior mediastinum and the dia- phragm. The lower fibres of the triangularis sterni are continuous with those of the diaphragm. Actions.—The intercostal muscles raise the ribs when they act from above, and depress them when they take their fixed point from below. They are, therefore, both inspiratory and expiratory muscles. The triangularis sterni draws down the costal cartilages, and is, therefore, an expiratory muscle. MUSCLES OF THE ABDOMEN. The muscles of this region are, the— Obliquus externus (descendens), Obliquus internus (ascendens), Cremaster, Transversalis, Rectus, Pyramidalis, Quadratus lumborum, Psoas parvus, Diaphragm. Dissection.—The dissection of the abdominal muscles is to be com- menced by making three incisions:—The first, vertical, in the middle line, from over the lower part of the sternum to the pubes; the second oblique, from the umbilicus, upwards and outwards, to the outer side of the chest, as high as the fifth or sixth rib; and the third, oblique, from the umbilicus, downwards and outwards, to the middle of the crest of the ilium. The three flaps included by these incisions should then be dissected back in the direction of the fibres of the external oblique muscle, beginning at the angle of each. The integu- ment and superficial fascia should be dissected off together so as to expose the fibres of the muscle at once. If the external oblique muscle be dissected on both sides, a white tendinous line will be seen along the middle of the abdomen, extending from the ensiform cartilage to the os pubis ; this is the linea alba. A little external to it, on each side, two curved lines will be observed extending from the sides of the chest to the os pubis, and bounding the recti muscles : these are the linea semilunares. Some transverse lines, linea transversa, three or four in number connect the lineae semi- lunares with the linea alba. The External Oblique Muscle (obliquus externus abdominis de- scendens) is the external flat muscle of the abdomen. Its name is 228 MUSCLES OF THE ABDOMEN. derived from the obliquity of its direction, and the descending course of its fibres. It arises by fleshy digitations from the external surface of the eight inferior ribs; the five upper digitations being received between corresponding processes of the serratus magnus, and the three lower of the latissimus dorsi. Soon after its origin it spreads out into a broad aponeurosis, which is inserted into the outer lip of the crest of the ilium for one half its length, the anterior superior spinous process of the ilium, spine of the os pubis, pectineal line, front of the os pubis, and linea alba. The lower border of the aponeurosis, which is stretched between the anterior superior spinous process of the ilium and the spine of the os pubis, is rounded from being folded inwards, and forms Poupart's ligament; the insertion into the pectineal line is GimbernaVs ligament. Just above the crest of the os pubis is the external abdominal ring, a triangular opening formed by the separation of the fibres of the aponeurosis of the external oblique. It is oblique in its direction, and corresponds with the course of the fibres of the aponeurosis. It is bounded below by the crest of the os pubis; on either side by the borders of the aponeurosis, which are called pillars; and above by some curved fibres (inter-columnar), which originate from Poupart's ligament, and cross the upper angle of the ring so as to give it strength. The external pillar, which is at the same time inferior from the obli- quity of the opening, is inserted into the spine of the os pubis; the internal or superior pillar forms an interlacement with its fellow of the opposite side over the front of the symphysis pubis. The external abdominal ring gives passage to the spermatic cord in the male and round ligament in the female : they are both invested in their passage through it by a thin fascia derived from the edges of the ring, and called inter-columnar fascia, or fascia spermatica. The pouch of inguinal hernia, in passing through this opening, re- ceives the inter-columnar fascia, as one of its coverings. Relations.—By its external surface with the superficial fascia and integument, and with the cutaneous vessels and nerves, particularly the superficial epigastric and superficial circumflexa ilii vessels. It is generally overlapped posteriorly by the latissimus dorsi. By its inter- nal surface with the internal oblique, the lower part of the eight infe- rior ribs and intercostal muscles, the cremaster, the spermatic cord in the male, and the round ligament in the female. The upper border of the external oblique is continuous with the pectoralis major. The external oblique is now to be removed by making an incision across the ribs, just below its origin, to its posterior border; and another along Poupart's ligament and the crest of the ilium. Pou- part's ligament should be left entire, as it gives attachment to the next muscles. The muscle may then be turned forwards towards the linea alba, or removed altogether. The Internal Oblique Muscle (obliquus internus abdominis as- cendens), is the middle flat muscle of the abdomen. It arises from the outer half of Poupart's ligament, from the middle of the crest of the ilium for two-thirds of its length, and by a thin aponeurosis from the spinous processes of the lumbar vertebrae. Its fibres diverge from OBLIQUUS INTERNUS ABDOMINIS. 229 their origin, so that those from Poupart's ligament curve downwards, those from the anterior part of the crest of the ilium pass transversely, and the rest ascend obliquely. The muscle is inserted into the pecti- neal line and crest of the os pubis, linea alba, and lower borders of the five inferior ribs. Fig. 112.* * The muscles of the anterior aspect of the trunk; on the left side the superficial layer is seen, and on the right the deeper layer. 1. The pectoralis major muscle. 2. The del- toid ; the interval between these muscles lodges the cephalic vein. 3. The anterior border of the latissimus dorsi. 4. The serrations of the serratus magnus. 5. The subclavius muscle of the right side. 6. The pectoralis minor. 7. The coracho-brachialis muscle. 8. The upper part of the biceps muscle, showing its two heads. 9. The coracoid process of the scapula. 10. The serratus magnus of the right side. 11. The external intercostal muscle of the fifth intercostal space. 12. The external oblique muscle. 13. Its aponeu- rosis ; the median line to the right of this number is the linea alba; the flexuous line to its left is the linea semilunaris; and the transverse lines above and below the number the line® transversa?. 14. Poupart's ligament. 15. The external abdominal ring ; the mar- gin above the ring is the superior or internal pillar; the margin below the ring, the infe- rior or external pillar ; the curved intercolumnar fibres are seen proceeding upwards from Poupart's ligament to strengthen the ring. The numbers 14 and 15 are situated upon the fascia lata of the thigh; the opening immediately to the right of 15 is the saphenous opening. 16. The rectus muscle of the right side brought into view by the removal of the anterior segment of its sheath: * the posterior segment of its sheath with the divided edge of the anterior segment. 17. The pyramidalis muscle. 18. The internal oblique muscle. 19. The conjoined tendon of the internal oblique and transversalis descending behind Poupart's ligament to the pectineal line. 20. The arch formed between the lower curved border of the internal oblique muscle and Poupart's ligament; it is beneath this arch that the spermatic cord and hernia pass. 20 230 MUSCLES OF THE ABDOMEN. Along the upper three fourths of the linea semilunaris, the aponeu- rosis of the internal oblique separates into two lamellae, which pass one in front and the other behind the rectus muscle to the linea alba, where they are inserted; along the lower fourth, the aponeurosis passes altogether in front of the rectus without separation. The two layers, which thus enclose the rectus, form for it a partial sheath. The lowest fibres of the internal oblique are inserted into the pecti- neal line of the os pubis in common with those of the transversalis muscle. Hence the tendon of this insertion is called the conjoined tendon of the internal oblique and transversalis. This structure cor- responds with the external abdominal ring, and forms a protection to what would otherwise be a weak point in the abdomen. Sometimes the tendon is insufficient to resist the pressure from within, and be- comes forced through the external ring ; it then forms the distinctive covering of direct inguinal hernia. The spermatic cord passes beneath the arched border of the inter- nal oblique muscle, between it and Poupart's ligament. During its passage some fibres are given off from the lower border of the muscle, which accompany the cord downwards to the testicle, and form loops around it: this is the cremaster muscle. In the descent of oblique inguinal hernia, which travels the same course with the spermatic cord, the cremaster muscle forms one of its coverings. The Cremaster, considered as a distinct muscle, arises from the middle of Poupart's ligament, and forms a series of loops upon the spermatic cord. A few of its fibres are inserted into the tunica vaginalis, the rest ascend along the inner side of the cord, to be in- serted, with the conjoined tendon, into the pectineal line of the os % pubis. Relations.—The internal oblique is in relation, by its external sur- face, with the external oblique, latissimus dorsi, spermatic cord, and external abdominal ring. By its internal surface, with the transver- salis muscle, the fascia transversalis, the internal abdominal ring, and spermatic cord. By its lower and arched border, with the spermatic cord, forming the upper boundary of the spermatic canal. The cremaster is in relation, by its external surface, with the apo- neurosis of the external oblique and intercolumnar fascia; and by its internal surface, with the fascia propria of the spermatic cord. The internal oblique muscle is to be removed by separating it from its attachments to the ribs above, and to the crest of the ilium and Poupart's ligament below. It should be divided behind by a vertical incision, extending from the last rib to the crest of the ilium, as its lumbar attachment cannot at present be examined. The muscle is then to be turned forwards. Some degree of care will be required in performing this dissection, from the difficulty of distinguishing between this muscle and the one beneath. A thin layer of cellular tissue is all that separates them for the greater part of their extent. Near the crest of the ilium, the circumflexa illii artery ascends be- tween the two muscles, and forms a valuable guide to their separa- tion. Just above Poupart's ligament they are so closely connected, that it is impossible to divide them. TRANSVERSALIS. 231 The Transversalis is the internal flat muscle of the abdomen; it is transverse in the direction of its fibres, as is implied in its name. It arises from the outer third of Poupart's ligament, from the internal lip of the crest of the ilium, its anterior two-thirds ; from the spinous and transverse processes of the lumbar vertebrae, and from the inner surfaces of the six inferior ribs, indigitating with the diaphragm. Its lower fibres curve downwards, to be inserted, with the lower fibres of the internal oblique, into the pectineal line, and form the conjoined tendon. Throughout the rest of its extent it is inserted into the crest of the os pubis and linea alba. The lower fourth of its aponeurosis passes in front of the rectus to the linea alba; the upper three-fourths, with the posterior lamella of the internal oblique, behind it. The posterior aponeurosis of the transversalis divides into three lamellae ; — anterior, which is attached to the bases of the transverse processes F'g- 113* of the lumbar vertebrae; middle, to the apices of the transverse processes; and posterior, to the apices of the spinous processes. The anterior and middle lamellae enclose the quadratus lumborum muscle; and the middle and posterior, the erector spkiae. The union of the posterior lamella of the transversalis with the posterior aponeurosis of the internal oblique, serratus posticus in- ferior, and latissimus dorsi, constitutes the lumbar fascia. Relations.—By its external surface with the internal oblique, the internal surfaces of the lower ribs, and internal intercostal muscles. By its internal sur- face with the transversalis fascia, which separates it from the peritoneum, with the psoas magnus, and with the lower part of the rectus and pyramidalis. The spermatic cord and oblique inguinal hernia pass beneath the lower border, but have no direct relation with it. To dissect the rectus muscle, its sheath should be opened by a ver- tical incision extending from over the cartilages of the lower ribs to * A lateral view of the trunk of the body, showing its muscles, and particularly the transversalis abdominis. 1. The costal origin of the latissimus dorsi muscle. 2. The serratus magnus. 3. The upper part of the external oblique muscle, divided in the direc- tion best calculated to show the muscles beneath, without interfering with its indigita- tions with the serratus magnus. 4. Two of the external intercostal muscles. 5. Two of the internal intercostals. 6. The transversalis muscle. 7. Its posterior aponeurosis. 8. Its anterior aponeurosis, forming the most posterior layer of the sheath of the rectus. 9. The lower part of the left rectus, with the aponeurosis of the tranversalis passing in front. 10. The right rectus muscle. 11. The arched opening left between the lower border of the transversalis muscle and Poupart's ligament, through which the spermatic cord and hernia pass. 12. The gluteus maximus, and medius, and tensor vagina femoris muscles invested by fascia lata. 232 MUSCLES OF THE ABDOMEN. the front of the os pubis. The sheath may then be dissected off and turned to either side; this is easily done excepting at the lineae trans- versae, where a close adhesion subsists between the muscle and the external boundary of the sheath. The sheath contains the rectus and pyramidalis muscle. The Rectus Muscle arises by a flattened tendon from the crest of the os pubis, and is inserted into the cartilages of the fifth, sixth, and seventh ribs. It is traversed by several tendinous zigzag intersec- tions, called lineae transversae. One of these is usually situated at the umbilicus, two above that point, and sometimes one below. They are vestiges of the abdominal ribs of reptiles, and very rarely extend completely through the muscle. Relations.—By its external surface with the anterior lamella of the aponeurosis of the internal oblique, below with the aponeurosis of the transversalis, and pyramidalis. By its internal surface with the ensi- form cartilage, the cartilages of the fifth, sixth, seventh, eighth and ninth ribs, with the posterior lamella of the internal oblique, the peri- toneum, and the epigastric artery and veins. The Pyramidalis Muscle arises from the crest of the os pubis in front of the rectus, and is inserted into the linea alba at about midway between the umbilicus and the os pubis. It is enclosed in the same sheath with the rectus, and rests against the lower par^of that muscle. This muscle is sometimes wanting. The rectus may now be divided across the middle, and the two ends drawn aside for the purpose of examining the mode of formation of its sheath. The sheath of the rectus is formed in front for the upper three-fourths of its extent, by the aponeurosis of the external oblique and the ante- rior lamella of the internal oblique, and behind by the posterior lamella of the internal oblique and the aponeurosis of the transversalis. At the commencement of the lower fourth, the posterior wall of the sheath terminates in a thin curved margin, the aponeurosis of the three muscles passing altogether in front of the rectus. The next two muscles can be examined only when the viscera of the abdomen are removed. To see the quadratus lumborum, it is also necessary to divide and draw aside the psoas muscle and the anterior lamella of the aponeurosis of the transversalis. The Quadratus Lumborum muscle is concealed from view by the anterior lamella of the aponeurosis of the transversalis muscle, which is inserted into the bases of the transverse processes of the lumbar vertebrae. When this lamella is divided, the muscle will be seen aris- ing from the last rib, and from the transverse processes of the four upper lumbar vertebrae. It is inserted into the crest of the ilium and ilio-lumbar ligament. If the muscle be cut across or removed, the middle lamella of the transversalis will be seen attached to the apices of the transverse processes; the quadratus being enclosed between the two lamellae as in a sheath. Relations.—Enclosed in the sheath formed by the transversalis ' muscle, it is in relation in front, with the kidney, the colon, the psoas DIAPHRAGM. 233 magnus, and the diaphragm. Behind, but also separated by its sheath, with the erector spinae. The Psoas Parvus arises from the tendinous arches and interverte- bral substance of the last dorsal and first lumbar vertebra, and termi- nates in a long slender tendon which expands inferiorly and is inserted into the ilio-pectineal line and eminence. The tendon is continuous by its outer border with the iliac fascia. Relations.—It rests upon the psoas magnus, and is covered in by the peritoneum ; superiorly it passes beneath the ligamentum arcuatum of the diaphragm. It is occasionally wanting. Diaphragm.—To obtain a good view of this important inspiratory muscle, the peritoneum should be dissected from its under surface. It is the muscular septum between the thorax and abdomen, and is com- posed of two portions, a greater and a lesser muscle. The greater muscle arises from the ensiform cartilage; from the inner surfaces of the six inferior ribs, indigitating with the transversalis; and from the ligamentum arcuatum externum and internum. From these points, which form the internal circumference of the trunk, the fibres con- verge and are inserted into the central tendon. The ligamentum arcuatum externum is the upper border of the an- terior lamella of the aponeurosis of the transversalis: it arches across the origin of the quadratus lumborum muscle, and is attached by one extremity to the base of the transverse process of the first lumbar vertebra, and by the other to the apex and lower margin of the last rib. The ligamentum arcuatum internum, or proprium, is a tendinous arch thrown across the psoas magnus muscle as it emerges from the chest. It is attached by one extremity to the base of the transverse process of the first lumbar vertebra, and by the other is continuous with the tendon of the lesser muscle opposite the body of the second. The tendinous centre of the diaphragm is shaped like a trefoil leaf, of which the central leaflet points to the ensiform cartilage, and is the largest; the lateral leaflets, right and left, occupy the corre- sponding portions of the muscle; the right being the larger and more rounded, and the left smaller and lengthened in its form. Between the sides of the ensiform cartilage and the cartilages of the adjoining ribs, is a small triangular space where the muscular fibres of the diaphragm are deficient. This space is closed only by peritoneum on the side of the abdomen, and by pleura within the chest. It is therefore a weak point, and a portion of the contents of the abdomen might, by violent exertion, be forced through it, pro- ducing phrenic, or diaphragmatic hernia. The lesser muscle of the diaphragm takes its origin from the bodies of the lumbar vertebrae by two tendons. The right, larger and longer than the left, arises from the anterior surface of the bodies of the second, third, and fourth vertebrae ; and the left from the side of the second and third. The tendons form two large fleshy bellies (crura), which ascend to be inserted into the central tendon. The inner fas- ciculi of the two crura cross each other in front of the aorta, and again diverge to surround the oesophagus, so as to present the appear- 20* 234 MUSCLES OF THE ABDOMEN. Fig. 114: ance of a figure of eight. The anterior fasciculus of the decussation is formed by the right crus. The openings in the dia- phragm are three: one,qua- drilateral, in the tendinous centre, at the union of the right and middle leaflets, for the passage of the in- ferior vena cava; a muscu- lar opening of an elliptic shape formed by the two crura, for the transmission of the asophagus and pneu- mogastric nerves; and a third, the aortic, which is formed by a tendinous arch thrown from the tendon of one crus to that of the other, beneath which pass the aor- ta, the right vena azygos, and thoracic duct. The great splanchnic nerves pass through openings in the lesser muscle on each side, and the lesser splanchnic nerves through the fibres which arise from the ligamen- tum arcuatum internum. Relations.—By its superior surface with the pleurae, the pericardium, the heart, and the lungs. By its inferior surface with the peritoneum; on the left with the stomach and spleen; on the right with the con- vexity of the liver; and behind with the kidneys, the supra-renal capsules, the duodenum, and the solar plexus. By its circum- ference with the ribs and intercostal muscles, and with the vertebral column. Actions.—The external oblique muscle, acting singly, would draw the thorax towards the pelvis, and twist the body to the opposite side. Both muscles, acting together, would flex the thorax directly on the * The under or abdominal side of the diaphragm. 1, 2, 3. The greater muscle; the figure 1 rests upon the central leaflet of the tendinous centre ; the number 2 on the left or smallest leaflet; and number 3 on the right leaflet. 4. The thin fasciculus which arises from the ensiform cartilage; a small triangular space is left on either side of this fasciculus, which is closed only by the serous membranes of the abdomen and chest. 5. The liga- mentum arcuatum externum of the left side. 6. The ligamentum arcuatum internum. 7. A small arched opening occasionally found, through which the lesser splanchnic nerve passes. 8. The right or larger tendon of the lesser muscle; a muscular fasciculus from this tendon curves to the left side of the greater muscle between the oesophageal and aortic openings. 9. The fourth lumbar vertebra. 10. The left or shorter tendon of the lesser muscle. 11. The aortic opening occupied by the aorta, which is cut short off". 12. A portion of the oesophagus issuing through the oesophageal opening; in this figure the oesophageal opening is tendinous at its anterior part, a structure which is not uncommon. 13. The opening for the inferior vena cava, in the tendinous centre of the diaphragm. 14. The psoas magnus muscle passing beneath the ligamentum arcuatum internum ; it has been removed on the opposite side to show the arch more distinctly. 15. The quad- ratus lumborum passing beneath the ligamentum arcuatum externum; this muscle has also been removed on the left side. MUSCLES OF THE PERINEUM. 235 pelvis. The internal oblique of one side draws the chest downwards and outwards: both together bend it directly forwards. Either trans- versalis muscle, acting singly, will diminish the size of the abdomen on its own side, and both together will constrict the entire cylinder of the cavity. The recti muscles, assisted by the pyramidales, flex the thorax upon the chest, and, through the medium of the lineae transversa), are enabled to act when their sheath is curved inwards by the action of the transversales. The pyramidales are tensors of the linea alba. The abdominal are expiratory muscles, and the chief agents of expulsion; by their action the foetus is expelled from the uterus, the urine from the bladder, the faeces from the rectum, the bile from the gall-bladder, the ingesta from the stomach and bowels in vomiting, and the mucous and irritating substances from the bronchial tubes, trachea, and nasal passages, during coughing and sneezing. To produce these efforts they all act together. Their violent and continued action produces hernia; and, acting spasmodically, they may occasion rupture of the viscera. The quadratus lumborum rfraws the last rib downwards, and is an expiratory muscle; it also serves to bend the vertebral column to one or the other side. The psoas parvus is a tensor of the iliac fascia, and, taking its fixed origin from below, it may assist in flexing the vertebral column for- wards. The diaphragm is an inspiratory muscle, and the sole agent in tranquil inspiration. When in action, the muscle is drawn down- wards, its plane being rendered oblique from the level of the ensiform cartilage, to that of the upper lumbar vertebra. During relaxation it is convex, and encroaches considerably on the cavity of the chest, particularly at the sides, where it corresponds with the lungs. It assists the abdominal muscles powerfully in expulsion, every act of that kind being preceded or accompanied by a deep inspiration. Spasmodic action of the diaphragm produces hiccough and sobbing, and its rapid alternation of contraction and relaxation, combined with laryngeal and facial movements, laughing and crying. MUSCLES OF THE PERINEUM. The muscles of the perineum are situated in the outlet of the pelvis, and consist of two groups, one of which belongs especially to the organs of generation and urethra, the other to the termination of the alimentary canal. To these may be added the only pair of muscles which is proper to the pelvis, the coccygeus. The muscles of the perineal region in the male, are the Accelerator urinae, Sphincter ani, Erector penis, Levator ani, Compressor urethrae, Coccygeus. Transversus perinei, Dissection.—To dissect the perineum, the subject should be fixed in the position for lithotomy, that is, the hands should be bound to the soles of the feet, and the knees kept apart. An easier plan is the drawing of the feet upwards by means of a cord passed through a 236 MUSCLES OF THE PERINEUM. hook in the ceiling. Both of these plans of preparation have for their object the full exposure of the perineum. And as this is a dissection which demands some degree of delicacy and nice manipulation, a strong light should be thrown upon the part. Having fixed the sub- ject, and drawn the scrotum upwards by means of a string or hook, carry an incision from the base of the scrotum along the ramus of the pubes and ischium and tuberosity of the ischium, to a point parallel with the apex of the coccyx; then describe a curve over the coccyx to the same point on the opposite side, and continue the incision on- wards along the opposite tuberosity, and along the ramus of the ischium and of the pubes, to the opposite side of the scrotum, where the two extremities may be connected by a transverse incision. This incision will completely surround the perineum, following very nearly the outline of its boundaries. Now let the student dissect off the in- tegument carefully from the whole of the included space, and he will expose the fatty cellular structure of the common superficial fascia, which exactly resembles the superficial fascia in every other situa- tion. The common superficial fascia is then to be removed to the same extent, exposing the superficial perineal fascia. This layer is also to be turned aside, when the muscles of the genital region of the perineum will be brought into view. The Acceleratores Urinae (bulbo-cavernosus) arise from a tendi- nous point in the centre of the perineum and from the fibrous raphe of the two muscles. From these origins the fibres diverge, like the plumes of a pen; the posterior fibres to be inserted into the ramus of the pubes and ischium; the middle to encircle the corpus spongiosum, and meet upon its upper side; and the anterior to spread out upon the corpus cavernosum on each side, and be inserted, partly into its fibrous structure, and partly into the fascia of the penis. The poste- rior and middle insertions of these muscles are best seen, by carefully raising one muscle from the corpus spongiosum and tracing its fibres. Relations.—By their superficial surface with the superficial perineal fascia, the dartos, the superficial vessels and nerves of the perineum, and on each side with the erector penis. By their deep surface with the corpus spongiosum and bulb of the urethra. The Erector Penis (ischio-cavernosus) arises from the ramus and tuberosity of the ischium, and curves around the root of the penis, to be inserted into the upper surface of the corpus cavernosum, where it is continuous with a strong fascia which covers the dorsum of the organ, the fascia penis. Relations.—By its superficial surface with the superficial perineal fascia, the dartos, and the superficial perineal vessels and nerve. By its deep surface with the corpus cavernosum penis. The Compressor Urethra (Wilson's and Guthrie's muscles), con- sists of two portions; one of which is transverse in its direction, and passes inwards, to embrace the membranous urethra; the other is perpendicular, and descends from the pubes. The transverse portion, particularly described by Mr. Guthrie, arises by a narrow tendinous point, from the upper part of the ramus of the ischium, on each side, and divides into two fasciculi, which pass inwards and slightly up- MUSCLES OF THE PERINEUM. 237 wards, and embrace the membranous pdrtion of the urethra and Cowper's glands. As they pass towards the urethra, they spread out and become fan-shaped, and are inserted into a tendinous raphe upon the upper and lower surfaces of the urethra, extending from the apex of the prostate gland, to which they are attached posteriorly, to the bulbous portion of the urethra, with which they are connected in front. When seen from above, these portions resemble two fans, connected by their expanded border along the middle line of the membranous urethra, from the prostate to the bulbous portion of the urethra. The same appearance is obtained by viewing them from below. Fig. 115.* The perpendicular portion] described by Mr. Wilson, arises by two tendinous points from the inner surface of the arch of the pubes, on each side of, and close to, the symphysis. The tendinous origins soon become muscular, and descend perpendicularly, to be inserted into the upper fasciculus of the transverse portion of the muscle; so that it is not a distinct muscle surrounding the membranous portion of the urethra, and supporting it as in a sling, as described by Mr. Wilson, but merely an upper origin of the transverse muscle. The compressor urethrae may be considered either as two symme- trical muscles meeting at the raphe, or as a single muscle: I have adopted the latter course in the above description, as appearing to me the more consistent with the general connexions of the muscle, and with its actions. * The muscles of the perineum. 1. The acceleratores urinse muscles; the figure rests upon the corpus spongiosum penis. 2. The corpus cavernosum of one side. 3. The erector penis of one side. 4. The transversus perinei of one side. 5. The triangular space through which the deep perineal fascia is seen. 6. The sphincter ani; its anterior extremity is cut off". 7. The levator ani of the left side; the deep space between the tube- rosity of the ischium (8) and the anus, is the ischio-rectal fossa; the same fossa is seen upon the opposite side. 9. The spine of the ischium. 10. The left coccygeus muscle. The boundaries of the perineum are well seen in this engraving. t Mr. Tyrrell, who made many careful dissections of the muscles of the perineum, did not observe this portion of the muscle ; he considers Wilson's muscle (with some other anatomists) to be the anterior fibres of the levator ani, not uniting beneath the urethra as de- scribed by Mr. Wilson ; but inserted into a portion of the pelvic fascia situated between the prostate gland and rectum, the recto-vesical fascia. 238 MUSCLES OF THE PERINEUM. The Transversus Perinei arises from the tuberosity of the ischium on each side, and is inserted into the central tendinous point of the perineum.* Relations.—By its superficial surface with the superficial perineal fascia, and superficial perineal artery. By its deep surface with the deep perineal fascia, and internal pudic artery and veins. By its pos- terior border it is in relation with that portion of the superficial peri- neal fascia which passes back to become continuous with the deep fascia. To dissect the compressor urethra, the whole of the preceding muscles should be removed, so as to render the glistening surface of the deep perineal fascia quite apparent. The anterior layer of the fascia should then be carefully dissected away, and the corpus spon- giosum penis divided through its middle, separated from the corpus cavernosum, and drawn forwards, to put the membranous portion of the urethra, upon which the muscle is spread out, on the stretch. The muscle is, however, better seen in a dissection made from within the pelvis, after having turned down the bladder from its attachment to the os pubis, and removed a plexus of veins and the posterior layer of the deep perineal fascia. The Sphincter Ani is a thin and elliptical plane of muscle closely adherent to the integument, and surrounding the opening of the anus. It arises posteriorly in the superficial fascia around the coccyx, and by a fibrous raphe from the apex of that bone ; and is inserted ante- riorly into the tendinous centre of the perineum, and into the raphe of the integument, nearly as far forwards £s the commencement of the scrotum. Relations.—By its superficial surface with the integument. By its deep surface with the internal sphincter, the levator ani, the cellular tissue and fat in the ischio-rectal fossa, and in front with the superfi- cial perineal fascia. The Sphincter Ani Internus is a muscular ring embracing the ex- tremity of the intestine, and formed by an aggregation of the circular fibres of the rectum. Part of the levator ani may be seen during the dissection of the anal portion of the perineum, by removing the fat which surrounds the termination of the rectum in the ischio-rectal fossa. But to study the entire muscle, a lateral section of the pelvis must be made by sawing through the pubes a little to one side of the symphysis, separating the bones behind at the sacro-iliac symphysis, and turning down the bladder and rectum. The pelvic fascia is then to be care- fully raised, beginning at the base of the bladder and-proceeding up- wards, until the whole extent of the muscle is exposed. The Levator Ani is a thin plane of muscular fibres, situated on each side of the pelvis. The muscle arises from the inner surface of * I have twice dissected a perineum in which the transversus perinei was of large size, and spread out as it approached the middle line so as to become fan-shaped. The posterior fibres were continuous with those of the muscle of the opposite side; but the anterior were prolonged forwards upon the bulb and corpus spongiosum of the urethra as far as the middle of the penis, forming a broad layer which usurped the place and office of the accelerator urince. MUSCLES OF THE PERINEUM. 239 the os pubis, from the spine of the ischium, and betwreen those points from the angle of division between the obturator and the pelvic fascia. Its fibres descend, to be inserted, into the extremity of the coccyx, into a fibrous raphe in front of that bone, into the lower part of the rectum, base of the bladder, and prostate gland. In the female, this muscle is inserted into the coccyx and fibrous raphe, lower part of the rectum and vagina. Relations.—By its external or perineal surface, with a thin layer of fascia, by which, and by the obturator fascia, it is separated from the obturator internus muscle; with the fat in the ischio-rectal fossa, me deep perineal fascia, the levator ani, and posteriorly with the gluteus maximus. By its internal or pelvic surface, with the pelvic fascia, which separates it from the viscera of the pelvis and peri- toneum. The Coccygeus Muscle is a tendino-muscular layer of triangular form. It arises from the spine of the ischium, and is inserted into the side of the coccyx and lower part of the sacrum. Relations.—By its internal or pelvic surface, with the rectum; by its external surface, with the lesser and greater sacro-ischiatic liga- ments. The muscles of the perineum in the female are the same as in the male, and have received analogous names. They are smaller in size, and are modified to suit the different form of the organs; they are— Constrictor vaginae, Sphincter ani, Erector clitoridis, Levator ani, Transversus perinei, Coccygeus. Compressor urethrae, The Constrictor vagina is analogous to the acceleratores urinae; it is continuous, posteriorly, with the sphincter ani, interlacing with its fibres, and is inserted, anteriorly, into the sides of the corpora cavernosa, and fascia of the clitoris. The Transversus perinei is inserted into the side of the constrictor vaginae, and the levator ani into the side of the vagina. The other muscles are precisely similar in their attachments to those in the male. Actions.—The acceleratores urinae being continuous at the middle line, and attached on each side to the bone, by means of their poste- rior fibres, will support the bulbous portion of the urethra, and acting suddenly, will propel the semen, or the last drops of urine, from the canal. The posterior and middle fibres, according to Krause,* con- tribute towards the erection of the corpus spongiosum, by producing compression upon the venous structure of the bulb; and the anterior fibres, according to Tyrrell,f assist in the erection of the entire organ by compressing the vena dorsalis, by means of their insertion into the fascia penis. The erector penis becomes entitled to its name from spreading out upon the dorsum of the organ, into a membranous * Miiller, Archiv fur Anatomie, Physiologie, &c. 1837. t Lectures in the College of Surgeons. 1839. 240 MUSCLES OF THE UPPER EXTREMITY. expansion, (fascia penis,) which, according to Krause, compresses the dorsal vein during the action of the muscle, and especially after the erection of the organ has commenced. The transverse muscles serve to steady the tendinous centre, that the muscles attached to it may ob- tain a firm point of support. According to Cruveilhier, they draw the anus backwards during the expulsion of the faeces, and antagonize the levatores ani, which carry the anus forwards. The compressor urethrae, taking its fixed point from the ramus of the ischium at each side, can, says Mr. Guthrie, "compress the urethra so as to close it; I conceive completely, after the manner of a sphincter." The trans- verse portion will also have a tendency to draw the urethra down- wards, whilst the perpendicular portion will draw it upwards towards the os pubis. The inferior fasciculus of the transverse muscle, en- closing Cowper's glands, will assist those bodies in evacuating their secretion. The external sphincter, being a cutaneous muscle, con- tracts the integument around the anus, and by its attachment to the tendinous centre, and to the point of the coccyx, assists the levator ani in giving support to the opening during expulsive efforts. The internal sphincter contracts the extremity of the cylinder of the in- testine. The use of the levator ani is expressed in its name. It is the antagonist of the diaphragm and the rest of the expulsory muscles, and serves to support the rectum and vagina during their expulsive efforts. The levator ani acts in unison with the diaphragm, and rises and falls like that muscle in forcible respiration. Yielding to the propulsive action of the abdominal muscles, it enables the outlet of the pelvis to bear a greater force than a resisting structure, and on the remission of such action it restores the perineum to its original form. The coccygei muscles restore the coccyx to its natural posi- tion, after it has been pressed backwards during defaecation or during parturition. MUSCLES OF THE UPPER EXTREMITY. The muscles of the upper extremity may be arranged into groups corresponding with the different regions of the limb, thus: Anterior Thoracic Region. Lateral Thoracic Region. Pectoralis major, Serratus magnus. Pectoralis minor, Subclavius. Anterior Scapular Region. Posterior Scapular Region. Subscapularis. Supra-spinatus, Infra-spinatus, Teres minor, Teres major. Acromial Region. Deltoid. MUSCLES OF THE UPPER EXTREMITY. 241 Anterior Humeral Reg-ion. Coraco-brachialis, Biceps, Brachialis anticus. Anterior Brachial Region. Superficial layer. Pronator radii teres, Flexor carpi radialis, Palmaris longus, Flexor sublimis digitorum, Flexor carpi ulnaris. Deep Layer. Flexor profundus digitorum, Flexor longus pollicis, Pronator quadratus. Radial Region (Thenar). Abductor pollicis, Flexor ossis metacarpi (opponens), Flexor brevis pollicis, Adductor pollicis. Posterior Humeral Region. Triceps. Posterior Brachial Region. Superficial Layer. Supinator longus, Extensor carpi radialis longior, Extensor carpi radialis brevior, Extensor communis digitorum, Extensor minimi digiti, Extensor carpi ulnaris, Anconeus. Deep Layer. Supinator brevis, Extensor ossis metacarpi pollicis, Extensor primi internodii pollicis, Extensor secundi internodii pollicis, Extensor indicis. Hi Ulnar Region (Hypothenar). Palmaris brevis, Abductor minimi digiti, Flexor brevis minimi digiti, Adductor minimi digiti. Palmar Region. Lumbricales, Interossei palmares, Interossei dorsales. Anterior Thoracic Region. Pectoralis major, Pectoralis minor, Subclavius. Dissection.—Make an incision along the line of the clavicle, from the upper part of the sternum to the acromion process; a second along the lower border of the great pectoral muscle, from the lower end of the sternum to the insertion of its tendon into the humerus, and connect the two by a third, carried longitudinally along the middle of the sternum. The integument and superficial fascia are to be dis- sected together from off the fibres of the muscle, and always in the direction of their course. For this purpose the dissector, if he have the right arm, will commence with the lower angle of the flap; if the 21 242 PECTORALIS MAJOR AND MINOR. left, with the upper angle. He will thus expose the pectoralis major muscle in its whole extent. The Pectoralis Major muscle arises from the sternal two-thirds of the clavicle, from one half the breadth of the sternum its whole length, from the cartilages of all the true ribs, excepting the first and last, and from the aponeurosis of the external oblique muscle of the abdo- men. It is inserted by a broad tendon into the anterior bicipital ridge of the humerus. That portion of the muscle which arises from the clavicle is sepa- rated from that connected with the sternum by a distinct cellular in- terspace ; hence we speak of the clavicular portion and sternal por- tion of the pectoralis major. The fibres from this very extensive origin converge towards a narrow insertion, giving the muscle a ra- diated appearance. But there is a peculiarity about the formation of its tendon which must be carefully noted. The whole of the lower border is folded inwards upon the upper portion, so that the tendon is doubled upon itself. Another peculiarity results from this arrange- ment: the fibres of the upper portion of the muscle are inserted into the lower part of the bicipital ridge; and those of the lower portion, into the upper part. Relations.—By its external surface with the fibres of origin of the platysma myoides, the mammary gland, the superficial fascia and inte- gument. By its internal, surface, on the thorax, with the clavicle, the sternum, the costal cartilages, intercostal muscles, subclavius, pec- toralis minor, and serratus magnus; in the axilla, with the axillary vessels and glands. By its external border with the deltoid, from which it is separated above by a cellular interspace lodging the cephalic vein and the descending branch of the thoracico-acromialis artery. Its lower border forms the anterior boundary of the axillary space. The pectoralis major is now to be removed by dividing its fibres along the lower border of the clavicle, and then carrying the incision perpendicularly downwards, parallel to the sternum, and at about three inches from its border. Divide some loose cellular tissue, and several small branches of the thoracic arteries, and reflect the muscle outwards. We thus bring into view a region of consi- derable interest, in the middle of which is situated the pectoralis minor. The Pectoralis Minor arises by three digitations from the third, fourth, and fifth ribs, and is inserted into the anterior border of the coracoid process of the scapula by a broad tendon. Relations.—By its anterior surface with the pectoralis major and superior thoracic vessels and nerves. By its posterior surface with the ribs, the intercostal muscles, serratus magnus, axillary space, and axillary vessels and nerves. Its upper border forms the lower boun- dary of a triangular space bounded above by the costo-coracoid mem- brane, and internally by the ribs. In this space are found the axillary vessels and nerves, and in it the subclavian artery may be tied below the clavicle. The Subclavius muscle arises by a round tendon from the cartilace ANTERIOR SCAPULAR REGION. 243 of the first rib, and is inserted into the under surface of the clavicle. This muscle is concealed by the costo-coracoid membrane, an ex- tension of the deep cervical fascia, by which it js invested. Relations.—By its upper surface with the clavicle. By the lower with the subclavian artery and vein and brachial plexus, which sepa- rate it from the first rib. In front with the pectoralis major, the costo- coracoid membrane being interposed. Actions.—The pectoralis major draws the arm against the thorax, while its upper fibres assist the upper part of the trapezius in raising the shoulder, as in supporting weights. The lower fibres depress the shoulder with the aid of the latissimus dorsi. Taking its fixed point from the shoulder, the pectoralis major assists the pectoralis minor, subclavius, and serratus magnus, in drawing up and expanding the chest. The pectoralis minor, in addition to this action, draws upon the coracoid process, and assists in rotating the scapula upon the chest. The subclavius draws the clavicle downwards and forwards, and thereby assists in steadying the shoulder. All the muscles of this group are agents in forced respiration, but are incapable of acting until the shoulders are fixed. Lateral Thoracic Region. Serratus magnus. The Serratus Magnus (serratus, indented like the edge of a saw), arises by fleshy serrations from the nine upper ribs excepting the first, and extends backwards upon the side of the chest, to be inserted into the whole length of the base of the scapula upon its anterior aspect. In structure the muscle is composed of three portions, a superior por- tion formed by two serrations attached to the second rib, and inserted into the inner surface of the superior angle of the scapula, a middle portion composed of the serrations connected with the third and fourth ribs, and inserted into the greater part of the posterior border, and an inferior portion consisting of the last five serrations which indigi- tato with the obliquus externus and form a thick muscular fasciculus which is inserted into the scapula near its inferior angle. Relations.—By its superficial surface with the pectoralis major and minor, the subscapularis, and the axillary vessels and nerves. By its deep surface with the ribs and intercostal muscles, to which it is con- nected by an extremely loose cellular tissue. Actions.—The serratus magnus is the great external inspiratory muscle, raising the ribs when the shoulders are fixed, and thereby in- creasing the cavity of the chest. Acting upon the scapula, it draws the shoulder forwards, as we see to be the case in diseased lungs, where the chest has become almost fixed from apprehension of the expanding action of the respiratory muscles. Anterior Scapular Region. Subscapularis. The Subscapularis muscle arises from the whole of the under sur- face of the scapula excepting the superior and inferior angle, and ter- minates by a broad and thick tendon, which is inserted into the lesser 244 POSTERIOR SCAPULAR REGION. tuberosity of the humerus. The substance of the muscle is traversed by several intersecting membranous layers from which muscular fibres arise, the intersections being attached to the ridges on the surface of the scapula. Its tendon forms part of the capsule of the joint, glides over a large bursa which separates it from the base of the coracoid process, and is lined by a prolongation of the synovial membrane of the articulation. Relations.—By its anterior surface with the serratus magnus, cora- co-brachialis, and axillary vessels and nerves. By its posterior sur- face with the scapula, the subscapular vessels and nerves, and the shoulder joint. Action.—It rotates the head of the humerus inwards, and is a powerful defence to the joint. When the arm is raised, it draws the humerus downwards. Posterior Scapular Region. Supra-spinatus, Teres minor, Infra-spinatus, Teres major. The Supra-spinatus muscle (supra, above; spina, the spine) arises from the whole of the supra-spinous fossa, and is inserted into the uppermost depression on the great tuberosity of the humerus. The tendon of this muscle cannot be well seen until the acromion process is removed. Relations.—By its upper surface, with the trapezius, the clavicle, acromion, and coraco-acromion ligament. From the trapezius it is separated by a strong fascia. By its lower surface, with the supra- spinous fossa, the supra-scapular vessels and nerve, and the upper part of the shoulder-joint, forming part of the capsular ligament. The Infra-spinatus (infra, beneath; spina, the spine) is covered in by a layer of tendinous fascia, which must be removed before the fibres of the muscle can be seen, the deltoid muscle having been pre- viously turned down from its scapular origin. It arises from the whole of the infra-spinous fossa, and from the fascia above-mentioned, and is inserted into the middle depression upon the greater tuberosity of the humerus. Relations.—By its posterior surface, with the deltoid, latissimus dorsi and integument. By its anterior surface, with the infra-spinous fossa, superior and dorsal scapular vessels, and shoulder-joint; its tendon being lined by a prolongation from the synovial membrane. By its upper border, it is in relation with the spine of the scapula, and by the lower, with the teres minor, with which it is closely united. The Teres Minor muscle (teres, round) arises from the middle third of the inferior border of the scapula, and is inserted into the lower depression on the great tuberosity of the humerus. The ten- dons of these three muscles, with that of the subscapularis, are in immediate contact with the shoulder-joint, and form part of its liga- mentous capsule, thereby preserving the solidity of the articulation. They are therefore the structures most frequently ruptured in dislo- cation of the head of the humerus. ACROMIAL REGION. 245 Relations.—By its posterior surface, with the deltoid, latissimus dorsi and integument. By its anterior surface, with the inferior bor- der, and part of the dorsum of the scapula, the dorsalis scapulae ves- sels, scapular head of the triceps, and shoulder-joint. By its upper- border, with the infra-spinatus; and by the lower, with the latissimus dorsi, teres major, and long head of the triceps. The Teres Major muscle arises from the lower third of the inferior border of the scapula, encroaching a little upon its dorsal aspect, and is inserted into the posterior bicipital ridge. Its tendon lies imme- diately behind that of the latissimus dorsi, from which it is separated by a synovial membrane. Relations.—By its posterior surface, with the latissimus dorsi, sca- pular head of the triceps and integument. By its anterior surface, with the subscapularis, latissimus dorsi, coraco-brachialis, short head of the biceps, axillary vessels, and branches of the brachial plexus. By its upper border, it is in relation with the teres minor, from which it is separated by the scapular head of the triceps; and by the lower, it forms with the latissimus dorsi, the lower and posterior border of the axilla. A large triangular space exists between the two teres muscles, which is divided into two minor spaces by the long head of the triceps. Actions. — The supra-spinatus raises the arm from the side; but only feebly, from the disadvantageous direction of the force. The infra-spinatus and teres minor are rotators of the head of the humerus outwards. The most important use of these three muscles is the protection of the joint, and defence against displacement of the head of the humerus, in which action they co-operate with the subscapu- laris. The teres major combines, with the latissimus dorsi, in rota- ting the arm inwards, and at the same time carrying it towards the side, and somewhat backwards. Acromial Region. Deltoid. The convexity of the shoulder is formed by a large triangular muscle, the deltoid (A, delta; sTSog, resemblance), which arises from the outer third of the clavicle, from the acromion process, and from the whole length of the spine of the scapula. The fibres from this broad origin converge to the middle of the outer side of the humerus, where they are inserted into a rough triangular elevation. This muscle is remarkable for its coarse texture, and for its numerous tendinous intersections from which muscular fibres arise. The del- toid muscle may now be cut away from its origin, and turned down, for the purpose of bringing into view the muscles and tendons placed immediately around the shoulder-joint. In so doing, a laro*e bursa will be seen between the under surface of the muscle and the head of the humerus. Relations. — By its superficial surface, with a thin aponeurotic fascia, a few fibres of the platysma myoides, the superficial fascia and integument. By its deep surface, with the shoulder-joint, from 21* 246 ANTERIOR HUMERAL REGION. which it is separated by a thin tendinous fascia, and by a synovial bursa; with the coraco-acromial ligament, coracoid process, pecto- ralis minor, coraco-brachialis, both heads of the biceps, tendon of the pectoralis major, tendon of the supra-spinatus, infra-spinatus, teres minor, teres major, scapular and external head of the triceps, the circumflex vessels anterior and posterior, and humerus. By its ante- rior border, with the external border of the pectoralis major, from which it is separated by a cellular interspace, lodging the cephalic vein and descending branch of the thoracico-acromialis artery. Its posterior border is thin and tendinous above, where it is connected with the aponeurotic covering of the infra-spinatus muscle, and thick below. Actions.—The deltoid is the elevator muscle of the arm in a direct line, and by means of its extensive origin can carry the arm forwards or backwards so as to range with the hand a considerable segment of a large circle. The arm, raised by the del- Fig. 116.* toid, is a good illustration of a lever of the third power, so common in the animal machine, by which velocity is gained at the expense of power. In this lever, the weight (hand) is at one extre- mity, the fulcrum (the glenoid cavity) at the op- posite end, and the power (the insertion of the muscle) between the two, but nearer to the ful- crum than to the weight. Anterior Humeral Region. Coraco-brachialis, Biceps, Brachialis anticus. Dissection.—These muscles are exposed, on the removal of the integument and fascia from the anterior half of the upper arm, and the clear- ing away of the cellular tissue. The Coraco-Brachialis, a name composed of its points of origin and insertion, arises from the coracoid process in common with the short head of the biceps; and is inserted into a rough line on the inner side of the middle of the hu- merus. Relations.—By its anterior surface with the deltoid, and pectoralis major. By its posterior surface with the shoulder-joint, the humerus, subscapularis, teres major, latissimus dorsi, short head of the triceps, and anterior circumflex vessels. By its internal border with the * The muscles of the anterior aspect of the upper arm. 1. The coracoid process of the scapula. 2. The coraco-clavicular ligament (trapezoid), passing upwards to the scapular end of the clavicle. 3. The coraco-acromial ligament, passing outwards to the acromion. 4. The subscapularis muscle. 5. The teres major; the triangular space above this muscle is that through which the dorsalis scapulae vessels pass. 6. The coraco-brachialis. 7. The biceps. 8. The upper end of the radius. 9. The brachialis anticus; a portion of the muscle is seen on the outer side of the tendon of the biceps. 10. The internal head of the triceps. POSTERIOR HUMERAL REGION. 247 axillary and brachial vessels and nerves, particularly with the median and external cutaneous nerve, by the latter of which it is pierced. By the external border with the short head of the biceps and brachi- alis anticus. The BicErs (bis— yistpaXai two heads) arises by two tendons, one the short head, from the coracoid process in common with the coraco- brachialis ; the other the long head, from the upper part of the glenoid cavity. The muscle is inserted by a rounded tendon, into the tuber- cle of the radius. The long head, a long slender tendon, passes through the capsular ligament of the shoulder-joint enclosed in a sheath of the synovial membrane ; after leaving the cavity of the joint, it is lodged in the deep groove that separates the two tuberosi- ties of the humerus, the bicipital groove. A small synovial bursa is interposed between the tendon of insertion, and the tubercle of the radius. At the bend of the elbow, the tendon of the biceps gives off from its inner side a broad tendinous band, which protects the brachial artery, and is continuous with the fascia of the fore-arm. Relations.—By its anterior surface with the deltoid, pectoralis major, superficial and deep fascia and integument. By its posterior surface the short head rests upon the subscapularis, from which it is separated by a bursa. In the rest of its extent the muscle is in rela- tion with the humerus, the teres major, latissimus dorsi, and brachi- alis anticus ; from the latter it is separated by the external cutaneous nerve. By its inner border with the coraco-brachialis, brachial artery and veins, and median nerve; the brachial vessels crossing its tendon at the bend of the elbow. By its outer border with the deltoid and supinator longus. The Brachialis Anticus is a broad muscle covering the whole of the anterior surface of the lower part of the humerus; it arises by two fleshy serrations from the depressions on either side of the inser- tion of the deltoid, from the anterior surface of the humerus, and from the intermuscular septa attached to the condyloid ridges. Its fibres converge to be inserted into the coronoid process of the ulna. Relations.—By its anterior surface with the biceps, external cuta- neous nerve, brachial artery and veins, and median nerve. By its posterior surface with the humerus, anterior ligament of the elbow- joint, and intermuscular aponeurosis. The latter separates it from the triceps. By its external border with the supinator longus, extensor carpi radialis longior, musculo-spiral nerve, and recurrent radial artery. By its internal border with the intermuscular aponeurosis, which separates it from the triceps and ulnar nerve, and with the pronator radii teres. Actions.—The coraco-brachialis draws the humerus inwards, and assists in flexing it upon the scapula. The biceps and brachialis anticus are flexors of the fore-arm, and the former a supinator. The brachialis anticus is a powerful protection to the elbow-joint. Posterior Humeral Region. Triceps extensor cubiti. Dissection.—Remove the integument and fascia from the posterior aspect of the upper arm. 248 TRICEPS. Fig. 117. The Triceps (rgjiS xefpaXa), three heads), arises by three heads. Considered in relation to their length, these heads have been named long, short, and middle ; and in reference to their position, internal, external, and middle; the term middle, in the former case, referring to the external head, and in the latter case to the long head. This has given rise to much confusion and mis- understanding. I shall, therefore, confine my- self to the designations derived from their rela- tions. The external head arises from the humerus, commencing immediately below the insertion of the teres minor, and from the intermuscular septum attached to the external condyloid ridge. The internal head (short) arises from the humerus, commencing imme- diately below the insertion of the teres ma- jor, and from the intermuscular septum at- tached to the internal condyloid ridge. The scapular head (long) lies between the two others, and arises from the upper third of the inferior border of the scapula. The three heads unite to form a broad muscle, which is in- serted by an aponeurotic tendon into the ole- cranon process of the ulna; a small bursa is situated between its tendon and the upper part of the olecranon. The scapular head of the triceps passes between the teres minor and major, and di- vides the triangular space between those two muscles into two smaller spaces, one of which is triangular, the other quadrangular. The triangular space is bounded by the teres minor, teres major, and scapular head of the triceps; it gives passage to the dorsalis scapulae artery and veins. The quadrangular space is bounded on three sides by the three preceding muscles, and on the fourth by the humerus. Through this space pass the posterior cir- cumflex artery and veins, and circumflex nerve. A few of the deep fibres of the triceps, attached above to the humerus and below to the capsule of the elbow-joint, have been named sub-anconeus; they are analogous to the sub-crureus. Relations.—By its posterior surface with the deep and superficial fascia and integument. By its anterior surface with the superior profunda artery, musculo-spiral nerve, humerus, intermuscular apo- neuroses which separate it from the brachialis anticus, and with the elbow-joint. The scapular head is in relation posteriorly with the deltoid and teres minor; anteriorly with the subscapularis, teres major, and latissimus dorsi; and externally with the posterior circum- flex vessels and nerve. * A posterior view of the upper arm, showing the triceps muscle. 1. Its external head. 2. Its long, or scapular head. 3. Its internal, or short head. 4. The olecranon process of the ulna. 5. The radius. 6. The capsular ligament of the shoulder-joint ANTERIOR BRACHIAL REGION. 249 Actions.—The triceps is an extensor of the fore- arm. Anterior Brachial Region. Superficial layer. Pronator radii teres, Flexor carpi radialis, Palmaris longus, Flexor sublimis digitorum, Flexor carpi ulnaris. Dissection.—These muscles are brought into view by making an incision through the integu- ment along the middle line of the fore-arm, cross- ing each extremity by a transverse incision, and turning aside the flaps. The superficial and deep fascia are then to be removed. The Pronator Radii Teres arises by two heads ; one from the inner condyle of the hume- rus, fascia of the fore-arm, and intermuscular apo- neurosis ; the other from the coronoid process of the ulna; the median nerve passing between them. Its tendon is flat and inserted into the middle third of the oblique ridge of the radius. The two heads of this muscle are best examined by cutting through that which arises from the in- ner condyle, and turning it aside. The second head will then be seen with the median nerve lying across it. Relations.—By its anterior surface with the fascia of the fore-arm, the supinator longus, extensor carpi radialis longior and brevior, ra- dial artery and veins, and radial nerve. By its posterior surface with the brachialis anticus, flexor sublimis digitorum, the ulnar artery and veins, and the median nerve after it has passed between the two heads of the muscle. By its upper border it forms the inner boundary of the triangular space, in which the termination of the brachial artery is situated. By its lower border it is in relation with the flexor carpi radialis. The Flexor Carpi Radialis arises from the inner condyle and from the intermuscular fascia. Its tendon passes through a groove formed by the scaphoid bone and trapezium, to be inserted into the base of the metacarpal bone of the index finger. * Superficial layer of the muscles of the fore-arm. 1. The lower part of the biceps, with its tendon. 2. A part of the brachialis anticus, seen beneath the biceps. 3. A part of the triceps. 4. The pronator radii teres. 5. The flexor carpi radialis. 6. The palmaris longus. 7. One of the fasciculi of the flexor sublimis digitorum; the rest of the muscle is seen beneath the tendons of the palmaris longus and flexor carpi radialis. 8. The flexor carpi ulnaris. 9. The palmar fascia. 10. The palmaris brevis muscle. 11. The abductor pollicis muscle. 12. One portion of the flexor brevis pollicis; the leading line crosses a part of the adductor pollicis. 13. The supinator longus muscle. 14. The extensor ossis metacarpi, and extensor primi internodii pollicis, curving around the lower border of the fore-arm. Fig. 118.* 250 FLEXOR CARPI RADIALIS. Relations.—By its anterior surface with the fascia of the fore-arm, and at the wrist with the tendinous canal through which its tendon passes. By its posterior surface with the flexor sublimis digitorum, flexor longus pollicis, wrist-joint, and groove in the scaphoid and tra- pezium bones. By its outer border with the pronator radii teres, and radial artery and veins. By its inner border with the palmaris longus. The tendon is surrounded by a synovial membrane where it plays through the tendinous canal of the wrist. The Palmaris Longus is a small muscle which arises from the inner condyle, and from the intermuscular fascia. It is inserted into the annular ligament and palmar fascia. Occasionally this muscle is wanting. Relations.—By its anterior surface with the fascia of the fore-arm. By the posterior surface with the flexor sublimis digitorum : to the external side by the* flexor carpi radialis; and to the internal side by the flexor carpi ulnaris. Cut the flexor carpi radialis and palmaris longus from their origins, in order to obtain a good view of the whole extent of origin of the flexor sublimis digitorum. The Flexor Sublimis Digitorum (perforatus) arises from the inner condyle, internal lateral ligament, coronoid process of the ulna, and oblique line of the radius. The median nerve and ulnar artery pass between its origins. It divides into four tendons, which pass beneath the annular ligament into the palm of the hand, and are inserted into the base of the second phalanges of the fingers, splitting at their ter- minations to give passage to the tendons of the deep flexors; thence its designation, perforates. In the thecae of the fingers several small tendinous fasciculi are generally found which pass between the pha- langes and the edges of the tendons; these have been termed the vin- cula accessoria. Relations.—In the fore-arm. By its anterior surface with the pro- nator radii teres, flexor carpi radialis, palmaris longus, flexor carpi ulnaris, and the deep fascia. By its posterior surface with the flexor profundus digitorum, flexor longus pollicis, ulnar artery, veins and nerve, and median nerve. This muscle frequently sends a fasciculus to the flexor longus pollicis or flexor profundus. In the hand: its tendons, after passing beneath the annular ligament, are in relation superficially with the superficial palmar arch, and palmar fascia ; and deeply with the tendons of the deep flexor and lumbricales. The Flexor Carpi Ulnaris arises by two heads, one from the inner condyle, the other from the olecranon and upper two-thirds of the inner border of the ulna. Its tendon is inserted into the pisiform bone, and base of the metacarpal bone of the little finger. Relations.—By its anterior surface with the fascia of the fore-arm, with which it is closely united superiorly. By its posterior surface with the flexor sublimis digitorum, flexor profundus, pronator quadra- tus, and ulnar artery, veins, and nerve. By its radial border with the palmaris longus, and in the lower third of the forearm with the ulnar vessels and nerve. The ulnar nerve, and the posterior ulnar recurrent artery, pass between its two heads of origin. DEEP LAYER. 251 Deep layer. Flexor profundus digitorum, Flexor longus pollicis, Pronator quadratus. Dissection.—This group is brought into view by removing the flexor sublimis, and drawing aside the pronator radii teres. The Flexor Profundus Digitorum (perforans) arises from the upper two-thirds of the ulna and part of the interosseous membrane, and terminates in four tendons, which pass beneath the annular liga- ment, and between the two slips of the tendons of the flexor sublimis (hence its designation, perforans), to be inserted into the base of the last phalanges. The tendon of the index finger is always distinct from the rest, the other three tendons being more or less intimately connected by cellular tissue and tendinous slips. Four little muscular fasciculi, called lumbricales, are connected with the tendons of this muscle in the palm. They will be described with the muscles of the hand. Relations.—In the fore-arm. By its anterior surface with the flexor sublimis digitorum, flexor carpi ulnaris, median nerve, and ulnar artery, veins, and nerve. By its posterior surface with the ulna, the interosseous membrane, the pronator quadratus, and the wrist- joint. By its radial border with the flexor longus pollicis, the anterior interosseous artery and nerve being interposed. By its ulnar border with the flexor carpi ulnaris. In the hand : its tendons are in relation superficially with the tendons of the superficial flexor; and deeply with the interossei muscles, adductor pollicis, and deep palmar arch. In the fingers: the tendons of the deep flexor are interposed between the tendons of the superficial flexor and the phalanges, and give at- tachment to vincula accessoria. The Flexor Longus Pollicis arises from the upper two-thirds of the radius, and part of the interosseous membrane. Its tendon passes beneath the annular ligament, to be inserted into the base of the last phalanx of the thumb. Relations.—By its anterior surface with the flexor sublimis digito- rum, flexor carpi radialis, supinator longus, and radial artery and veins. By its posterior surface with the radius, interosseous mem- brane, pronator quadratus, and wrist-joint. By its ulnar border it is separated from the flexor profundus digitorum by the anterior inter- osseous artery and nerve. In the hand: after passing beneath the annular ligament, it is lodged in the interspace between the two por- tions of the flexor brevis pollicis, and afterwards in the tendinous theea of the phalanges. If the tendons of the last two muscles be drawn aside or divided, the third muscle of this group will be brought into view, lying across the lower part of the two bones. The Pronator Quadratus arises from the ulna, and is inserted into the lower fourth of the oblique line, on the outer side of the radius. This muscle occupies about the lower fourth of the two bones, is broad at its origin, and narrower at its insertion. 252 POSTERIOR BRACHIAL REGION. Fig. 119.* Relations.—By its anterior surface with the tendons of the supinator longus, flexor carpi radi- alis, flexor longus pollicis, flexor profundus digito- rum, and flexor carpi ulnaris, radial artery and veins, and ulnar artery, veins, and nerve. By its posterior surface with the radius, ulna, and in- terosseous membrane. Actions.—The pronator radii teres and prona- tor quadratus muscles rotate the radius upon the ulna, and render the hand prone. The remaining muscles are flexors: two flexors of the wrist, flexor carpi radialis and ulnaris; two of the fin- gers, flexor sublimis and profundus, the former flexing the second phalanges, the latter the last; one flexor of the last phalanx of the thumb, flexor longus pollicis. The palmaris longus is prima- rily a tensor of the palmar fascia, and seconda- rily a flexor of the wrist and fore-arm. Posterior Brachial Region. Superficial layer. Supinator longus, Extensor carpi radialis longior, Extensor carpi radialis brevior, Extensor communis digitorum, Extensor minimi digiti, Extensor carpi ulnaris, Anconeus. Dissection.—The integument is to be divided and turned aside, and the fasciae removed in the same manner as for the anterior bra- chial region. The Supinator. Longus muscle is placed along the radial border of the fore-arm. It arises from the external condyloid ridge of the hu- merus, nearly as high as the insertion of the deltoid, and is inserted into the base of the styloid process of the radius. Relations.—By its superficial surface with the extensor ossis meta- carpi pollicis, extensor primi internodii pollicis, and fascia of the fore- arm. By its deep surface with the brachialis anticus, extensor carpi radialis longior, tendon of the biceps, supinator brevis, pronator radii teres, flexor carpi radialis, flexor sublimis digitorum, flexor longus pollicis, pronator quadratus, radius, musculo-spiral nerve, radial and posterior interosseous nerve, and radial artery and veins. This muscle must be divided through the middle, and the two ends turned to either side to expose the next muscle. * The deep layer of muscles of the fore-arm. 1. The internal lateral ligament of the elbow-joint. 2. The anterior ligament. 3. The orbicular ligament of the head of the radius. 4. The flexor profundus digitorum muscle. 5. The flexor longus pollicis. 6. The pronator quadratus. 7. The adductor pollicis muscle. 8. The dorsal interosseous muscle of the middle finger, and palmar interosseous of the ring finger. 9. The dorsal inferos. seous muscle of the ring finger, and palmar interosseous of the little-finger. EXTENSOR COMMUNIS DIGITORUM. 253 The Extensor Carpi Radialis Longior arises from the external condyloid ridge below the pre- ceding, and from the intermuscular fascia. Its tendon passes through a groove in the radius, immediately behind the styloid process, to be inserted into the base of the metacarpal bone of the index finger. Relations.—By its superficial surface, with the supinator longus, extensor ossis metacarpi pollicis, extensor primi internodii pollicis, exten- sor secundi internodii pollicis, radial nerve, fascia of the fore-arm, and posterior annular ligament. By its deep surface, with the brachialis anticus, extensor carpi radialis brevior, radius and wrist- joint. The Extensor Carpi Radialis Brevior is seen by drawing aside the former muscle. It arises from the external condyle of the humerus and intermuscular fascia, and is inserted into the base of the metacarpal bone of the middle fin- ger. Its tendon is lodged in the same groove, on the radius, with the extensor carpi radialis longior. Relations.—By its superficial surface, with the extensor carpi radialis longior, extensor ossis metacarpi pollicis, extensor primi internodii pol- licis, extensor secundi internodii pollicis, fascia of the fore-arm, and posterior annular ligament. By its deep surface, with the supinator brevis, tendon of the prona- tor radii teres, radius and wrist-joint. By its ulnar border, with the extensor communis digitorum. The Extensor Communis Digitorum arises from the external con- dyle, and intermuscular fascia; and divides into four tendons, which are inserted into the second and third phalanges of the fingers. At the metacarpo-phalangeal articulation, each tendon becomes narrow and thick, and sends a thin fasciculus upon each side of the joint. It then spreads out, and receiving, the tendon of the lumbricalis, and some tendinous fasciculi from the interossei, forms a broad aponeu- rosis, which covers the whole of the posterior aspect of the finger. At the first phalangeal joint, the aponeurosis divides into three slips. The middle slip is inserted into the base of the second phalanx, and * The superficial layer of muscles of the posterior aspect of the fore-arm. 1. The lower part of the biceps. 2. Part of the brachialis anticus. 3. The lower part of the triceps, inserted into the olecranon. 4. The supinator longus. 5. The extensor carpi radialis longior. 6. The extensor carpi radialis brevior. 7. The tendons of insertion of these two muscles. 8. The extensor communis digitorum. 9. The extensor minimi digiti. 10. The extensor carpi ulnaris. 11. The anconeus. 12. Part of the flexor carpi ulnaris. 13. The extensor ossis metacarpi and extensor primi internodii muscle, lying together. 14. The extensor secundi internodii; its tendon is seen crossing the two tendons of the extensor carpi radialis longior and brevior. 15. The posterior annular ligament. The tendons of the common extensor are seen upon the back of the hand, and their mode of distribution on the dorsum of the fingers. 22 254 ANCONEUS, the two lateral portions are continued onwards on each side of the joint, to be inserted into the last. Little oblique tendinous slips con- nect the tendons of the middle, ring, and little finger, as they cross the back of the hand. Relations.—By its superficial surface, with the fascia of the fore- arm and back of the hand, and with the posterior annular ligament. By its deep surface, with the supinator brevis, extensor ossis meta- carpi pollicis, extensor primi internodii, extensor secundi internodii, extensor indicis, posterior interosseous artery and nerve, wrist-joint, metacarpal bones and interossei muscles, and phalanges. By its radial border, with the extensor carpi radialis longior and brevior. By the ulnar border, with the extensor minimi digiti, and extensor carpi ulnaris. The Extensor Minimi Digiti (auricularis) is an offset from the extensor communis, with which it is connected by means of a tendi- nous slip. Passing down to the inferior extremity of the ulna, it tra- verses a distinct fibrous sheath, and at the metacarpo-phalangeal arti- culation unites with the tendon derived from the common extensor. The common tendon then spreads out into a broad expansion, which divides into three slips, to be inserted, as in the other fingers, into the last two phalanges. It is to this muscle that the little finger owes its power of separate extension; and from being called into action when the point of the finger is introduced into the meatus of the ear, for the purpose of removing unpleasant sensations or producing titilla- tion, the muscle was called by the old writers "auricularis." The Extensor Carpi Ulnaris arises from the external condyle and from the upper two-thirds of the border of the ulna. Its tendon passes through the posterior groove, in the lower extremity of the ulna, to be inserted into the base of the metacarpal bone of the little finger. Relations.—By its superficial surface, with the fascia of the fore- arm, and posterior annular ligament. By its deep surface, with the supinator brevis, extensor ossis metacarpi pollicis, extensor secundi internodii, extensor indicis, ulna, and wrist-joint. By its radial bor- der, it is in relation with the extensor communis digitorum, and ex- tensor minimi digiti: and by the ulnar border, with the anconeus. The Anconeus is a small triangular muscle, having the appearance of being a continuation of the triceps; it arises from the outer con- dyle, and is inserted into the olecranon and triangular surface on the upper extremity of the ulna. Relations.—By its superficial surface with a strong tendinous apo- neurosis derived from the triceps. By its deep surface with the elbow- joint, orbicular ligament, and slightly with the supinator brevis. Deep Layer. Supinator brevis, Extensor ossis metacarpi pollicis, Extensor primi internodii pollicis, Extensor secundi internodii pollicis, Extensor indicis. EXTENSOR PRIMI INTERNODII POLLICIS. 255 Dissection.—The muscles of the superficial Fi&- 121-* layer should be removed in order to bring the deep group completely into view. The Supinator Brevis cannot be seen in its entire extent until the radial extensors of the carpus are divided from their origin. It arises from the external condyle, from the external lateral and orbicular ligament, and from the ulna, and winds around the upper part of the radius, to be inserted into the upper third of its oblique line. The posterior interosseous artery and nerve are seen perforating the lower border of this muscle. Relations.—By its superficial surface with the pronator radii teres, supinator longus, extensor carpi radialis longior and brevior, extensor com- munis digitorum, extensor carpi ulnaris, anco- neus, the radial artery and veins, the musculo- spiral nerve, radial and posterior interosseous nerve. By its deep surface with the elbow-joint and its ligaments, the interosseous membrane, and the radius. The Extensor Ossis Metacarpi Pollicis is placed immediately below the supinator bre- vis. It arises from the ulna, interosseous mem- brane, and radius, and is inserted, as its name implies, into the base of the metacarpal bone of the thumb. Its tendon passes through the groove immediately in front of the styloid process of the radius. Relations.—By its superficial surface with the extensor carpi ulnaris, extensor minimi digiti, extensor communis digitorum, fascia of the fore-arm, and annular ligament. By its deep surface with the ulna, interosseous membrane, radius, tendons of the extensor carpi radialis longior and brevior, and supinator longus, and at the wrist with the radial artery. By its upper border with the edge of the supinator brevis. By its lower border with the extensor secundi and primi in- ternodii. The muscle is crossed by branches of the posterior inter- osseous artery and nerve. The Extensor Primi Internodii Pollicis, the smallest of the mus- cles in this layer, arises from the interosseous membrane and radius, and passes through the same groove with the extensor ossis metacarpi, to be inserted into the base of the first phalanx of the thumb. Relations.—The same as those of the preceding muscle with the exception of the extensor carpi ulnaris. The muscle accompanies the extensor ossis metacarpi. * The deep layer of muscles on the posterior aspect of the fore-arm. 1. The lower part of the humerus. 2. The olecranon. 3. The ulna. 4. The anconeus muscle. 5. The supinator brevis muscle. 6. The extensor ossis metacarpi pollicis. 7. The extensor primi internodii pollicis. 8. The extensor secundi internodii pollicis. 9. The extensor indicis. 10. The first dorsal interosseous muscle. The other three dorsal interossei are seen between the metacarpal bones of their respective fingers. 256 MUSCLES OF THE HAND. The Extensor Secundi Internodii Pollicis arises from the ulna, and interosseous membrane. Its tendon passes through a distinct canal in the annular ligament, and is inserted into the base of the last phalanx of the thumb. Relations.—By its external surface with the same relations as the extensor ossis metacarpi. By its deep surface with the ulna, inter- osseous membrane, radius, wrist-joint, radial artery, and metacarpal bone of the thumb. The muscle is placed between the extensor primi internodii and extensor indicis. The Extensor Indicis arises from the ulna, as high up as the ex- tensor ossis metacarpi pollicis, and from the interosseous membrane. Its tendon passes through a distinct groove in the radius, and is in- serted into the aponeurosis formed by the common extensor tendon of the index finger. Relations.—The same as those of the preceding muscle, with the exception of the hand, where the tendon rests upon the metacarpal bone of the fore-finger and second interosseous muscle, and has no relation with the radial artery. The tendons of the extensors, as of the flexor muscles of the fore- arm, are provided with synovial bursae as they pass beneath the an- nular ligaments: those of the back of the wrist have distinct sheaths, formed by the posterior annular ligament. Actions.—The anconeus is associated in its action with the triceps extensor cubiti: it assists in extending the fore-arm upon the arm. The supinator longus and brevis effect the supination of the fore-arm, and antagonize the two pronators. The extensor carpi radialis lon- gior and brevior, and ulnaris, extend the wrist in opposition to the two flexors of the carpus. The extensor communis digitorum re- stores the fingers to the straight position, after being flexed by the two flexors, sublimis and profundus. The extensor ossis metacarpi, primi internodii, and secundi internodii pollicis, are the especial ex- tensors of the thumb, and serve to balance the actions of the flexor ossis metacarpi, flexor brevis, and flexor longus pollicis. The ex- tensor indicis gives the character of extension to the index finger, and is hence named " indicator," and the extensor minimi digiti sup- plies that finger with the power of exercising a distinct extension. MUSCLES OF THE HAND. Radial or Thenar Region. Abductor pollicis, Flexor brevis pollicis. Flexor ossis metacarpi (opponens), Adductor pollicis. Dissection.—The hand is best dissected by making an incision along the middle of the palm, from the wrist to the base of the fingers, and crossing it at each extremity by a transverse incision, then turn- ing aside the flaps of integument. For exposing the muscles of the radial region, the removal of the integument and fascia on the radial side will be sufficient. The Abductor Pollicis is a small, thin muscle, which arises from the scaphoid bone and annular ligament. It is inserted into the base of the first phalanx of the thumb. MUSCLES OF THE HAND. 257 Relations.—By its superficial sur- FiS-122* face, with the external portion of the palmar fascia. By its deep surface, with the flexor ossis metacarpi. On its inner side it is separated by a nar- row cellular interspace from the flexor brevis pollicis. This muscle must be divided from its origin and turned upwards, in order to see the next. The Flexor Ossis Metacarpi (op- ponens pollicis) arises from the trape- zium and annular ligament, and is inserted into the whole length of the metacarpal bone. Relations.—By its superficial sur- face, with the abductor pollicis. By its deep surface, with the trapezio- metacarpal articulation, and with the metacarpal bone. Internally, with the flexor brevis pollicis. The flexor ossis metacarpi may now be divided from its origin and turned aside, in order to show the next muscle. The Flexor Brevis Pollicis consists of two portions, between which lies the tendon of the flexor longus pollicis. The external portion arises from the trapezium and annular ligament; the internal portion, from the trapezoides and os magnum. They are both in- serted into the base of the first phalanx of the thumb, having a sesa- moid bone in each of their tendons, to protect the joint. Relations.—By its superficial surface, with the external portion of the palmar fascia. By its deep surface, with the adductor pollicis, tendon of the flexor carpi radialis, and trapezio-metacarpal articula- tion. By its external surface, with the flexor ossis metacarpi and metacarpal bone. By its inner surface, with the tendons of the long flexor muscles and first lumbricalis. The Adductor Pollicis is a triangular muscle; it arises from the whole length of the metacarpal bone of the middle finger; and the fibres converge to its insertion into the base of the first phalanx. Relations.—By its anterior surface with the flexor brevis pollicis, * The muscles of the hand. 1. The annular ligament. 2, 2. The origin and insertion of the abductor pollicis muscle; the middle portion has been removed. 3. The flexor ossis metacarpi, or opponens pollicis. 4. One portion of the flexor brevis pollicis. 5. The deep portion of the flexor brevis pollicis. 6. The adductor pollicis. 7, 7. The lumbri- calcs muscles, arising from the deep flexor tendons, upon which the numbers are placed. The tendons of the flexor sublimis have been removed from the palm of the hand. 8. One of the tendons of the deep flexor, passing between the two terminal slips of the ten- don of the flexor sublimis, to reach the last phalanx. 9. The tendon of the flexor longus pollicis, passing between the two portions of the flexor brevis to the last phalanx. 10. The abductor minimi digiti. 11. The flexor brevis minimi digiti. The edge of the flexor ossis metacarpi, or adductor minimi digiti, is seen projecting beyond the inner bor- der of the flexor brevis. 12. The prominence of the pisiform bone. 13. The first dorsal interosseous muscle. 22* 258 MUSCLES OF THE HAND. tendons of the deep flexor of the fingers, lumbricales, and deep palmar arch. By its posterior surface with the metacarpal bones of the index and middle fingers, the interossei of the second interosseous space, and the abductor indicis. Its inferior border is subcutaneous. Ulnar, or Hypothenar Region. Palmaris brevis, Abductor minimi digiti, Flexor brevis minimi digiti, Flexor ossis metacarpi (adductor). Dissection.—Turn aside the ulnar flap of integument in the palm of the hand: in doing this, a subcutaneous muscle, the palmaris brevis will be exposed. After examining this muscle remove it with the deep fascia, in order-to bring into view the muscles of the little finger. The Palmaris Brevis is a thin plane of muscular fibres which arises from the annular ligament and palmar fascia, and passes trans- versely inwards, to be inserted into the integument on the inner border of the hand. Relations.—By its superficial surface with the fat and integument of the ball of the little finger. By its deep surface with the internal portion of the palmar fascia, which separates it from the ulnar artery, veins, and nerve, and from the muscles of the inner border of the hand. The Abductor Minimi Digiti is a small tapering muscle which arises from the pisiform bone, and is inserted into the base of the first phalanx of the little finger. Relations.—By its superficial surface w7ith the internal portion of the deep fascia and the palmaris brevis: by its deep surface with the flexor ossis metacarpi and metacarpal bone. By its inner border with the flexor brevis minimi digiti. The Flexor Brevis Minimi Digiti is a small muscle arising from the unciform bone and annular ligament, and inserted into the base of the first phalanx. It is sometimes wanting. Relations.—By its superficial surface with the internal portion of the palmar fascia, and the palmaris brevis. By its deep surface with the flexor ossis metacarpi, and metacarpal bone. Externally with the abductor minimi digiti, from which it is separated near its origin by the deep palmar branch of the ulnar nerve and communicating artery. Internally with the tendons of the flexor sublimis and profundus. The Flexor Ossis Metacarpi (adductor, opponens) arises from the unciform bone and annular ligament, and is inserted into the whole length of the metacarpal bone of the little finger. Relations.—By its superficial surface with the flexor brevis and ab- ductor minimi digiti. By its deep surface with the interossei muscles of the last metacarpal space, the metacarpal bone, and the flexor ten- dons of the little finger. Palmar Region. Lumbricales, Interossei palmares, Interossei dorsales. MUSCLES OF THE HAND. 259 The Lumbricales, four in number, are accessories to the deep flexor muscle. They arise from the tendons of the deep flexor; the first and second from the palmar side, the third from the ulnar, and the fourth from the radial side ; and are inserted into the aponeurotic expansion of the extensor tendons on the radial side of the fingers. The third, or that of the tendon of the ring finger, sometimes bifurcates, otherwise it is inserted wholly into the extensor tendon of the middle finger. Relations.—In the palm of the hand with the flexor tendons; at their insertion, with the tendons of the interossei and the metacarpo- phalangeal articulations. Fig. 124.T The Palmar Interossei, three in number, are placed upon the me- tacarpal bones, rather than between them. They arise from the base of the metacarpal bone of one finger, and are inserted into the base of the first phalanx and aponeurotic expansion of the extensor tendon of the same finger. The first belongs to the index finger; the second to the ring finger; and the third, to the little finger; the middle finger being excluded. Relations.—By their palmar surface with the flexor tendons and with the deep muscles in the palm of the hand. By their dorsal sur- face with the dorsal interossei. On one side with the metacarpal bone, on the other with the corresponding dorsal interosseous. Dorsal Interossei.—On turning to the dorsum of the hand, the four dorsal interossei are seen in the four spaces between the metacar- pal bones. They are bipenniform muscles and arise by two heads, from the adjoining sides of the base of the metacarpal bones. They are inserted into the base of the first phalanges, and aponeurosis of the extensor tendons. * Palmar interossei. 1. Adductor indicis. 2. Abductor annularis. 3. Interosseus auricularis. t Dorsal interossei. 1. Abductor indicis. 2. Abductor medii. 3. Adductor medii. 4. Adductor annularis. Fig. 123* 260 MUSCLES OF THE LOWER EXTREMITY. The first is inserted into the index finger, and from its use is called abductor indicis,* the second and third are inserted into the middle finger compensating its exclusion from the palmar group; the fourth is attached to the ring finger; so that each finger is provided with two interossei, with the exception of the little finger, as may be shown by means of a table, thus;— T j _c { one dorsal (abductor indicis), Index finger ] i v ' J ° ( one palmar. Middle finger, two dorsal. n- r { one dorsal, Ring linger, X , b j a > ^ one palmar, Little finger, remaining palmar. Relations.—By their dorsal surface with a thin aponeurosis which separates them from the tendons on the dorsum of the hand. By their palmar surface with the muscles and tendons in the palm of the hand. By one side with the metacarpal bone; by the other with the corre- sponding palmar interosseous. The abductor indicis is in relation by its palmar surface with the adductor pollicis, the arteria magna pol- licis being interposed. The radial artery passes into the palm of the hand between the two heads of the first dorsal interosseous muscle and the perforating branches of the deep palmar arch, between the heads of the other dorsal interossei. Actions.—The actions of the muscles of the hand are expressed in their names. Those of the radial region belong to the thumb, and provide for three of its movements, abduction, adduction, and flexion. The ulnar group, in like manner, are subservient to the same motions of the little finger, and the interossei are abductors and adductors of the several fingers. The lumbricales are accessory in their actions to the deep flexors: they were called by the earlier anatomists, fidi- cinii, i. e. fiddlers' muscles, from an idea that they might effect the fractional movements by which the performer is enabled to produce the various notes on that instrument. In relation to the axis of the hand, the four dorsal interossei are abductors, and the three palmar, adductors. It will therefore be seen that each finger is provided with its proper adductor and abductor, two flexors, and (with the exception of the middle and ring fingers) two extensors. The thumb has moreover a flexor and extensor of the metacarpal bone; and the little finger a flexor of the metacarpal bone without an extensor. MUSCLES OF THE LOWER EXTREMITY. The muscles of the lower extremity may be arranged into groups corresponding with the regions of the hip, thigh, leg, and foot, as in the following table:— * Horner divides this muscle and calls one portion of it abductor indicis and the other prior indicis. Wilson's description is the best, as it makes the analogy between the foot and hand complete, whilst there is a great discrepancy in Horner's mode of describing them.—G. MUSCLES OF THE LOWER EXTREMITY. 261 Gluteus maximus, Gluteus minimus, Gemellus superior, Gemellus inferior, Quadratus femoris. hip. Gluteal Region. Gluteus medius, Pyriformis, Obturator internus, Obturator externus. Anterior Femoral Region. Tensor vaginae femoris, Sartorius, Rectus, Vastus internus, Vastus externus, Crureus. thigh. Internal Femoral Region. Iliacus internus, Psoas magnus, Pectineus, Adductor longus, Adductor brevis, Adductor magnus, Gracilis. Posterior Femoral Region. Biceps, Semitendinosus, Semimembranosus. Anterior Tibial Region. Tibialis anticus, Extensor longus digitorum, Peroneus tertius, Extensor longus pollicis. Fibular Region. Peroneus longus, Peroneus brevis. Posterior Tibial Region. Superficial Group. Gastrocnemius, Plantaris, Soleus. Deep \_posterior] Layer. Popliteus, Flexor longus pollicis, Flexor longus digitorum, Tibialis posticus. FOOT. Dorsal Region. Extensor brevis digitorum, Interossei dorsales. Plantar Region. 1st Layer. 3d Layer. Abductor pollicis, Flexor brevis pollicis, Abductor minimi digiti, Adductor pollicis, Flexor brevis digitorum. Flexor brevis minimi digiti, Transversus pedis. 2d Layer. 4th Layer. Musculus accessorius, Interossei plantares. Lumbricales. 262 MUSCLES OF THE GLUTEAL REGION. GLUTEAL REGION. Gluteus maximus, Obturator internus, Gluteus medius, Gemellus inferior, Gluteus minimus, Obturator externus, Pyriformis, Quadratus femoris. Gemellus superior, Dissection.—The subject being turned on its face, and a block placed beneath the os pubis to support the pelvis, the student com- mences the dissection of this region, by carrying an incision from the apex of the coccyx along the crest of the ilium to its anterior supe- rior spinous process; or vice versa, if he be on the left side. He then makes an incision from the posterior fifth of the crest of the ilium, to the apex of the trochanter major, this marks the upper border of the gluteus maximus; and a third incision from the apex of the coccyx along the fleshy margin of the lower border of the gluteus maximus, to the outer side of the thigh, about four inches below the apex of the trochanter major. He then reflects the integument, superficial fascia, and deep fascia, which latter is very thin over this muscle, from the gluteus maximus, following rigidly the course of its fibres; and having exposed the muscle in its entire extent, he dissects the integu- ment and superficial fascia from off the deep fascia which binds down the gluteus medius, the other portion of this region. The Gluteus Maximus (/Xoutoj, Fls-125* nates) is the thick, fleshy mass of muscle, of a quadrangular shape, which forms the convexity of the nates. In structure, it is extremely coarse, being made up of large fibres, which are collected into fasciculi, and these again into distinct muscular masses, separated by deep cellular furrows. It arises from the posterior fifth of the crest of the ilium, from the posterior surface of the sacrum and coccyx, and from the great sacro-ischiatic ligament. It passes obliquely outwards and down- wards, to be inserted into the rough line leading from the trochanter major to the linea aspera, and is continuous by means of its tendon with the fascia lata covering the outer side of the thigh. A large bursa is situated between the broad tendon of this muscle and the femur. * The deep muscles of the gluteal region. 1. The external surface of the ilium. 2. The posterior surface of the sacrum. 3. The posterior sacro-iliac ligaments. 4. The tuberosity of the ischium. 5. The great or posterior sacro-ischiatic ligament. 6. The lesser or anterior sacro-ischiatic ligament. 7. The trochanter major. 8. The gluteus minimus. 9. The pyriformis. 10. The gemellus superior. 11. The obturator internus muscle, passing out of the lesser sacro-ischiatic foramen. 12. The gemellus inferior. 13. The quadratus femoris. 14. The upper part of the adductor magnus. 15. The vastus externus. 16. The biceps. 17. The gracilis. 18. The semitendinosus. PYRIFORMIS MUSCLE. 263 Relations.—By its superficial surface with a thin aponeurotic fascia which separates it from the superficial fascia and integument, and with the vastus externus, a bursa being interposed. By its deep sur- face with the gluteus medius, pyriformis, gemelli, obturator internus, quadratus femoris, sacro-ischiatic foramina, great sacro-ischiatic liga- ment, tuberosity of the ischium, semimembranosus, semitendinosus, biceps, and adductor magnus; the gluteal vessels and nerves, ischiatic vessels and nerves, and internal pudic vessels and nerve. By its upper border it overlaps the gluteus medius; and by the lower border forms the lower margin of the nates. The gluteus maximus must, be turned down from its origin, in order to bring the next muscles into view. The Gluteus Medius is placed in front of, rather than beneath the gluteus maximus; and is covered in by a process of the deep fascia, which is very thick and dense. It arises from the outer lip of the crest of the ilium for four-fifths of its length, from the surface of bone between that border and the superior curved line on the dorsum ilii, and from the dense fascia above-mentioned. Its fibres converge to the outer part of the trochanter major, into which its tendon is inserted. Relations.—By its superficial surfacewith the tensor vaginae femoris, gluteus maximus, and its fascia. By its deep surface with the gluteus minimus, and gluteal vessels and nerves. By its lower border with the pyriformis muscle. A bursa is interposed between its tendon and the upper part of the trochanter major. This muscle should now be removed from its origin and turned down, so as to expose the next which is situated beneath it. The Gluteus Minimus is a radiated muscle, arising from the sur- face of the dorsum ilii, between the superior and inferior curved lines; its fibres converge to the anterior border of the trochanter major, into which it is inserted by means of a rounded tendon. There is no distinct line of separation between the gluteus medius and minimus anteriorly. Relations.—By its superficial surface with the gluteus medius, and gluteal vessels. By its deep surface with the surface of the ilium, the long tendon of the rectus femoris, and the capsule of the hip-joint. A bursa is interposed between the tendon of the muscle and the tro- chanter. The Pyriformis muscle (pyrum, a pear, i. e. pear-shaped) arises from the anterior surface of the sacrum, by little slips that are inter- posed between the first and fourth anterior sacral foramina, and from the adjoining surface of the ilium. It passes out of the pelvis, through the great sacro-ischiatic foramen, and is inserted by a rounded tendon into the trochanteric fossa of the femur. Relations.—By its superficial or external surface with the sacrum and gluteus maximus. By its deep or pelvic surface with the rectum, the sacral plexus of nerves, the branches of the internal iliac artery, the great sacro-ischiatic notch, and the capsule of the hip-joint. By its upper border with the gluteus medius and gluteal vessels and 264 OBTURATOR EXTERNUS. nerves. By its lower border with the gemellus superior, ischiatic vessels and nerves, and internal pudic vessels and nerve. The Gemellus Superior (gemellus, double, twin), is a small slip of muscle situated immediately below the pyriformis; it arises from the spine of the ischium, and is inserted into the upper border of the tendon of the obturator internus, and into the trochanteric fossa of the femur. The gemellus superior is not unfrequently wanting. Relations.—By its superficial surface with the gluteus maximus, the ischiatic vessels and nerves, and internal pudic vessels and nerve. By its deep surface with the pelvis, and capsule of the hip-joint. The Obturator Internus arises from the inner surface of the an- terior wall of the pelvis, being attached to the margin of bone around the obturator foramen, and to the obturator membrane. It passes out of the pelvis through the lesser sacro-ischiatic foramen, and is in- serted by a flattened tendon into the trochanteric fossa of the femur. The lesser sacro-ischiatic notch, over which this muscle plays as through a pulley, is faced with cartilage, and provided with a syno- vial bursa to facilitate its movements. The tendon of the obtura- tor is supported on each side by the two gemelli muscles (hence their names), which are inserted into the sides of the tendon, and appear to be auxiliaries or superadded portions of the obturator in- ternus. Relations.—By its superficial or posterior surface with the internal pudic vessels and nerve, the obturator fascia, which separates it from the levator ani and viscera of the pelvis, the sacro-ischiatic ligaments, gluteus maximus, and ischiatic vessels and nerves. By its deep or anterior surface with the obturator membrane and the margin of bone surrounding it, the cartilaginous pulley of the lesser ischiatic foramen, the external surface of the pelvis, and the capsular ligament of the hip-joint. By its upper border, within the pelvis, with the obturator vessels and nerve; externally to the pelvis, with the gemellus superior. By its lower border with the gemellus inferior. The Gemellus Inferior arises from the posterior point of the tuberosity of the ischium, and is inserted into the lower, border of the tendon of the obturator internus, and into the trochanteric fossa of the femur. Relations.—By its superficial surface with the gluteus maximus, and ischiatic vessels and nerves. By its deep surface with the ex- ternal surface of the pelvis, and capsule of the hip-joint. By its upper border with the tendon of the obturator internus. By its lower border with the tendon of the obturator externus and quadratus femoris. In this region the tendon only of the obturator externus can be seen, situated deeply between the gemellus inferior and the upper border of the quadratus femoris. To expose this muscle fully, it is necessary to dissect it from the anterior part of the thigh, after the removal of the pectineus, adductor longus and adductor brevis muscles. The Obturator Externus muscle (obturare, to stop up) arises from the obturator membrane, and from the surface of bone immediately surrounding it anteriorly, viz. from the ramus of the os pubis and ANTERIOR FEMORAL REGION. 265 ischium : its tendon passes behind the neck of the femur, to be inserted with the external rotator muscles, into the trochanteric fossa of the femur. Relations.—By its superficial or anterior surface with the tendon of the psoas and iliacus, pectineus, adductor brevis and magnus, the obturator vessels and nerve. By its deep or posterior surface with the obturator membrane and the margin of bone which surrounds it, the lower part of the capsule of the hip-joint and the quadratus femoris. The Quadratus Femoris (square-shaped) arises from the external border of the tuberosity of the ischium, and is inserted into a rough line on the posterior border of the trochanter major, which is thence named linea quadrati. Relations.—By its posterior surface with the gluteus maximus, and ischiatic vessels and nerves. By its anterior surface with the tendon of the obturator externus, and trochanter minor, a synovial bursa often separating it from the latter. By its upper border with the gemellus inferior; and by the lower border with the adductor magnus. Actions.—The glutei muscles are abductors of the thigh, when they take their fixed point from the pelvis. Taking their fixed point from the thigh, they steady the pelvis on the head of the femur; this action is peculiarly obvious in standing on one leg; they assist also in car- rying the leg forward, in progression. The gluteus minimus being attached to the anterior border of the trochanter major, rotates the limb slightly inwards. The gluteus medius and maximus, from their insertion into the posterior aspect of the bone, rotate the limb out- wards ; the latter is, moreover, a tensor of the fascia of the thigh. The other muscles rotate the limb outwards, everting the knee and foot; hence they are named external rotators. Anterior Femoral Region. Tensor vaginae femoris, Vastus internus, Sartorius, Vastus externus, Rectus, Crureus. Dissection.—Make an incision along the line of Poupart's ligament, from the anterior superior spinous process of the ilium to the spine of the os pubis; and a second, from the middle of the preceding down the inner side of the thigh, and across the inner condyle of the femur, to the head of the tibia, where it may be bounded by a transverse incision. Turn back the integument from the whole of this region, and examine the superficial fascia; which is next to be removed in the same manner. After the deep fascia has been well considered, it is likewise to be removed, by dissecting it off in the course of the fibres of the muscles. As it might not be convenient to the junior student to expose so large a surface at once as ordered in this dissection, the vertical incision may be crossed by one or two transverse incisions, as may be deemed most proper. The Tensor Vaginae Femoris (stretcher of the sheath of the thigh) is a short flat muscle, situated on the outer side of the hip. It arises from the crest of the ilium, near its anterior superior spinous process, 23 266 SARTORIUS—RECTUS. Fig. 126.* and is inserted between two layers of the fascia lata at about one-fourth down the thigh. Relations.—By its superficial surface with the fascia lata and integument. By its deep surface with the internal layer of the fascia lata, gluteus medius, rectus and vastus externus. By its inner border near its origin with the sartorius. The Sartorius (tailor's muscle) is a long riband- like muscle, arising from the anterior superior spi- nous process of the ilium, and from the notch im- mediately below that process; it crosses obliquely the upper third of the thigh, descends behind the inner condyle of the femur, and is inserted by an aponeurotic expansion into the inner tuberosity of the tibia. This expansion covers in the insertion of the tendons of the gracilis and semitendinosus muscles. The inner border of the sartorius mus- cle is the guide to the operation for tying the femoral artery in the middle of its course. Relations.—By its superficial surface with the fascia lata and some cutaneous nerves. By its deep surface with the psoas and iliacus, rectus, sheath of the femoral vessels and saphenous nerves, vas- tus internus, adductor longus, adductor magnus, gracilis, long saphenous nerve, internal lateral ligament of the knee-joint. By its expanded in- sertion with the tendons of the gracilis and semi- tendinosus, a synovial bursa being interposed. At the knee-joint its posterior border is in relation with the internal saphenous vein. At the upper third of the thigh the sartorius forms, with the lower border of the adductor longus, an isosceles triangle, whereof the base corresponds with Poupart's ligament. A perpendicular line drawn from the middle of the base of the apex of this triangle, im- mediately overlies the femoral artery with its sheath. The Rectus (straight) muscle is fusiform in its shape and bipenni- form in the disposition of its fibres. It arises by two round tendons, one from the anterior inferior spinous process of the ilium, the other from the upper lip of the acetabulum ; and is inserted by a broad and strong tendon, into the upper border of the patella. It is more correct to consider the patella as a sesamoid bone, developed within the ten- don of the rectus ; and the ligamentum patellae as the continuation of the tendon to its insertion into the tubercle of the tibia. Relations.—By its superficial surface with the gluteus medius, psoas and iliacus, sartorius; and, for the lower three-fourths of its extent, * The muscles of the anterior femoral region. 1. The crest of the ilium. 2. Its ante- rior superior spinous process. 3. The gluteus medius. 4. The tensor vagina femoris; its insertion into the fascia lata is shown inferiorly. 5. The sartorius. 6. The rectus. 7. The vastus externus. 8. The vastus internus. 9. The patella. 10. The iliacus inter- nus. 11. The psoas magnus. 12. The pectineus. 13. The adductor longus. 14. Part of the adductor magnus. 15. The gracilis. CRUREUS. 267 with the fascia lata. By its deep surface with the capsule of the hip- joint, the external circumflex vessels, crureus, and vastus internus and externus. The rectus must now be divided through its middle, and the two ends turned aside, to bring clearly into view the next muscles. The three next muscles are generally considered collectively under the name of triceps extensor cruris. Adopting this view, the muscle surrounds the whole of the femur, excepting the rough line (linea aspera) upon its posterior aspect. Its division into three parts is not well defined; the fleshy mass upon each side being distinguished by the names of vastus internus and externus, the middle portion by that of crureus. The Vastus Externus, narrow below and broad above, arises from the outer border of the patella, and is inserted into the femur and outer side of the linea aspera, as high as the base of the tro- chanter major. Relations.—By its superficial surface with the fascia lata, rectus, biceps, semi-membranosus and gluteus maximus, a synovial bursa being interposed between it and the latter. By its deep surface with the crureus and femur. The Vastus Internus, broad below and narrow above, arises from the inner border of the patella, and is inserted into the femur and inner side of the linea aspera as high up as the anterior intertrochan- teric line. Relations.—By its superficial surface with the psoas and iliacus, rectus, sartorius, femoral artery and vein and saphenous nerves, pec- tineus, adductor longus, brevis, and magnus, and fascia lata. By its deep surface with the crureus and femur. The Crureus (crus, the leg) arises from the upper border of the patella, and is inserted into the front aspect of the femur, as high as the anterior intertrochanteric line. When the crureus is divided from its insertion, a small muscular fasciculus is often seen upon the lower part of the femur, which is inserted into the pouch of synovial mem- brane, that extends upwards from the knee-joint, behind the patella. This is named, from its situation, sub-crureus, and would seem to be intended to support the synovial membrane. Relations.—By its superficial surface with the external circumflex vessels, the rectus, vastus internus and externus. By its deep surface with the femur, the sub-crureus, and synovial membrane of the knee- joint. Actions.—The tensor vaginae femoris renders the fascia lata tense, and slightly inverts the limb. The sartorius flexes the leg upon the thigh, and, continuing to act, the thigh upon the pelvis, at the same time carrying the leg across that of the opposite side, into the position in which tailors sit; hence its name. Taking its fixed point from below, it assists the extensor muscles in steadying the leg, for the sup- port of the trunk. The other four muscles have been collectively named quadriceps extensor, from their similarity of action. They extend the leg upon the thigh, and obtain a great increase of power by their attachment to the patella, which acts as a fulcrum. Taking 268 INTERNAL FEMORAL REGION. thetr fixed point from the tibia, they steady the femur upon the leg, and the rectus, by being attached to the pelvis, serves to balance the trunk upon the lower extremity. Internal Femoral Region. Iliacus internus, Adductor brevis, Psoas magnus, Adductor magnus, Pectineus, Gracilis. Adductor longus, Dissection.—These muscles are exposed by the removal of the inner flap of integument recommended in the dissection of the ante- rior femoral region. The iliacus and psoas arising from within the abdomen, can only be seen in their entire extent after the removal of the viscera from that cavity. The Iliacus Internus is a flat radiated muscle. It arises from the whole extent of the inner concave surface of the ilium; and, after joining w7ith the tendon of the psoas, is inserted into the trochanter minor of the femur. A few fibres of this muscle are derived from the base of the sacrum, and others from the capsular ligament of the hip- joint. Relations.—By its anterior surface, within the pelvis, with the ex- ternal cutaneous nerve, and with the iliac fascia, which separates the muscle from the peritoneum, on the right from the caecum, and on the left from the sigmoid flexure of the colon; externally to the pelvis with the fascia lata, rectus, and sartorius. By its posterior surface with the iliac fossa, margin of the pelvis, and with the capsule of the hip-joint, a synovial bursa of large size being interposed, which is sometimes continuous with the synovial membrane of the articulation. By its inner border with the psoas magnus and crural nerve. The Psoas Magnus (-^oa, lumbus, a loin), situated by the side of the vertebral column in the loins, is a long fusiform muscle. It arises from the intervertebral substances, part of the bodies and bases of the transverse processes, and from a series of tendinous arches, thrown across the constricted portion of the last dorsal and four upper lumbar vertebrae. These arches are intended to protect the lumbar arteries and sympathetic filaments of nerves from pressure, in their passage beneath the muscle. From this extensive origin, the muscle passes along the margin of the brim of the pelvis, and beneath Poupart's ligament, to its insertion. The tendon of the psoas magnus unites with that of the iliacus, and the conjoined tendon is inserted into the posterior part of the trochanter minor, a bursa being interposed. Relations.—By its anterior surface, with the ligamentum arcuatum internum of the diaphragm, the kidney, the psoas parvus, genito- crural nerve, sympathetic nerve, its proper fascia, the peritoneum and colon, and along its pelvic border with the common and external iliac artery and vein. By its posterior surface, with the lumbar ver- tebrae, the lumbar arteries, quadratus lumborum, from which it is separated by the anterior layer of the aponeurosis of the transversalis, and with the crural nerve, which, near Poupart's ligament, gets to its outer side. The lumbar plexus of nerves is situated in the sub- ADDUCTOR BREVIS. 269 stance of the posterior part of the muscle. In the thigh, the muscle is in relation with the fascia lata in front; the border of the pelvis and hip-joint, from which it is separated by the synovial membrane, common to it and the preceding muscle, behind; with the crural nerve and iliacus, to the outer side; and with the femoral artery, by which it is slightly overlaid, to the inner side. The Pectineus is a flat and quadrangular muscle; it arises from the pectineal line (pecten, a crest) of the os pubis, and from the sur- face of bone in front of that bone. It is inserted into the line leading from the anterior intertrochanteric line to the linea aspera of the femur. Relations.—By its anterior surface, with the pubic portion of the fascia lata, which separates it from the Femoral artery and vein and internal saphenous vein, and lower down with the profunda artery. By its posterior surface, with the capsule of the hip-joint, and with the obturator externus and adductor brevis, the obturator vessels being interposed. By its external border, with the psoas, the femo- ral artery resting upon the line of interval. By its internal border, with the outer edge of the adductor longus. Obturator hernia is situated directly behind this muscle, which forms one of its cover- ings. The Adductor Longus (adducere, to draw to), the most superficial of the three adductors, arises, by a round and thick tendon, from the front surface of the os pubis, immediately below the angle; and assuming a flattened and expanded form as it descends, is inserted into the middle third of the linea aspera. Relations. — By its anterior surface, with the pubic portion of the fascia lata, and near its insertion with the femoral artery and vein. By its posterior surface, with the adductor brevis and magnus, the anterior branches of" the obturator vessels and nerves, and near its insertion with the profunda artery and vein. By its outer border, with the pectineus; and by the inner border, with the gracilis. The pectineus must be divided near its origin and turned out- wards, and the adductor longus through its middle, turning its ends to either side, to bring into view the adductor brevis. The Adductor Brevis, placed beneath the pectineus and adductor longus, is fleshy, and thicker than the adductor longus; it arises from the body and ramus of the os pubis, and is inserted into the upper third of the linea aspera. Relations. — By its anterior surface, with the pectineus, adductor longus, and anterior branches of the obturator vessels and nerve. By its posterior surface, with the adductor magnus, and posterior branches of the obturator vessels and nerve. By its outer border, with the obturator externus, and conjoined tendon of the psoas and iliacus. By its inner border, with the gracilis and adductor magnus. The adductor brevis is pierced near its insertion by the middle per- forating artery. The adductor brevis may now be divided from its origin and turned outwards, or its inner two-thirds may be cut away entirely, when the adductor magnus muscle will be exposed in its entire extent. 23* 270 POSTERIOR FEMORAL REGION. The Adductor Magnus is a broad triangular muscle, forming a septum of division between the muscles situated on the anterior and those on the posterior aspect of the thigh. It arises, by fleshy fibres, from the ramus of the pubes and ischium, and from the side of the tuber ischii; and radiating in its passage outwards, is inserted into the whole length of the linea aspera, and inner condyle of the femur. The adductor magnus is pierced by five openings: the three superior, for the three perforating arteries ; and the fourth, for the termination of the profunda. The fifth is the large oval opening, in the tendinous portion of the muscle, that gives passage to the femoral vessels. Relations. — By its anterior surface, with the pectineus, adductor brevis, adductor longus, femoral artery and vein, profunda artery and vein, with their branches, and with the posterior branches of the obturator vessels and nerve. By its posterior surface, with the semi- tendinosus, semi-membranosus, biceps, and gluteus maximus. By its inner border, with the gracilis and sartorius. By its upper border, with the obturator externus and quadratus femoris. The Gracilis (slender) is situated along the inner border of the thigh. It arises by a broad, but very thin tendon, from the body of the os pubis, along the edge of the symphysis, and from the margin of the ramus of the pubes and ischium; and is inserted, by a rounded tendon, into the inner tuberosity of the tibia, beneath the expansion of the sartorius. Relations.—By its inner or superficial surface, with the fascia lata, and below, with the sartorius and internal saphenous nerve; the in- ternal saphenous vein crosses it, lying superficially to the fascia lata. By its outer or deep surface, with the adductor longus, brevis, and magnus, and the internal lateral ligament of the knee-joint, from which it is separated by a synovial bursa, common to the tendons of the gracilis and semi-tendinosus. Actions.—The iliacus, psoas, pectineus, and adductor longus mus- cles bend the thigh upon the pelvis, and, at the same time, from the obliquity of their insertion into the lesser trochanter and linea aspera, rotate the entire limb outwards; the pectineus and adductors adduct the thigh powerfully; and from the manner of their insertion into the linea aspera, they assist in rotating the limb outwards. The gracilis is likewise an adductor of the thigh; but contributes also to the flexion of the leg, by its attachment to the inner tuberosity of the tibia. Posterior Femoral Region. Biceps, Semi-tendinosus, Semi-membranosus. Dissection.—Remove the integument and fascia on the posterior part of the thigh by two flaps, as on the anterior region, and turn aside the gluteus maximus from the upper part; the muscles may then be examined. The Biceps Femoris (bis, double, xscpaXi), head) arises by two heads, one by a common tendon with the semi-tendinosus; the other muscu- lar and much shorter, from the lower two-thirds of the external SEMIMEMBRANOSUS. 271 border of the linea aspera. This muscle forms the outer hamstring, and is inserted by a strong tendon into the head of the fibula; a por- tion of the tendon is continued downwards into the fascia of the leg, and another is attached to the outer tuberosity of the tibia. Relations.—By its superficial or posterior surface with the gluteus maximus and fascia lata. By its deep or anterior surface with the semi-membra- nosus, adductor magnus, vastus externus, the great sciatic nerve, popliteal artery and vein, and near its insertion with the external head of the gastroc- nemius, and plantaris. By its inner border with the semi-tendinosus, and in the popliteal space with the popliteal artery and vein. The Semi-tendinosus, remarkable for its long tendon, arises in common with the long head of the biceps, from the tuberosity of the ischium; the two muscles being closely united for several inches below their origin. It is inserted into the inner tuberosity of the tibia. Relations.—By its superficial surface with the gluteus maximus, fascia lata, and at its insertion with the synovial bursa which separates its ten- don from the expansion of the sartorius. By its deep surface with the semi-membranosus, adduc- tor magnus, internal head of the gastrocnemius, and internal lateral ligament of the knee-joint, the synovial bursa common to it and the tendon of the gracilis being interposed. By its inner border with the gracilis; and by its outer border with the biceps. These two muscles must be dissected from the tuberosity of the ischium, to bring into view the origin of the next. The Semi-membranosus, remarkable for the tendinous expansion upon its anterior and posterior surface, arises from the tuberosity of the ischium, in front of the common origin of the two preceding muscles. It is inserted into the posterior part of the inner tuberosity of the tibia; at its insertion the tendon splits into three portions, one of which is inserted in a groove on the inner side of the head of the tibia, beneath the internal lateral ligament. The second is continuous with an aponeurotic expansion that binds down the popliteus muscle the popliteal fascia; and the third turns upwards and outwards to the external condyle of the femur, forming the middle portion of the pos- terior ligament of the knee-joint (ligamentum posticum Winslowii). * The muscles of the posterior femoral and gluteal region. 1. The gluteus medius. 2. The gluteus maximus. 3. The vastus externus covered in by fascia lata. 4. The long head of the biceps. 5. Its short head. 6. The semi-tendinosus. 7. The semi-membra- nosus. 8. The gracilis. 9. A part of the inner border of the adductor magnus. 10. The edge of the sartorius. 11. The popliteal space. 12. The gastrocnemius muscle ; its two heads. The tendon of the biceps forms the outer hamstring; and the sartorius with the tendons of the gracilis, semi-tendinosus, and semimembranosus, the inner hamstring. 272 ANTERIOR TIBIAL REGION. The tendons of the last two muscles, viz. the semi-tendinosus and semi-membranosus, with those of the gracilis and sartorius, form the inner hamstring. Relations.—By its superficial surface with the gluteus maximus, biceps, semi-tendinosus, fascia lata, and at its insertion with the ten- dinous expansion of the sartorius. By its deep surface with the quad- ratus femoris, adductor magnus, internal head of the gastrocnemius, the knee-joint from which it is separated by a synovial membrane, and the popliteal artery and vein. By its inner border with the gra- cilis. By its outer border with the great ischiatic nerve, and in the popliteal space with the popliteal artery and vein. If the semi-membranosus muscle be turned down from its origin, the student will bring into view the broad and radiated expanse of the adductor magnus, upon which the three flexor muscles above described rest. Actions.—These three hamstring muscles are the direct flexors of the leg upon the thigh; and by taking their origin from below, they balance the pelvis on the lower extremities. The biceps, from the obliquity of its direction, everts the leg when partly flexed, and the semi-tendinosus turns the leg inwards when in the same state of flexion. Anterior Tibial Region. Tibialis anticus, Extensor longus digitorum, Peroneus tertius, Extensor proprius pollicis. Dissection.—The dissection of the anterior tibial region is to be commenced by carrying an incision along the middle of the leg, mid- way between the tibia and the fibula, from the knee to the ankle, and bounding it inferiorly by a transverse incision extending from one malleolus to the other. And to expose the tendons on the dorsum of the foot, the longitudinal incision may be carried onwards to the outer side of the base of the great toe, and be terminated by another incision directed across the heads of the metatarsal bones. The Tibialis Anticus muscle (flexor tarsi tibialis) arises from the upper two-thirds of the tibia, from the interosseous membrane, and from the deep fascia; its tendon passes through a distinct sheath in the annular ligament, and is inserted into the inner side of the inter- nal cuneiform bone, and base of the metatarsal bone of the great toe. Relations.—By its anterior surface with the deep fascia, from which many of its superior fibres arise, and with the anterior annular liga- ment. By its posterior surface with the interosseous membrane, tibia, ankle-joint, and bones of the tarsus with their articulations. By its internal surface with the tibia. By the external surface with the extensor longus digitorum, extensor proprius pollicis, and the anterior tibial vessels and nerve. The Extensor Longus Digitorum arises from the head of the tibia, from the upper three-fourths of the fibula, from the interosseous mem- brane, and from the deep fascia. Below, it divides into four tendons, EXTENSOR PROPRIUS POLLICIS. 273 which pass beneath the annular ligament, to be inserted into the second and third phalanges of the four lesser toes. The mode of insertion of the extensor Fig. 128.* tendons, both in the hand and in the foot, is remarkable : each tendon spreads into a broad aponeurosis over the first phalanx; this aponeu- rosis divides into three slips; the middle one is inserted into the base of the second phalanx, and the two lateral slips are continued on- wards, to be inserted into the base of the third. Relations.—By its anterior surface with the deep fascia of the leg and foot, and with the anterior annular ligament. By its posterior sur- face with the interosseous membrane, fibula, ankle-joint, extensor brevis digitorum which 9 separates its tendons from the tarsus, and with the metatarsus and phalanges. By its inner surface with the tibialis anticus, extensor pro- prius pollicis, and anterior tibial vessels. By its outer border with the peroneus longus and brevis. The Peroneus Tertius (flexor tarsi fibularis) arises from the lower fourth of the fibula, and is inserted into the base of the metatarsal bone of the little toe. Although apparently but a mere division or continuation of the extensor longus digitorum, this muscle may be looked upon as analogous to the flexor carpi ulnaris of the fore-arm. Sometimes it is altogether want- ing. The Extensor Proprius Pollicis lies between the tibialis anticus and extensor longus digitorum. It arises from the lower two-thirds of the fibula and interosseous membrane. Its tendon passes through a distinct sheath in the annular ligament, and is inserted into the base of the last phalanx of the great toe. Relations.—By its anterior surface, with the deep fascia of the leg and foot, and with the anterior annular ligament. By its posterior surface, with the interosseous membrane, the fibula, the tibia, the ankle-joint, the extensor brevis digitorum, and the bones and articu- lations of the great toe. It is crossed upon this aspect by the ante- rior tibial vessels and nerve. By its outer side, with the extensor longus digitorum, and in the foot with the dorsalis pedis artery and veins; the outer side of its tendon upon the dorsum of the foot being * The muscles of the anterior tibial region. 1. The extensor muscles inserted into the patella. 2. The subcutaneous surface of the tibia. 3. The tibialis anticus. 4. The ex- tensor longus digitorum. 5. The extensor proprius pollicis. 6. The peroneus tertius. 7. The peroneus longus. 8. The peroneus brevis. 9, 9. The borders of the soleus muscle. 10. A part of the inner belly of the gastrocnemius. 11. The extensor brevis digitorum; the tendon in front of this number is that of the peroneus tertius; and that behind it, the tendon of the peroneus brevis. 274 POSTERIOR TIBIAL REGION. Fig. 129.' the guide to those vessels. By its inner side, with the tibialis anticus, and with the anterior tibial vessels. Actions. — The tibialis anticus and peroneus tertius are direct flexors of the tarsus upon the leg; acting in conjunction with the tibialis posticus, they direct the foot inwards, and with the peroneus longus and brevis, outwards. They assist also in preserving the flat- ness of the foot during progression. The extensor longus digitorum and extensor proprius pollicis, are direct extensors of the phalanges; but, continuing their action, they assist the tibialis anticus and pero- neus tertius in flexing the entire foot upon the leg. Taking their origin from below, they increase the stability of the ankle-joint. Posterior Tibial Region. Superficial Group. Gastrocnemius, Plantaris, Soleus. Dissection. — Make an incision from the middle of the popliteal space, down the middle of the pos- terior part of the leg to the heel, bounding it infe- riorly by a transverse incision, passing between the two malleoli. Turn aside the flaps of integument, and remove the fasciae from the whole of this region; the gastrocnemius muscle will then be exposed. The Gastrocnemius (yatfT^oxv^iov, the bellied part of the leg) arises, by two heads, from the two con- dyles of the femur, the inner head being the longest. They unite to form the beautiful muscle so cha- racteristic of this region of the limb. It is inserted, by means of the tendo Achillis, into the lower part of the posterior tuberosity of the os calcis, a syno- vial bursa being placed between that tendon and the upper part of the tuberosity. The gastrocnemius must be removed from its origin, and turned down, in order to expose the next muscle. Relations. — By its superficial surface, with the deep fascia of the leg, which separates it from the external saphenous vein, and with the external saphe- nous nerve. By its deep surface, with the lateral portions of the posterior ligament of the knee-joint, the popliteus, plantaris, and soleus. The internal head of the muscle rests against the posterior surface of the internal condyle of the femur; the exter- nal head against the outer side of the external condyle. In the latter, a sesamoid bone is sometimes found. * The superficial muscles of the posterior aspect of the leg. 1. The biceps muscle forming the outer hamstring. 2. The tendons forming the inner hamstring. 3. The popliteal space. 4. The gastrocnemius muscle. 5, 5. The soleus. 6. The tendo Achillis. 7. The posterior tuberosity of the os calcis. 8. The tendons of the peroneus longus and brevis muscles passing behind the outer ankle. 9. The tendons of the tibialis posticus and flexor longus digitorum passing into the foot behind the inner ankle. POPLITEUS. 275 The Plantaris (planta, the sole of the foot), an extremely diminu- tive muscle, situated between the gastrocnemius and soleus, arises from the outer condyle of the femur; and is inserted, by its long and delicately slender tendon, into the inner side of the posterior tube- rosity of the os calcis, by the side of the tendo Achillis: having crossed obliquely between the two muscles. The Soleus (solea, a sole), is the broad muscle upon which the plantaris rests. It arises, from the head and upper third of the fibula, from the oblique line and middle third of the tibia. Its fibres con- verge to the tendo Achillis, by which it is inserted into the posterior tuberosity of the os calcis. Between the fibular and tibial origins of this muscle is a tendinous arch, beneath which the popliteal vessels and nerve pass into the leg. Relations.—By its superficial surface, with the gastrocnemius and plantaris. By its deep surface, with the intermuscular fascia, which separates it from the flexor longus digitorum, tibialis posticus, flexor longus pollicis, from the posterior tibial vessels and nerve, and from the peroneal vessels. Actions.—The three muscles of the calf draw powerfully on the os calcis, and lift the heel; continuing their action, they raise the entire body. This action is attained by means of a lever of the second power, the fulcrum (the toes) being at one end, the weight (the body supported on the tibia) in the middle, and the power (these muscles) at the other extremity. They are, therefore, the walking muscles, and perform all move- ments that require the support of the whole body from the ground, as dancing, leaping, &c. Taking their fixed point from below, they steady the leg upon the foot. Deep Layer. Popliteus, Flexor longus pollicis, Flexor longus digitorum, Tibialis posticus. Dissection.—After the removal of the soleus, the deep layer will be found bound down by an intermuscular fascia which is to be dissected away ; the muscles may then be examined. The Popliteus muscle (poples, the ham of the leg), forms the floor of the popliteal region at its lower part, and is bound tightly down by a strong fascia derived from the middle slip of the tendon of the semi- membranosus muscle. It arises by a rounded tendon from a deep groove on the outer side of the external condyle of the femur, beneath the external lateral ligament; and spreading obliquely over the head of the tibia, is inserted into the surface of bone above its oblique line. This line is called, from being the limit of insertion of the popliteal muscle, the popliteal line. Relations.—By its superficial surface with a thick fascia which se- parates it from the two heads of the gastrocnemius, the plantaris, and the popliteal vessels and nerve. By its deep surface- with the synovial membrane of the knee-joint and with the upper part of the tibia. 276 POSTERIOR TIBIAL REGION. Fig. 130.* The Flexor Longus Pollicis is the most superficial of the next three muscles. It arises from the lower two-thirds of the fibula, and passes through a groove in the astragalus and os calcis, which is converted by tendinous fibres into a distinct sheath lined by a synovial mem- brane, into the sole of the foot; it is inserted into the base of the last phalanx of the great toe. Relations.—By its superficial surface with the intermuscular fascia, which separates it from the soleus and tendo Achillis. By its deep surface with the tibialis posticus, fibula, fibular vessels, interosseous membrane, and ankle-joint. By its outer border with the peroneus longus and brevis. By its inner border with the flexor longus digitorum. In the foot, the tendon of the flexor longus pollicis is connected with that of the flexor longus digitorum by a short tendinous slip. The Flexor Longus Digitorum (perforans) arises from the surface of the tibia, immediately below the popliteal line. Its tendon passes through a sheath common to it and the tibialis posticus behind the inner malleolus; it then passes through a second sheath which is con- nected with a groove in the astragalus and os calcis, into the sole of the foot, where it divides into four tendons, which are inserted into the base of the last phalanx of the four lesser toes, perforating the ten- dons of the flexor brevis digitorum. Relations.—By its superficial surface with the in- termuscular fascia, which separates it from the soleus, and with the posterior tibial vessels and nerve. By its deep surface with the tibia and tibialis posticus. In the sole of the foot its tendon is in relation with the abductor pollicis and flexor brevis digitorum, which lie superficially to it, and it crosses the tendon of the flexor longus pollicis. At the point of crossing it receives the tendinous slip of communication from the latter. The flexor longus pollicis must now be removed from its origin, and the flexor longus digitorum drawn aside, to bring into view the entire extent of the tibialis posticus. The Tibialis Posticus (extensor tarsi tibialis) lies upon the interosseous membrane, between the two bones of the leg. It arises by two heads from the adjacent sides of the tibia and fibula their whole length, and from the interosseous membrane. Its tendon passes in- *The deep layer of muscles of the posterior tibial region. 1. The lower extremity of the femur. 2. The ligamentum posticum Winslowii. 3. The tendon of the semi-mem- branosus muscle dividing into its three slips. 4. The internal lateral ligament of the knee- joint. 5. The external lateral ligament. 6. The popliteus muscle. 7. The flexor longus digitorum. 8. The tibialis posticus. 9. The flexor longus pollicis. 10. The peroneus longus muscle. 11. The peroneus brevis. 12. The tendo Achillis divided near its in- sertion into the os calcis. 13. The tendons of the tibialis posticus and flexor longus digitorum muscles, just as they are about to pass beneath the internal annular ligament of the ankle; the interval between the latter tendon and the tendon of the flexor longus pollicis is occupied by the posterior tibial vessels and nerve. FIBULAR REGION. 277 wards beneath the tendon of the flexor longus digitorum, and runs in the same sheath; it then passes through a proper sheath over the , deltoid ligament, and beneath the calcaneo-scaphoid articulation to be inserted into the tuberosity of the scaphoid- and internal cuneiform bone. While in the common sheath behind the internal malleolus, the tendon of the tibialis posticus lies internally to that of the flexor lon- gus digitorum, from which it is separated by a thin fibrous partition. A sesamoid bone is usually met with in the tendon close to its inser- tion. Relations.—By its superficial surface with the intermuscular septum, the flexor longus pollicis, flexor longus digitorum, posterior tibial vessels and nerve, peroneal vessels, and in the sole of the foot with the abductor pollicis. By its deep surface with the interosseous mem- brane, the fibula and tibia, the ankle-joint, and the astragalus. The anterior tibial artery passes between the two heads of the muscle. The student will observe that the two latter muscles change their relative position to each other in their course. Thus, in the leg, the position of the three muscles from within outwards, is, flexor longus digitorum, tibialis posticus, flexor longus pollicis. At the inner mal- leolus, the relation of the tendons is, tibialis posticus, flexor longus di- gitorum, both in the same sheath; then a broad groove, which lodges the posterior tibial artery, venae comites, and nerve; and lastly, the flexor longus pollicis. Actions.—The popliteus is a flexor of the tibia upon the thigh, carrying it at the same time inwards so as to invert the leg. The flexor longus pollicis, and flexor longus digitorum are the long flexors of the toes; their tendons are connected in the foot by a short tendi- nous band, hence they necessarily act together. The tibialis posticus is an extensor of the tarsus upon the leg, and an antagonist to the tibialis anticus. It combines with the tibialis anticus in adduction of the foot. Fibular Region. Peroneus longus, Peroneus brevis. Dissection.—These muscles are exposed by continuing the dissec- tion of the anterior tibial region outwards beyond the fibula, to the border of the posterior tibial region. The Peuoneus Longus (iregovri, fibula, extensor tarsi fibularis lon- gior) muscle arises from the head and upper third of the outer side of the fibula, and terminates in a long tendon, which passes behind the external malleolus, and obliquely across the sole of the foot, through the groove in the cuboid bone, to be inserted into the base of the me- tatarsal bone of the great toe. Its tendon is thickened where it glides behind the external malleolus, and a sesamoid bone is developed in that part which plays upon the cuboid bone. Relations.—By its superficial surface with the fascia of the leg and foot. By its deep surface with the fibula, peroneus brevis, os calcis, and cuboid bone, and near the head of the fibula with the fibular nerve. By its anterior border it is separated from the extensor longus 24 278 FOOT—DORSAL REGION. digitorum by the attachment of the fascia of the leg to the fibula; and by the posterior border by the same medium from the soleus and flexor longus pollicis. The peroneus longus is furnished with three tendinous sheaths and as many synovial membranes; the first is situated behind the external malleolus, and is common to this muscle and the peroneus brevis, the second on the outer side of the os calcis, and the third on the cuboid bone. The Peroneus Brevis (extensor tarsi fibularis brevior) lies beneath the peroneus longus; it arises from the lower half of the fibula, and terminates in a tendon which passes behind the external malleolus and through a groove in the os calcis, to be inserted into the base of the metatarsal bone of the little toe. Relations.—By its superficial surface with the peroneus longus and fascia of the leg and foot.' By its deep surface with the fibula, the os calcis, and cuboid bone. The lateral relations are the same as those of the peroneus longus. The tendon of the peroneus brevis has but two tendinous sheaths and two synovial membranes, one behind the external malleolus and common to both peronei, the other upon the side of the os calcis. Actions.—The peronei muscles are extensors of the foot, conjointly with the tibialis posticus. They antagonize the tibialis anticus and peroneus tertius, which are flexors of the foot. The whole of these muscles acting together, tend to maintain the flatness of the foot, so necessary to security in walking. FOOT. Dorsal Region. Extensor brevis digitorum, Interossei dorsales. The Extensor Brevis Digitorum muscle arises from the outer side of the os calcis, crosses the foot obliquely, and terminates in four ten- dons, the innermost of which is inserted into the base of the first phalanx of the great toe, and the other three into the sides of the long extensor tendons of the second, third, and fourth toes. Relations.—By its upper surface with the tendons of the extensor longus digitorum, peroneus brevis, and with the deep fascia of the foot. By its under surface with the tarsal and metatarsal bones. Its inner border is in relation with the dorsalis pedis artery, and the innermost tendon of the muscle crosses that artery just before its division. The Dorsal Interossei muscles are placed between the metatarsal bones; they resemble the analogous muscles in the hand in arising by two heads from the adjacent sides of the metatarsal bones; their tendons are inserted into the base of the first phalanx, and into the digital expansion of the tendons of the long extensor. The first dorsal interosseous is inserted into the inner side of the second toe, and is therefore an adductor; the other three are inserted into the outer side of the second, third, and fourth toes, and are con- sequently abductors. Relations.—By their upper surface with a strong fascia which PLANTAR REGION. 279 separates them from the extensor tendons. By their under surface with the plantar interossei. Each of the muscles gives passage to a small artery (posterior perforating) which communicates with the external plantar artery. And between the heads of the first interos- seous muscle the communicating artery of the dorsalis pedis takes its course. Fig. 131.* Plantar Region. First Layer. Adductor pollicis, Abductor minimi digiti, Flexor brevis digitorum. Dissection.—The sole of the foot is best dissected by carrying an incision around the heel, and along the inner and outer borders of the foot, to the great, and little toes. This incision should divide the in- tegument and superficial fascia, and both together should be dissected from the deep fascia, as far forward as the base of the phalanges, where they may be removed from the foot altogether. The deep fascia should then be removed, and the first layer of muscles will be brought into view. The Abductor Pollicis lies along the inner border of the foot; it arises by two heads, between which the tendons of the long flexors, * Dorsal interossei. 1. Abductor secundi. 2. Adductor secundi. 3. Adductor tertii. 4. Adductor quarti. t The first layer of muscles in the sole of the foot; this layer is exposed by the removal of the plantar fascia. 1. The os calcis. 2. The posterior part of the plantar fascia divided transversely. 3. The abductor pollicis. 4. The abductor minimi digiti. 5. The flexor brevis digitorum. 6. The tendon of the flexor longus pollicis muscle. 7, 7. The lumbricales. On the second and third toes, the tendons of the flexor longus digitorum are seen passing through the bifurcation of the tendons of the flexor brevis digitorum. Fig. 132.t 280 MUSCLES OF THE SOLE OF THE FOOT. arteries, veins, and nerves enter the sole of the foot. One head arises from the inner tuberosity of the os calcis, the other from the internal annular ligament and plantar fascia. Insertion, into the base of the first phalanx of the great toe, and into the internal sesamoid bone. Relations.—By its superficial surface with the internal portion of the plantar fascia. By its deep surface with the flexor brevis pollicis, musculus accessorius, tendons of the flexor longus digitorum and flexor longus pollicis, tendons of the tibialis anticus and posticus, the plantar vessels and nerves, and the tarsal bones. On its outer border with the flexor brevis digitorum, from which it is separated by a ver- tical septum of the plantar fascia. Fig. 133.* The Abductor Minimi Digiti lies along the outer border of the sole of the foot. It arises from the outer tuberosity of the os calcis, and from the plantar fascia, as far forward as the base of the fifth metatarsal bone, and is inserted into the base of the first phalanx of the little toe. Relations.—By its superficial surface with the external portion of the plantar fascia. By its deep surface with the musculus accessorius, flexor brevis minimi digiti, with the tarsal bones, and with the metatarsal bone of the little toe. By its inner side with the flexor brevis digito- rum, from which it is separated by the vertical septum of the plantar fascia. The Flexor Brevis Digitorum (perforatus) is placed between the two preceding muscles. It arises from the under surface of the os calcis, from the plantar fascia and intermuscular septa, and is inserted by four tendons into the base of the second phalanx of the four lesser toes. Each ten- don divides, previously to its insertion, to give passage to the tendon of the long flexor; hence its cognomen per- foratus. Relations.—By its superficial surface with the plantar fascia. By its deep surface with a thin layer of fascia which separates it from the musculus accessorius, tendons of the flexor longus digitorum and flexor longus pollicis, and plantar vessels and nerves. By its borders with the vertical septa of the plantar fascia, which separate the mus- cle, on the one side from the abductor pollicis, and on the other from the abductor minimi digiti. Second Layer. Musculus accessorius, Lumbricales. Dissection.—The three preceding muscles must be divided from * The third and a part of the second layer of muscles of the sole of the foot. 1. The divided edge of the plantar fascia. 2. The musculus accessorius. 3. The tendon of the flexor longus digitorum. 4. The tendon of the flexor longus pollicis. 5. The flexor brevis pollicis. 6. The adductor pollicis. 7. The flexor brevis minimi digiti. .8. The transversus pedis. 9. Interossei muscles, plantar and dorsal. A convex ridge formed by the tendon of the peroneus longus muscle in its oblique course across the foot. MUSCLES OF THE SOLE OF THE FOOT. 281 Fig. 134.* their origin, and anteriorly through their tendons, and removed, in order to bring into view the second layer. The Musculus Accessorius arises by two slips from either side of the under surface of the os calcis; the inner slip being fleshy, the outer, tendinous. The muscle is inserted into the outer side and upper surface of the tendon of the flexor longus digitorum. Relations.—By its superficial surface, with the three muscles of the superficial layer, from which it is separated by their fascial sheaths, and with the external plantar vessels and nerves. By its deep sur- face, with the under surface of the os calcis and the long calcaneo- cuboid ligament. The Lumbricales (lumbricus, an earthworm) are four little muscles, arising from the tibial side of the tendons of the flexor longus digi- torum, and inserted into the expansion of the extensor tendons, and into the base of the first phalanx of the four lesser toes. Relations.—By their superficial surface, with the tendons of the flexor brevis digitorum. By their deep surface, with the third layer of muscles of the sole of the foot. They pass between the digital slips of the deep fascia to reach their insertion. Third Layer. Flexor brevis pollicis, Adductor pollicis, Flexor brevis minimi digiti, Transversus pedis. Dissection.—The tendons of the long flexors, and the muscles connected with them, must be remo- ved, to see clearly the attachments of the third layer. The Flexor Brevis Pollicis arises, by a pointed tendinous process, from the side of the cuboid, and from the external cuneiform bone; it is inserted, by two heads, into the base of the first phalanx of the great toe. Two sesamoid bones are developed in the tendons of insertion of these two heads, and the tendon of the flexor longus pollicis lies in the groove between them. Relations. — By its superficial surface, with the abductor pollicis, tendon of the flexor longus pollicis, and plantar fascia. By its deep surface, with the tarsal bones and their ligaments, the metatarsal bone of the great toe, and the insertion of the tendon of the peroneus longus. By its inner border, with the abductor pollicis ; and by its outer border, with the adductor pollicis; with both of these muscles it is blended near its insertion. The Adductor Pollicis arises from the cuboid bone, from the sheath of the tendon of the peroneus longus, and from the base of the * Deep-seated muscles in the sole of the foot. 1. Tendon of the flexor longus pollicis. 2. Tendon of the flexor communis digitorum pedis. 3. Flexor accessorius. 4, 4. Lum- bricales. 5. Flexor brevis digitorum. 6. Flexor brevis pollicis pedis. 7. Flexor brevis minimi digiti pedis. 24* 282 MUSCLES OF THE SOLE OF THE FOOT. third and fourth metatarsal bones. It is inserted into the base of the first phalanx of the great toe. Relations.—By its superficial surface, with the tendons of the flexor longus and flexor brevis digitorum, the musculus accessorius, and lumbricales. By its deep surface, with the tarsal bones and liga- ments, the external plantar artery and veins, the interossei muscles, tendon of the peroneus longus, and metatarsal bone of the great toe. By its inner border, with the flexor brevis pollicis; with which its fibres are blended. The Flexor Brevis Minimi Digiti arises from the base of the metatarsal bone of the little toe, and from the sheath of the tendon of the peroneus longus. It is inserted into the base of the first phalanx of the little toe. Relations.—By its superficial surface, with the tendons of the flexor longus and flexor brevis digitorum, the fourth lumbricalis, abductor minimi digiti, and plantar fascia. By its deep surface, with the plantar interosseous muscle of the fourth metatarsal space, and the metatarsal bone. The Transversus Pedis arises, by fleshy slips, from the heads of the metatarsal bones of the four lesser toes. Its tendon is inserted into the base of the first phalanx of the great toe, being blended with that of the adductor pollicis. Relations.—By its superficial surface, w7ith the tendons of the flexor longus and flexor brevis digitorum, and the lumbricales. By its deep surface, with the interossei, and heads of the metatarsal bones. Fourth Layer. Interossei Plantares. The Plantar Interossei muscles are three in number, and are placed upon, rather than between, the metatarsal bones. They arise from the base of the metatarsal bones of the three outer toes, and are inserted into the inner side of the extensor tendon and base of the first phalanx of the same toes. Relations.—By their superficial surface, with the dorsal interossei and the metatarsal bones. By their deep surface, with the external plantar artery and veins, the adductor pollicis, transversus pedis, and flexor minimi digiti. Actions. — All the preceding muscles act upon the toes; and the movements which they are capable of executing may be referred to four lieads, viz. flexion, extension, adduction, and abduction. In these actions they are grouped in the following manner :— Flexion. Extension. Flexor longus digitorum, Extensor longus digitorum, Flexor brevis digitorum, Extensor brevis digitorum. Flexor accessorius, Flexor minimi digiti. Adduction. Abduction. Interossei i °ne dorsa1' Interossei, three dorsal, ' I three plantar. Abductor minimi digiti. THE FASCIAE. 283 The great toe, like the thumb in the hand, enjoys an independent action, and is provided with dis- tinct muscles to perform its movements. These movements are precisely the same as those of the other toes, viz.: Flexion. Flexor longus pollicis, Flexor brevis pollicis. Extension. Extensor proprius pollicis, Extensor brevis digitorum. Adduction. Adductor pollicis. Abduction. Abductor pollicis. The only muscles excluded from this table are the lumbricales, four small muscles, which, from their attachments to the tendons of the long flexor, ap- pear to be assistants to its action; and the transversus pedis, a small muscle placed transversely in the foot across the heads of the meta- tarsal bones, which has for its office the drawing together of the toes. CHAPTER V. ON THE FASCIAE. Fascia (fascia, a bandage) is the name assigned to laminae of va- rious extent and thickness, which are distributed through the different regions of the body, for the purpose of investing or protecting the softer and more delicate organs. From a consideration of their structure, these fasciae maybe arranged into two groups: cellulo- fibrous fasciae, and aponeurotic fasciae. The cellulo-fibrous fascia is best illustrated in the common subcuta- neous investment of the entire body, the superficial fascia. This structure is situated immediately beneath the integument over every part of the frame, and is the medium of connexion between that layer and the deeper parts. It is composed of cellulo-fibrous tissue con- taining in its areolae an abundance of adipose cells. The fat being a bad conductor of caloric, serves to retain the warmth of the body; while it forms at the same time a yielding tissue, through which the minute vessels and nerves pass to the papillary layer of the skin, with- out incurring the risk of obstruction from injury or pressure upon the * Plantar interossei. 1. Abductor tertii. 2. Abductor quarti. 3. Interosseous minimi digiti. 284 FASCIAE OF THE HEAD AND NECK. surface. By dissection, the superficial fascia may be separated into two layers, between which are found the superficial or cutaneous ves- sels and nerves; as the superficial epigastric artery, the saphenous veins, the radial and ulnar veins, the superficial lymphatic vessels, also the cutaneous muscles, as the platysma myoides, orbicularis palpe- brarum, sphincter ani, &c. In other situations, the cellulo-fibrous fas- cia is found condensed into a strong and inelastic membrane, as is exemplified in the deep fascia of the neck, the thoracic, transversalis, and perineal fasciae, and the sheaths of vessels. The aponeurotic fascia is the strongest kind of investing membrane; it is composed of tendinous fibres, running parallel with each other, and connected by other fibres of the same kind passing in different directions. Wrhen freshly exposed, it is brilliant and nacreous, and is tough, inelastic, and unyielding. In the limbs it forms the deep fas- cia, enclosing and forming distinct sheaths to all the muscles and tendons. It is thick upon the outer and least protected side of the limb, and thinner upon its inner side. It is firmly connected to the bones, and to the prominent points of each region, as to the pelvis, knee, and ankle, in the lower, and to the clavicle, scapula, elbow, and wrist, in the upper extremity. It assists the muscles in their action, by keeping up a tonic pressure on their surface; aids materially in the circulation of the fluids in opposition to the laws of gravity; and in the palm of the hand and sole of the foot is a powerful protection to the structures which enter into the composition of these regions. In some situations its tension is regulated by muscular action, as by the tensor vaginae femoris and gluteus maximus in the thigh, by the biceps in the leg, and by the biceps and palmaris longus in the arm; in other situations it affords an extensive surface for the origin of the fibres of muscles. The fasciae may be arranged like the other textures of the body into, 1. Those of the head and neck. 2. Those of the trunk. 3. Those of the upper extremity. 4. Those of the lower extremity. FASCIA OF THE HEAD- AND NECK. The Temporal Fascia is a strong aponeurotic membrane which covers in the temporal muscle at each side of the head, and gives origin by its internal surface to some of its muscular fibres. It is attached to the whole extent of the temporal ridge above, and to the zygomatic arch below; in the latter situation it is thick and divided into two layers, the external being connected to the upper border of the arch, and the internal to its inner surface. A small quantity of fat is usually found between these two layers, together with the orbital branch of the temporal artery. Cervical Fascia.—The fasciae of the neck are the superficial and the deep. The superficial cervical fascia is a part of the common superficial fascia of the entire body, and is only interesting from containing between its layers the platysma myoides muscle. The deep cervical fascia is a strong cellulo-fibrous layer which invests the muscles of the neck, and retains and supports the vessels FASCIAE OF THE TRUNK. 285 Fig. 136/ and nerves. It commences posteriorly at the ligamentum nuchae, and passes forwards at each side beneath the trapezius muscle to the posterior border of the sterno-mastoid ; here it divides into two layers, which embrace that muscle and unite upon its anterior border to be prolonged onwards to the middle line of the neck, where it becomes continuous with the fascia of the opposite side. Besides thus consti- tuting a sheath for the sterno-mastoid, it also forms sheaths for the other muscles of the neck over which it passes. If the superficial layer of the sheath of the sterno-mastoid be traced upwards, it will be found to pass over the parotid gland and masseter muscle, and to be inserted into the zygomatic arch; and if it be traced downwards, it will be seen to pass in front of the clavicle, and become lost upon the pectoralis major muscle. If the deep layer of the sheath be examined superiorly, ii will be found attached to the styloid process, from which it is reflected to the an- gle of the lower jaw, forming the sty- lo-maxillary ligament; and if it be followed downwards, it will be found connected with the tendon of the omo- hyoid muscle, and may thence be traced behind the clavicle, where it encloses the subclavius muscle, and, being extended from the cartilage of the first rib to the coracoid process, constitutes the costo-coracoid mem- brane. In front of the sterno-mas- toid muscle, the deep fascia is attach- ed to the border of the lower jaw and os hyoides, and forms a distinct sheath for the submaxillary gland. Inferiorly it divides into two layers, one of which passes in front of the sternum, while the other is attached to its superior border. FASCIiE OF THE TRUNK. The thoracic fascia-f is a dense layer of cellulo-fibrous membrane * A transverse section of the neck, showing the deep cervical fascia and its numerous prolongations, forming sheaths for the different muscles. As the figure is symmetrical, the figures of reference are placed only on one side. 1. The platysma myoides. 2. The trapezius. 3. The ligamentum nucha?, from which the fascia may be traced forwards beneath the trapezius, enclosing the other muscles of the neck. 4. The point at which the fascia divides, to form a sheath for the sterno-mastoid muscle (5). 6. The point of reunion of the two layers of the sterno-mastoid sheath. 7. The point of union of the deep cervical fascia of opposite sides of the neck. 8. Section of the sterno-hyoid. 9. Omo- hyoid. 10. Sterno-thyroid. II. The lateral lobe of the thyroid gland. 12. The trachea. 13. The oesophagus. 14. The sheath containing the common carotid artery, internal jugular vein, and pneumogastric nerve. 15. The longus colli. The nerve in front of the sheath of this muscle is the sympathetic. 16. The rectus anticus major. 17. Scalenus anticus. 18. Scalenus posticus. 19. The splenitis capitis. 20. Splenitis colli. 21. Leva- tor anguli scapulae. 22. Complexus. 23. Trachelo-mastoid. 24. Transversalis colli. 25. Cervicalis ascendens. 26. The semi-spinalis colli. 27. The multifidus spinae. 28. A cervical vertebra. The transverse processes are seen to be traversed by the vertebral artery and vein. t For an excellent description of this fascia, see Sir Astley Cooper's work on the " Anatomy of the Thymus Gland." 286 ABDOMINAL FASCLE. stretched horizontally across the superior opening of the thorax. It is firmly attached to the concave margin of the first rib, and to the inner surface of the sternum. In front it leaves an opening for the connexion of the cervical with the thoracic portion of the thymus gland, and behind it forms an arch across the vertebral column, to give passage to the oesophagus. At the point where the great vessels and trachea pass through the thoracic fascia, it divides into an ascending and descending layer. The ascending layer is attached to the trachea, and becomes conti- nuous with the sheath of the carotid vessels, and with the deep cer- vical fascia; the descending layer descends upon the trachea to its bifurcation, surrounds the large vessels arising from the arch of the aorta, and the upper part of the arch itself, and is continuous with the fibrous layer of the pericardium. It is connected also with the venae innominatae and superior cava, and is attached to the cellular capsule of the thymus gland. " The thoracic fascia," writes Sir Astley Cooper, " performs three important offices:— " 1st. It forms the upper boundary of the chest, as the diaphragm does the lower. " 2d. It steadily preserves the relative situation of the parts which enter and quit the thoracic opening. " 3d. It attaches and supports the heart in its situation, through the medium of its connexion with the aorta and large vessels which are placed at its curvature." abdominal fascia The lower part of the parietes of the abdomen, and the cavity of the pelvis, are strengthened by a layer of fascia which lines their in- ternal surface, and at the bottom of the latter cavity is reflected in- wards to the sides of the bladder. This fascia is continuous through- out the whole of the above-mentioned surface; but for convenience of description is considered under the several names of transversalis fascia, iliac fascia, and pelvic fascia; the two former meet at the crest of the ilium and Poupart's ligament, and the latter is confined to the cavity of the true pelvis. The fascia transversalis (Fascia Cooperi)* is a cellulo-fibrous lamella which lines the inner surface of the transversalis muscle. It is thick and dense below, near the lower part of the abdomen; but becomes thinner as it ascends, and is gradually lost in the subserous cellular tissue. It is attached inferiorly to the reflected margin of Poupart's ligament and to the crest of the ilium; internally, to the border of the rectus muscle ; and, at the inner third of the femoral arch, is continued beneath Poupart's ligament, and forms the anterior segment of the crural canal, or sheath of the femoral vessels. The internal abdominal ring is situated in this fascia, at about mid- way between the spine of the os pubis and the anterior superior spine of the ilium, and half an inch above Poupart's ligament; it is bounded * Sir Astley Cooper first described this fascia in its important relation to inguinal hernia. INGUINAL HERNIA. - 287 upon its inner side by a well-marked falciform border, but is ill defined around its outer margin. From the circumference of this ring is given off an infundibuliform process, which surrounds the tes- ticle and spermatic cord, constituting the fascia propria of the latter, and forms the first investment to the sac of oblique inguinal hernia. It is the strength of this fascia, in the interval between the tendon of the rectus and the internal abdominal ring, that defends this portion of the parietes from the frequent occurrence of direct inguinal hernia. INGUINAL HERNIA. Inguinal hernia is of two kinds, oblique and direct. In Oblique Inguinal Hernia, the intestine escapes from the cavity of the abdomen into the spermatic canal, through the internal abdo- minal ring, pressing before it a pouch of peritoneum which consti- tutes the hernial sac, and distending the infundibuliform process of the transversalis fascia. After emerging through the internal abdo- minal ring, it passes first beneath the lower and arched border of the transversalis muscle ; then beneath the lower border of the internal oblique muscle; and finally through the external abdominal ring in the aponeurosis of the external oblique. From the transversalis muscle it receives no investment; while passing beneath the lower border of the internal oblique it obtains the cremaster muscle; and, upon escaping at the external abdominal ring, receives the inter- columnar fascia. So that the coverings of an oblique inguinal hernia, after it has emerged through the external abdominal ring, are, from the surface to the intestine, the Integument, Cremaster muscle, Superficial fascia, Transversalis, or infundibuliform fascia, Intercolumnar fascia, Peritoneal sac. The spermatic canal, which, in the normal condition of the abdo- minal parietes serves for the passage of the spermatic cord in the male, and the round ligament with its vessels in the female, is about one inch and a half in length. It is bounded in front by the aponeu- rosis of the external oblique muscle; behind by the transversalis fascia, and the conjoined tendon of the internal oblique and transver- salis muscle; above by the arched borders of the internal oblique and transversalis; below by the grooved border of Poupart's ligament, and at each extremity by one of the abdominal rings, the internal ring at the inner termination, the external ring at the outer extremity. These relations may be more distinctly illustrated by the following plan— Above. Lower borders of internal oblique and transversalis muscle. In Front. Behind. Transversalis fascia. Conjoined tendon of internal oblique and transversalis. Below. Grooved border of Poupart's ligament. Aponeurosis of external oblique. Spermatic canal. 288 ILIAC FASCIA. There are three varieties of oblique inguinal hernia:—common, congenital, and encysted. Common oblique hernia is that which has been described above. Congenital hernia results from the nonclosure of the pouch of peri- toneum carried downwards into the scrotum by the testicle, during its descent in the foetus. The intestine at some period of life is forced into this canal, and descends through it into the tunica vaginalis where it lies in contact with the testicle; so that congenital hernia has no proper sac, but is contained within the tunica vaginalis. The other coverings are the same as those of common inguinal hernia. Encysted hernia (hernia infantilis, of Hey) is that form of protrusion in which the pouch of peritoneum forming the tunica vaginalis, being only partially closed, and remaining open externally to the abdomen, admits of the hernia passing into the scrotum, behind the tunica vagi- nalis. So that the surgeon in operating upon this variety, requires to divide three layers of serous membrane; the first and second layers being those of the tunica vaginalis; and the third the true sac of the hernia. Direct Inguinal Hernia has received its name from passing di- rectly through the external abdominal ring, and forcing before it the opposing parietes. This portion of the wall of the abdomen is strengthened by the conjoined tendon of the internal oblique and transversalis muscle, which is pressed before the hernia, and forms one of its investments. Its coverings are, the Integument, Conjoined tendon, Superficial fascia, Transversalis fascia, Intercolumnar fascia, Peritoneal sac. Direct inguinal hernia differs from oblique in never attaining the same bulk, in consequence of the resisting nature of the conjoined tendon of the internal oblique and transversalis and of the transver- salis fascia; in its direction, having a tendency to protrude from the middle line rather than towards it. Thirdly, in making for itself a new passage through the abdominal parietes, instead of following a natural channel; and fourthly, in the relation of the neck of its sac to the epigastric artery; that vessel lying to the outer side of the opening of the sac of direct hernia, and to the inner side of that of oblique hernia. All the forms of inguinal hernia are designated scrotal, when they have descended into that cavity. The Fascia Iliaca is the aponeurotic investment of the psoas and iliacus muscles; and, like the fascia transversalis, is thick below, and becomes gradually thinner as it ascends. It is attached superiorly along the edge of the psoas, to the anterior lamella of the aponeurosis of the transversalis muscle, to the ligamentum arcuatum internum, and to the bodies of the lumbar vertebrae, leaving arches correspond- ing with the constricted portions of the vertebrae for the passage of the lumbar vessels. Lower down it passes beneath the externaf iliac vessels, and is attached along the margin of the true pelvis; externally, PELVIC FASCIAE. 289 it is connected to the crest of the ilium; and, inferiorly, to the outer two-thirds of Poupart's ligament, where it is continuous with the fascia transversalis. Passing beneath Poupart's ligament, it surrounds the psoas and iliacus muscles to their termination, and beneath the inner third of the femoral arch forms the posterior segment of the sheath of the femoral vessels. The Fascia Pelvica is attached to the inner surface of the os pubis and along the margin of the brim of the pelvis, where it is continuous with the iliac fascia. From this extensive origin it descends into the pelvis, and divides into two layers, the pelvic and obturator. The pelvic layer or fascia, when traced from the internal surface of the os pubis near the symphysis, is seen to be reflected inwards to the neck of the bladder, so as to form the anterior vesical ligaments. Traced backwards, it passes between the sacral plexus of nerves and the internal iliac vessels, and is attached to the an- terior surface of the sa- crum ; and followed from the sides of the pelvis, it descends to the base of the bladder and divides into three layers, one ascend- ing, is reflected upon the side of that viscus, enclo- ses the vesical plexus of veins, and forms the lateral ligaments of the bladder. A middle layer passes in- wards between the base of the bladder and the upper surface of the rectum, and was named by Mr. Tyrrell the recto-vesical fascia; and an inferior layer passes behind the rectum, and, with the layer of the opposite side, completely invests that intestine. The obturator fascia passes directly downwards from the splitting of the layers of the pelvic fascia, and covers in the obturator internus muscle and the internal pudic vessels and nerve; it is attached to the ramus of the os pubis and ischium in front, and below to the falciform margin of the great sacro-ischiatic ligament. Lying between these two layers of fascia is the levator ani muscle, which arises from their angle of separation. The levator ani is covered in inferiorly by a third layer of fascia, which is given off by the obturator fascia, and * A transverse section of the pelvis, showing the distribution of the pelvic fascia. 1. The bladder. 2. The vesicula seminalis of one side divided across. 3. The rectum. 4. The iliac fascia covering in the iliacus and psoas muscles (5); and forming a sheath for the external iliac vessels (6). 7. The anterior crural nerve excluded from the sheath. 8. The pelvic fascia. 9. Its ascending layer, forming the lateral ligament of the bladder of one side, and a sheath to the vesical plexus of veins. 10. The recto-vesical fascia of Mr. Tyrrell formed by the middle layer. 11. The inferior layer surrounding the rectum and meeting at the middle line with the fascia of the opposite side. 12. The levator ani muscle. 13. The obturator internus muscle, covered in by the obturator fascia, which also forms a sheath for the internal pudic vessels and nerve (14). 15. The layer of fascia which invests the under surface of the levator ani muscle, the anal fascia. 25 290 DEEP PERINEAL FASCIA. is continued downwards upon the inferior surface of the muscle to the extremity of the rectum, where it is lost. This layer may be named from its position and inferior attachment the anal fascia. Perineal Fascia.—In the perineum there are two fasciae of much importance, the superficial and deep perineal fascia. Fig. 138.* The superficial perineal fascia is a thin aponeurotic layer, which covers in the muscles of the genital portion of the perineum and the root of the penis. It is firmly attached at each side to the ramus of the os pubis and ischium; posteriorly it is reflected backwards beneath the transversi perinei muscles to become connected with the deep perineal fascia; while anteriorly it is continuous with the dartos of the scrotum. The deep perineal fascia (Camper's ligament, triangular ligament) is situated behind the root of the penis, and is firmly stretched across between the ramus of the os pubis and ischium of each side, so as to constitute a strong septum of defence to the outlet of the pelvis. At its inferior border it divides into two layers, one of which is continued forwards, and is continuous with the superficial perineal fascia; while the other is prolonged backwards to the rectum, and, joining with the anal fascia, assists in supporting the extremity of that intestine. The deep perineal fascia is composed of two layers, which are separated from each other by several important parts, and traversed by the membranous portion of the urethra. The anterior layer is nearly plane in its direction, and sends a sheath forwards around the ante- rior termination of the membranous urethra to be attached to the posterior part of the bul\ The posterior layer is oblique and sends * The pubic arch with the attachments of the perineal fasciae. 1, 1, 1. The superficial perineal fascia divided by a a. shaped incision into three flaps ; the lateral flaps are turned over the ramus of the os pubis and ischium at each side, to which they are firmly attached; the posterior flap is continuous with the deep perineal fascia. 2. The deep peri- neal fascia. 3. The opening for the passage of the membranous portion of the urethra, previously to entering the bulb. 4. Two projections of the anterior layer of the deep perineal fascia, corresponding with the position of Cowpei's glands. 9999999999 FASCIAE OF THE UPPER EXTREMITY. 291 a funnel-shaped process back- wards, which invests the com- mencement of the membra- nous urethra and the prostate gland. The inferior segment of this funnel-shaped process is continued backward be- neath the prostate gland and the vesiculae seminalcs, and is continuous with the recto-ve- sical fascia of Tyrrell, which is attached posteriorly to the recto-vesical fold of perito- neum, and serves the important office of retaining that duplicature in its proper situation. Between the two layers of the deep perineal fascia are situated, therefore, the whole extent of the membranous portion of the urethra, the compressor urethrae muscle, Cowper's glands, the internal pudic and bulbous arteries, and a plexus of veins. Mr. Tyrrell considers the anterior lamella alone as the deep perineal fascia, and the poste- rior lamella as a distinct layer of fascia, covering in a considerable plexus of veins. FASCIiE OF THE UPPER EXTREMITY. The superficial fascia of the upper extremity contains between its layers the superficial veins and lymphatics, and the superficial nerves. The deep fascia is thin over the deltoid and pectoralis major muscles, and in the axillary space, but thick upon the dorsum of the scapula, where it binds down the infra-spinatus muscle. It is attached to the clavicle, acromion process, and spine of the scapula. In the upper arm it is somewhat stronger, and is inserted into the condyloid * A side view of the viscera of the pelvis, showing the distribution of the perineal and pelvic fascia?. 1. The symphysis pubis. 2. The bladder. 3. The recto-vesical fold of peritoneum, passing from the anterior surface of the rectum to the posterior part of the bladder ; from the upper part of the fundus of the bladder it is reflected upon the abdo- minal parietes. 4. The ureter. 5. The vas deferens crossing the direction of the ureter. 6. The vesicula seminalis of the right side. 7, 7. The prostate gland divided by a longi- tudinal section. 8, 8. The section of a ring of elastic tissue encircling the prostatic por- tion of the urethra at its commencement. 9. The prostatic portion of the urethra. 10. The membranous portion, enclosed by the compressor urethras muscle. 11. The commence- ment of the corpus spongiosum penis, the bulb. 12. The anterior ligaments of the bladder formed by the reflection of the pelvic fascia, from the internal surface of the os pubis to the neck of the bladder. 13. The edge of the pelvic, fascia at the point where it is reflected upon the rectum. 14. An interval between the pelvic fascia and deep perineal fascia, occupied by a plexus of veins. 15. The deep perineal fascia; its two layers. 16. Cowper's gland of the right side situated between the two layers below the membranous portion of the urethra. 17. The superficial perineal fascia ascending in front of the root of the penis to become continuous with the dartos of the scrotum (18). 19. The layer of the deep fascia which is prolonged to the rectum. 20. The lower part of the levator ani; its fibres are concealed by the anal fascia. 21. The inferior segment of the funnel-shaped process given off from the posterior layer of the deep perineal fascia, which is continuous with the recto-vesical fascia of Tyrrell. The attachment of this fascia to the recto-vesical fold of peritoneum is seen at 22. 292 FASCIAE OF THE LOWER EXTREMITY. ridges, forming the intermuscular septa. In the fore-arm it is very strong, and at the bend of the elbow its thickness is augmented by a broad band, which is given off from the inner side of the tendon of the biceps. It is firmly attached to the olecranon process, to the ulna, and to the prominent points about the wrist. Upon the front of the wrist it is continuous with the anterior annular ligament, which is considered by some anatomists to be formed by the deep fascia, but which I am more disposed to regard as a ligament of the wrist. On the posterior aspect of this joint, it forms a strong transverse.band, the posterior annular ligament, beneath which the tendons of the ex- tensor muscles pass, in distinct sheaths. The attachments of the pos- terior annular ligament are, the radius on one side, and the ulna and pisiform bone on the opposite side of the joint. The tendons, as they pass beneath the annular ligaments, are sur- rounded by synovial bursae. The dorsum of the hand is invested by a thin fascia, which is continuous with the posterior annular liga- ment. The palmar fascia is divided into three portions. A central por- tion, which occupies the middle of the palm, and two lateral portions, which spread out over the sides of the hand, and are continuous with the dorsal fascia. The, central portion is strong and tendinous : it is narrow at the wrist, where it is attached to the annular ligament, and broad over the heads of the metacarpal bones, where it divides into eight slips, which are inserted into the sides of the base of the first phalanx of each finger. The fascia is strengthened at its point of division into slips, by strong fasciculi of transverse fibres, and the arched interval left between the slips gives passage to the tendons of the flexor muscles. The arches between the fingers transmit the digital vessels and nerve, and lumbricales muscles. FASCliE OF THE LOWER EXTREMITY. The superficial fascia contains between its two layers the superfi- cial vessels and nerves of the lower extremity. At the groin these two layers are separated from each other by the superficial lymphatic glands, and the deep layer is attached to Poupart's ligament, while the superficial layer is continuous with the superficial fascia of the abdomen. The deep fascia of the thigh is named, from its great extent, the fascia lata; it is thick and strong upon the outer side of the limb, and thinner upon its posterior side. That portion of fascia which in- vests the gluteus maximus is very thin, but that which covers in the gluteus medius is excessively thick, and gives origin by its inner sur- face, to the superficial fibres of that muscle. The fascia lata is at- tached superiorly to Poupart's ligament, the crestof the ilium, sacrum, coccyx, tuberosity of the ischium, ramus of the ischium, and pubes; in the thigh it is inserted into the linea aspera, and around the knee is connected with the prominent points of that joint. It possesses also two muscular attachments, by means of the tensor vaginae femoris, which is inserted between its two layers on the outer side, and the gluteus maximus, which is attached to it behind. FASCIA LATA. 293 Fig. 140.* In addition to the smaller openings in the fascia lata which trans- mit the small cutaneous vessels and nerves, there exists at the upper and inner extremity of the thigh, an oblique foramen, which gives passage to the superficial lymphatic vessels, and the large subcuta- neous vein of the lower extremity, the internal saphenous vein, and is thence named the saphenous opening. The existence of this opening has given rise to the division of the upper part of the fascia lata into two portions, an iliac portion and a pubic portion. The iliac portion is situated upon the iliac side of the opening. It is attached to the crest of the ilium, and along Poupart's ligament to the spine of the os pubis, whence it is reflected downwards and out- wards, in an arched direction, and forms a falciform border, which constitutes the outer boundary of the saphenous opening. The edge of this border immediately overlies, and is reflected upon the sheath of the femoral vessels, and the lower extremity of the curve is con- tinuous with the pubic portion. The pubic portion, occupying the pubic side of the saphenous opening, is attached to the spine of the os pubis and pectineal line; and, passing outwards behind the sheath of the femoral vessels, divides into two layers ; the anterior layer is continuous with that portion of the iliac fascia which forms the sheath of the iliacus and psoas muscles, and the posterior layer is lost upon the capsule of the hip-joint. The interval between the falci- form border of the iliac portion and the opposite surface of the pubic portion is closed by a fibrous layer, which is pierced by numerous openings for the passage of lymphatic vessels, and is thence named cribriform fascia. The cribriform fascia is connected with the sheath of the femoral vessels, and forms one of the coverings of femoral hernia. When the iliac portion of the fascia lata is removed from its attachment to Poupart's ligament and is turned aside, the sheath of the femoral vessels (the femoral or crural canal) is brought into view; and if Poupart's ligament * A section of the structures which pass beneath the femoral arch. 1. Poupart's liga- ment. 2, 2. The iliac portion of the fascia, lata, attached along the margin of the crest of the ilium, and along Poupart's ligament, as far as the spine of the os pubis (3). 4. The pubic portion of the fascia lata, continuous at 3 with the iliac portion, and passing out- wards behind the sheath of the femoral vessels to its outer border at 5, where it divides into two layers; one is continuous with the sheath of the psoas (6) and iliacus (7); the other (8) is lost upon the capsule of the hip-joint (9). 10. The crural nerve, enclosed in the sheath of the psoas and iliacus. 11. Gimbernat's ligament. 12. The femoral ring, within the femoral sheath. 13. The femoral vein. 14. The femoral artery; the two ves- sels and the ring are surrounded by the femoral sheath, and thin septa are sent between the anterior and posterior wall of the sheath, dividing the artery from the vein, and the vein from the femoral ring. 25* 294 FEMORAL HERNIA. be carefully divided, the sheath may be isolated, and its continuation with the transversalis and iliac fascia clearly demonstrated. In this view the sheath of the femoral vessels is an infundibuliform continuation of the abdominal fasciae, closely adherent to the vessels a little way down the thigh, but much larger than the vessels it contains at Poupart's ligament. If the sheath be opened, the artery and vein will be found lying side by side, and occupying the outer two-thirds of the sheath, leaving an infundibuliform interval between the vein and the inner wall of the sheath. The superior opening of this space is named the fe- moral ring; it is bounded in front by Poupart's ligament, behind by the os pubis, internally by Gimbernat's ligament, and externally by the femoral vein. The interval itself serves for the passage of the superficial lymphatic vessels from the saphenous opening to a lym- phatic gland, which generally occupies the femoral ring; and from thence they proceed into the current of the deep lymphatics. The femoral ring is closed merely by a thin layer of subserous areolar,. tissue,* which retains the lymphatic gland in its position and is named septum crurale; and by the peritoneum. It follows from this de- scription, that the femoral ring must be a weak point in the parietes of the abdomen, particularly in the female, where the femoral arch, or space included between Poupart's ligament and the border of the pelvis, is larger than in the male, while the structures which pass through it are smaller. It happens consequently, that, if violent or continued pressure be made upon the abdominal viscera, a portion of intestine may be forced through the femoral ring into the infundibuliform space in the sheath of the femoral vessels, carrying before it the peritoneum and the septum crurale,—this constitutes femoral hernia. If the causes which give rise to the formation of this hernia continue, the intestine, unable to extend further down the sheath, from the close connexion of the latter with the vessels, will in the next place be forced forwards through the saphenous opening in the fascia lata, car- rying before it two additional coverings, the sheath of the vessels, or fascia propria, and the cribriform fascia; and then curving upwards over Poupart's ligament, the hernia will become placed beneath the superficial fascia and integument. The direction which femoral hernia takes in its descent is at first downwards, then forwards, and then upwards; and in endeavouring to reduce it, the application of the taxis must have reference to this course, and be directed in precisely the reverse order. The cover- ings of femoral hernia are the Integument, Fascia propria, Superficial fascia, Septum crurale, Cribriform fascia, Peritoneal sac. The Fascia of the Leg is strong in the anterior tibial region, and gives origin by its inner surface to the upper part of the tibialis anti- cus, and extensor longus digitorum muscles. * This areolar tissue is sometimes very considerably thickened by a deposit of fat within its areolae, and forms a thick stratum over the hernial sac. FASCIAE OF THE LEG AND FOOT. 29 It is firmly attached to the tibia and fibula at each side, and becomes thickened inferiorly into a narrow band, the anterior annu- lar ligament, beneath which the tendons of the extensor muscles pass into the dorsum of the foot, in distinct sheaths lined by synovial bursa:. Upon the outer side it forms a distinct sheath which enve- lopes the peronei muscles, and ties them to the fibula. The anterior annular ligament is attached by one extremity to the outer side of the os calcis, and divides in front of the joint into two bands; one of which is inserted into the inner malleolus, while the other spreads over the inner side of the foot, and becomes continuous with the internal portion of the plantar fascia. The fascia of the dorsum of the foot is a thin layer given off from the lower border of the anterior annular ligament; it is continuous at each side with the lateral portions of the plantar fascia The fascia of the posterior part of the leg is much thinner than the anterior, and consists of two layers, superficial and deep. The superficial layer is continuous with the posterior fascia of the thigh, and is increased in thickness upon the outer side of the leg by an expansion derived from the tendon of the biceps; it terminates infe- riorly in the external and internal annular ligaments. The deep layer is stretched across between the tibia and fibula, and forms the intermuscular fascia between the superficial and deep layer of mus- cles. It covers in superiorly the popliteus muscle, receiving a tendi- nous expansion from the semi-membranosus muscle, and is attached to the oblique line of the tibia. The internal annular ligament is a strong fibrous band attached above to the internal malleolus, and below to the side of the inner tuberosity of the os calcis. It is continuous above with the posterior fascia of the leg, and below with the plantar fascia, forming sheaths for the passage of the flexor tendons and vessels, into the sole of the foot. The external annular ligament, shorter than the internal, extends from the extremity of the outer malleolus to the side of the os calcis, and serves to bind down the tendons of the peronei muscles in their passage beneath the external ankle. The Plantar Fascia consists of three portions, a middle and two lateral. The middle portion is thick and dense, and is composed of strong aponeurotic fibres, closely interwoven with each other. It is attached posteriorly to the inner tuberosity of the os calcis, and terminates under the heads of the metatarsal bones in five fasciculi. Each of these fasciculi divides into two slips, which are inserted one on each side into the bases of the first phalanges of the toes, leaving an inter- val between them for the passage of the flexor tendons. The point of division of this fascia into fasciculi and slips, is strengthened by transverse bands, which preserve the solidity of the fascia at its broadest part. The intervals between the toes give passage to the digital arteries and nerves and the lumbricales muscles. The lateral portions are thin, and cover the sides of the sole of the foot; they are continuous behind with the internal and external 296 ARTERIES. annular ligaments; on the inner side with the middle portion, and externally with the dorsal fascia. Besides constituting a strong layer of investment and defence to the soft parts situated in the sole of the foot, these three portions of fascia send processes inwards, which form sheaths for the different muscles. A strong septum is given off from each side of the middle portion of the plantar fascia, which is attached to the tarsal bones, and divides the muscles into three groups, a middle and two lateral; and transverse septa are stretched between these, to separate the layers. The superficial layer of muscles derive a part of their origin from the plantar fascia. CHAPTER VI. ON THE ARTERIES. The arteries are the cylindrical tubes which convey the blood from the ventricles of the heart to every part of the body. They are dense in structure, and preserve, for the most part, the cylindrical form, when emptied of their blood, which is their condition after death: hence they were considered by the ancients as the vessels for the tpansmission of the vital spirits,* and were therefore named arteries (ufy rygeTv, to contain air). The artery proceeding from the left ventricle of the heart contains the pure or arterial blood, which is distributed throughout the entire system, and constitutes, with its returning veins, the greater or sys- temic circulation. That which emanates from the right ventricle, conveys the impure blood to the lungs; and, with its corresponding veins, establishes the lesser or pulmonary circulation. The whole of the arteries of the systemic circulation proceed from a single trunk, named the aorta, from which they are given off as branches, and divide and subdivide to their ultimate ramifications, constituting the great arterial tree which pervades, by its minute sub- divisions, every part of the animal frame. The mode in which the division into branches takes place, is deserving of remark. From the aorta, the branches, for the most part, pass off at right angles, as if for the purpose of checking the impetus with which the blood would otherwise rush along their cylinders, from the main trunk; but in the limbs, a very different arrangement is adopted; the branches are given off from the principal artery at an acute angle, so that no impediment may be offered to the free circulation of the vital fluid. The division of arteries is usually dichotomous, as of * To Galen is due the honour of having discovered that arteries contained blood, and not air. GENERAL ANATOMY OF ARTERIES. 297 the aorta into the two common iliacs, common carotid into the ex- ternal and internal, &c.; but in some few instances a short trunk divides suddenly into several branches, which proceed in different directions: this mode of division is termed an axis, as the thyroid and coeliac axis. In the division of an artery into two branches, it is observed that the combined areac of the two branches are somewhat greater than that of the single trunk; and if the combined areae of all the branches at the periphery of the body were compared with that of the aorta, it would be seen that the blood, in passing from the aorta into the numerous distributing branches, was flowing through a conical tube, of which the apex might be represented by the aorta, and the base by the surface of the body. The advantage of this important prin- ciple, in facilitating the circulation, is sufficiently obvious ; for the increased channel, which is thus provided for the current of the blood, serves to compensate for the retarding influence of friction, resulting from the distance of the heart and the division of the vessels. Communications between the arteries are very free and numerous, and increase in frequency with the diminution in the size of the branches; so that through the medium of the minute ramifications, the entire body may be considered as one uninterrupted circle of in- osculations, or anastomoses (dvd between, tfrofjoa mouth). This increase in the frequency of anastomosis in the smaller branches is a provision for counteracting the greater liability to impediment existing in them than in the larger branches. Where freedom of circulation is of vital importance, this communication of the arteries is very remarka- ble, as in the circle of Willis in the cranium, or in the distribution of the arteries of the heart. It is also strikingly seen in situations where obstruction is most likely to occur, as in the distribution to the ali- mentary canal, around joints, or in the hand and foot. Upon this free communication existing every where between arterial branches is founded the principle of cure in the ligature of large arteries; the ramifications of the branches given off from the artery above the ligature inosculate with those which proceed from the trunk of the vessel below the ligature; these anastomosing branches enlarge and constitute a collateral circulation, in which, as is shown in the beauti- ful preparations made by Sir Astley Cooper, several large branches perform the office of the single obliterated trunk.* The arteries do not terminate directly in veins; but in an interme- diate system of vessels, which, from their minute size (about -3-^0 of an inch in diameter), are termed capillaries (capillus, a hair). The capillaries constitute a microscopic network, which is distributed through every part of the body, so as to render it impossible to introduce the smallest needle point beneath the skin without wound- ing several of these fine vessels. It is through the medium of the capillaries, that all the phenomena of nutrition and secretion are * I have a preparation, showing the collateral circulation in a dog, in which I tied the abdominal aorta; the animal died from over-feeding nearly two years after the operation. 298 GENERAL ANATOMY OF ARTERIES. performed. They are remarkable for their uniformity of diameter, and for the constant divisions and communications which take place between them, without any alteration of size. They inosculate on one hand with the terminal ramusculi of the arteries; and on the other with the minute radicles of the veins. Arteries are composed of three coats, external, middle, and internal. The external or cellulo-fibrous coat is firm and strong, and serves at the same time as the chief means of resistance of the vessel, and of connexion to surrounding parts. It consists of condensed fibro-cellu- lar tissue, strengthened by an interlacement of glistening fibres which are partly longitudinal and partly encircle the cylinder of the tube in an oblique direction. Upon the surface the cellular tissue is loose, to permit of the movements of the artery in distention and contrac- tion. The middle coat is that upon which the thickness of the artery depends; it is yellowish in colour, and so brittle as to be cut through by the thread in the ligature of a vessel. The internal coat is a thin serous membrane which lines the inte- rior of the artery, and gives it the smooth polish which that surface presents. It is continuous with the lining membrane of the heart, and through the medium of the capillaries with that of the venous system. In intimate structure an artery is more complicated than the above description would imply. The internal coat, for example, is com- posed of two layers, and the middle of three, so that with the exter- nal coat there are six layers entering into the composition of an artery. The innermost coat is a tessellated epithelium analogous to that of other serous membranes. The second coat from within is a thin, rigid membrane, pierced with a number of round or oval-shaped holes, and supporting a thin layer of flat, longitudinal fibres. From these characters it has been denominated the fenestrated or striated coat. The third layer, which is the innermost part of the middle coat, is composed of flat, longitudinal fibres, analogous to those of organic muscle. The fourth layer, the thickest of the whole, is com- posed of muscular fibres of organic life, arranged in a circular direc- tion around the vessel. The fifth, or outermost part of the middle coat is a thin layer of elastic tissue; this is present only in the large arteries. The sixth is the external or cellulo-fibrous coat. The arteries in their distribution through the body are included in a loose cellular investment which separates them from the surround- ing tissues, and is called a sheath. Around the principal vessels the sheath is an important structure; it is composed of cellulo-fibrous tissue, intermingled with tendinous fibres, and is continuous with the fasciae of the region in which the arteries are situated, as with the thoracic and cervical fasciae in the neck, transversalis and iliac fasciae, and fascia lata in the thigh, &c. The sheath of the arteries contains also their accompanying veins, and sometimes a nerve. The coats of arteries are supplied with blood like other organs of the body, and the vessels which are distributed to them are named AORTA. 299 vasa vasorum. They are also provided with nerves; but the mode of distribution of the nerves is at present unknown. In the consideration of the arteries we shall first describe the aorta, and the branches of that trunk, with their subdivisions, which toge- ther constitute the efferent portion of the systemic circulation; and then the pulmonary artery as the efferent trunk of the pulmonary circulation. Fig. 141. AORTA. The aorta arises from the left ventricle, at the middle of the root of the heart, and op- posite the articulation of the fourth costal cartilage with the sternum. At its commence- ment it presents three dilata- tions, called the sinus aortici, which correspond with the three semilunar valves. It as- cends at first to the right, then curves backwards and to the left, and descends on the left side of the vertebral column to the fourth lumbar vertebra. Hence it is divided into—as- cending—arch—and descend- ing aorta. Relations.—The ascending aorta has in relation with it, in front, the trunk of the pul- monary artery, thoracic fas- cia, and pericardium; behind, the right pulmonary veins and artery; to the right side, the right auricle and superior cava; and to the left, the left auricle and the trunk of the pulmonary artery. * The large vessels which proceed from the root of the heart, with their relations; the heart has been removed. 1. The ascending aorta. 2. The arch. 3. The thoracic por- tion of the descending aorta. 4. The arteria innominata dividing into, 5, the right carotid, which again divides at 6, into the external and internal carotid; and 7, the right subclavian artery. 8. The axillary artery; its extent is designated by a dotted line. 9. The brachial artery. 10. The right pneumogastric nerve running by the side of the common carotid, in front of the right subclavian artery, and behind the root of the right lung. 11. The left common carotid, having to its outer side the left pneumogastric nerve, which crosses the arch of the aorta, and as it reaches its lower border is seen to give off the left recurrent nerve. 12. The left subclavian artery becoming axillary, and brachial in its course, like the artery of the opposite side. 13. The trunk of the pulmonary artery connected to the concavity of the arch of the aorta by a fibrous cord, the remains of the ductus arteriosus. 14. The left pulmonary artery. 15. The right pulmonary artery. 16. The trachea. 17. The right bronchus. 18. The left bronchus. 19, 19. The pulmo- nary veins. 17, 15, and 19, on the right side, and 14, 18, and 19, on the left, constitute the roots of the corresponding lungs, and the relative position of these vessels is preserved. 20. Bronchial arteries. 21,21. Intercostal arteries; the branches from the front of the aorta above and below the number 3 are pericardiac and oesophageal branches. 300 THORACIC AORTA. Plan of the Relations of the Ascending Aorta. In Front, Pericardium, Thoracic fascia, Pulmonary artery. Right Side, Superior cava, Right auricle. Ascending Aorta. Left Side. Pulmonary artery, Left auricle. Behind. Right pulmonary artery. Right pulmonary veins. Arch.—The upper border of the arch of the aorta is parallel with the upper border of the second sterno-costal articulation of the right side in front, and the second dorsal vertebra behind, and terminates opposite the lower border of the third. The anterior surface of the arch is crossed by the left pneumogas- tric nerve, and by the cardiac branches of that nerve and of the sympathetic. The posterior surface of the arch is in relation with the bifurcation of the trachea and great cardiac plexus, the cardiac nerves, left recurrent nerve, and the thoracic duct. The superior- border gives off the three great arteries, viz. the innominata, left carotid, and left subclavian. The inferior border, or concavity of the arch, is in relation with the remains of the ductus arteriosus, the cardiac ganglion and left recurrent nerve, and has passing beneath it the right pulmonary artery and left bronchus. Plan of the Relations of the Arch of the Aorta. Above. Arteria innominata, Left carotid, Left subclavian. In Front. Left pneumogastric nerve, Cardiac nerves. Arch of the Aorta. Behind. Bifurcation of the trachea, Great cardiac plexus, Cardiac nerves, Left recurrent nerve, Thoracic duct. Below. Cardiac ganglion, Remains of ductus arteriosus, Left recurrent nerve, Right pulmonary artery, Left bronchus. The descending aorta is subdivided in correspondence with the two great cavities of the trunk, into the thoracic and abdominal aorta. The Thoracic Aorta is situated to the left side of the vertebral column, but approaches the middle line as it descends, and at the aortic opening of the diaphragm is altogether in front of the column. After entering the abdomen it again falls back to the left side. » ABDOMINAL AORTA. 301 Relations.—It is in relation, behind with the vertebral column and lesser vena azygos; in front with the oesophagus and right pneu- mogastric nerve; to the left side with the pleura; and to the right with the thoracic duct. Plan of the Relations of the Thoracic Aorta. In Front. (Esophagus, Right pneumogastric nerve. Right Side. Thoracic duct. Thoracic Aorta. Left Side. Pleura. Behind. Lesser vena azygos, Vertebral column. The Abdominal Aorta enters the abdomen through the aortic opening of the diaphragm, and descends, lying rather to the left side of the vertebral column, to the fourth lumbar vertebra, where it divides into the two common iliac arteries. Relations.—It is crossed, in front by the left renal vein, pancreas, transverse duodenum, and mesentery, and is embraceaVby the aortic plexus; behind it is in relation with the thoracic duct, receptaculum chyli, and left lumbar veins. . On its left side is the left semilunar ganglion and sympathetic nerve; and on the right the vena cava, right semilunar ganglion, and the commencement of the vena azygos. Plan of the Relations of the Abdominal Aorta. In Front. Left renal vein, Pancreas, Transverse duodenum, Mesentery, Aortic plexus. Right Side. Vena cava, Right semilunar ganglion. Vena azygos. Abdominal Aorta. Left Side. Left semilunar ganglion. Sympathetic nerve. Behind. Thoracic duct, Receptaculum chyli, Left lumbar veins. Branches.—The branches of the aorta, arranged in a tabular form, are,— Ascending aorta . Coronary. , „. . 4 4., ° . . . ( Right carotid, ( Arteria innominata, ] -p,.^. cl^n]^r\ Arch of the aorta . \ Left carotid, ( Left subclavian. 26 Right subclavian. 302 ARTERIA INNOMINATA. Thoracic aorta Abdominal aorta < {Pericardiac, Bronchial, (Esophageal, Intercostal. r Phrenic, ( Gastric, Coeliac axis, 1 Hepatic, ( Splenic. Supra-renal, Renal, Superior mesenteric, Spermatic, Inferior mesenteric, Lumbar, Sacra media, Common iliacs. The Coronary Arteries arise from the aortic sinuses at the com- mencement of the ascending aorta, immediately above the free mar- gin of the semilunar valves. The left, or anterior coronary, passes forwards, between the pulmonary artery and left appendix auriculae, and divides into two branches; one of which winds around the base of the left ventricle in the auriculo-ventricular groove, and inoscu- lates with the right coronary, forming an arterial circle around the base of the heart; while the other passes along the line of union of the two ventricles, upon the anterior aspect of the heart, to its apex, where it anastomoses with the descending branch of the right coro- nary. It supplies the left auricle and the adjoining sides of both ventricles. The right, or posterior coronary, passes forwards, between the root of the pulmonary artery and the right auricle, and winds along the auriculo-ventricular groove, to the posterior median furrow, where it descends upon the posterior aspect of the heart to its apex, and inosculates with the left coronary. It is distributed to the right auricle, and to the posterior surface of both ventricles, and sends a large branch along the sharp margin of the right ventricle to the apex of the heart. arteria innominata. The Arteria innominata (fig. 141, No. 4) is the first artery given off by the arch of the aorta. It is an inch and a half in length, and ascends obliquely towards the right sterno-clavicular articulation, where it divides into the right carotid and right subclavian artery. Relations.—It is in relation, in front with the left vena innominata, the thymus gland, and the origins of the sterno-thyroid arid sterno- hyoid muscles, which separate it from the sternum. Behind with the trachea, pneumogastric nerve and cardiac nerves; externally with the right vena innominata and pleura; and internally with the origin of the left carotid. COMMON CAROTID ARTERIES. 303 Plan of the Relations of the Arteria Innominata. In Front. Left vena innominata, Thymus gland, Sterno-thyroid, Sterno-hyoid. Right Side. Right vena inno- minata, Pleura. Arteria innominata. Left Side. Left carotid. Behind. Trachea, Pneumogastric nerve, Cardiac nerves. The arteria innominata occasionally gives off a small branch, which ascends along the middle of the trachea to the thyroid gland. This branch was described by Neubauer, and Dr. Harrison names it the middle thyroid artery. A knowledge of its existence is important in performing the operation of tracheotomy. COMMON CAROTID ARTERIES. . The common carotid arteries (xo^a, the head), arise, the right from the bifurcation of the arteria innominata opposite the right sterno- clavicular articulation, the left from the arch of the aorta. It follows, therefore, that the right carotid is shorter than the left; it is also more anterior; and, in consequence of proceeding from a branch instead of from the main trunk, it is larger than its fellow. The Right common carotid artery (fig. 141, No. 5) ascends the neck perpendicularly, from the right sterno-clavicular articulation to a level with the upper border of the thyroid cartilage, where it divides into the external and internal carotid. The Left common carotid (fig. 141, No. 11) passes somewhat ob- liquely outwards from the arch of the aorta to the side of the neck, and thence upwards to a level with the upper border of the thyroid cartilage, where it divides like the right common carotid into the ex- ternal and internal carotid. Relations.—The right common carotid rests, first, upon the longus colli muscle, then upon the rectus anticus major, the sympathetic nerve being interposed. The inferior thyroid artery and recurrent laryngeal nerve pass behind it at its lower part. To its inner side is the trachea, recurrent laryngeal nerve, and larynx; to its outer side, and enclosed in the same sheath, the jugular vein and pneumogastric nerve; and in front the sterno-thyroid, sterno-hyoid, sterno-mastoid, omo-hyoid, and platysma muscles, and the descendens noni nerve. The left common carotid, in addition to the relations just enumerated, which are common to both, is crossed near its commencement by the left vena innominata; it lies upon the trachea ; then gets to its side, and is in relation with the oesophagus and thoracic duct: to facilitate the study of these relations, I have arranged them in a tabular form. 304 EXTERNAL CAROTID ARTERY. Plan of the Relations of the Common Carotid Artery. In Front. Platysma, Descendens noni nerve, Omo-hyoid, Sterno-mastoid, Sterno-hyoid, Sterno-thyroid. Externally. Internal jugular vein, Pneumogastric nerve. Common Carotid Artery. Internally. Trachea, Larynx, Recurrent laryngeal nerve. Behind. Longus colli, Rectus anticus major, Sympathetic, Inferior thyroid artery, Recurrent laryngeal nerve. Additional Relations of the Left Common Carotid. In Front. Behind. Internally. Externally. Left vena innominata, Trachea, Thoracic duct, Arteria innominata, GEsophagus. Pleura, EXTERNAL CAROTID ARTERY. The External carotid artery ascends nearly perpendicularly from opposite the upper border of the thyroid cartilage, to the space be- tween the neck of the lower jaw and the meatus auditorius, where it divides into the temporal and internal maxillary artery. Relations.—In front it is crossed by the posterior belly of the digas- tricus, stylo-hyoideus, and platysma myoides muscles; by the hypo- glossal nerve near its origin; higher up it is situated in the substance of the parotid gland, and is crossed by the facial nerve. Behind, it is separated from the internal carotid by the stylo-pharyngeus and stylo-glossus muscles, glosso-pharyngeal nerve, and part of the parotid gland. Plan of the Relations of the External Carotid Artery. In Front. Platysma, Digastricus, Stylo-hyoid, Hypoglossal nerve, Facial nerve, Parotid gland. External Carotid Artery. Behind. Stylo-ph aryngeus, Stylo-glossus, Glosso-pharyngeal nerve, Parotid gland. BRANCHES OF EXTERNAL CAROTID. 305 Branches. — The branches of the external carotid are eleven in number, and may be arranged into four groups, viz. Anterior. Posterior. 1. 2. 3. Superior thyroid, Lingual, Facial, 4. 5. 6. Mastoid, Occipital, Posterior auricular. 7. 8. 9. Superior. Parotidean, Ascending pharyngeal, Transverse facial. 10. 11. Terminal. Temporal, Internal maxillary. Fig. 142.* The anterior branches arise from the commencement of the external carotid, within a short distance of each other. The lingual and facial bifur- cate, not unfrequently, from a common trunk. 1. The Superior Thyroid Artery (the first of the bran- ches of the external carotid) curves downwards to the thyroid gland, to which it is distributed, anastomosing with its fellow of the opposite side and with the inferior thyroid arteries. In its course it passes beneath the omo-hyoid, sterno-thyroid, and sterno-hyoid muscles. Branches.—Hyoid, Superior laryngeal, Inferior laryngeal, Muscular. The Hyoid branch passes forwards beneath the thyro-hyoideus, and is distributed to the depressor muscles of the os hyoides near their insertion. The Superior laryngeal pierces the thyro-hyoidean membrane in company wdth the superior laryngeal nerve, and supplies the mucous membrane, and muscles of the larynx, sending a branch upwards to the epiglottis. * The carotid arteries with the branches of the external carotid. 1. The common carotid. 2. The external carotid. 3. The internal carotid. 4. The carotid foramen in the petrous portion of the temporal bone. 5. The superior thyroid artery. 6. The lingual artery. 7. The facial artery. 8. The mastoid artery. 9. The occipital. 10. The poste- rior auricular. 11. The transverse facial artery. 12. The internal maxillary. 13. The temporal. 14. The ascending pharyngeal artery. 26* 306 BRANCHES OF EXTERNAL CAROTID. The Inferior laryngeal is a small branch which crosses the crico- thyroidean membrane along the lower border of the thyroid carti- lage. It sends branches through the membrane to supply the mucous lining of the larynx, and inosculates with its fellow of the opposite side. The Muscular branches are distributed to the depressor muscles of the os hyoides and larynx. One of these branches crosses the sheath of the common carotid to the under surface of the sterno-mastoid muscle. 2. The Lingual Artery ascends obliquely from its origin, it then passes forwards parallel with the os hyoides; thirdly, it ascends to the under surface of the tongue; and fourthly, runs forward in a ser- pentine direction to its tip, under the name of the ranine artery, where it terminates by inosculating with its fellow of the opposite side. Relations.—The first part of its course rests upon the middle con- strictor muscle of the pharynx, being covered in by the tendon of the digastricus and the stylo-hyoid muscle ; the second is situated between the middle constrictor and hyo-glossus muscle, the latter separating it from the hypoglossal nerve; in the third part of its course it lies be- tween the hyo-glossus and genio-hyo-glossus; and in the fourth (ra- nine) rests upon the lingualis to the tip of the tongue. Branches.—Hyoid, Dorsalis linguae, Sublingual. The Hyoid branch runs along the upper border of the os hyoides, and is distributed to the elevator muscles of the os hyoides near their origin, inosculating with its fellow of the opposite side. The Dorsalis lingua ascends along the posterior border of the hyo- glossus muscle to the dorsum of the tongue, and is distributed to the tongue, the fauces, and epiglottis, anastomosing with its fellow of the opposite side. The Sublingual branch, sometimes considered as a branch of bi- furcation of the lingual, runs along the anterior border of the hyo- glossus, and is distributed to the sublingual gland and to the muscles of the tongue. It is situated between the mylo-hyoideus and genio- hyo-glossus, generally accompanies Wharton's duct for a part of its course, and sends a branch to the fraenum linguae. It is the latter branch which affords the considerable haemorrhage which sometimes follows the operation of snipping the fraenum in children. 3. Facial Artery.—The Facial artery arises a little above the great cornu of the os hyoides, and descends obliquely to the sub- maxillary gland, in which it lies embedded. It then curves around the body of the lower jaw, close to the anterior inferior angle of the mas- seter muscle, ascends to the angle of the mouth, and thence to the angle of the eye, where it is named the angular artery. The facial artery is tortuous in its course over the buccinator muscle, to accom- modate itself to the movements of the jaws. BRANCHES OF EXTERNAL CAROTID. 307 Relations.—Below the jaw it passes beneath the digastricus and stylo-hyoid muscles; on the body of the lower jaw it is covered by the platysma myoides, and at the angle of the mouth by the de- pressor anguli oris and zygomatic muscles. It rests upon the sub- maxillary gland, the lower jaw, buccinator, orbicularis oris, levator anguli oris, levator labii superioris proprius, and levator labii supe- rioris alaeque nasi. Its branches are divided into those which are given off below the jaw and these on the face: they may be thus arranged:— Below the Jaw.—Inferior palatine, Submaxillary, Submental, Pterygoid. On the Face.—Masseteric, Inferior labial, Inferior coronary, Superior coronary, Lateralis nasi. The Inferior palatine branch ascends between the stylo-glossus and stylo-pharyngeus muscles, to be distributed to the tonsil and soft palate, and anastomoses with the posterior palatine branch of the in- ternal maxillary artery. The Submaxillary are four or five branches which supply the sub- maxillary gland. The Submental branch runs forwards upon the mylo-hyoid muscle, under cover of the body of the lower jaw, and anastomoses with branches of the sublingual and inferior dental artery. The Pterygoid branch is distributed to the internal pterygoid muscle. The Masseteric branches are distributed to the masseter and bucci- nator muscles. The Inferior labial branch is distributed to the muscles and integu- ment of the lower lip. The Inferior coronary runs along the edge of the lower lip, between the mucous membrane and the orbicularis oris; it inosculates with the corresponding artery of the opposite side. The Superior coronary follows the same course along the upper lip, inosculating with the opposite superior coronary artery, and at the middle of the lip it sends a branch upwards to supply the septum of the nose and the mucous membrane. The Lateralis nasi is distributed to the ala and septum of the nose. The Inosculations of the facial artery are very numerous: thus, it anastomoses with the sublingual branch of the lingual, with the ascending pharyngeal and posterior palatine arteries, with the inferior dental as it escapes from the mental foramen, infra-orbital at the in- fra-orbital foramen, transverse facial on the side of the face, and at the angle of the eye with the nasal and frontal branches of the oph- thalmic artery. The facial artery is subject to considerable variety in its extent; it 308 BRANCHES OF EXTERNAL CAROTID. not unfrequently terminates at the angle of the nose or mouth, and is rarely symmetrical on both sides of the face. 4. The Mastoid Artery turns downwards from its origin, to be distributed to the sterno-mastoid muscle, and to the lymphatic glands of the neck; sometimes it is replaced by two small branches. 5. The Occipital Artery, smaller than the anterior branches, passes backwards beneath the posterior belly of the digastricus, the trachelo-mastoid and sterno-mastoid muscles, to the occipital groove in the mastoid portion of the temporal bone. It then ascends between the splenius and complexus muscles, and divides into two branches which are distributed upon the occiput, anastomosing with the oppo- site occipital, the posterior auricular, and temporal artery. The hypo- glossal nerve curves around this artery near its origin from the ex- ternal carotid. Branches.—It gives off only two branches deserving of name, the inferior meningeal and princeps cervicis. The Inferior meningeal ascends by the side of the internal jugular vein, and passes through the foramen lacerum posterius, to be distri- buted to the dura mater. The Arteria princeps cervicis is a large and irregular branch. It descends the neck between the complexus and semi-spinalis colli, and inosculates with the profunda cervicis of the subclavian. This branch is the means of establishing a very important collateral circulation between the branches of the carotid and subclavian, after ligature of the common carotid artery. 6. The Posterior Auricular Artery arises from the external ca- rotid, above the level of the digastric and stylo-hyoid muscles, and ascends beneath the lower border of the parotid gland, and behind the concha, to be distributed by two branches to the external ear and side of the head, anastomosing with the occipital and temporal arte- ries ; some of its branches pass through fissures in the fibro-cartilage, to be distributed to the anterior surface of the pinna. The anterior auricular arteries are branches of the temporal. Branches.—The posterior auricular gives off but one named branch, the stylo-mastoid, which enters the stylo-mastoid foramen to be distri- buted to the aquaeductus Fallopii and tympanum. 7. The Parotidean Arteries are four or five large branches which are given off from the external carotid whilst that vessel is situated in the parotid gland. They are distributed to the structure of the gland, their terminal branches reaching the integumant and the side of the face. 8. The Ascending Pharyngeal Artery, the smallest of the branches of the external carotid arises from that trunk near its bifurcation, and ascends between the internal carotid and the side of the pharynx to the base of the skull, where it divides into two branches; meningeal, which enters the foramen lacerum posterius, to be distributed to the BRANCHES OF EXTERNAL CAROTID. 309 dura mater; and pharyngeal. It supplies the pharynx, tonsils, and Eustachian tube. 9. The Transversalis Faciei arises from the external carotid whilst that trunk is lodged within the parotid gland; it crosses the masseter muscle, lying parallel with and a little above Stenon's duct; and is distributed to the temporo-maxillary articulation, and to the muscles and integument on the side of the face, inosculating with the infra-orbital and facial artery. This artery is not unfrequently a branch of the temporal. 10. The Temporal Artery is one of the two terminal branches of the external carotid. It ascends over the root of the zygoma; and, at about an inch and a half above the zygomatic arch, divides into an anterior and a posterior temporal branch. The anterior temporal is distributed over the front of the temple and arch of the skull, and anastomoses with the opposite anterior temporal, and with the supra- orbital and frontal artery. The posterior temporal curves upwards and backwards, and inosculates with its fellow of the opposite side, with the posterior auricular and occipital artery. The trunk of the temporal artery is covered in by the parotid gland and by the attrahens aurem muscle, and rests upon the temporal fascia. Branches.—Orbitar, Anterior auricular, Middle temporal. The Orbitar artery is a small branch, not always present, which passes forwards immediately above the zygoma, between the two layers of the temporal fascia, and inosculates beneath the orbicularis palpebrarum with the palpebral arteries. The Anterior auricular arteries are distributed to the anterior por- tion of the pinna. The Middle temporal branch passes through an opening in the tem- poral fascia, immediately above the zygoma, and supplies the tem- poral muscle, inosculating with the deep temporal arteries. 11. The Internal Maxillary Artery, the other terminal branch of the external carotid, has next to be examined. Dissection.—The Internal maxillary artery passes inwards, behind the neck of the lower jaw, to the deep structures in the face; we re- quire, therefore, to remove several parts, for the purpose of seeing it completely. To obtain a good view of the vessel, the zygoma should be sawn across in front of the external ear, and the malar bone near the orbit. Turn down the zygomatic arch with the masseter muscle. In doing this, a small artery and nerve will be seen crossing the sig- moid notch of the lower jaw, and entering the masseter muscle (the masseteric). Cut away the. tendon of the temporal muscle from its insertion into the coronoid process, and turn it upwards towards its origin; some vessels will be seen entering its under surface: these are the deep temporal. Then saw the ramus of the jaw across its 310 BRANCHES OF EXTERNAL CAROTID. Fig. 143.' middle, and dislocate it from its articulation with the temporal bone. Be careful, in doing this, to carry the blade of the knife close to the bone, lest any branches of nerves should be injured. Next raise this portion of bone, and with it the external pterygoid muscle. The artery, together with the deep branches of the inferior maxillary nerve, will be seen lying upon the pterygoid muscles. These are to be carefully freed from fat and areolar tissue, and then examined. This artery (fig 142, No. 12) com- mences in the substance of the paro- tid gland, opposite the meatus audi- torius externus; it passes in the first instance horizontally forwards, behind the neck of the lower jaw; next, curves around the lower border of the external pterygoid muscle near its ori- gin, and ascends obliquely forwards upon the outer side of that muscle; it then passes between the two heads of the external pterygoid, and enters the pterygo-maxillary fossa. Occasion- ally it passes between the two ptery- goid muscles, without appearing on the outer surface of the external pterygoid. In consideration of its course, this artery may be divided into three portions: maxillary, pterygoid, and spheno-maxillary. Relations. — The maxillary portion is situated between the ramus of the jaw and the internal lateral ligament, lying parallel with the auricular nerve; the pterygoid portion, between the external ptery- goid muscle, and the masseter and temporal muscle. The pterygo- maxillary portion lies between the two heads of the external ptery- goid muscle, and, in the spheno-maxillary fossa, is in relation with Meckel's ganglion. Branches. Maxillary Portion. Tympanic, Inferior dental, Arteria meningea media, Arteria meningea parva. Pterygoid Portion. Deep temporal branches, External pterygoid, Internal pterygoid, Masseteric, Buccal. * 1. The external carotid artery. 2. The trunk of the transverse facial artery. 3,4. The two terminal branches of the external carotid. 3. The temporal artery; and 4. The in- ternal maxillary, the first or maxillary portion of its course: the limit of this portion is marked by an arrow. 5. The second, or pterygoid portion, of the artery; the limits are bounded by the arrows. 6. The third or pterygo-maxillary portion. The branches of the maxillary portion are, 7. A tympanic branch. 8. The arteria meningea magna. 9. The arteria meningea parva. 10. The inferior dental artery. The branches of the second por- tion are wholly muscular, the ascending ones being distributed to the temporal, and the descending to the four other muscles of the inter-maxillary region, viz. the two pterygoids, the masseter and buccinator. The branches of the pterygo-maxillary portion of the artery are, 11. The superior dental artery. 12. The infra-orbital artery. 13. The posterior pala- tine. 14. The spheno-palatine or nasal. 15. The pterygo-palatine. 16. The Vidian. * The remarkable bend which the third portion of the artery makes as it turns inwards to enter the pterygo-maxillary fossa. BRANCHES OF EXTERNAL CAROTID. 311 Pterygo-maxillary Portion. Superior dental, Spheno-palatine, Infra-orbital, Posterior palatine, Pterygo-palatine, Vidian. The Tympanic branch is small, and not likely to be seen in an ordinary dissection; it is distributed to the temporo-maxillary articu- lation and meatus, and passes into the tympanum through the fissura Glaseri. The Inferior dental descends to the dental foramen, and enters the canal of the lower jaw, in company with the dental nerve. Opposite the bicuspid teeth, it divides into two branches, one of which is con- tinued outwards within the bone, as far as the symphysis, to supply the incisor teeth, while the other escapes with the nerve at the mental foramen, and anastomoses with the inferior labial and submental branch of the facial. It supplies the teeth of the lower jaw, sending small branches along the canals in their roots. The Arteria meningea media ascends behind the temporo-maxillary articulation to the foramen spinosum in the spinous process of the sphenoid bone, and, entering the cranium, divides into an anterior and a posterior branch. The anterior branch crosses the great ala of the sphenoid, to the groove or canal in the anterior inferior angle of the parietal bone, and divides into branches, which ramify upon the external surface of the dura mater, and anastomose with correspond- ing branches from the opposite side. The posterior branch crosses the squamous portion of the temporal bone, to the posterior part of the dura mater and cranium. The branches of the arteria meningea media are distributed chiefly to the bones of the skull; in the middle fossa it sends a small branch through the hiatus Fallopii to the facial nerve. The Meningea parva is a small branch which ascends to the fora- men ovale, and passes into the skull, to be distributed to the Casse- rian ganglion and dura mater. It gives off a twig to the nasal fossae and soft palate. The Muscular branches are distributed, as their names imply, to the five muscles of the maxillary region; the temporal branches (temporales profunda?) are two in number. The Superior dental artery is given off from the internal maxillary, just as that vessel is about to make its turn into the spheno-maxillary fossa. It descends upon the tuberosity of the superior maxillary bone, and sends its branches through several small foramina, to sup- ply the posterior teeth of the upper jaw, and the antrum. The ter- minal branches are continued forwards upon the alveolar process, to be distributed to the gums and to the sockets of the teeth. The Infra-orbital would appear, from its size, to be the proper con- tinuation of the artery. It runs along the infra-orbital canal with the superior maxillary nerve, sending branches into the orbit and down- wards through canals in the bone, to supply the mucous lining of the antrum and the teeth of the upper jaw, and escapes from the infra- 312 INTERNAL CAROTID ARTERY. orbital foramen. The branch which supplies the incisor teeth is the anterior dental artery; on the face the infra-orbital inosculates with the facial and transverse facial arteries. The Pterygo-palatine is a small branch which passes through the pterygo-palatine canal, and supplies the upper part of the pharynx and Eustachian tube. The Spheno-palatine, or nasal, enters the superior meatus of the nose through the spheno-palatine foramen in company with the nasal branches of Meckel's ganglion, and divides into two branches ; one of which is distributed in the mucous membrane of the septum, while the other supplies the mucous membrane of the lateral wall of the nares, together with the sphenoid and ethmoid cells. The Posterior palatine artery descends along the posterior palatine canal, in company with the posterior palatine branches of Meckel's ganglion, to the posterior palatine foramen; it then curves forwards lying in a groove upon the bone, and is distributed to the palate. While in the posterior palatine canal it sends a branch backwards, through the small posterior palatine foramen to supply the soft palate, and anteriorly it distributes a branch to the anterior palatine canal, which reaches the nares and inosculates with the branches of the spheno-palatine artery. The Vidian branch passes backwards along the pterygoid canal, and is distributed to the sheath of the Vidian nerve, and to the Eus- tachian tube. • INTERNAL CAROTID AR.TERY. The internal carotid artery curves slightly outwards from the bifur- cation of the common carotid, and then ascends nearly perpendicu- larly through the maxillo-pharyngeal space* to the carotid foramen in the petrous bone. It next passes inwards, along the carotid canal, forwards by the side of the sella turcica, and upwards by the anterior clinoid process, where it pierces the dura mater and divides into three terminal branches. The course of this artery is remarkable for the number of angular curves which it forms; one or two of these flexures are sometimes seen in the cervical portion of the vessel near the base of the skull; and by the side of the sella turcica it resembles the italic letter s, placed horizontally. Relations.—In consideration of its connexions, the artery is divisible into a cervical, petrous, cavernous, and cerebral portion. The Cer- vical portion is in relation posteriorly with the rectus anticus major, sympathetic nerve, pharyngeal and laryngeal nerves which cross behind it, and near the carotid foramen with the glosso-pharyngeal, pneumogastric and lingual nerves, and partially with the internal jugular vein. Internally it is in relation with the side of the pharynx, the tonsil, and the ascending pharyngeal artery. Externally with the internal jugular vein, glosso-pharyngeal, pneumogastric, and hypo- glossal nerves; and in front with the stylo-glossus, and stylo-pharyn- geus muscle, glosso-pharyngeal nerve, and parotid gland. * For the boundaries of this space see page 202. BRANCHES OF INTERNAL CAROTID. 313 Plan of the relations of the cervical portion of the internal carotid artery. In Front. Internally. Pharynx, Tonsil, Ascending pharyn- geal artery. Parotid gland, Stylo-glossus muscle, Stylo-pharyngeus muscle, Glosso-pharyngeal nerve. Internal Carotid Artery. Externally. Jugular vein, Glosso- phary ngeal, Pneumogastric, Hypoglossal nerve. Behind. Superior cervical ganglion, Pneumogastric nerve, Glosso-pharyngeal, Pharyngeal nerve, Superior laryngeal nerve, Sympathetic nerve, Rectus anticus major. The Petrous portion is separated from the bony wall of the carotid canal by a lining of dura mater; it is in relation with the carotid plexus, and is covered in by the Casserian ganglion. The Cavernous portion is situated in the inner wall of the cavernous sinus, and is in relation by its outer side with the lining membrane of the sinus, the sixth nerve, and the ascending branches of the carotid plexus. The third, fourth, and ophthalmic nerves are placed in the outer wall of the cavernous sinus, and are separated from the artery by the lining membrane of the sinus. The Cerebral portion of the artery is enclosed in a sheath of the arachnoid, and is in relation with the optic nerve. At its point of division it is situated in the fissure of Sylvius. Branches.—The cervical portion of the internal carotid gives off no branches: from the other portions are derived the following:— Tympanic, Anterior meningeal, Ophthalmic, Anterior cerebral, Middle cerebral, Posterior communicating, Choroidean. The Tympanic is a small branch which enters the tympanum through a minute foramen in the carotid canal. The Anterior meningeal is distributed to the dura mater and Cas- serian ganglion. The Ophthalmic artery arises from the cerebral portion of the inter- nal carotid, and enters the orbit through the foramen opticum, imme- diately to the outer side of the optic nerve. It then crosses the optic nerve to the inner wall of the orbit, and runs along the lower border of the superior oblique muscle, to the inner angle of the eye, where it divides into two terminal branches, the frontal and nasal. Branches.—The branches of the ophthalmic artery may be arranged into two groups: first, those distributed to the orbit and surrounding parts; and secondly, those which supply the muscles and globe of the eye. They are— J J 27 314 BRANCHES OF INTERNAL CAROTID. First Group. Second Group. Lachrymal, Muscular, Supra-orbital; Anterior ciliary, Posterior ethmoidal, Ciliary short and long, Anterior ethmoidal, Centralis retinae. Palpebral, Frontal, Nasal. The Lachrymal is the first branch of the ophthalmic artery, and is usually given off immediately before that artery enters the optic fo- ramen. It follows the course of the lachrymal nerve, along the upper border of the external rectus muscle, and is distributed to the lachry- mal gland. The small branches which escape from the gland supply the conjunctiva and upper eyelid. The lachrymal artery gives off a malar branch which passes through the malar bone into the temporal fossa and inosculates with the deep temporal arteries, while some of its branches become subcutaneous on the cheek and anastomose with the transverse facial. The Supra-orbital artery follows the course of the frontal nerve, resting on the levator palpebrae muscle ; it passes through the supra- orbital foramen and divides into a superficial and deep branch, which are distributed to the muscles and integument of the forehead and to the pericranium. At the supra-orbital foramen it sends a branch in- wards to the diploe. The Ethmoidal arteries, posterior and anterior, pass through the eth- moidal foramina, and are distributed to the falx cerebri and to the eth- moidal cells and nasal fossae. The latter accompanies the nasal nerve. The Palpebral arteries, superior and inferior, are given off from the ophthalmic, near the inner angle of the orbit; they encircle the eyelids, forming a superior and an inferior arch near the borders of the lids, between the orbicularis palpebrarum and tarsal cartilage. At the outer angle of the eyelids the superior palpebral inosculates with the orbitar branch of the temporal artery. The inferior palpe- bral artery sends a branch to the nasal duct. The Frontal artery, one of the terminal branches of the ophthalmic, emerges from the orbit at its inner angle, and ascends along the middle of the forehead. It is distributed to the integument, muscles, and pericranium. The Nasal artery, the other terminal branch of the ophthalmic, passes out of the orbit above the tendo oculi, and divides into two branches: one of which inosculates with the angular artery, while the other, the dorsalis nasi, runs along the ridge of the nose and is distributed to the entire surface of that organ. The nasal artery sends a small branch to the lachrymal sac. The Muscular branches, usually two in number, superior and infe- rior, supply the muscles of the orbit; and upon the anterior aspect of the globe of the eye give off the anterior ciliary arteries, which pierce the sclerotic near its margin of connexion with the cornea, and are distributed to the iris. It is the congestion of these vessels that gives rise to the vascular zone around the cornea in iritis. SUBCLAVIAN. 315 The Ciliary arteries are divisible into three groups, short, long, and anterior. The Short ciliary are very numerous; they pierce the sclerotic around the entrance of the optic nerve, and supply the choroid coat and ciliary processes. The long ciliary, two in number, pierce the sclerotic on opposite sides of the globe of the eye, and pass forwards between it and the choroid to the iris. They form an arterial circle around the circumference of the iris by inosculating with each other, and from this circle branches are given off which ramify in the sub- stance of the iris, and form a second circle around the pupil. The anterior ciliary are branches of the muscular arteries; they termi- nate in the great arterial circle of the iris. The Centralis retina artery pierces the optic nerve obliquely, and passes forwards in the centre of its cylinder to the retina, where it divides into branches, which ramify in the inner layer of that mem- brane. It supplies the retina, hyaloid membrane, and zonula ciliaris; and, by means of a branch sent forwards through the centre of the vitreous humour in a tubular sheath of the hyaloid membrane, the capsule of the lens. The Anterior cerebral artery passes forwards in the great longitu- dinal fissure between the two hemispheres of the brain; then curves backwards along the corpus callosum to its posterior extremity. It gives branches to the olfactory and optic nerves, to the under sur- face of the anterior lobes, the third ventricle, the corpus callosum, and the inner surface of the hemispheres. The two anterior cerebral arteries are connected soon after their origin by a short anastomosing trunk, the anterior communicating. The Middle cerebral artery, larger than the preceding, passes out- wards along the fissure of Sylvius, and divides into three principal branches, which supply the anterior and middle lobes, and the island of Reil. Near its origin it gives off the numerous small branches which enter the substantia perforata, to be distributed to the corpus striatum. The Posterior Communicating artery, very variable in size, some- times double, and sometimes altogether absent, passes backwards and inosculates with the posterior cerebral, a branch of the basilar artery. Occasionally it is so large as to take the place of the posterior cere- bral artery. The Choroidean is a small branch which is given off from the in- ternal carotid, near the origin of the posterior communicating artery, and passes beneath the edge of the middle lobe of the brain to enter the descending cornu of the lateral ventricle. It is distributed to the choroid plexus, and to the walls of the middle cornu. SUBCLAVIAN ARTERY. The Subclavian artery, on the right side, arises from the arteria in- nominata, opposite the sterno-clavicular articulation, and on the left, from the arch of the aorta. The right is consequently shorter than the left, and is situated nearer to the anterior wall of the chest; it is also somewhat greater in diameter, from being a branch of a branch, in place of a division from the main trunk. 316 SUBCLAVIAN. The course of the subclavian artery is divisible, for the sake of precision and surgical observation, into three portions. The first portions of the right and left arteries differ in their course and rela- tions in correspondence with their dissimilarity of origin. The other two portions are precisely alike on both sides. The first portion, on the right side, ascends obliquely outwards to the inner border of the scalenus anticus. On the left side it ascends perpendicularly to the inner border of that muscle. The second por- tion curves outwards behind the scalenus anticus; and the third por- tion passes downwards and outwards beneath the clavicle, to the lower border of the first rib, where it becomes the axillary artery. Relations.—The first portion, on the right side, is in relation in front with the internal jugular and subclavian vein at their point of junc- tion, and is crossed by the pneumogastric nerve, cardiac nerves, and phrenic nerve. Behind and beneath it is invested by the pleura, is crossed by the right recurrent laryngeal nerve and vertebral vein. and is in relation with the transverse process of the seventh cervical vertebra. The first portion on the left side is in relation in front with the pleura, the vena innominata, the pneumogastric and phrenic nerves (which lie parallel to it), and the left carotid artery. To its inner side is the oesophagus; to its outer side the pleura ; and behind, the thoracic duct, longus colli, and vertebral column. Plan of the relations of theirs/ portion of the Right Subclavian Artery. In Front. Internal jugular vein, Subclavian vein, Pneumogastric nerve, Cardiac nerves, Phrenic nerve. Behind and Beneath. Pleura, Recurrent laryngeal nerve, Vertebral vein, Transverse process of 7th cervical vertebra. Plan of the relations of the first portion of the Left Subclavian Artery. In Front. Pleura, Vena innominata, Pneumogastric nerve, Phrenic nerve, Left carotid artery. Inner Side. r~ " Outer Side. CEsophagus. Left Subclavian Artery. Pleura. Behind, Thoracic duct, Longus colli, Vertebral column. BRANCHES OF SUBCLAVIAN. 317 The Second portion is situated between the two scaleni, and is sup- ported by the margin of the first rib. The scalenus anticus separates it from the subclavian vein and phrenic nerve. Behind it is in rela- tion with the brachial plexus. The Third portion is in relation, in front with the subclavian vein and subclavius muscle; behind with the brachial plexus and scalenus posticus; beloui with the first rib; and above with the supra-scapular artery and platysma. Plan of the relations of the third portion of the Subclavian Artery. Above. Supra-scapular artery, Platysma myoides. In Front. Subclavian vein, Subclavius. Subclavian artery, Third portion. Behind. Brachial plexus, Scalenus posticus. Below. First rib. Branches.—The greater part of the branches of the subclavian are given off from the artery before it arrives at the margin of the first rib. The profunda cervicis and superior intercostal frequently encroach upon the second portion, and not unfrequently a branch or branches may be found proceeding from the third portion. The primary branches are five in number, the first three being ascending, and the remaining two descending; they are the— Vertebral, Fig. 144.* f Inferior thyroid, rpt -i • J Supra-scapular, 1 hyroid axis, < r> . • i J ] Posterior scapular, (^ Superficialis cervicis. Profunda cervicis, Superior intercostal, Internal mammary. The Vertebral Artery is the first and the largest of the branches of the subcla- vian artery; it ascends through the fora- mina in the transverse processes of all the cervical vertebrae, excepting the last; then winds backwards around the articu- lating process of the atlas; and, piercing the dura mater, enters the skull through the foramen magnum. The two arteries unite at the lower border of the pons Varolii, to form the basilar artery. In the foramina of the transverse processes of the vertebrae the artery lies in front of the cervical nerves. * The branches of the right subclavian artery. 1. The arteria innominata. 2. The right carotid. 3. The first portion of the subclavian artery. 4. The second portion. 5. The third portion. 6. The vertebral artery. 7. The inferior thyroid. 8. The thyroid axis. 9. The superficialis cervicis. 10. The profunda cervicis. 11. The posterior scapu- lur or transversalis colli. 12. The supra-scapular. 13. The internal mammary artery. 14. The superior intercostal. 27* 318 BRANCHES OF SUBCLAVIAN. Dr. John Davy* has observed that, when the vertebral arteries differ in size, the left is generally the larger: thus in ninety-eight cases he found the left vertebral the larger twenty-six times, and the right only eight. In the same number of cases he found a small band stretching across the cylinder of the basilar artery, near the junction of the twro vertebral arteries, seventeen times, and in a few instances a small communicating trunk between the two vertebral arteries previously to their union. I have several times seen this communicating branch, and have a preparation now before me in which it is exhibited. The Basilar Artery, so named from its position at the base of the brain, runs forwards to the anterior border of the pons Varolii, where it divides into four ultimate branches, two to either side. Branches.—The branches of the vertebral and basilar arteries are the following:— f Lateral spinal, Posterior meningeal, Vertebral, -^ Anterior spinal, Posterior spinal, (^ Inferior cerebellar, C Transverse, Basilar, < Superior cerebellar, t Posterior cerebral. The Lateral spinal branches enter the intervertebral foramina, and are distributed to the spinal cord and to its membranes. Where the vertebral artery curves around the articular process of the atlas, it gives off several muscular branches. The Posterior meningeal are one or two small branches which enter the cranium through the foramen magnum, to be distributed to the dura mater of the cerebellar fossae, and to the falx cerebelli. One branch, described by Soemmering, passes into the cranium along the first cervical nerve. The Anterior spinal is a small branch which unites with its fellow of the opposite side, on the front of the medulla oblongata. The artery formed by the union of these two vessels descends along the anterior aspect of the spinal cord, to which it distributes branches. The Posterior spinal winds around the medulla oblongata to the posterior aspect of the cord, and descends on either side, communi- cating very freely with the spinal branches of the intercostal and lumbar arteries. Near its commencement it sends a branch upwards to the fourth ventricle. The Inferior cerebellar arteries wind around the upper part of the medulla oblongata to the under surface of the cerebellum, to which they are distributed. They pass between the filaments of origin of the hypoglossal nerve in their course, and anastomose with the supe- rior cerebellar arteries. The Transverse branches of the basilar artery supply the pons Varolii, and adjacent parts of the brain. One of these branches, * Edinburgh Medical and Surgical Journal, 1839. BRANCHES OF SUBCLAVIAN. 319 larger than the rest, passes along the crus cerebelli, to be distributed to the anterior border of the cerebellum. This may be called the middle cerebellar artery. The Superior cerebellar arteries, two of the terminal branches of the basilar, wind around the crus cerebri on each side, in relation with the fourth nerve, and are distributed to the upper surface of the cerebellum, inosculating with the inferior cerebellar. This artery gives off a small branch, which accompanies the seventh pair of nerves into the meatus auditorius internus. The Posterior cerebral arteries, the other two terminal branches of the basilar, wind around the crus cerebri at each side, and are dis- tributed to the posterior lobes of the cerebrum. They are separated from the superior cerebellar artery, near their origin, by the third Fig. 145.* pair of nerves, and are in close relation with the fourth pair, in their course around the crura cerebri. Anteriorly, near their origin, they give off a tuft of small vessels, which enter the locus perforatus, and * The circle of Willis. The arteries have references only on one side, on account of their symmetrical distribution. 1. The vertebral arteries. 2. The two anterior spinal branches uniting to form a single vessel. 3. One of the posterior spinal arteries. 4. The posterior meningeal. 5. The inferior cerebellar. 6. The basilar artery giving off its transverse branches to either side. 7. The superior cerebellar artery. 8. The posterior cerebral. 9. The posterior communicating branch of the internal carotid. 10. The in- ternal carotid artery, showing the curvatures it makes within the skull. 11. The oph- thalmic artery divided across. 12. The middle cerebral artery. 13. The anterior cerebral arteries connected by, 14. The anterior communicating artery. 320 BRANCHES OF SUBCLAVIAN. they receive the posterior communicating arteries from the internal carotid. They also send a branch to the velum interpositum and plexus choroides. The communications established between the anterior cerebral arteries in front, and the internal carotids and posterior cerebral arteries behind, by the communicating arteries, constitute the circle of Willis. This remarkable communication at the base of the brain is formed by the anterior communicating branch, anterior cerebrals, and internal carotid arteries, in front, and by the posterior communi- cating, posterior cerebrals, and basilar artery, behind. The Thyroid Axis is a short trunk, which divides almost immedi- ately after its origin into four branches, some of which are occasion- ally branches of the subclavian artery itself. The Inferior Thyroid Artery ascends obliquely, in a serpentine course, behind the sheath of the carotid vessels, to the inferior part of the thyroid gland, to which it is distributed; it sends branches also to the trachea, lower part of the larynx, and oesophagus. It is in relation with the middle cervical ganglion of the sympathetic, which lies in front of it. The Supra-scapular Artery (transversalis humeri) passes ob- liquely outwards behind the clavicle, and over the ligament of the supra-scapular notch, to the supra-spinatus fossa. It crosses, in its course, the scalenus anticus muscle, phrenic nerve, and subclavian artery, is distributed to the muscles on the dorsum of the scapula, and inosculates with the posterior scapular, and beneath the acro- mion process, with the dorsal branch of the subscapular artery. At the supra-scapular notch, it sends a large branch to the trapezius muscle. The supra-scapular artery is not unfrequently a branch of the subclavian. The Posterior Scapular Artery (transversalis colli) passes trans- versely across the subclavian triangle, at the root of the neck, to the superior angle of the scapula. It then descends along the posterior border of that bone to its inferior angle, where it inosculates with the subscapular artery, a branch of the axillary. In its course across the neck, it passes in front of the scalenus anticus, and across the brachial plexus; in the rest of its course it is covered in by the tra- pezius, levator anguli scapulae, rhomboideus minor, and rhomboideus major muscles. Sometimes it passes behind the scalenus anticus, and between the nerves which constitute the brachial plexus. This artery, which is very irregular in its origin, proceeds more fre- quently from the third portion of the subclavian artery than from the first. The posterior scapular gives branches to the neck, and opposite the angle of the scapula inosculates with the profunda cervicis. It supplies the muscles along the posterior border of the scapula, and establishes an important anastomotic communication between the branches of the external carotid, subclavian, and axillary arteries. The Superficialis Cervicis Artery (cervicalis anterior) is a small BRANCHES OF SUBCLAVIAN. 321 vessel, which ascends upon the anterior tubercles of the transverse processes of the cervical vertebrae, lying in the groove between the scalenus anticus and rectus anticus major. It is distributed to the deep muscles and glands of the neck, and sends branches through the intervertebral foramina, to supply the spinal cord and its mem- branes. The Profunda Cervicis (cervicalis posterior) passes backwards, between the transverse processes of the seventh cervical and first dorsal vertebra, and then ascends the back part of the neck, between the complexus and semi-spinalis colli muscles. It inosculates above with the princeps cervicis of the occipital artery, and below, by a descending branch, with the posterior scapular. The Superior Intercostal Artery descends behind the pleura, upon the necks of the first two ribs, and inosculates with the first aortic intercostal. It gives off two branches, which supply the first two intercostal spaces. The Internal Mammary Artery descends by the side of the ster- num, resting upon the costal cartilages, to the diaphragm; it then pierces the anterior fibres of the diaphragm; and enters the sheath of the rectus, where it inosculates with the epigastric artery, a branch of the external iliac. In the upper part of its course it is crossed by the phrenic nerve, and lower down, lies between the tri- angularis sterni and the internal intercostal muscles. The Branches of the internal mammary are,— Anterior intercostal, Mediastinal, Mammary, Pericardiac, Comes nervi phrenici, Musculo-phrenic. The Anterior intercostals supply the intercostal muscles of the front of the chest, and inosculate with the aortic intercostal arteries. Each of the first three anterior intercostals gives off a large branch to the mammary gland, which anastomoses freely with the thoracic branches of the axillary artery; the corresponding branches from the remaining intercostals supply the integument and pectoralis major muscle. There are usually two anterior intercostal arteries in each space. The Comes nervi phrenici is a long and slender branch, which accompanies the phrenic nerve. Thp mediastinal and pericardiac branches are small vessels, dis- tributed to the anterior mediastinum, the thymus gland, and peri- cardium. The Musculo-phrenic artery winds along the attachment of the diaphragm to the ribs, supplying that muscle and sending branches to the inferior intercdstal spaces. " The mammary arteries," says Dr. Harrison, " are remarkable for the number of their inosculations, and for the distant parts of the arterial system which they serve to connect. They anastomose with each other, and their inoscula- tions, with the thoracic aorta, encircle the thorax. On the parietes 322 AXILLARY ARTERY. of this cavity, their branches connect the axillary and subclavian arteries; on the diaphragm, they form a link in the chain of inoscu- lations between the subclavian artery and abdominal aorta; and in the parietes of the abdomen, they form an anastomosis most remark- able for the distance between those vessels which it serves to con- nect ; namely, the arteries of the superior and inferior extremities." Varieties of the Subclavian Arteries.—Varieties in these arteries are rare; that which most frequently occurs is the origin of the right subclavian, from the left extremity of the arch of the aorta, below the left subclavian artery. The vessel, in this case, curves behind the oesophagus and right carotid artery, and sometimes between the oeso- phagus and trachea, to the upper border of the first rib on the right side of the chest, where it assumes its ordinary course. In a case* of subclavian aneurism on the right side, above the clavicle, which happened during the summer of 1839, Mr. Liston proceeded to per- form the operation of tying the carotid and subclavian arteries at their point of division from the innominata. Upon reaching the point where the bifurcation should have existed, he found that there was no subclavian artery. With that admirable self-possession which dis- tinguishes this eminent surgeon in all cases of emergency, he con- tinued his dissection more deeply, towards the vertebral column, and succeeded in securing the artery. It was ascertained after death, that the arteria innominata was extremely short, and that the subclavian was given off within the chest from the posterior aspect of its trunk, and pursued a deep course to the upper margin of the first rib. In a preparation which was shown to me in Heidelberg some years since by Professor Tiedemann, the right subclavian artery arose from the thoracic aorta, as low down as the fourth dorsal vertebra, and ascended from that point to the border of the first rib. Varieties in the branches of the subclavian are not unfrequent; the most interesting is the origin of the left vertebral, from the arch of the aorta, of which I possess several preparations. AXILLARY ARTERY. The axillary artery forms a gentle curve through the middle of the axillary space from the lower border of the first rib to the lower border of the latissimus dorsi, where it becomes the brachial. Relations.—After emerging from beneath the margin of the costo- coracoid membrane, it is in relation with the axillary vein, which lies at first to the inner side, and then in front of the artery. Near the middle of the axilla it is embraced by the two heads of the median nerve, and is covered in by the pectoral muscles. Upon the inner or thoracic side it is in relation, first, with the first intercostal muscle; it next rests upon the first serration of the serratus magnus; and is then separated from the chest by the brachial plexus of nerves. By its outer or humeral side it is at first separated from the brachial plexus by a triangular cellular interval; it next rests against the ten- don of the subscapularis muscle; and thirdly, upon the coraco-bra- chialis muscle. * This case is recorded in the Lancet, vol. i. 1839-40, pp. 37 and 419. AXILLARY ARTERY. 323 The relations of the axillary artery may be thus arranged:— In Front. Pectoralis major, Pectoralis minor, Pectoralis major. Inner or Thoracic Side. Outer or Humeral Side. First intercostal muscle, First serration of ser- ratus magnus, Plexus of nerves. Plexus of nerves, Tendon of sub- scapularis, Coraco-brachialis. Fig. 146.* Branches.—The branches of the Ax- illary artery are seven in number:— Thoracica acromialis, Superior thoracic, Inferior thoracic, Thoracica axillaris, Subscapular, Circumflex anterior, Circumflex posterior. The thoracica acromialis and supe- rior thoracic are found in the triangular space above the pectoralis minor. The inferior thoracic and thoracica axil- laris, below the pectoralis minor. And the three remaining branches below the lower border of the subscapularis. The Thoracica acromialis is a short trunk which ascends to the space above the pectoralis minor muscle, and divides into three branches, thoracic, which is distributed to the pectoral muscles and mammary gland; acromial, which passes outwards to the acromion, and inoscu- lates with branches of the supra-sca- pular artery; and descending, which follows the interspace between * The axillary and brachial artery, with their branches. 1. The deltoid muscle. 2. The biceps. 3. The tendinous process given off from the tendon of the biceps, to the deep fascia of the fore-arm. It is this process which separates the median basilic vein from the brachial artery. 4. The outer border of the brachialis anticus muscle. 5. The supinator longus. 6. The coraco-brachialis. 7. The middle portion of the triceps muscle. 8. Its inner head. 9. The axillary artery. 10. The brachial artery;—a dark line marks the limit between these two vessels. 11. The thoracica acromialis artery dividing into its three branches ; the number rests upon the coracoid process. 12. The superior and infe- rior thoracic arteries. 13. The serratus magnus muscle. 14. The subscapular artery. The posterior circumflex and thoracica axillaris branches are seen in the figure between the inferior thoracic and subscapular. The anterior circumflex is observed, between the two heads of the biceps, crossing the neck of the humerus. 15. The superior profunda artery. 16. The inferior profunda. 17. The anastomotica magna inosculating inferiorly with the anterior ulnar recurrent. 18. The termination of the superior profunda, inoscu- lating with the radial recurrent in the interspace between the brachialis anticus and supi- nator longus. 324 BRANCHES OF AXILLARY. the deltoid and pectoralis major muscles, and is in relation with the cephalic vein. The Superior thoracic (short) frequently arises by a common trunk with the preceding; it runs along the upper border of the pectoralis minor, and is distributed to the pectoral muscles and mammary gland, inosculating with the intercostal and mammary arteries. The Inferior thoracic (long external mammary) descends along the lower border of the pectoralis minor to the side of the chest. It is distributed to the pectoralis major and minor, serratus magnus, and subscapularis muscle, to the axillary glands and mammary gland; inosculating with the superior thoracic, intercostal, and mammary arteries. The Thoracica axillaris is a small branch distributed to the plexus of nerves and glands in the axilla. It is frequently derived from one of the other thoracic branches. The Subscapular artery, the largest of the branches of the axillary, runs along the lower border of the subscapularis muscle, to the infe- rior angle of the scapula, where it inosculates with the posterior scapular, a branch of the subclavian. It supplies, in its course, the muscles on the under surface and inferior border of the scapula, and the side of the chest. At about an inch and a half from the axillary, it gives off a large branch, the dorsalis scapula, which passes back- wards through the triangular space bounded by the teres minor, teres major, and scapular head of the triceps, and beneath the infra- spinatus to the dorsum of the scapula, where it is distributed, inoscu- lating with the supra-scapular and posterior scapular arteries. The Circumflex arteries wind around the neck of the humerus. The anterior, very small, passes beneath the coraco-brachialis and short head of the biceps, and sends a branch upwards along the bicipital groove to supply the shoulder-joint. The Posterior circumflex, of larger size, passes backwards through the quadrangular space bounded by the teres minor and major, the scapular head of the triceps and the humerus, and is distributed to the deltoid muscle and joint. Sometimes this artery is a branch of the superior profunda of the brachial. It then ascends behind the tendon of the teres major, and is distributed to the deltoid without passing through the quadrangular space. The posterior circumflex artery sends branches to the shoulder-joint. Varieties of the Axillary Artery.—The most frequent peculiarity of this kind is the division of the vessel into two trunks of equal size: a muscular trunk, which gives off some of the ordinary axillary branches and supplies the upper arm, and a continued trunk, which represents the brachial artery. The next most frequent variety is the high division of the ulnar which passes down the arm by the side of the brachial artery, and superficially to the muscles proceed- ing from the inner condyle, to its ordinary distribution in the hand. In this course it lies immediately beneath the deep fascia of the fore- arm, and may be seen and felt pulsating beneath the integument. The high division of the radial from the axillary is rare. In one instance, I saw the axillary artery divide into three branches of BRACHIAL ARTERY. 325 nearly equal size, which passed together down the arm, and at the bend of the elbow resolved themselves into radial, ulnar, and interos- seous. But the most interesting variety, both in a physiological and surgical sense, is that described by Dr. Quain, in his " Elements of Anatomy." " I found in the dissecting-room, a few years ago, a variety not hitherto noticed; it was at first taken for the ordinary high division of the ulnar artery. The two vessels descended from the point of division at the border of the axilla, and lay parallel with one another in their course through the arm; but instead of diverg- ing, as is usual, at the bend of the elbow, they converged, and united so as to form a short trunk which soon divided again into the radial and ulnar arteries in the regular way." In a subject, dissected by myself, this variety existed in both arms; and I have seen several instances of a similar kind. BRACHIAL ARTERY. The Brachial artery passes down the inner side of the arm, from the lower border of the latissimus dorsi to the bend of the elbow, where it divides into the radial and ulnar arteries. Relations.—In its course downwards, it rests upon the coraco-bra- chialis muscle, internal head of the triceps, brachialis anticus, and the tendon of the biceps. To its inner side, is the ulnar nerve, to the outer side, the coraco-brachialis and biceps muscles; in front it has the basilic vein, and is crossed by the median nerve. Its relations, within its sheath, are the venae comites. Plan of the relations of the Brachial Artery. In Front. Basilic vein, Deep fascia, " Median nerve. Inner Side. | Ulnar nerve. Brachial Artery. Outer Side. Coraco-brachialis, Biceps. Behind. Short head of triceps, Coraco-brachialis, Brachialis anticus, Tendon of biceps. The branches of the brachial artery are, the— Superior profunda, Inferior profunda, Anastomotica magna, Muscular. The Superior profunda arises opposite the lower border of the la- tissimus dorsi, and winds around the humerus, between the triceps and the bone, to the space between the brachialis anticus and supinator longus, where it inosculates with the radial recurrent branch. It ac- companies the musculo-spiral nerve. In its course it gives off the posterior articular artery, which descends to the elbow-joint, and a 28 326 RADIAL. Fig. 147/ more superficial branch which inosculates with the interosseous arti- cular artery. The Inferior profunda arises from about the middle of the brachial artery, and descends to the space between the inner condyle and ole- cranon in company with the ulnar nerve, where it inosculates with the posterior ulnar recurrent. The Anastomotica magna is given off nearly at right angles from the brachial, at about two inches above the joint. It passes directly inwards, and di- vides into two branches which inosculate with the anterior and posterior ulnar recur- rent arteries and with the inferior profunda. The Muscular branches are distributed to the muscles in the course of the artery, viz.: to the coraco-brachialis, biceps, deltoid, brachialis anticus and triceps. Varieties of the Brachial Artery.—The most frequent peculiarity in the distribution of branches from this artery is the high division of the radial, which arises generally from about the upper third of the brachial artery, and descends to its normal position at the bend of the elbow. The ulnar artery sometimes arises from the brachial at about two inches above the elbow, and pursues either a superficial or deep course to the wrist; and, in more than one instance, I have seen the interosseous artery arise from the brachial a little above the bend of the elbow. The two profunda arteries occa- sionally arise by a common trunk, or there -may be two superior profundae. RADIAL ARTERY. The Radial artery, one of the divisions of the brachial, appears from its direction to be the continuation of that trunk. It runs along the radial side of the fore-arm, from the bend of the elbow to the * The arteries of the fore-arm. 1. The lower part of the biceps muscle. 2. The inner condyle of the humerus with the humeral origin of the pronator radii teres and flexor carpi radialis divided across. 3. The deep portion of the pronator radii teres. 4. The supinator longus muscle. 5. The flexor longus pollicis. 6. The pronator quadratus. 7. The flexor profundus digitorum. 8. The flexor carpi ulnaris. 9. The annular liga- ment with the tendons passing beneath it into the pajm of the hand; the figure is placed on the tendon of the palmaris longus muscle, divided close to its insertion. 10. The brachial artery. 11. The anastomotica magna inosculating superiorly with the inferior profunda, and inferiorly with the anterior ulnar recurrent. 12. The radial artery. 13. The radial recurrent artery inosculating with the termination of the superior profunda. 14. The superficialis volse. 15. The ulnar artery. 16. Its superficial palmar arch giving off digital branches to three fingers and a half. 17. The magna pollicis and radialis indicis arteries. 18. The posterior ulnar recurrent. 19. The anterior interosseous artery. 20. The posterior interosseous, as it is passing through the interosseous membrane. RADIAL.-BRANCHES. 327 wrist; it there turns around the base of the thumb, beneath its exten- sor tendons, and passes between the two heads of the first dorsal in- terosseous muscle, into the palm of the hand. It then crosses the metacarpal bones to the ulnar side of the hand, forming the deep pal- mar arch, and terminates by inosculating with the superficial palmar arch. In the upper half of its course, the radial artery is situated between the supinator longus muscle, by which it is overlapped superiorly, and the pronator radii teres ; in the lower half, between the tendons of the supinator longus and flexor carpi radialis. It rests in its course downwards, upon the supinator brevis, pronator radii teres, radial origin of the flexor sublimis, flexor longus pollicis, and pronator quad- ratus ; and is covered in by the integument and fasciae. At the wrist it is situated in contact with the dorsal carpal ligaments and beneath the extensor tendons of the thumb; and, in the palm of the hand, be- neath the flexor tendons. It is accompanied by venae comites throughout its course, and by its middle third is in close relation with the radial nerve. Plan of the relations of the Radial Artery in the Fore-arm. In Front. Deep fascia, Supinator longus. Inner Side. Pronator radii teres, Flexor carpi radialis. Outer Side. Supinator longus, Radial nerve (middle third of its course). Behind. Supinator brevis, Pronator radii teres, Flexor sublimis digitorum, Flexor longus pollicis, Pronator quadratus, Wrist-joint. The Branches of the radial artery may be arranged into three groups, corresponding with the three regions, the fore-arm, the wrist, and the hand ; they are— Fore-arm, Wrist, Hand, ( Recurrent radial, \ Muscular. Superficialis volae, Carpalis anterior, Carpalis posterior, Metacarpalis, Dorsales pollicis. Princeps pollicis, Radialis indicis, Interosseae, Perforantes. The Recurrent branch is given off immediately below the elbow? 328 ULNAR. it ascends in the space between the supinator longus and brachialis anticus to supply the joint, and inosculates with the terminal branches of the superior profunda. This vessel gives off numerous muscular branches. The Muscular branches are distributed to the muscles on the radial side of the fore-arm. The Superficialis vola is given off from the radial artery while at the wrist. It passes between the fibres of the abductor pollicis muscle, and inosculates with the termination of the ulnar artery, completing the superficial palmar arch. This artery is very variable in size, being sometimes as large as the continuation of the radial, and at other times a mere muscular ramusculus, or entirely wanting; when of large size it supplies the palmar side of the thumb and the radial side of the index finger. The Carpal branches are intended for the supply of the wrist, the anterior carpal in front, and the posterior, the larger of the two, be- hind. The carpalis posterior crosses the carpus transversely to the ulnar border of the hand, where it inosculates with the posterior car- pal branch of the ulnar artery. Superiorly it sends branches which inosculate with the termination of the anterior interosseous artery; inferiorly, it gives offposterior interosseous branches, which anastomose with the perforating branches of the deep palmar arch, and then run forward upon the dorsal interossei muscles. The Metacarpal branch runs forward on the second dorsal interos- seous muscle, and inosculates with the digital branch of the superfi- cial palmar arch, which supplies the adjoining sides of the index and middle fingers. Sometimes it is of large size, and the true continua- tion of the radial artery. The Dor sales pollicis are two small branches which run along the sides of the dorsal aspect of the thumb. The Princeps pollicis descends along the border of the metacarpal bone, between the abductor indicis and adductor pollicis to the base of the first phalanx, where it divides into two branches, which are distributed to the two sides of the palmar aspect of the thumb. The Radialis indicis is also situated between the abductor indicis and the adductor pollicis, and runs along the radial side of the index finger, forming its collateral artery. This vessel is frequently a branch of the princeps pollicis. * The Interossea, three or four in number, are branches of the deep palmar arch; they pass forward upon the interossei muscles and in- osculate with the digital branches of the superficial arch, opposite the heads of the metacarpal bones. The Perforantes, three in number, pass directly backwards between the heads of the dorsal interossei muscles, and inosculate with the posterior interosseous arteries. ulnar artery. The Ulnar artery, the other division of the brachial artery, crosses the arm obliquely to the commencement of its middle third; it then ULNAR—BRANCHES. 329 runs down the ulnar side of the fore-arm to the wrist, crosses the annular ligament, and forms the superficial palmar arch, which ter- minates by inosculating with the superficialis volae. Relations.—In the upper or oblique portion of its course, it lies upon the brachialis anticus and flexor profundus digitorum; and is covered in by the superficial layer of muscles of the fore-arm and the median nerve. In the second part of its course, it is placed upon the flexor profundus and pronator quadratus, lying between the flexor carpi ulnaris and flexor sublimis digitorum. While crossing the an- nular ligament it is protected from injury by a strong tendinous arch, thrown over it from the pisiform bone; and in the palm it rests upon the tendons of the flexor sublimis, being covered in by the palmaris brevis muscle and palmar fascia. It is accompanied in its course by the venae comites, and is in relation with the ulnar nerve for the lower two-thirds of its extent. Plan of the relations of the Ulnar Artery. In Front. Deep fascia, Superficial layer of muscles, Median nerve. In the Hand. Tendinous arch from the pisiform bone, Palmaris brevis muscle, Palmar fascia. Inner Side. Flexor carpi ulnaris, Ulnar nerve (lower two-thirds). Ulnar Artery, Outer Side. Flexor sublimis digi- torum. Behind. Brachialis anticus, Flexor profundus digitorum, Pronator quadratus. In the Hand. Annular ligament, Tendons of the flexor sublimis digitorum. The Branches of the ulnar artery may be arranged like those of the radial into three groups:— Anterior ulnar recurrent, Posterior ulnar recurrent, ( Anterior interosseous, Interosseous, j Posterior interosseous. Muscular. Carpalis anterior, Carpalis posterior. Disritales. Fore-arm, Wrist, Hand, The Anterior ulnar recurrent arises immediately below the elbow, and ascends in front of the joint between the pronator radii teres and 28* 330 ULNAR—BRANCHES. brachialis anticus, where it inosculates with the anastomotica magna and inferior profunda. The two recurrent arteries frequently arise by a common trunk. The Posterior ulnar recurrent, larger than the preceding, arises immediately below the elbow joint, and passes backwards beneath the origins of the superficial layer of muscles; it then ascends between the two heads of the flexor carpi ulnaris, and beneath the ulnar nerve, and inosculates with the inferior profunda and anasto- motica magna. The Common interosseous artery is a short trunk which arises from the ulnar, opposite the bicipital tuberosity of the radius. It divides into two branches, the anterior and posterior interosseous arteries. The Anterior interosseous passes down the fore-arm upon the inter- osseous membrane, between the flexor profundus digitorum and flexor longus pollicis, and, behind the pronator quadratus, it pierces that membrane and descends to the back of the wrist, where it inosculates with the posterior carpal branches of the radial and ulnar. It is re- tained in connexion with the interosseous membrane by means of a thin aponeurotic arch. The anterior interosseous artery sends a branch to the median nerve, which it accompanies into the hand. The median artery is sometimes of large size, and occasionally takes the place of the su- perficial palmar arch. The Posterior interosseous artery passes backwards through an opening between the upper part of the interosseous membrane and the oblique ligament, and is distributed to the muscles on the posterior aspect of the fore-arm. It gives off a recurrent branch, which re- turns upon the elbow between the anconeus, extensor carpi ulnaris and supinator brevis muscles, and anastomoses with the posterior ter- minal branches of the superior profunda. The Muscular branches supply the muscles situated along the ulnar border of the fore-arm. The Carpal branches, anterior and posterior, are distributed to the anterior and posterior aspects of the wrist-joint, where they inoscu- late with corresponding branches of the radial artery. The Digital branches are given off from the superficial palmar arch, and are four in number. The first and smallest is distributed to the ulnar side of the little finger. The other three are short trunks, which divide between the heads of the metacarpal bones, and form the collateral branch of the radial side of the little finger, the collateral branches of the ring and middle fingers, and the collateral branch of the ulnar side of the index finger. The Superficial palmar arch receives the termination of the deep palmar arch from between the abductor minimi digiti and flexor brevis minimi digiti near their origins, and terminates by inosculating with the superficialis volae upon the ball of the thumb. The commu- nication between the superficial and deep arch is generally described as the communicating branch of the ulnar artery. The mode of distribution of the arteries to the hand is subject to frequent variety. BRANCHES OF THE THORACIC AND ABDOMINAL AORTA. 33I BRANCHES OF THE THORACIC AORTA. Bronchial, (Esophageal, Intercostal. The Bronchial Arteries are four in number, and vary both in size and origin. They are distributed to the bronchial glands and tubes, and send branches to the oesophagus, pericardium, and left auricle of the heart. These are the nutritious vessels of the lungs. The (Esophageal Arteries are numerous small branches; they arise from the anterior part of the aorta, are distributed to the oeso- phagus, and establish a chain of anastomoses along that tube: the superior inosculate with the bronchial arteries, and with oesopha- geal branches of the inferior thyroid arteries ; and the inferior with similar branches of the phrenic and gastric arteries. The Intercostal, or posterior intercostal arteries, arise from the posterior part of the aorta; they are nine in number on each side, the two superior spaces being supplied by the superior intercostal artery, a branch of the subclavian. The right intercostals are longer than the left, on account of the position of the aorta. They ascend some- what obliquely from their origin, and cross the vertebral column be- hind the thoracic duct, vena azygos major, and sympathetic nerve, to the intercostal spaces, the left passing beneath the superior intercostal vein, the vena azygos minor and sympathetic. In the intercostal spaces, or rather, upon the external intercostal muscles, each artery gives off a dorsal branch, which passes back between the transverse processes of the vertebrae, lying internally to the middle costo-transverse ligament, and divides into a spinal branch, which supplies the spinal cord and vertebrae, and a muscular branch which is distributed to the muscles and integument of the back. The artery then comes into re- lation with its vein and nerve, the former being above and the latter below, and divides into two branches which run along the borders of contiguous ribs between the two planes of intercostal muscles, and anastomose with the anterior intercostal arteries, branches of the in- ternal mammary. The branch corresponding with the lower border of each rib is the larger of the two. They are protected from pres- sure during the action of the intercostal muscles, by little tendinous arches thrown across them and attached by each extremity to the bone. branches of the abdominal aorta. Phrenic, ( Gastric, Coeliac axis \ Hepatic, ( Splenic. Superior mesenteric, Spermatic, Inferior mesenteric, Supra-renal, 332 CCELIAC AXIS-HEPATIC. Renal, Lumbar, Sacra media. The Phrenic Arteries are given off from the anterior part of the aorta as soon as that trunk Fig. 148/ has passed through the aortic opening Passing obliquely outwards upon the under sur- face of the diaphragm, each artery divides into two bran- ches, an internal branch which runs forwards and inosculates with its fellow of the opposite side in front of the oesophageal opening ; and an external branch which proceeds out- wards towards the great cir- cumference of the muscle, and sends branches to the supra- renal capsules. The phrenic arteries inosculate with bran- ches of the internal mammary, inferior intercostal, epigastric, oesophageal, gastric, hepatic, and supra-renal arteries. They are not unfrequently derived from the coeliac axis, or from one of its divisions, and some- times they give off the supra- renal arteries. The Cceliac Axis (xoiXi'a, ven- triculus) is the first single trunk given off from the abdominal aorta. It arises opposite the upper border of the first lumbar vertebra, is about half an inch in length, and divides into three large branches, gastric, hepatic, and splenic. Relations.—The trunk of the cceliac axis has in relation with it, in front the lesser omentum; on the right side the right semilunar gan- glion and lobus Spigelii of the liver; on the left side the left semilunar ganglion and cardiac portion of the stomach; and below, the upper * The abdominal aorta with its branches. 1. The phrenic arteries. 2. The coeliac axis. 3. The gastric artery. 4. The hepatic artery, dividing into the right and left hepatic branches. 5. The splenic artery, passing outwards to the spleen. 6. The supra- renal artery of the right side. 7. The right renal artery, which is longer than the left, passing outwards to the right kidney. 8. The lumbar arteries. 9. The superior mesen- teric artery. 10. The two spermatic arteries. 11. The inferior mesenteric artery. 12. The sacra media. 13. The common iliacs. 14. The internal iliac of the right side. 15. The external iliac artery. 16. The epigastric artery. 17. The circumflexa ilii artery. 18. The femoral artery. HEPATIC. 333 border of the pancreas and lesser curve of the stomach. It is com- pletely surrounded by the solar plexus. The Gastric Artery (coronaria ventriculi), the smallest of the three branches of the coeliac axis, ascends between the two layers of the lesser omentum to the cardiac orifice of the stomach, then runs along the lesser curvature to the pylorus, and inosculates with the pyloric branch of the hepatic. It is distributed to the lower extremity of the oesophagus and lesser curve of the stomach, and anastomoses with the oesophageal arteries and vasa brevia of the splenic artery. The Hepatic Artery curves forwards, and ascends along the right border of the lesser omentum to the liver, where it divides into two branches (right and left), which enter the transverse fissure, and are distributed along the portal canals to the right and left lobes.* It is in relation in the right border of the lesser omentum, with the ductus communis choledochus and portal vein, and is surrounded by the he- patic plexus of nerves and numerous lymphatics. There are some- times two hepatic arteries, in which case one is derived from the su- perior mesenteric artery. The Branches of the hepatic artery are, the Pyloric, Gastro-duodenalis, i Gastro-epiploica dextra, { Pancreatico-duodenalis. Cystic. The Pyloric branch given off from the hepatic near the pylorus, is distributed to the commencement of the duodenum and to the lesser curve of the stomach, where it inosculates with the gastric artery. The Gastro-duodenalis artery is a short but large trunk, which de- scends behind the pylorus, and divides into two branches, the gastro- epiploica dextra, and pancreatico-duodenalis. Previously to its divi- sion, it gives off some inferior pyloric branches to the small end of the stomach. The Gastro-epiploica dextra runs along the great curve of the sto- mach lying between the two layers of the great omentum, and inos- culates at about its middle with the gastro-epiploica sinistra, a branch of the splenic artery. It supplies the great curve of the stomach and the great omentum; hence the derivation of its name. The Pancreatico-duodenalis curves along the fixed border of the duodenum, partly concealed by the attachment of the pancreas, and is distributed to the pancreas and duodenum. It inosculates inferiorly with the first jejunal, and with the pancreatic branches of the superior mesenteric artery. The Cystic artery, generally a branch of the right hepatic, is of small size, and ramifies between the coats of the gall bladder, pre- viously to its distribution to the mucous membrane. * For the mode of distribution of the hepatic artery within the liver, see the "Minute Anatomy" of that organ in the Chapter on the Viscera. 334 SPLENIC—BRANCHES. The Splenic Artery, the largest of the three branches of the cceliac axis, passes horizontally to the left along the upper border of the pancreas, and divides into five or six large branches which enter the hilus of the spleen and are distributed to its structure. In its course it is tortuous and serpentine, and frequently makes a complete turn upon itself. It lies in a narrow groove in the upper border of the pancreas, and is accompanied by the splenic vein, and by the splenic plexus of nerves. The Branches of the splenic artery are the— Pancreaticae parvae, Pancreatica magna, Vasa brevia, Gastro-epiploica sinistra. The Pancreatica parva are numerous small branches distributed to the pancreas, as the splenic artery runs along its upper border. One of these, larger than the rest, follows the course of the pancre- atic duct, and is called pancreatica magna. Fig. 149.* * The distribution of the branches of the cceliac axis. 1. The liver. 2. Its transverse fissure. 3. The gall-bladder. 4. The stomach. 5. The entrance of the oesophagus. 6. The pylorus. 7. The duodenum, its descending portion. 8. The transverse portion of the duodenum. 9. The pancreas. 10. The spleen. 11. The aorta. 12. The coeliac axis. 13. The gastric artery. 14. The hepatic artery. 15. Its pyloric branch. 16. The gastro-duodenalis. 17. The gastro-epiploica dextra. 18. The pancreatico-duodenalis, in- osculating with a branch from the superior mesenteric artery. 19. The division of the hepatic artery into its right and left branches; the right giving off the cystic branch. 20. The splenic artery, traced by dotted lines behind the stomach to the spleen. 21. The gastro-epiploica sinistra, inosculating along the great curvature of the stomach with the gastro-epiploica dextra. 22. The pancreatica magna. 23. The vasa brevia to the great end of the stomach, inosculating with branches of the gastric artery. 24. The superior mesenteric artery, emerging from between the pancreas and transverse portion of the duo- denum. SUPERIOR MESENTERIC. 335 The Vasa brevia are five or six branches of small size which pass from the extremity of the splenic artery and its terminal branches, between the layers of the gastro-splenic omentum, to the great end of the stomach, to which they are distributed, inosculating with branches of the gastric artery and gastro-epiploica sinistra. The Gastro-epiploica sinistra appears to be the continuation of the splenic artery; it passes forwards from left to right, along the great curve of the stomach, lying between the layers of the great omentum, and inosculates with the gastro-epiploica dextra. It is distributed to the greater curve of the stomach and to the great omentum. The Superior Mesenteric Artery, the second of the single trunks, and next in size to the coeliac axis, arises from the aorta immediately below that vessel, and behind the pancreas. It passes forwards be- tween the pancreas and transverse duodenum, and descends within the layers of the mesentery, to the right iliac fossa, where it terminates very much diminished in size. It forms a curve in its course, the Fig. 150.* * The course and distribution of the superior mesenteric artery. 1. The descending portion of the duodenum. 2. The transverse portion. 3. The pancreas. 4. The jejunum. 5. The ileum. 6. The ccecum, from which the appendix vermiformis is seen projecting. 7. The ascendino- colon. S. The transverse colon. 9. The commencement of the descend- ing colon. 10. The superior mesenteric artery. 11. The colica media. 12. The branch which inosculates with the colica sinistra. 13. The branch of the superior mesenteric artery, which inosculates with the pancreatico-duodenalis. 14. The colica dextra. 15. The ileo-colica. 16, 16. The branches from the convexity of the superior mesenteric to the small intestines. 336 SPERMATIC. convexity being directed towards the left, and the concavity to the right. It is in relation near its commencement with the portal vein: and is accompanied by two veins, and the superior mesenteric plexus of nerves. The branches of the Superior Mesenteric Artery are,— Vasa intestini tenuis, Colica dextra, Ileo-colica, Colica media. The Vasa intestini tenuis arise from the convexity of the superior mesenteric artery. They vary from fifteen to twenty in number, and are distributed to the small intestine, from the duodenum to the ter- mination of the ileum. In their course between the layers of the mesentery, they form a series of arches by the inosculation of their larger branches; from these, are developed secondary arches, and from the latter a third series of arches, from which the branches arise which are distributed to the coats of the intestine. From the middle branches a fourth, and sometimes even a fifth series of arches is produced. By means of these arches, a direct communi- cation is established between all the branches given off. from the convexity of the superior mesenteric artery; the superior branches, moreover, supply the pancreas and duodenum, and inosculate with the pancreatico-duodenalis; and the inferior with the ileo-colica. The lleo-colic artery is the last branch given off from the concavity of the superior mesenteric. It descends to the .right iliac fossa, and divides into branches which communicate and form arches, from which branches are distributed to the termination of the ileum, the caecum, and the commencement of the colon. This artery inoscu- lates on the one hand with the last branches of the vasa intestini tenuis, and on the other with the colica dextra. The Colica dextra arises from about the middle of the concavity of the superior mesenteric, and divides into branches which form arches, and are distributed to the ascending colon. Its descending branches inosculate with the ileo-colica, and the ascending with the colica media. The Colica media arises from the upper part of the concavity of the superior mesenteric, and passes forwards between the layers of the transverse mesocolon where it forms arches, and is distributed to the transverse colon. It inosculates on the right with the colica dex- tra ; and on the left with the colica sinistra, a branch of the inferior mesenteric artery. The Spermatic Arteries are two small vessels, which arise from the front of the aorta, below the superior mesenteric; from this origin each artery passes obliquely outwards, and accompanies the corresponding ureter, along the front of the psoas muscle, to the border of the pelvis, where it is in relation with the external iliac artery. It is then directed outwards to the internal abdominal ring, and follows the course of the spermatic cord, along the spermatic canal and through the scrotum, to the testicle, to which it is distri- buted. The right spermatic artery lies in front of the vena cava, THE LARYNX. The larynx is a short, quadrangular cavity, larger above than below, com- posed chiefly of a series of cartilages connected by muscles and ligaments, and lined by mucous membrane. Its position is in front of the verte- bral column, from which it is separated by the pharynx; in front, it is directly beneath the in- teguments; above, it opens into the pharynx, and below into the trachea. The cartilaginous basis of the larynx consists of five principal parts called the thyroid, the cri- coid, the two arytenoid and the epiglottis carti- lages, together with some subordinate structures of the same kind. ■fcrii Fig. 255. Larynx and trachea viewed in front. 1, Os hy- oides; 2, 2, its cornua; 3, 3, its appendices; 4, 4, lateral thyro- hyoid ligaments; 5, 5, superior cornua of the thyroid cartilage- 6, 6, body of that cartilage; 7, pomum Adami; 8, middle thyro- hyoid membrane or ligament; 9, cricoid cartilage; 10, middle crico-thyroid membrane; 11, 11, trachea; 12, bronchi. 374. Larynx and trachea. After Weber. Fig. 374. Eye of the right side, show- ing the ophthalmic lenticular, or ciliary ganglion, its roots and branches, to- gether with the ganglion of Gasser. 1, optic nerve; 2, trunk of the motor oculi; 3, inferior branch of the latter nerve; 4, ganglion of Gasser; 5, its ophthalmic branch; 6, nasal branch of the ophthalmic, cut off; 7, superior maxillary branch of the trigeminus; 8, inferior maxillary branch of the same nerve ; 9, posterior portion of the sclerotic coat, perforated by the ciliary nerves; 10, choroid coat; 11, anterior portion of the sclerotic coat, traversed from within outwards by the ciliary nerves ; 12, inferior segment of the cornea ; 13, ciliary ligament; 14, iris; 15, pupil; 16, sensitive root of the ophthalmic ganglion, derived from the nasal branch of die ophthalmic nerve; 17, its short or motor branch; 18, sympathetic filament; 19, ophthalmic gan- glion; 20, the strait or direct ciliary nerve, derived from the nasal branch; 21, anastomosis between the nasal branch and short ciliary nerve; 22, ciliary nerves from the ophthalmic ganglion ; 23, the Nerves of the eyeball. From Longet. 459537855� centic edge, overhanging the femoral vessels, passes inwards to be inserted into the crista of the pubis continuous with Gimbernat's ligament. This margin forms a second arched border over the femoral vessels; and having been shown by Mr. Hey to be a common seat of stricture in femoral hernia, has received the name of Keys ligament. The continuity of these portions of the femoral and abdominal aponeu- roses shows the importance of position in the employment of the taxis; for, by rotating the thigh inwards and carrying it across the opposite limb, the greatest degree of relaxation is obtained. Fig. 204. Fig. 204.* Dissection of some of the parts concerned in femoral and inguinal hernia. 1, Tendon of the external oblique muscle; 2, tendon of the internal oblique, the first named muscle being dis- sected off; 3, cribriform fascia; 4, vena saphena; 5, external abdominal ring and spermatic cord; 6, Poupart's ligament; 7, abdominal canal laid open; 8, cremaster muscle, covering the cord from Poupart's ligament; 9, additional slips to the cremaster, arising from the spine of the pubis; 10, sus- pensory ligament of the penis; 11, femoral vessels; 12, point at which the saphenous vein joins the femoral; 13, sartorial fascia ; 14, pectineal fascia; 15, lower horn of the crescent formed by the sartorial fascia ; 16, upper horn of the crescent, the extreme point of which is inserted into the spine of the pubis, forming Hey's ligament. The opening of the fossa ovalis is filled by loose fibrous layers of the fascia superficialis, perforated by many foramina for the transmission of the super- ficial lymphatics to the parts beneath. This is the cribriform fascia. It also encloses many lymphatic glands, and thus fills up the inequalities of this re- gion of the thigh. * Modified from a drawing in Bonamy and Beau by my friend Dr. William Gambel, to whom I am also indebted for various important suggestions in preparing this section. INFERIOR MESENTERIC. 337 and both vessels are accompanied by their corresponding veins, and by the spermatic plexuses of nerves. Fig. 151.* The spermatic arteries in the female descend into the pelvis, and pass between the two layers of the broad ligaments of the uterus, to be distributed to the ovaries, Fallopian tubes, and round ligaments; along the latter, they are continued to the inguinal canal and labium at each side. They inosculate with the uterine arteries. The Inferior Mesenteric Artery, smaller than the superior, arises from the abdominal aorta, about two inches below the origin of that vessel, and descends between the layers of the left mesocolon, to the left iliac fossa, where it divides into three branches: * The distribution and branches of the inferior mesenteric artery. 1, 1. The superior mesenteric artery, with its branches and the small intestines turned over to the right side. 2. The cecum and appendix cceci. 3. The ascending colon 4. The transverse colon raised upwards. 5. The descending colon. 6. Its sigmoid flexure. 7. The rectum. 8. The aorta. 9. The inferior mesenteric artery. 10. The colica sinistra, inosculating with, 11, the colica media, a branch of the superior mesenteric artery. U, U. Sigmoid branches. 13. The superior hemorrhoidal artery. 14. The pancreas. 15. The descend- ing portion of the duodenum. 338 RENAL—LUMBAR. Colica sinistra, Sigmoideae, Superior haemorrhoidal. The Colica sinistra is distributed to the descending colon, and ascends to inosculate with the colica media. This is the largest arterial inosculation in the body. The Sigmoidea are several large branches, which are distributed to the sigmoid flexure of the descending colon. They form arches, and inosculate above with the colica sinistra, and below with the superior haemorrhoidal artery. The Superior hamorrhoidal artery is the continuation of the inferior mesenteric. It crosses the ureter and common iliac artery of the left side, and descends between the two layers of the meso-rectum as far as the middle of the rectum, to which it is distributed, anasto- mosing with the middle and external haemorrhoidal arteries. The Supra-renal are two small vessels, which arise from the aorta, immediately above the renal arteries, and are distributed to the supra-renal capsules. They are sometimes branches of the phrenic or of the renal arteries. The Renal Arteries (emulgent) are two large trunks, given off from the sides of the aorta, immediately below the superior mesen- teric artery; the right is longer than the left, on account of the posi- tion of the aorta, and passes behind the vena cava to the kidney of that side. The left is somewhat higher than the right. They divide into several large branches, previously to entering the kidney, and ramify very minutely in its vascular portion. The renal arteries supply several small branches to the supra-renal capsules. The Lumbar Arteries correspond with the intercostals in the chest; they are four or five in number on each side, and curve around the bodies of the lumbar vertebrae beneath the psoas muscles, and divide into two branches; one of which passes backwards, be- tween the transverse processes, and is distributed to the vertebrae and spinal cord, and to the muscles of the back, whilst the other takes its course behind the quadratus lumborum muscle, and supplies the abdominal muscles. The first lumbar artery runs along the lower border of the last rib, and the last along the crest of the ilium. In passing between the psoas muscles and the vertebrae, they are protected by a series of tendinous arches, which defend them, and the communicating branches of the sympathetic nerve, from pres- sure during the action of the muscle. The Sacra Media arises from the posterior part of the aorta at its bifurcation, and descends along the middle of the anterior surface of the sacrum to the first piece of the coccyx where it terminates by inosculating with the lateral sacral arteries. It distributes branches to the rectum and anterior sacral nerves, and inosculates on either side with the lateral sacral arteries. Varieties in the Branches of the Abdominal Aorta.—The phrenic COMMON ILIAC. 339 arteries are very rarely both derived from the aorta. One or both may be branches of (he cceliac axis; one may proceed from the gastric artery, from the renal, or from the upper lumbar artery. There are occasionally three or more phrenic arteries. The coeliac axis is very variable in length, and gives off its branches irregularly. There are sometimes two or even three hepatic arteries, one of which may be derived from the gastric or even from the superior mesenteric. The colica media is sometimes derived from the hepatic artery. The spermatic arteries are very variable both in origin and number. The right spermatic may be a branch of the renal artery, and the left a branch of the inferior mesenteric. The supra-renal arteries may be derived from the phrenic or renal arteries. The renal arteries present several varieties in number; there may be three or even four arteries on one side, and one only on the other. When there are several renal arteries on one side, one may arise from the common iliac artery, from the front of the aorta near its lower part, or from the internal iliac. common iliac arteries. The abdominal aorta divides opposite the fourth lumbar vertebra into the two common iliac arteries. Sometimes the bifurcation takes place as high as the third, and occasionally as low as the fifth lumbar vertebra. The com- mon iliac arteries are about two inches and a half in length; they diverge from the ter- mination of the aorta, and pass downwards and outwards on each side to the margin of the pelvis opposite the sacro-iliac symphysis, where they divide into the internal and ex- ternal iliac arteries. In old persons the common iliac arteries course. * The distribution and branches of the iliac arteries. 1. The aorta. 2. The left common iliac artery. 3. The external iliac. 4. The epigastric artery. 5. The circumflexa ilii. 6. The internal iliac artery. 7. Its anterior trunk. 8. Its posterior trunk. 9. The umbi- lical artery giving off (10) the superior vesical artery. After the origin of this branch, the umbilical artery becomes converted into a fibrous cord—the umbilical ligament. 11. The internal pudic artery passing behind the spine of the ischium (12) and lesser sacro-ischiatic ligament. 13. The middle hemorrhoidal artery. 14. The ischiatic artery, also passing behind the anterior sacro-ischiatic ligament to escape from the pelvis. 15. Its inferior vesical branch. 16. The iliolumbar, the first branch of the posterior trunk (8) ascending to inosculate with the circumflexa ilii artery (5) and form an arch along the crest of the ilium. 17. The obturator artery. 18. The lateral sacral. 19. The gluteal artery escaping from the pelvis through the upper part of the great sacro-ischiatic foramen. 20. The sacra media. 21. The right common iliac artery cut short. 22. The femoral artery. are more or less dilated and curved in their 340 INTERNAL ILIAC. The Right common iliac is somewhat longer than the left, and forms a more obtuse angle with the termination of the aorta; the angle of bifurcation is greater in the female than in the male. Relations.—The relations of the two arteries are different on the two sides of the body. The right common iliac is in relation in front with the peritoneum, and is crossed at its bifurcation by the ureter. It is in relation posteriorly with the two common iliac veins, and externally with the psoas magnus. The left is in relation in front with the peritoneum, and is crossed by the rectum and superior haemorrhoidal artery, and at its bifurcation by the ureter. It is in relation behind with the left common iliac vein, and externally with the psoas magnus. internal iliac artery. The Internal Iliac Artery is a short trunk, varying in length from an inch to two inches. It descends obliquely to a point opposite the upper margin of the great sacro-ischiatic foramen, where it divides into an anterior and a posterior trunk. Relations.—This artery rests externally upon the sacral plexus and upon the origin of the pyriformis muscle; posteriorly it is in relation with the internal iliac vein, and anteriorly with the ureter. Branches.—The branches of the anterior trunk are the— Umbilical, Ischiatic, Middle vesical, Internal pudic. Middle haemorrhoidal, And in the female the— Uterine, Vaginal. And of the posterior trunk, the— Ilio-lumbar, Lateral sacral, Obturator, Gluteal. The umbilical artery is the commencement of the fibrous cord into which the umbilical artery of the foetus is converted after birth. In after life, the cord remains pervious for a short distance and consti- tutes the umbilical artery of the adult, from which the superior vesi- cal artery is given off to the fundus and anterior aspect of the blad- der. The cord may be traced forwards by the side of the fundus of the bladder to near its apex, whence it ascends by the side of the linea alba and urachus to the umbilicus. The Middle vesical artery is generally a branch of the umbilical, and sometimes of the internal iliac. It is somewhat larger than the superior vesical, and is distributed to the posterior part of the body of the bladder, the vesiculae seminales, and prostate gland. The Middle hamorrhoidal artery is as frequently derived from the ischiatic or internal pudic as from the internal iliac. It is of variable size, and is distributed to the rectum, base of the bladder, vesiculae seminales, and prostate gland; and inosculates with the superior and external haemorrhoidal arteries. The Ischiatic Artery is the larger of the two terminal branches INTERNAL PUDIC. 341 of the anterior division of the internal iliac. It passes downwards between the posterior border of the levator ani, and the pyriformis, resting upon the sacral plexus of nerves and lying behind the internal pudic artery, to the lower border of the great ischiatic notch, where it escapes from the pelvis below the pyriformis muscle. It then de- scends in the space between the trochanter major and the tuberosity of the ischium in company with the ischiatic nerves, and divides into branches. Its branches within the pelvis are hamorrhoidal which supply the rectum conjointly with the middle haemorrhoidal and sometimes take the place of that artery, and the inferior vesical which is distributed to the base and neck of the bladder, the vesiculae seminales, and prostate gland. The branches external to the pelvis are four in number, namely, coccygeal, inferior gluteal, comes nervi ischiatici, and muscular branches. The Coccygeal branch pierces the great sacro-ischiatic ligament, and is distributed to the coccygeus and levator ani muscles, and to the integument around the anus and coccyx. The Inferior gluteal branches supply the gluteus maximus muscle. The Comes nervi ischiatici is a small but regular branch, which accompanies the great ischiatic nerve to the lower part of the thigh. The Muscular branches supply the muscles of the posterior part of the hip and thigh, and inosculate with the internal and external cir- cumflex arteries, with the obturator, and with the superior perforating artery. The Internal Pudic Artery, the other terminal branch of the an- terior trunk of the internal iliac, descends in front of the ischiatic artery to the lower border of the great ischiatic foramen. It emerges from the pelvis through the great sacro-ischiatic foramen below the pyriformis muscle, crosses the spine of the ischium, and re-enters the pelvis through the lesser sacro-ischiatic foramen; it then crosses the internal obturator muscle to the ramus of the ischium, being situated at about an inch from the margin of the tuberosity, and bound down by the obturator fascia; it next ascends the ramus of the ischium, enters between the two layers of the deep perineal fascia lying along the border of the ramus of the os pubis, and at the symphysis pierces the anterior layer of the deep perineal fascia, and very much diminished in size reaches the dorsum of the penis along which it runs, supplying that organ under the name of the dorsalis penis. Branches.—The branches of the internal pudic artery within the pelvis are several small ramuscules to the base of the bladder, the vesiculae seminales, and the prostate gland; and hamorrhoidal branches which supply the middle of the rectum, and frequently take the place of the middle haemorrhoidal branch of the internal iliac. The ' anches, external to the pelvis, are the External haemorrhoidal, Arteria bulbosi, Superficialis perinei, Arteria corporis cavernosi, Transversalis perinei, Arteria dorsalis penis. 29* 342 INTERNAL PUDIC—BRANCHES. The External hamorrhoidal arteries are three or four small branches, given off by the internal pudic while behind the tuberosity of the ischium. They are distributed to the anus, and to the muscles, the fascia, and the integument in the anal region of the perineum. The Superficial perineal artery is given off near the attachment of the crus penis ; it pierces the connecting layer of the superficial and deep perineal fascia, and runs forward across the transversus perinei muscle, and along the groove between the accelerator urinae and erector penis to the septum scroti, upon which it ramifies under the name of arteria septi. It distributes branches to the scrotum, and to the perineum in its course forwards. One of the latter, larger than the rest, crosses the perineum, resting on the transversus perinei muscle, and is named the transversalis perinei. The Artery of the bulb is given off from the pudic nearly opposite the opening for the transmission of the urethra; it passes almost transversely inwards between the two layers of the deep perineal fas- cia, and pierces the anterior layer to enter the corpus spongiosum at its bulbous extremity. It is distributed to the corpus spongiosum. Fig. 153* The Artery of the corpus cavernosum pierces the crus penis, and runs forward in the interior of the corpus cavernosum, by the side of * The arteries of the perineum; on the right side the superficial arteries are seen, and on the left the deep. 1. The penis, consisting of corpus spongiosum and corpus caver- nosum. The crus penis on the left side is cut through. 2. The acceleratores urinaa muscles, enclosing the bulbous portion of the corpus spongiosum. 3. The erector penis, spread out upon the crus penis of the right side. 4. The anus, surrounded by the sphincter ani muscle. 5. The ramus of the ischium and os pubis. 6. The tuberosity of the ischium. 7. The lesser sacro-ischiatic ligament, attached by its small extremity to the spine of the ischium. 8. The coccyx. 9. The internal pudic artery, crossing the spine of the ischium, and entering the perineum. 10. External haemorrhoidal branches. 11. The superficialis perinei artery, giving off a small branch, transversalis perinei, upon the transversus perinei muscle. 12. The same artery on the left side cut off. 13. The artery of the bulb. 14. The two terminal brandies of the internal pudic artery; one is seen entering the divided extremity of the crus penis, the artery of the corpus cavernosum ; the other, the dorsalis penis, ascends upon the dorsum of the organ. INTERNAL PUDIC—BRANCHES. 343 the septum pectiniforme. It ramifies in the parenchyma of the venous structure of the corpus cavernosum. The Dorsal artery of the penis ascends between the two crura and symphysis pubis to the dorsum penis, and runs forward through the suspensory ligament in the groove of the corpus cavernosum to the glans, distributing branches in its course to the body of the organ and to the integument. The Internal pudic artery in the female is smaller than in the male; its branches, with their distribution, are in principle the same. The superficial perineal artery supplies the analogue of the lateral half of the scrotum, viz. the greater labium. The artery of the bulb supplies the meatus urinarius, and the vestibule ; the artery of the cor- pus cavernosum, the cavernous body of the clitoris, and the arteria dorsalis clitoridis, the dorsum of that organ. The Uterine and Vaginal arteries of the female are derived either from the internal iliac, or from the umbilical, internal pudic, or ischi- atic arteries. The former are very tortuous in their course, and as- cend between the layers of the broad ligament, to be distributed to the uterus. The latter ramify upon the exterior of the vagina, and supply its mucous membrane. Branches of the Posterior Trunk. The Ilio-lumbar artery ascends beneath the external iliac vessels and psoas muscle, to the posterior part of the crest of the ilium, where it divides into two branches, a lumbar branch which supplies the psoas and iliacus muscles, and sends a ramuscule through the fifth interver- tebral foramen to the spinal cord and its membranes ; and an iliac branch which passes along the crest of the ilium distributing branches to the iliacus and abdominal muscles, and inosculating with the lumbar and gluteal arteries, and with the circumflexa ilii. The Obturator Artery is exceedingly variable in point of origin; it generally proceeds from the posterior trunk of the internal iliac artery, and passes forwards a little below the brim of the pelvis to the upper border of the obturator foramen. It there escapes from the pelvis through a tendinous arch formed by the obturator membrane, and divides into two branches; an internal branch which curves in- wards around the bony margin of the obturator foramen, between the obturator externus muscle and the ramus of the ischium, and distri- butes branches to the obturator muscles, the pectineus, the adductor muscles, and to the organs of generation, and inosculates with the internal circumflex artery. And an external branch which pursues its course along the outer margin of the obturator foramen to the space between the gemellus inferior and quadratus femoris, where it inosculates with the ischiatic artery. In its course backwards it anastomoses with the internal circumflex, and sends a branch through the notch in the acetabulum to the hip-joint. Within the pelvis the obturator artery gives off a branch to the iliacus muscle, and a small ramuscule which inosculates with the epigastric artery. The Lateral Sacral Arteries are generally two in number on 344 EXTERNAL ILIAC. each side; superior and inferior. The superior passes inwards to the first sacral foramen and is distributed to the contents of the spinal canal, from which it escapes by the posterior sacral foramen, and supplies the integument on the dorsum of the sacrum. The inferior passes down by the side of the anterior sacral foramina to the coc- cyx ; it first pierces and then rests upon the origin of the pyriformis, and sends branches into the sacral canal to supply the sacral nerves. Both arteries inosculate with each other and with the sacra media. The Gluteal Artery is the continuation of the posterior trunk of the internal iliac: it passes backwards between the lumbo-sacral and first lumbar nerve through the upper part of the great sacro-ischiatic foramen, and above the pyriformis muscle, and divides into three branches, superficial, deep superior, and deep inferior. The Superficial branch is directed forwards, between the gluteus maximus and medius, and divides into numerous branches, which are distributed to the upper part of the gluteus maximus and to the inte- gument of the gluteal region. The Deep superior branch passes along the superior curved line of the ilium, between the gluteus medius and minimus to the anterior superior spinous process, where it inosculates with the superficial cir- cumflexa ilii and external circumflex artery. There are frequently two arteries which follow this course. The Deep inferior branches are several large arteries which cross the gluteus minimus obliquely to the trochanter major, where they inosculate with branches of the external circumflex artery, and send branches through the gluteus minimus to supply the capsule of the hip-joint. Varieties in the Branches of the Internal Iliac.—The most import- ant of the varieties occurring among these branches is the origin of the dorsal artery of the penis from the internal iliac or ischiatic. The artery in this case passes forwards by the side of the prostate gland, and through the upper part of the deep perineal fascia. It would be endangered in the operation of lithotomy. The dorsal artery of the penis is sometimes derived from the obturator, and sometimes from one of the external pudic arteries. The artery of the bulb, in its normal course, passes almost transversely inwards to the corpus spongiosum. Occasionally, however, it is so oblique in its direction as to render its division in lithotomy unavoidable. The obturator artery may be very small or altogether wanting, its place being sup- plied by a branch from the external iliac or epigastric. external iliac artery. The external iliac artery of each side passes obliquely downwards along the inner border of the psoas muscle, from opposite the sacro- iliac symphysis to the femoral arch, where it becomes the femoral artery. Relations.—It is in relation in front with the spermatic vessels, the peritoneum, and a thin layer of fascia, derived from the iliac fascia, which surrounds the artery and vein. At its commencement it is EXTERNAL ILIAC—BRANCHES. 345 crossed by the ureter, and near its termination by the crural branch of the genito-crural nerve and the circumflexa ilii vein. Externally it lies against the psoas muscle, from which it is separated by the iliac fascia; and posteriorly it is in relation with the external iliac vein, which, at the femoral arch, becomes placed to its inner side. The artery is surrounded throughout the whole of its course by lymphatic vessels and glands. Branches.—Besides several small branches which supply the glands surrounding the artery, the external iliac gives off two branches, the— Epigastric, Circumflexa ilii. The Epigastric artery arises from the external iliac near Pou- part's ligament; and passing forwards between the peritoneum and transversalis fascia, ascends obliquely to the border of the sheath of the rectus. It enters the sheath near its lower third, passes upwards behind the rectus muscle, to which it is distributed, and in the sub- stance of that muscle inosculates near the ensiform cartilage with the termination of the internal mammary artery. It lies internally to the internal abdominal ring and immediately above the femoral ring, and is crossed near its origin by the vas deferens in the male, and by the round ligament in the female. The only branches of the epigastric artery worthy of distinct notice are the Cremasteric, which accompanies the spermatic cord and sup- plies the cremaster muscle; and the ramusculus which inosculates with the obturator artery. The epigastric artery forms a prominence of the peritoneum which divides the iliac fossa into an internal and an external portion; it is from the former that direct inguinal hernia issues, and from the latter, oblique inguinal hernia. :> ":-y\ The Circumflexa ilii arises from the outer side of the external iliac, nearly opposite the epigastric artery. It ascends obliquely along Poupart's ligament, and curving around the crest of the ilium between the attachments of the internal oblique and transversalis muscle, inos- culates with the ilio-lumbar and inferior lumbar artery. Opposite the anterior superior spinous process of the ilium, it gives off a large ascending branch which passes upwards between the internal oblique and transversalis, and divides into numerous branches which supply the abdominal muscles, and inosculate with the inferior intercostal and with the lumbar arteries. Varieties in the Branches of the External Iliac. — The epigastric artery not unfrequently* gives off the obturator, which descends in contact with the external iliac vein, to the obturator foramen. In this situation the artery would lie to the outer side of the femoral ring, and would not be endangered in the operation for dividing the stricture of femoral hernia. But occasionally the obturator passes * The proportion in which high division of the obturator artery from the epigastric occurs, is stated to be one in three. In two hundred and fifty subjects examined by Clo- quet with a view to ascertain how frequently the high division took place, he found the obturator arising from the epigastric on both sides one hundred and fifty times ; on one side twenty-eight times, and six times it arose from the femoral artery. 346 FEMORAL. along the free margin of Gimbernat's ligament, in its course to the obturator foramen, and would completely encircle the neck of the hernial sac; a position in which it could scarcely escape the knife of the operator. In a preparation in my anatomical collection, the branch of communication between the epigastric and obturator arteries is very much enlarged, and takes this dangerous course. FEMORAL ARTERY. Fig. 154.: Emerging from beneath Poupart's ligament, the external iliac artery enters the thigh and becomes the femoral. The femoral artery passes down the inner side of the thigh, from Poupart's ligament, at a point midway between the anterior superior spinous process of the ilium and the symphysis pubis, to the opening in the adductor magnus, at the junction of the middle with the inferior third of the thigh, where it becomes the popliteal artery. The femoral artery and vein are enclosed in a strong sheath, femoral or crural canal, which is formed for the greater part of its extent by aponeurotic and areolar tissue, and by a process of fascia, sent inwards from the fascia lata. Near Poupart's ligament, this sheath is much larger than the vessels it contains and is continuous with the fascia transversalis, and iliac fascia. If the sheath be opened at this point, the artery will be seen to be situ- ated in contact with the outer wall of the sheath. The vein lies next the artery, being separated from it by a fibrous septum, and be- tween the vein and the inner wall of the sheath, and divided from the vein by another thin fibrous septum, is a triangular interval, into which the sac is protruded in femoral hernia. This space is occupied, in the normal state of the parts, by loose areolar tissue, and by lym- phatic vessels, which pierce the inner wall of the sheath, to make their way to a gland, situated in the femoral ring. * A view of the anterior and inner aspect of the thigh, showing the course and branches of the femoral artery. 1. The lower part of the aponeurosis of the external oblique muscle; its inferior margin is Poupart's ligament. 2. The external abdominal ring. 3, 3. The upper and lower part of the sartorius muscle ; its middle portion having been removed. 4. The rectus. 5. The vastus internus. 6. The patella. 7. The iliacus and psoas; the latter being nearest the artery. 8. The pectineus. 9. The adductor longus. 10. The tendinous canal for the femoral artery formed by the adductor magnus, and vastus internus muscles. 11. The adductor magnus. 12. The gracilis. 13. The tendon of the semi-tendinosus. 14. The femoral artery. 15. The superficial circumflexa ilii artery taking its course along the line of Poupart's ligament, to the crest of the ilium. 2. The superficial epigastric artery. 16. The two external pudic arteries, superficial and deep. 17. The profunda artery, giving off 18, its external circumflex branch ; and lower down the three perforantes. A small bend of the internal circumflex artery (8) is seen behind the inner margin of the femoral, just below the deep external pudic artery. 19. The anastomotica magna, descending to the knee, upon which it ramifies (6). FEMORAL. 347 Relations.—The upper third of the femoral artery is superficial, being covered only by the integument, inguinal glands, and by the superficial and deep fasciae. The lower two-thirds are covered by the sartorius muscle. To its outer side, the artery is first in relation with the psoas and iliacus, and then with the vastus internus. Behind, it rests upon the inner border of the psoas muscle; it is next separated from the pectineus by the femoral vein, profunda vein and artery, and then lies on the adductor longus to its termination: near the lower border of the adductor longus, it is placed in an aponeurotic canal, formed by an arch of tendinous fibres, thrown from the border of the adductor longus and the border of the opening in the adductor mag- nus, to the side of the vastus internus. To its inner side, it is in rela- tion at its upper part with the femoral vein, and lower down, with the pectineus, adductor longus, and sartorius. The immediate relations of the artery are the femoral vein, and two saphenous nerves. The vein at Poupart's ligament lies to the inner side of the artery; but lower down gets altogether behind it, and inclines to its outer side. The short saphenous nerve lies to the outer side, and somewhat upon the sheath for the lower two-thirds of its extent; and the long saphenous nerve is situated within the sheath, and in front of the artery for the same extent. Plan of the Relations of the Femoral Artery. Front. Fascia lata, Saphenous nerves, Sartorius, Arch of the tendinous canal. Inner Side. Femoral vein, Pectineus, Adductor longus, Sartorius. Femoral artery. Outer Side. Psoas, Iliacus, Vastus internus. Behind. Psoas muscle, Femoral vein, Adductor longus. Branches.—The branches of the Femoral Artery are the- Superficial circumflexa ilii, Superficial epigastric, Profunda Superficial external pudic, Deep external pudic, Muscular, Anastomotica magna. External circumflex, Internal circumflex, Three perforating, The Superficial circumflexa ilii artery arises from the femoral, immediately below Poupart's ligament, pierces the fascia lata, and passes obliquely outwards towards the crest of the ilium. It sup- plies the integument of the groin, the superficial fascia, and inguinal glands. The Superficial epigastric arises from the femoral, immediately 348 PROFUNDA. below Poupart's ligament, pierces the fascia lata, and ascends ob- liquely towards the umbilicus, between the two layers of superficial fascia. It distributes branches to the inguinal glands and integument, and inosculates with branches of the deep epigastric and internal mammary artery. The Superficial external pudic arises near the superficial epigastric artery; it pierces the fascia lata, at the saphenous opening, and passes transversely inwards, crossing the spermatic cord, to be dis- tributed to the integument of the penis and scrotum in the male, and to the labia in the female. The Deep external pudic arises from the femoral, a little lower down than the preceding: it crosses the femoral vein immediately below the termination of the internal saphenous vein, and piercing the pubic portion of the fascia lata, passes beneath that fascia to the inner border of the thigh, where it again pierces the fascia; having become superficial, it is distributed to the integument of the scrotum and perineum. The Profunda Femoris arises from the femoral artery at two inches below Poupart's ligament: it passes downwards and back- wards and a little outwards, behind the adductor longus muscle, pierces the adductor magnus, and is distributed to the flexor muscles on the posterior part of the thigh. Relations.—In its course downwards it rests successively upon the pectineus, the conjoined tendon of the psoas and iliacus, adductor brevis, and adductor magnus muscles. To its outer side, the tendi- nous insertion of the vastus internus muscle intervenes between it and the femur; on its inner side it is in relation with the pectineus, ad- ductor brevis and adductor magnus; and in front it is separated from the femoral artery, above, by the profunda vein and femoral vein, and below, by the adductor longus muscle. Plan of the relations of the Profunda Artery. In Front. Profunda vein, Adductor longus. Inner Side. Pectineus, Adductor brevis, Adductor magnus. Profunda artery. Outer Side. Psoas and iliacus, Vastus internus, Femur. Behind. Pectineus, Tendon of psoas and iliacus, Adductor brevis, Adductor magnus. Branches.—The branches of the profunda artery are the external circumflex, internal circumflex, and three perforating arteries. The External circumflex artery passes obliquely outwrards between the divisions of the crural nerve, then between the rectus and crureus muscle, and divides into three branches ; ascending, which inosculates with the terminal branches of the gluteal artery ; descending, which POPLITEAL. 349 inosculates with the superior external articular artery; and middle, which continues the original course of the artery around the thigh, and anastomoses with branches of the ischiatic, internal circumflex, and superior perforating artery. It supplies the muscles on the ante- rior and outer side of the thigh. The Internal circumflex artery is larger than the external; it winds around the inner side of the neck of the femur, passing between the pectineus and psoas, and along the border of the external obturator muscle, to the space between the quadratus femoris and upper border of the adductor magnus, where it anastomoses with the ischiatic, ex- ternal circumflex, and superior perforating artery. It supplies the muscles on the upper and inner side of the thigh, anastomosing with the obturator artery, and sends a small branch through the notch in the acetabulum into the hip-joint. The Superior perforating artery passes backwards between the pec- tineus and adductor brevis, pierces the adductor magnus near the femur, and is distributed to the posterior muscles of the thigh; inos- culating freely with the circumflex and ischiatic arteries, and with the branches of the middle perforating artery. The Middle perforating artery pierces the tendons of the adductor brevis and magnus, and is distributed like the superior; inosculating with the superior and inferior perforantes. This branch frequently gives off the nutritious artery of the femur. The Inferior perforating artery is given off below the adductor brevis, and pierces the tendon of the adductor magnus, supplying it and the flexor muscles, and inosculating with the middle perforating artery above, and with the articular branches of the popliteal below. It is through the medium of these branches that the collateral circulation is maintained in the limb after ligature of the femoral artery. The Muscular branches are given off by the femoral artery through out the whole of its course. They supply the muscles in immediate proximity with the artery, particularly those of the anterior aspect of the thigh. One of these branches, larger than the rest, arises from the femoral immediately below the origin of the profunda, and passing outwards between the rectus and sartorius divides into branches which are distributed to all the muscles of the anterior aspect of the thigh. This may be named the superior muscular artery. The Anastomotica magna arises from the femoral while in the ten- dinous canal formed by the adductors and vastus internus. It runs along the tendon of the adductor magnus to the inner condyle, and inosculates with the superior internal articular artery: some of its branches are distributed to the vastus internus muscle and to the cru- reus, and terminate by anastomosing with the branches of the exter- nal circumflex and superior external articular artery. popliteal artery. The popliteal artery commences from the termination of the femoral at the opening in the adductor magnus muscle, and passes obliquely outwards through the middle of the popliteal space to the lower 30 350 POPLITEAL—BRANCHES. border of the popliteus muscle, where it divides into the anterior and posterior tibial artery. Relations.—In its course downwards it rests first on the femur, then on the posterior ligament of the knee-joint, then on the fascia covering the popliteus muscle. Superficially it is in relation with the semi-membranosus muscle, next with a quantity of fat which sepa- rates it from the deep fascia, and near its termination with the gas- trocnemius, plantaris, and soleus; superficial and external to it is the popliteal vein, and still more superficial and external, the popliteal nerve. By its inner side it is in relation with the semi-membranosus, internal condyle of the femur, and inner head of the gastrocnemius; and by its outer side with the biceps, external condyle of the femur, the outer head of the gastrocnemius, the plantaris and the soleus. Plan of the relations of the Popliteal Artery. Superficially. Semi-membranosus, Popliteal nerve, Popliteal vein, Gastrocnemius, Plantaris, Soleus. Inner Side. Semi-membranosus, Internal condyle, Gastrocnemius. Popliteal artery. Outer Side. Biceps, External condyle, Gastrocnemius, Plantaris, Soleus. Deeply. Femur, Ligamentum posticum Winslowii, Popliteal fascia. Branches.—The branches of the popliteal artery are the Superior external articular, Inferior external articular, Superior internal articular, Inferior internal articular, Azygos articular, Sural. The Superior articular arteries, external and internal, wind around the femur immediately above the condyles, to the front of the knee- joint, anastomosing with each other, with the external circumflex, the anastomotica magna, the inferior articular, and the recurrent of the anterior tibial. The external passes beneath the tendon of the biceps, and the internal through an arched opening beneath the tendon of the adductor magnus. They supply the knee-joint and the lower part of the femur. The Azygos articular artery pierces the posterior ligament of the joint, the ligamentum posticum Winslowii, and supplies the synovial membrane in its interior. There are frequently several posterior arti- cular arteries. The Inferior articular arteries wind around the head of the tibia immediately below the joint, and anastomose with each other, the superior articular arteries, and the recurrent of the anterior tibial. The external passes beneath the two external lateral ligaments of the ANTERIOR TIBIAL. 351 joint, and the internal beneath the internal lateral ligament. They supply the knee-joint and the heads of the tibia and fibula. The Sural arteries (sura, the calf) are two large muscular branches, which are distributed to the two heads of the gastrocnemius muscle. anterior tibial artery. The anterior tibial artery passes forwards be- tween the two heads of the tibialis posticus muscle, and through the opening in the upper part of the interosseous membrane, to the anterior tibial re- gion. It then runs down the anterior aspect of the leg to the ankle-joint, where it becomes the dorsalis pedis. Relations.—In its course downwards it rests upon the interosseous membrane (to which it is connect- ed by a little tendinous arch which is thrown across it), the lower part of the tibia, and the anterior ligament of the joint. In the upper third of its course it is situated between the tibialis anticus and extensor longus digitorum, lower down be- tween the tibialis anticus and extensor proprius pollicis; and just before it reaches the ankle it is crossed by the tendon of the extensor proprius pol- licis, and becomes placed between that tendon and the tendons of the extensor longus digitorum. Its immediate relations are the venae comites and the anterior tibial nerve, which latter lies at first to its outer side, and at about the middle of the leg be- comes placed superficially to the artery. Plan of the relations of the Anterior Tibial Artery. Front. Deep fascia, Tibialis anticus, Extensor longus digitorum, Extensor proprius pollicis, Anterior tibial nerve. Fig. 155.* Inner Side. Tibialis anticus, Tendon of the exten- sor proprius pollicis. Anterior tibial artery. Outer Side. Anterior tibial nerve, Extensor longus digitorum, Extensor proprius pollicis, Tendons of the extensor longus digitorum. Behind. Interosseous membrane, Tibia (lower fourth), Ankle-joint. * The anterior aspect of the leg and foot, showing the anterior tibial and dorsalis pedis arteries, with their branches. 1. The tendon of insertion of the quadriceps extensor muscle. 2. The insertion of the ligamentum patella? into the lower border of the patella. 3. The tibia. 4. The extensor proprius pollicis muscle. 5. The extensor longus digito- 352 DORSALIS PEDIS. Branches.—The branches of the Anterior Tibial Artery are the— Recurrent, External malleolar, Muscular, Internal malleolar. The Recurrent branch passes upwards beneath the origin of the tibialis anticus muscle to the front of the knee-joint, upon which it is distributed, anastomosing with the articular arteries. The Muscular branches are very numerous, they supply the mus- cles of the anterior tibial region. The Malleolar arteries are distributed to the ankle-joint; the external, passing beneath the tendons of the extensor longus digito- rum and peroneus tertius, inosculates with the anterior peroneal artery and with the branches of the dorsalis pedis; the internal, beneath the tendons of the extensor proprius pollicis and tibialis anticus, inosculates with branches of the posterior tibial and internal plantar artery. They supply branches to the ankle-joint. The Dorsalis Pedis Artery is continued forward along the tibial side of the dorsum of the foot, from the ankle to the base of the metatarsal bone of the great toe, where it divides into two branches, the dorsalis hallucis and communicating. Relations.—The dorsalis pedis is situated along the outer border of the tendon of the extensor proprius pollicis; on its fibular side is the innermost tendon of the extensor longus digitorum, and near its termination it is crossed by the inner tendon of the extensor brevis digitorum. It is accompanied by venae comites, and has the conti- nuation of the anterior tibial nerve to its outer side. Plan of the relations of the Dorsalis Pedis Artery. In Front. Integument, Deep fascia, Inner tendon of the extensor brevis digitorum. Inner Side. Tendon of the ex- tensor proprius pollicis. Dorsalis Pedis Artery. Outer Side. Tendon of the extensor longus digitorum, Border of the extensor brevis digitorum muscle; Behind. Bones of the tarsus, with their ligaments. Branches.—The branches of this artery are the— Tarsea, Dorsalis hallucis,—collateral digital, Metatarsea,—interosseae, Communicating. rum. 6. The peronei muscles. 7. The inner belly of the gastrocnemius and the soleus. 8. The annular ligament beneath which the extensor tendons and the anterior tibial artery pass into the dorsum of the foot. 9. The anterior tibial artery. 10. Its recurrent branch inosculating with (2) the inferior articular, and (1) the superior articular arteries, branches of the popliteal. 11. The internal malleolar artery. 17. The external malleolar inosculating with the anterior peroneal artery 12. 13. The dorsalis pedis artery. 14. The tarsea and metatarsea arteries ; the tarsea is nearest the ankle, the metatarsea is seen giving off the interosseae. 15. The dorsalis hallucis artery. 16. The communicating' branch. POSTERIOR TIBIAL. 353 The Tarsea arches transversely across the tarsus, beneath the extensor brevis digitorum muscle, and supplies the articulations of the tarsal bones and the outer side of the foot; it anastomoses with the external malleolar, the peroneal arteries, and the external plantar. The Metatarsea forms an arch across the base of the metatarsal bones, and supplies the outer side of the foot, anastomosing with the tarsea and with the external plantar artery. The metatarsea gives "off three branches, the interossea, which pass forward upon the dorsal interossei muscles, and divide into two collateral branches for adjoining toes. At their commencement these interosseous branches receive the posterior perforating arteries from the plantar arch, and opposite the heads of the metatarsal bones they are joined by the anterior perforating branches from the digital arteries. The Dorsalis hallucis runs forward upon the first dorsal interosseous muscle, and at the base of the first phalanx divides into two branches, one of which passes inwards beneath the tendon of the extensor proprius pollicis, and is distributed to the inner border of the great toe, while the other bifurcates for the supply of the adjacent sides of the great and second toes. The Communicating artery passes into the sole of the foot between the two heads of the first dor- sal interosseous muscle, and inosculates with the termination of the external plantar artery. Besides the preceding, numerous branches are distributed to the bones and articulations of the foot, particularly along the inner border of the latter. 'V POSTERIOR TIBIAL ARTERY. f^ ^ The posterior tibial artery passes obliquely down- wards along the tibial side of the leg from the lower border of the popliteus muscle to the concavity of the os calcis, where it divides into the internal and external plantar artery- Relations.—In its course downwards it lies first upon the tibialis posticus, next upon the flexor longus digitorum, and then upon the tibia; it is covered in by the intermuscular fascia which se- parates it above from the soleus, and below from the deep fascia of the leg and the integument. It is accompanied by its venae comites, and by the * A posterior view of the leg, showing the popliteal and posterior tibial artery. 1. The tendons forming the inner hamstring. 2. The tendon of the biceps forming the outer hamstring. 3. The popliteus muscle. 4. The flexor longus digitorum. 5. The tibialis posticus. 6. The fibula; immediately below the figure is the origin of the flexor longus pollicis; the muscle has been removed in order to expose the peroneal artery. 7. The peronei muscles, longus and brevis. 8. The lower part of the flexor longus pollicis muscle with its tendon. 9. The popliteal artery giving off its articular and muscular brandies; the two superior articular are seen in the upper part of the popliteal space passing above 30* 354 PERONEAL. posterior tibial nerve, which latter lies at first to its outer side, then superficially to it, and again to its outer side. Plan of the relations of the Posterior Tibial Artery. Superficially, Soleus, Deep fascia, The intermuscular fascia. Inner Side. Vein. Posterior Tibial Artery. Outer Side. Posterior tibial nerve, Vein. Deeply. Tibialis posticus, Flexor longus digitorum, Tibia. Branches.—The branches of the posterior tibial artery are the— Peroneal, Internal calcanean, Nutritious, Internal plantar, Muscular, External plantar. The Peroneal artery is given off from the posterior tibial at about two inches below the lower border of the popliteus muscle; it is nearly as large as the anterior tibial artery, and passes obliquely out- wards to the fibula. It then runs downwards along the inner border of the fibula to its lower third, where it divides into the anterior and posterior peroneal artery. Relations.—The peroneal artery rests upon the tibialis posticus muscle, and is covered in by the soleus, the intermuscular fascia, and the flexor longus pollicis, having the fibula to its outer side. Plan of the relations of the Peroneal Artery. In Front. Soleus, Intermuscular fascia, Flexor longus pollicis. Outer Side. Fibula. Behind. Tibialis posticus. Branches.—The branches of the peroneal artery are muscular to the neighbouring muscles, particularly to the soleus, and the two ter- minal branches anterior and posterior peroneal. the two heads of the gastrocnemius muscle, which are cut through near their origin The two inferior are in relation with the popliteus muscle. 10. The anterior tibial arterv passing through the angular interspace between the two heads of the tibialis posticus muscle 11. The posterior tibial artery. 12. The relative position of the tendons and artery at the inner ankle from within outwards, previously to their passing beneath the internal annular ligament. 13. The peroneal artery, dividing into two branches • the anterior peroneal is seen piercing the interosseous membrane. 14 The posterior PLANTAR. 355 The Anterior peroneal pierces the interosseous membrane at the lower third of the leg, and is distributed on the front of the outer malleolus, anastomosing with the external malleolar and tarsal artery. This branch is very variable in size. The Posterior peroneal continues onwards along the posterior aspect of the outer malleolus to the side of the os calcis, to which and to the muscles arising from it, it distributes external calcanean branches. It anastomoses with the anterior peroneal, tarsal, external plantar, and posterior tibial artery. The Nutritious artery of the tibia arises from the trunk of the tibial, frequently above the origin of the peroneal, and proceeds to the nutritious canal which it traverses obliquely from below upwards. The Muscular branches of the posterior tibial artery are distributed to the soleus and to the deep muscles on the posterior aspect of the leg. One of these branches is deserving of notice, a recurrent branch, which arises from the posterior tibial above the origin of the peroneal artery, pierces the soleus and is distributed upon the inner side of the head of the tibia, anastomosing with the inferior internal articular. The Internal calcanean branches, three or four in number, proceed from the posterior tibial artery immediately before its division; they are distributed to the inner side of the os calcis, to the integument, and to the muscles which arise from its inner tuberosity, and they anastomose with the ex- ternal calcanean branches, and with all the neighbouring arteries. PLANTAR ARTERIES. The Internal plantar artery proceeds from the bifurcation of the posterior tibial at the inner malleolus and passes along the inner border of the foot between the abductor pol- licis and flexor brevis digitorum muscles, sup- plying the inner border of the foot and great toe. The External plantar artery, much larger than the internal, passes obliquely outwards, between the first and second layers of the plan- tar muscles, to the fifth metatarsal space. It then turns horizontally inwards, between the second and third layers, to the first metatarsal space, where it inosculates with the communi- cating branch from the dorsalis pedis. The horizontal portion of the artery describes a slight curve, having the convexity forwards; this is the plantar arch. * The arteries of the sole of the foot; the first and a part of the second layer of muscles having been removed. 1. The under and posterior part of the os calcis; to which the origins of the first layer of muscles remain attached. 2. The musculus accessorius. 3. The long flexor tendons. 4. The tendon of the peroneus longus. 5. The termination of the posterior tibial artery. 6. The internal plantar. 7. The external plantar artery. 8. The plantar arch giving off four digital branches, which pass forwards on the inter- ossei muscles to divide into collateral branches. 35G VARIETIES IN THE ARTERIES OF THE LOWER EXTREMITY. Branches.—The branches of the external plantar artery are the— Muscular, • Digital,—anterior perforating, Articular, Posterior perforating. The Muscular branches are distributed to the muscles in the sole of the foot. The Articular branches supply the ligaments of the articulations of the tarsus, and their synovial membranes. The Digital branches are four in number:—the first is distributed to the outer side of the little toe; the three others pass forwards to the cleft between the toes and divide into collateral branches, which supply the adjacent sides of the three external toes, and the outer side of the second. At the bifurcation of the toes, a small branch is sent upwards from each digital artery, to inosculate with the interos- seous branches of the metatarsea ; these are the anterior perforating arteries. The Posterior perforating are three small branches, which pass upwards, beneath the heads of the three external dorsal interossei muscles, to inosculate with the arch formed by the metatarsea artery. Varieties in the Arteries of the Lower Extremity.—The femoral artery occasionally divides at Poupart's ligament into two branches, and sometimes into three; the former is an instance of the high divi- sion of the profunda artery; and in a case of the latter kind which occurred during my dissections, the branches were the profunda, the superficial femoral, and internal circumflex artery. Dr. Quain, in his "Elements of Anatomy," records an instance of a high division of the femoral artery, in which the two vessels became again united in the popliteal region. The point of origin of the profunda artery varies considerably in different subjects, being sometimes nearer to, and sometimes farther from, Poupart's ligament, but more frequently the former. The branches of the popliteal artery are very liable to variety in size; and in all these cases the compensating principle, so constant in the vascular system, is strikingly manifested. When the anterior tibial is of small size, the peroneal is large; and, in place of dividing into two terminal branches at the lower third of the leg, de- scends to the lower part of the interosseous membrane, and emerges upon the front of the ankle, to supply the dorsum of the foot: or the posterior tibial and plantar arteries are large, and the external plantar is continued between the heads of the first dorsal interosseous muscle, to be distributed to the dorsal surface of the foot. Sometimes the posterior tibial artery is small and thread-like; and the peroneal, after descending to the ankle, curves inwards to the inner malleolus, and divides into the two plantar arteries. If in this case the posterior tibial be sufficiently large to reach the ankle, it inosculates with the peroneal, previously to its division. The internal plantar artery sometimes takes the distribution of the external plantar, which is short and diminutive, and the latter not unfrequently replaces a defi- cient dorsalis pedis. The varieties of arteries are interesting in the practical application PULMONARY. 357 of a knowledge of their principal forms to surgical operations; in their transcendental anatomy, as illustrating the normal distribution in animals; or in many cases, as diverticula permitted by Nature, to teach her observers two important principles:—first, in respect to herself, that, however in her means she may indulge in change, the end is never overlooked, and a limb is as surely supplied by a leash of arteries, various in their course, as by those which we are pleased to consider normal in distribution: and secondly, with regard to us, that wc should ever be keenly alive to what is passing beneath our observation, and ever ready in the most serious operation to deviate from our course, and avoid—or give eyes to our knife, that it may see—the concealed dangers which it is our pride to be able to con- tend with and vanquish. PULMONARY ARTERY. The pulmonary artery arises from the left side of the base of the right ventricle, in front of the origin of the aorta, and ascends ob- liquely to the under surface of the arch of the aorta, where it divides into the right and left pulmonary arteries. In its course upwards and backwards, it inclines to the left side, crossing the commencement of the aorta, and is connected to the under surface of the arch by a liga- mentous cord, the remains of the ductus arteriosus. Relations.—It is enclosed for one half of its extent by the pericar- dium, and receives the attachment of the fibrous portion of the peri- cardium by its upper portion. Behind, it rests against the ascending aorta; on either side is the appendix of the corresponding auricle with a coronary artery; and above, the cardiac ganglion and the remains of the ductus arteriosus. The Right pulmonary artery passes beneath the arch and behind the ascending aorta, and in the root of the lungs divides into three branches for the three lobes. The Left pulmonary artery, rather larger than the right, passes in front of the descending aorta, to the root of the left lung, to which it is distributed. These arteries divide and subdivide in the structure of the lungs, and terminate in capillary vessels which form a network around the bronchial cells, and become continuous with the radicles of the pulmonary veins. Relations.—In the root of the right lung examined from above downwards, the pulmonary artery is situated between the bronchus, and pulmonary veins, the former being above, the latter below ; while in the left lung the artery is the highest, next the bronchus, and then the veins. On both sides, from before backwards, the artery is situ- ated between the veins and bronchi, the former being in front, and the latter behind. 358 OF THE VEINS. CHAPTER VII. OF THE VEINS. The veins are the vessels which return the blood to the auricles of the heart after it has been circulated by the arteries through the va- rious tissues of the body. They are much thinner in structure than the arteries, so that when emptied of their blood they become flattened and collapsed. The veins of the systemic circulation convey the dark-coloured and impure or venous blood from the capillary system to the right auricle of the heart, and they are found after death to be more or less distended with that fluid. The veins of the pulmonary circulation resemble the arteries of the systemic circulation in contain- ing during life the pure or arterial blood, which they transmit from the capillaries of the lungs to the left auricle. The veins commence by minute radicles in the capillaries which are every where distributed through the textures of the body, and con- verge to constitute larger and larger branches, till they terminate in the large trunks which convey the venous blood directly to the heart. In diameter they are larger than the arteries, and like those vessels their combined areae would constitute an imaginary cone, whereof the apex is placed at the heart, and the base at the surface of the body. It follows from this arrangement, that the blood in returning to the heart is passing from a larger into a smaller channel, and therefore that it increases in rapidity during its course. Veins admit of a threefold division, into superficial, deep, and sinuses. The Superficial veins return the blood from the integument and su- perficial structures, and take their course between the layers of the superficial fascia; they then pierce the deep fascia in the most con- venient and protected situations, and terminate in the deep veins. They are unaccompanied by arteries, and are the vessels usually se- < lected for venesection. The Deep veins are situated among the deeper structures of the body and generally in relation with the arteries; in the limbs they are enclosed in the same sheath with those vessels, and they return the venous blood from the capillaries of the deep tissues. In company with all the smaller, and also with the secondary arteries, as the bra- chial, radial, and ulnar in the upper, and the tibial and peroneal in the lower extremity, there are two veins, placed one on each side of the artery, and named vena comites. The larger arteries, as the axillary, subclavian, carotid, popliteal, femoral, &c, are accompanied by a single venous trunk. Sinuses differ from veins in their structure; and also in their mode of distribution, being confined to especial organs and situated within their substance. The principal venous sinuses are those of the dura mater, the diploe, the cancellous structure of bones, and the uterus. STRUCTURE OF VEINS. 359 The communications between veins are even more frequent than those of arteries, and they take place between the larger as well as among the smaller vessels ; the venae comites communicate with each other very frequently in their course, by means of short trans- verse branches which pass across from one to the other. These communications are strikingly exhibited in the frequent inosculations of the spinal veins, and in the various venous plexuses, as the sper- matic plexus, vesical plexus, &c. The office of these inosculations is very apparent, as tending to obviate the obstructions to which the veins are particularly liable from the thinness of their coats, and from their inability to overcome much impediment by the force of their current. Veins, like arteries, are composed of three coats, external or cellulo- fibrous, middle or fibrous, and internal or serous. The external coat is firm and strong, and resembles that of arteries. The middle coat consists of two layers, an outer layer of contractile fibrous tissue disposed in a circular direction around the vessel, and an inner layer of organic muscular fibres arranged longitudinally. This latter re- sembles the inner layer of the middle coat of arteries, but is some- what thicker, and is not unfrequently hypertrophied. The internal coat as in arteries, consists of a striated or fenestrated layer, and a layer of epithelium ; it is continuous with the internal coat of arteries through the medium of the lining membrane of the heart on the one hand, and through the capillary vessels on the other. The differences in structure, therefore, between arteries and veins relate to the diffe- rence of thickness of their component layers, and to the absence of the elastic coat in the latter. Moreover, another difference occurs in the presence of valves. The valves of veins are composed of a thin layer of fibrous membrane, lined upon its two surfaces by epithelium. The segments or flaps of the valves of veins are semilunar in form and arranged in pairs, one upon either side of the vessel; in some in- stances there is but a single flap, which has a spiral direction, and occasionally there are three. The free border of the valvular flaps is concave, and directed forwards, so that while the current of blood ,is permitted to flow freely towards the heart, the valves are distended and the current intercepted if the stream becomes retrograde in its course. Upon the cardiac side of each valve the vein is expanded into two pou«hes (sinuses), corresponding with the flaps of the valves, which give to the distended or injected vein a knotted appearance. The valves are most numerous in the veins of the extremities, parti- cularly in the deeper veins, and they are generally absent in the very small veins, and in the veins of the viscera, as in the portal and cere- bral veins: they are also absent in the large trunks, as in the venae cava?, venae azygos, innominatae, and iliac veins. Sinuses are venous channels, excavated in the structure of an organ, and lined by the internal coat of the veins; of this structure are the sinuses of the dura mater, whose external covering is the fibrous tissue of the membrane, and the internal the serous layer of the veins. The external investment of the sinuses of the uterus is the 360 VEINS OF THE HEAD AND NECK. tissue of that organ; and that of the bones, the lining membrane of the cells and canals. Veins, like arteries, are supplied with nutritious vessels, the vasa vasorum; and it is to be presumed that nervous filaments are distri- buted in their coats. I shall describe the veins according to the primary division of the body; taking first, those of the head and neck; next, those of the upper extremity; then, those of the lower extremity; and lastly, the veins of the trunk. VEINS OF THE HEAD AND NECK. The veins of the head and neck may be arranged into three groups, viz. 1. Veins of the exterior of the head. 2. Veins of the diploe and interior of the cranium. 3. Veins of the neck. The veins of the exterior of the head are the— Facial, Temporo-maxillary, Internal maxillary, Posterior auricular, Temporal, Occipital. The Facial vein commences upon the anterior part of the skull in a venous plexus, formed by the communications of the branches of the temporal, and descends along the middle line of the forehead, under the name of frontal vein, to the root of the nose, where it is connected with its fellow of the opposite side by a communicating trunk which constitutes the nasal arch. There are usually two frontal veins which communicate by a transverse inosculation; but sometimes the vein is single and bifurcates at the root of the nose, into the two angular veins. From the nasal arch, the frontal is continued down- wards by the side of the root of the nose, under the name of the angular vein; it then passes beneath the zygomatic muscles and becomes the facial vein, and descends along the anterior border of the masseter muscle, crossing the body of the lower jaw, by the side of the facial artery, to the submaxillary gland, and from thence to the internal jugular vein in which it terminates. The branches which the facial vein receives in its course are, the supra-orbital, which joins the frontal vein; the dorsal veins of the nose which terminate in the nasal arch; the ophthalmic, which com- municates with the angular vein ; the palpebral and nasa?, which open into the angular vein; a considerable trunk, the alveolar, which re- turns the blood from the spheno-maxillary fossa, and from the infra- orbital, palatine, vidian, and spheno-palatine veins, and joins the facial beneath the zygomatic process of the superior maxillary bone, and the veins corresponding with the branches of the facial artery. The Internal maxillary vein receives the branches from the zygo- matic and pterygoid fossae; these are so numerous and communicate so freely as to constitute a pterygoid plexus. Passing backwards behind the neck of the lower jaw, the internal maxillary joins with the temporal vein, and the common trunk resulting from this union constitutes the temporo-maxillary vein. The Temporal vein commences on the vertex of the head by a VEINS OF THE DIPLOE. 361 plexiform network which is continuous with the frontal, the temporal, auricular and occipital veins. The ramifications of this plexus form an anterior and a posterior branch which unite immediately above the zygoma; the trunk is here joined by another large vein, the middle temporal, which collects the blood from the temporal muscle, and around the outer segment of the orbit, and pierces the temporal fascia near the root of the zygoma. The temporal vein then descends between the meatus auditorius externus and the condyle of the lower jaw, and unites with the internal maxillary vein, to form the temporo- maxillary. The Temporo-maxillary vein formed by the union of the temporal and internal maxillary, passes downwards in the substance of the parotid gland to its lower border, where it becomes the external jugular vein. It receives in its course the anterior auricular, masse- teric, transverse facial, and parotid veins, and near its termination is joined by the posterior auricular vein. The Posterior auricular vein communicates with the plexus upon the vertex of the head, and descends behind the ear to the temporo- maxillary vein, immediately before that vessel merges in the external jugular. It receives in its course the veins from the external ear and the stylo-mastoid vein. The Occipital vein commencing posteriorly in the plexus of the vertex of the head, follows the direction of the occipital artery, and passing deeply beneath the muscles of the back part of the neck, ter- minates in the internal jugular vein. This vein communicates with the lateral sinus by means of a large branch which passes through the mastoid foramen, the mastoid vein. VEINS OF THE DIPLOE. • The diploe of the bones of the head is furnished in the adult with irregular sinuses, which are formed by a continuation of the internal coat of the veins into the osseous canals in which they are lodged. At the middle period of life these sinuses are confined to the particular bones; but in old age, after the ossification of the sutures, they may be traced from one bone to the next. They receive their blood from the capillaries supplying the cellular structure of the diploe, and ter- minate externally in the veins of the pericranium, and internally in the veins and sinuses of the dura mater. These veins are separated from the bony walls of the canals by a thin layer of medulla. CEREBRAL AND CEREBELLAR VEINS. The cerebral veins are remarkable for the absence of valves, and for the extreme tenuity of their coats. They may be arranged into the superficial, and deep or ventricular veins. The Superficial cerebral veins are situated upon the surface of the hemispheres, lying in the grooves formed by the convexities of the convolutions. They are named from the position which they may chance to occupy upon the surface of this organ, either superior or inferior, internal or external, anterior or posterior. The Superior cerebral veins, seven or eight in number on each side, 31 362 SINUSES OF THE DURA MATER. pass obliquely forwards, and terminate in the superior longitudinal sinus, in the opposite direction to the course of the stream of blood in the sinus. The Deep or Ventricular veins commence within the lateral ven- tricles by the veins of the corpora striata and those of the choroid plexus, which unite to form the two venae Galeni. The Vena Galeni pass backwards in the structure of the velum interpositum ; and escaping through the fissure of Bichat, terminate in the straight sinus. The Cerebellar veins are disposed, like those of the cerebrum, on the surface of the lobes of the cerebellum; they are situated some upon the superior, and some upon the inferior surface, while others occupy the borders of the organ. They terminate in the lateral and petrosal sinuses. SINUSES OF THE DURA MATER. The sinuses of the dura mater are irregular channels, formed by the splitting of the layers of that membrane, and lined upon their in- ner surface by a continuation of the internal coat of the veins. They may be divided into two groups:—1. Those situated at the upper and back part of the skull. 2. The sinuses at the base of the skull. The former are, the Occipital sinuses, Lateral sinuses. The Superior longitudinal sinus is situated in the at- tached margin of the falx ce- rebri, and extends along the middle line of the arch of the skull, from the foramen cae- cum in the frontal, to the inner tuberosity of the occi- pital bone, where it divides into the two lateral sinuses. It is triangular in form, is small in front, and increases gradually in size as it passes backwards; it receives the superior cerebral veins which open into it obliquely, nume- rous small veins from the diploe, and near the posterior extremity of the sagittal suture the * The sinuses of the upper and back part of the skull. 1. The superior longitudinal sinus. 2, 2. The cerebral veins opening into the sinus from behind forwards. 3. The falx cerebri. 4. The inferior longitudinal sinus. 5. The straight or fourth sinus. 6. The vena? Galeni. 7. The torcular Herophili. 8. The two lateral sinuses, with the occipital sinuses between them. 9. The termination of the inferior petrosal sinus of one side. 10 The dilatations corresponding with the jugular fossae. 11. The internal jugular veins. Superior longitudinal sinus, Inferior longitudinal sinus, Straight sinus, Fig. 158.* LATERAL SINUSES. 363 parietal veins, from the pericranium and scalp. Examined in its interior, it presents numerous transverse fibrous bands (trabeculae) the chordae Willisii, which are stretched across its inferior angle; and some small white granular masses, the glandulae Pacchioni; the oblique openings of the cerebral veins, with their valve-like margin, are also seen upon the walls of the sinus. The termination of the superior longitudinal sinus in the two late- ral sinuses forms a considerable dilatation, into which the straight sinus opens from the front, and the occipital sinuses from below. This dilatation is named the torcular Herophili,* and is the point of communication of six sinuses, the superior longitudinal, two lateral, two occipital and the straight. The Inferior longitudinal sinus is situated in the free margin of the falx cerebri; it is cylindrical in form, and extends from near the crista galli to the anterior border of the tentorium, where it termi- nates in the straight sinus. It receives in its course several veins from the falx. The Straight or fourth sinus is the sinus of the tentorium; it is situated at the line of union of the falx with the tentorium; is prismoid in form, and extends across the tentorium, from the termi- nation of the inferior longitudinal sinus to the torcular Herophili. It receives the venae Galeni, the cerebral veins from the inferior part of the posterior lobes, and the superior cerebellar veins. The Occipital sinuses are two canals of small size, situated in the attached border of the falx cerebelli; they commence by several small veins around the foramen magnum, and terminate by separate openings in the torcular Herophili. They not unfrequently commu- nicate with the termination of the lateral sinuses. The Lateral sinuses, commencing at the torcular Herophili, pass horizontally outwards, in the attached margin of the tentorium, and then curve downwards and inwards along the base of the petrous portion of the temporal bone, at each side, to the foramina lacera posteriora, where they terminate in the internal jugular veins. Each sinus rests in its course upon the transverse groove of the occipital bone, posterior inferior angle of the parietal, mastoid portion of the temporal, and again on the occipital bone. They receive the cere- bral veins from the inferior surface of the posterior lobes, the inferior cerebellar veins, the superior petrosal sinuses, the mastoid, and pos- terior condyloid veins, and at their termination, the inferior petrosal sinuses. These sinuses are often unequal in size, the right being larger than the left. The sinuses of the base of the skull are the— Cavernous, Superior petrosal, Inferior petrosal, Transverse. Circular, The Cavernous sinuses are named from presenting a structure similar to that of the corpus cavernosum penis. They are situated * Torcular (a press), from a supposition entertained by the older anatomists that the columns of blood, coming in different directions, compressed each other at this point. 364 VEINS OF THE NECK. on each side of the sella turcica, receiving, anteriorly, the ophthalmic veins through the sphenoidal fissures, and terminating posteriorly in the inferior petrosal sinuses. In the internal wall of each cavernous sinus is the internal carotid artery, accompanied by several filaments of the carotid plexus, and crossed by the sixth nerve; and, in its external wall, the third, fourth, and ophthalmic nerves. These struc- tures are separated from the blood flowing through the sinus, by the tubular lining membrane. The cerebral veins from the under sur- face of the anterior lobes, open into the cavernous sinuses. They communicate by means of the ophthalmic with the facial veins, by the circular sinus with each other, and by the superior petrosal with the lateral sinuses. The Inferior petrosal sinuses are the continuations of the cavernous sinuses backwards along the lower border of the petrous portion of the temporal bone at each side of the Fls-159* base of the skull, to the foramina lacera posteriora, where they terminate with the lateral sinuses in the commencement of the internal jugular veins. The Circular sinus (sinus of Ridley) is situated in the sella turcica, surround- ing the pituitary gland, and communi- cating on each side with the cavernous sinus. The posterior segment is larger than the anterior. The Superior petrosal sinuses pass ob- liquely backwards along the attached border of the tentorium, on the upper margin of the petrous portion of the tem- poral bone, and establish a communi- cation between the cavernous and lateral sinus at each side. They receive one or two cerebral veins from the inferior part of the middle lobes, and a cerebel- lar vein from the anterior border of the cerebellum. Near the extremity of the petrous bone these sinuses cross the oval aperture which transmits the fifth nerve. The Transverse sinus (basilar, anterior occipital) passes transversely across the basilar process of the occipital bone, forming a communica- tion between the two inferior petrosal sinuses. Sometimes there are two sinuses in this situation. VEINS OF THE NECK. The veins of the neck which return the blood from the head are the— * The sinuses of the base of the skull. 1. The ophthalmic veins. 2. The cavernous sinus of one side. 3. The circular sinus ; the figure occupies the position of the pituitary gland in the sella turcica. 4. The inferior petrosal sinus. 5. The transverse or anterior occipital sinus. 6. The superior petrosal sinus. 7. The internal jugular vein. 8. The foramen magnum. 9. The occipital sinuses. 10. The torcular Herophili. 11, 11. The lateral sinuses. VEINS OF THE NECK. 365 External jugular, Internal jugular, Anterior jugular, Vertebral. The External jugular vein is formed by the union of the posterior auricular vein with the temporo-maxillary, and commences at the lower border of the parotid gland, in front of the sterno-mastoid muscle. It descends the neck in the direction of a line drawn from the angle of the lower jaw to the middle of the clavicle, crosses the sterno-mas- toid, and terminates near the posterior and inferior attachment of that muscle in the subclavian vein. In its course downwards it lies upon the anterior lamella of the deep cervical fascia, which separates it from the sterno-mastoid muscle, and is covered in by the platysma myoides and superficial fascia. At the root of the neck it pierces the deep cervical fascia ; it is accompanied, for the upper half of its course, by the auricularis magnus nerve. The branches which it receives are the occipital cutaneous and posterior cervical cutaneous, and, near its termination, the supra and posterior scapular. The external jugular vein is very variable in size, and is occasion- ally replaced by two veins. In the parotid gland it receives a large communicating branch from the internal jugular vein. The Anterior jugular vein is a trunk of variable size, which collects the blood from the integument and superficial structures on the fore part of the neck. It passes downwards along the anterior border of the sterno-mastoid muscle, and opens into the subclavian vein, near the termination of the external jugular. The two veins communicate with each other, with the external, and with the internal jugular vein. The Internal jugular vein, formed by the convergence of the lateral and inferior petrosal sinus, commences at the foramen lacerum poste- rius on each side of the base of the skull, and descends the side of the neck, lying, in the first instance, to the outer side of the internal carotid, and then upon the outer side of the common carotid artery to the root of the neck, where it unites with the subclavian, and consti- tutes the vena innominata. At its commencement, the internal jugu- lar vein is posterior and external to the internal carotid artery, and the eighth and ninth pairs of nerves; lower down, the vein and artery are on the same plane, the glosso-pharyngeal and hypoglossal nerves passing forwards between them, the pneumogastric being between and behind in the same sheath, and the nervus accessorius crossing ob- liquely behind the vein. The Branches which the internal jugular receives in its course are, the facial, the lingual, the inferior pharyngeal, the occipital, and the superior and inferior thyroid veins. The Vertebral vein descends by the side of the vertebral artery in the canal formed by the foramina in the transverse processes of the cervical vertebrae, and terminates at the root of the neck in the com- mencement of the vena innominata. In the lower part of the verte- bral canal it frequently divides into two branches, one of which ad- vances forwards, while the other passes through the foramen in the transverse process of the seventh cervical vertebra, before opening into the vena innominata. 31* 366 VEINS OF THE UPPER EXTREMITY. The Branches which it receives in its course are the posterior con- dyloid vein, muscular branches, the cervical meningo-rachidian veins, and, near its termination, the superficial and deep cervical veins. The Inferior thyroid veins, two, and frequently more in number, are situated one on each side of the trachea, and receive the venous blood from the thyroid gland. They communicate with each other and with the superior thyroid veins, and form a plexus upon the front of the trachea. The right vein terminates in the right vena innominata, just at its union with the superior cava, and the left in the left vena innominata. VEINS OF THE UPPER EXTREMITY. The veins of the upper extremity are the deep and superficial. The deep veins accompany the branches and trunks of the arteries, and constitute their vena comites. The venae comites of the radial and ulnar arteries are enclosed in the same sheath with those vessels, and terminate at the bend of the elbow in the brachial veins. The brachial venae comites are situated one on each side of the artery, and open into the axillary vein; the axillary becomes the subclavian, and the subclavian unites with the internal jugular to form the vena innominata. The Superficial veins of the fore-arm are the— Anterior ulnar vein, Cephalic vein, Posterior ulnar vein, Median vein, Basilic vein, Median basilic, Radial vein, Median cephalic. The Anterior ulnar vein collects the venous blood from the inner border of the hand, and from the vein of the little finger, vena salva- tella, and ascends the inner side of the fore-arm to the bend of the elbow, where it becomes the basilic vein. The Posterior ulnar vein, irregular in size, and frequently absent, commences upon the inner border and posterior aspect of the hand, and ascending the fore-arm terminates in front of the inner condyle, in the anterior ulnar vein. The Basilic vein (Budikmog, royal, or principal) ascends from the common ulnar vein formed by the two preceding, along the inner side of the upper arm, and near its middle pierces the fascia; it then passes upwards to the axilla, and becomes the axillary vein. The Radial vein commences in the large vein of the thumb, on the outer and posterior aspect of the hand, and ascends along the outer border of the fore-arm to the bend of the elbow, where it becomes the cephalic vein. The Cephalic vein (xeyukri, the head) ascends along the outer side of the arm to its upper third; it then enters the groove between the pectoralis major and deltoid muscles, where it is in relation with the descending branch of the thoracico-acromialis artery, and terminates beneath the clavicle in the subclavian vein. A large communicating branch sometimes crosses the clavicle between the external jugular SUBCLAVIAN VEIN. 367 and this vein, which gives it the appearance of being derived directly from the head—hence its appellation. The Median vein is intermediate between the anterior ulnar and radial vein; it collects the blood from the anterior aspect of the fore- arm, communicating with the two preceding. At the bend of the elbow it receives a branch from the deep veins, and divides into two branches, the median cephalic and median basilic. The Median cephalic vein, generally the smaller of the two, passes obliquely outwards, in the groove between the biceps and supi- nator longus, to join the cephalic vein. The branches of the external cutaneous nerve pass behind it. The Median basilic vein passes obliquely inwards, in the groove between the biceps and pronator radii teres, and terminates in the basilic vein. This vein is crossed by one or two filaments of the internal cutaneous nerve, and is separated from the brachial artery by the aponeurotic slip given off by the tendon of the biceps. AXILLARY VEIN. The axillary vein is formed by the union of the venae comites of the brachial artery with the basilic vein. It lies in front of the artery, and receives numerous branches from the collateral veins of the branches of the axillary artery; and, at the lower border of the first rib, becomes the subclavian vein. SUBCLAVIAN VEIN. The subclavian vein crosses over the first rib and beneath the clavicle, and unites with the internal jugular vein to form the vena innominata. It lies at first in front of the subclavian artery, and then in front of the scalenus anticus, which separates it from that vessel. The phrenic and pneumogastric nerves pass between the artery and vein. The veins opening into the subclavian are the cephalic below the clavicle, and the external and anterior jugulars above ; occasion- * The veins of the fore-arm and bend of the elbow. 1. The radial vein. 2. The cephalic vein. 3. The anterior ulnar vein. 4. The posterior ulnar vein. 5. The trunk formed by their union. 6. The basilic vein, piercing the deep fascia at 7. 9. A communicating branch between the deep veins of the fore-arm and the upper part of the median vein. 10. The median cephalic vein. 11. The median basilic. 12. A slight convexity of the deep fascia, formed by the brachial artery. 13. The process of fascia, derived from the tendon of the biceps, and separating the median basilic vein from the brachial artery. 14. The external cutaneous nerve, piercing the deep fascia, and dividing into two branches, which pass behind the median cephalic vein. 15. The internal cutaneous nerve, dividing into branches, which pass in front of the median basilic vein. 16. The intercosto-humeral cutaneous nerve. 17. The spiral cutaneous nerve, a branch of the musculo-spiral. 368 FEMORAL VEIN. ally some small veins from the neighbouring parts also terminate in it. VEINS OF THE LOWER EXTREMITY. The veins of the lower extremity are the deep and superficial. The deep veins accompany the branches of the arteries in pairs, and form the venae comites of the anterior and posterior tibial and pero- neal arteries. These veins unite, in the popliteal region, to form a single vein of large size, the popliteal, which successively becomes in its course the femoral and the external iliac vein. POPLITEAL VEIN. The popliteal vein ascends through the popliteal region, lying, in the first instance, directly upon the artery, and then getting somewhat to its outer side. It receives several muscular and articular branches, and the external saphenous vein. The valves in this vein are four or five in number. FEMORAL VEIN. The femoral vein, passing through the opening in the adductor magnus muscle, ascends the thigh in the sheath of the femoral artery, and entering the pelvis beneath Poupart's ligament, becomes the ex- ternal iliac vein. In the lower part of its course it is situated upon the outer side of the artery; it then becomes placed behind that ves- sel, and, at Poupart's ligament, lies to its inner side. It receives the muscular veins, and the profunda, and, through the saphenous open- ing,%the internal saphenous vein. The valves in this vein are four or five in number. The Profunda vein is formed by the convergence of the numerous small veins which accompany the branches of the artery; it is a vein of large size, lying in front of the profunda artery, and termi- nates in the femoral, at about an inch and a half below Poupart's ligament. The Superficial veins are the external or short, and the internal or long saphenous. The External saphenous vein collects the blood from the outer side of the foot and leg. It passes behind the outer ankle, ascends along the posterior aspect of the leg, lying in the groove between the two bellies of the gastrocnemius muscle, and pierces the deep fascia in the popliteal region, to join the popliteal vein. It receives several cutaneous branches in the popliteal region, before passing through the deep fascia, and is accompanied in its course by the external saphenous nerve. The Internal saphenous vein commences upon the dorsum and inner side of the foot. It ascends in front of the inner ankle, and along the inner side of the leg; it then passes behind the inner con- dyle of the femur, and along the inner side of the thigh, to the saphe- nous opening, where it pierces the sheath of the femoral vessels, and terminates in the femoral vein, at about one inch and a half below Poupart's ligament. SUPERIOR VENA CAVA. 369 It receives in its course the cutaneous veins of the leg and thigh, and communicates freely with the deep veins. At the saphenous opening it is joined by the superficial epigastric and circumflexa ilii veins, and by the external pudic. The situation of this vein in the thigh is not unfrequently occupied by two or even three trunks of nearly equal size. VEINS OF THE TRUNK. The veins of the trunk may be divided into 1. The superior vena cava, with its formative branches. 2. The inferior vena cava, with its formative branches. 3. The azygos veins. 4. The vertebral and spinal veins. 5. The cardiac veins. 6. The portal vein. 7. The pulmonary veins. SUPERIOR VENA CAVA, WITH ITS FORMATIVE BRANCHES. Vena Innominata. The Vena innominata are two large trunks, formed by the union of the internal jugular and subclavian vein, at each side of the root of the neck. The Right vena innominata, about, an inch and a quarter in length, lies superficially and externally to the arteria innominata, and de- scends almost vertically to unite with its fellow of the opposite side in the formation of the superior cava. At the junction of the jugular and subclavian veins it receives from behind the ductus lymphaticus dexter, and lower down it has opening into it the right vertebral, right internal mammari/, and right inferior thyroid vein. The Left vena innominata, considerably longer than the right, ex- tends almost horizontally across the roots of the three arteries arising from the arch of the aorta, to the right side of the mediastinum, where it unites with the right vena innominata, to constitute the su- perior cava. It is in relation in front with the left sterno-clavicular articulation and the first piece of the sternum. At its commencement it receives the thoracic duct which opens into it from behind, and in its course is joihed by the left vertebral, left inferior thyroid, left mammary, and by the superior intercostal vein. It also receives some small veins from the mediastinum and thymus gland. There are no valves in the venae innominatae. SUPERIOR VENA CAVA. The superior cava is a short trunk about three inches in length, formed by the junction of the two venae innominatae. It descends perpendicularly on the right side of the mediastinum, and entering the pericardium terminates in the upper part of the right auricle. It is in relation in front with the thoracic fascia, which separates it from the thymus gland, and with the pericardium; behind with the right pulmonary artery, and right superior pulmonary vein ; internally with the ascending aorta; externally with the right phrenic nerve, 370 INFERIOR VENA CAVA. Fig. 161.* and right lung. Immediately before entering the pericardium it re- ceives the vena azygos major. INFERIOR VENA CAVA WITH ITS FORMATIVE BRANCHES. Iliac Veins. The External iliac vein lies to the inner side of the corresponding artery at the os pubis; but gradually gets behind it as it passes upwards along the brim of the pelvis, and terminates opposite the sacro-iliac symphysis by uniting with the internal iliac to form the common iliac vein. Immediately above Poupart's liga- ment it receives the epigastric and cir- cumflexa ilii veins ; it has no valves. The Internal iliac vein is formed by vessels which correspond with the branches of the internal iliac artery; it receives the returning blood from the gluteal, ischiatic, internal pudic, and obturator veins, exter- nally to the pelvis ; and from the vesical and uterine plexuses within the pelvis. The vein lies to the inner side of the inter- nal iliac artery, and terminates by uniting with the external iliac vein, to form the common iliac. The Vesical and prostatic plexus is an important plexus of veins which surrounds the neck and base of the bladder and pro- state gland, and receives its blood from the great dorsal vein of the penis, and from the veins of the external organs of gene- ration. It is retained in connexion with the sides of the bladder by a reflection of the pelvic fascia. The Uterine plexus is situated around the vagina, and upon the sides of the uterus, between the two layers of the broad ligaments. The veins forming the vesical and uterine plexus are very subject to the production of phlebolites. * The veins of the trunk and neck. 1. The superior vena cava. 2. The left vena innominata. 3. The right vena innominata. 4. The right subclavian vein. 5. The in. ternal jugular vein. 6. The external jugular. 7. The anterior jugular. 8. The inferior vena cava. 9. The external iliac vein. 10. The internal iliac vein. 11. The common iliac veins; the small vein between these is the vena sacra media. 12, 12. Lumbar veins. 13. The right spermatic vein. 14. The left spermatic, opening into the left renal vein. 15. The right renal vein. 16. The trunk of the hepatic veins. 17. The greater vena azygos, commencing inferiorly in the lumbar veins. 18. The lesser vena azygos, also commencing in the lumbar veins. 19. A branch of communication with the left renal vein. 20. The termination of the lesser in the greater vena azygos. 21. The superior intercostal vein; communicating inferiorly with the lesser vena azygos, and terminating superiorly in the left vena innominata. INFERIOR VENA CAVA. 371 The Common iliac veins are formed by the union of the external and internal iliac vein on each side of the pelvis. The right common iliac, shorter than the left, ascends obliquely behind the correspond- ing artery; and upon the intervertebral substance between the fourth and fifth lumbar vertebrae, unites with the vein of the opposite side, to form the inferior cava. The left common iliac, longer and more oblique than the right, ascends behind, and a little internally to the corresponding artery, and passes beneath the right common iliac artery, near its origin, to unite with the right vein in the formation of the inferior vena cava. The right common iliac vein has no branch opening into it; the left receives the vena sacra media. These veins have no valves. INFERIOR VENA CAVA. The inferior vena cava is formed by the union of the two common iliac veins, upon the intervertebral substance between the fourth and fifth lumbar vertebra. It ascends along the front of the vertebral column, on the right side of the abdominal aorta, and passing through the fissure in the posterior border of the liver and the quadrilateral opening in the tendinous centre of the diaphragm, terminates in the inferior and posterior part of the right auricle. There are no valves in this vein. It is in relation from below upwards, in front, with the mesentery, transverse duodenum, portal vein, pancreas, and liver, which latter nearly and sometimes completely surrounds it; behind, it rests upon the vertebral column and right crus of the diaphragm, from which it is separated by the right renal and lumbar arteries; to the right, it has the peritoneum and sympathetic nerve; and to the left, the aorta. The Branches which the inferior cava receives in its course, are the— Lumbar, Supra-renal, Right spermatic, Phrenic, Renal, Hepatic. The Lumbar veins, three or four in number on each side, collect the venous blood from the muscles and integument of the loins, and from the spinal veins; the left are longer than the right, from the position of the vena cava. The Right spermatic vein is formed by the two veins which return the blood from the venous plexus, situated in the spermatic cord. These veins follow the course of the spermatic artery, and unite to form the single trunk which opens into the inferior vena cava. The left spermatic vein terminates in the left renal vein. The Ovarian veins represent the spermatic veins of the male, and collect the venous blood from the ovaries, round ligaments, and Fal- lopian tubes, and communicate with the uterine sinuses. They ter- minate as in the male. The Renal or emulgent veins return the blood from the kidneys; their branches are situated in front of the divisions of the renal arteries, and the left opens into the vena cava somewhat higher than 372 VERTEBRAL AND SPINAL VEINS. the right. The left is longer than the right, in consequence of the position of the vena cava, and crosses the aorta immediately below the origin of the superior mesenteric artery. It receives the left spermatic vein, which terminates in it at right angles : hence the more frequent occurrence of varicocele on the left than on the right side. The Supra-renal veins terminate partly in the renal veins, and partly in the inferior vena cava. The Phrenic veins return the blood from the ramifications of the phrenic arteries; they open into the inferior cava. The Hepatic veins form two principal trunks and numerous smaller veins which open into the inferior cava, while that vessel is situated in the posterior border of the liver. The hepatic veins commence in the liver by minute venules, the intralobular veins, in the centre of each lobule; these pour their blood into larger vessels, the sublobular veins; and the sublobular veins constitute, by their convergence and union, the hepatic trunks, which terminate in the inferior vena cava. AZYGOS VEINS. The azygos veins form a system of communication between the superior and inferior vena cava, and serve to return the blood from that part of the trunk of the body in which those vessels are defi- cient, on account of their connexion with the heart. This system consists of three vessels, the Vena azygos major, Vena azygos minor, Superior intercostal vein. The Vena azygos major commences in the lumbar region by a communication with the lumbar veins; sometimes it is joined by a branch directly from the inferior vena cava, or by one from the renal vein. It passes through the aortic opening in the diaphragm, and ascends upon the right side of the vertebral column to the third dor- sal vertebra, where it arches forwards over the right bronchus, and terminates in the superior cava. It receives all the intercostal veins of the right side, the vena azygos minor, and the bronchial veins. The Vena azygos minor commences in the lumbar region, on the left side, by a communication with the lumbar or renal veins. It passes beneath the border of the diaphragm, and ascending upon the left side of the vertebral column crosses the fifth or sixth dorsal ver- tebra to open into the vena azygos major. It receives the six or seven lower intercostal veins of the left side. The azygos veins have no valves. The Superior intercostal vein is the trunk formed by the union of the five or six upper intercostal veins of the left side. It communi- cates below with the vena azygos minor, and ascends to terminate in the left vena innominata. VERTEBRAL AND SPINAL VEINS. The numerous venous plexuses of the vertebral column and spinal cord may be arranged into three groups:— CARDIAC VEINS. 373 Dorsi-spinal, Meningo-rachidian, Medulli-spinal. The Dorsi-spinal veins form a plexus around the spinous, trans- verse and articular processes, and arches of the vertebrae. They receive the returning blood from the dorsal muscles and surrounding structures, and transmit it, in part to the meningo-rachidian, and in part to the vertebral, intercostal, lumbar, and sacral veins. The Meningo-rachidian veins are situated between the theca ver- tebralis and the vertebrae. They communicate freely with each other by means of a complicated plexus. In front they form two longitu- dinal trunks, (longitudinal spinal sinuses,) which extend the whole length of the column on each side of the posterior common ligament, and are joined on the body of each vertebra by transverse trunks, which pass beneath the ligament, and receive the large basi-vertebral veins from the interior of each vertebra. The meningo-rachidian veins communicate superiorly through the anterior condyloid fora- mina with the internal jugulars ; in the neck they pour their blood into the vertebral veins; in the thorax, into the intercostals ; and in the loins and pelvis into the lumbar and sacral veins, .the communi- cations being established through the intervertebral foramina. The Medulli-spinal veins are situated between the pia mater and arachnoid ; they communicate freely with each other to form plexuses, and send branches through the intervertebral foramina with each of the spinal nerves, to join the veins of the trunk. CARDIAC VEINS. The veins returning the blood from the substance of the heart, are the— Great cardiac vein, Anterior cardiac veins, Posterior cardiac veins, Venae Thebesii. The Great cardiac vein (coronary) commences at the apex of the heart, and ascends along the anterior ventricular groove to the base of the ventricles; it then curves around the left auriculo-ventricular groove to the posterior part of the heart, where it terminates in the right auricle. It receives in its course the left cardiac veins from the left auricle and ventricle, and the posterior cardiac veins from the posterior ventricular groove. The Posterior cardiac vein, frequently two in number, commences also at the apex of the heart, and ascends along the posterior ventri- cular groove, to terminate in the great cardiac vein. It receives the veins from the posterior aspect of the two ventricles. The Anterior cardiac veins collect the blood from the anterior sur- face of the right ventricle; one larger than the rest runs along the right border of the heart and joins the trunk formed by these veins, which curves around the right auriculo-ventricular groove, to termi- nate in the great cardiac vein near its entrance into the right auricle. The Vena Thebesii are numerous minute venules which convey 374 PORTAL SYSTEM. the venous blood directly from the substance of the heart into its four cavities. Their existence is denied by some anatomists. PORTAL SYSTEM. The portal system is composed of four large veins which return the blood from the chylopoietic viscera; they are the— Inferior mesenteric vein, Splenic vein, Superior mesenteric vein, Gastric veins. The Inferior mesenteric vein receives its blood from the rectum by means of the haemorrhoidal veins, and from the sigmoid flexure and descending colon, and ascends behind the transverse duodenum and pancreas, to terminate in the splenic vein. Its haemorrhoidal branches inosculate with the branches of the internal iliac vein, and thus esta- blish a communication between the portal and general venous system. The Superior mesenteric vein is formed by branches which collect the venous blood from the capillaries of the superior mesenteric artery; they constitute by their junction a large trunk, which ascends by the side of the corresponding artery, crosses the transverse duodenum, Fig. 162.* * The portal vein. 1. The inferior mesenteric vein; it is traced by means of dotted lines behind the pancreas (2) to terminate in the splenic vein (3). 4. The spleen. 5. Gas- tric veins, opening into the splenic vein. 6. The superior mesenteric vein. 7. The descending portion of the duodenum. 8. Its transverse portion, which is crossed by the superior mesenteric vein and by a part of the trunk of the superior mesenteric artery 9« Tmu Pj—!-Vein" 10- The hePatic artery- n- The ductus communis choledochus] 12. The division of the duct and vessels at the transverse fissure of the liver. 13. The cystic duct leading to the gall bladder. PULMONARY VEINS. 375 and unites behind the pancreas with the splenic in the formation of the portal vein. The Splenic vein commences in the structure of the spleen, and quits that organ by several large veins; it is larger than the splenic artery, and perfectly straight in its course. It passes horizontally in- wards behind the pancreas, and terminates near its greater end by uniting with the superior mesenteric and forming the portal vein. It receives in its course the gastric and pancreatic veins, and near its termination the inferior mesenteric vein. The Gastric veins correspond with the gastric, gastro-epiploic, and vasa brevia arteries, and terminate in the splenic vein. The Vena Ported, formed by the union of the splenic and superior mesenteric vein behind the pancreas, ascends through the right border of the lesser omentum to the transverse fissure of the liver, where it divides into two branches, one for each lateral lobe. In the right border of the lesser omentum it is situated behind and between the hepatic artery and ductus communis choledochus, and is sur- rounded by the hepatic plexus of nerves and lymphatics. At the transverse fissure, each primary branch divides into numerous secon- dary branches which ramify through the portal canals, and give off vaginal and interlobular veins, and the latter terminate in the lobular venous plexus of the lobules of the liver. The portal vein within the liver receives the venous blood from the capillaries of the hepatic artery. PULMONARY VEINS. The pulmonary veins, four in number, return the arterial blood from the lungs to the left auricle of the heart; they differ from the veins in general, in the area of their cylinders being very little larger than the corresponding arteries, and in accompanying singly each branch of the pulmonary artery. They commence in the capillaries upon the parietes of the bronchial cells, and unite to form a single trunk for each lobe. The vein of the middle lobe of the right lung unites with the superior vein so as to form the two trunks which open into the left auricle. Sometimes they remain separate, and then there are three pulmonary veins on the right side. The right pulmonary veins pass behind the superior vena cava to the left auri- cle, and the left behind the pulmonary artery; they both pierce the pericardium. Within the lung the branches of the pulmonary veins are behind the bronchial tubes, and those of the pulmonary artery in front; but at the root of the lungs the veins are in front, next the arteries, and then the bronchi. There are no valves in the pulmo- nary veins. 376 ON THE LYMPHATICS. CHAPTER VIII. ON THE LYMPHATICS. The lymphatic vessels, or absorbents, have received their double appellation from certain phenomena which they present; the for- mer name being derivable from the appearance of the limpid fluid (lympha, water) which they convey; and the latter, from their sup- posed property of absorbing foreign substances into the system. They are minute, delicate, and transparent vessels, remarkable for their general uniformity of size, for a knotted appearance which is due to the presence of numerous valves, for the frequent dichotomous divisions which occur in their course, and for their division into several branches immediately before entering a gland. Their office is to collect the products of digestion and the detrita of nutrition, and convey them into the venous circulation near to the heart. Lymphatic vessels commence in a delicate network which is dis- tributed upon the cutaneous surface of the body, upon the various surfaces of organs and throughout their internal structure; and from this network the lymphatic vessels proceed, nearly in straight lines, in a direction towards the root of the neck. In their course they are intercepted by numerous small spheroid or oblong bodies, more or less flattened on their surface, lymphatic glands. The lymphatic vessels entering these glands are termed vasa inferentia or afferentia, and those which quit them vasa efferentia. The vasa inferentia vary in number from two to six, they divide at the distance of a few lines from the gland into several smaller vessels and enter it by one of the flattened surfaces.* The vasa efferentia escape from the gland on the opposite, but not unfrequently on the same surface; they consist like the vasa inferentia at their junction with the gland of several small vessels which unite after a course of a few lines to form from one to three trunks, often twice as large as the vasa inferentia. Lymphatic vessels admit of a threefold division into superficial, deep, and lacteals. The superficial lymphatic vessels, upon the sur- face of the hody, follow the course of the veins, and pierce the deep fascia in convenient situations, to join the deep lymphatics. Upon the surface of organs they converge to the nearest lymphatic trunks. The superficial lymphatic glands are placed in the most protected situations of the superficial fascia, as in the hollow of the ham and groin in the lower extremity, and upon the inner side of the arm in the upper extremity. The deep lymphatics, fewer in number and somewhat larger than the superficial vessels, accompany the deeper veins; those from the lower parts of the body converging to the numerous glands seated * See Mr. Lane's article on the " Lymphatic System," in the Cyclopaedia of Anatomy and Physiology. ON THE LYMPHATICS. 377 around the iliac veins and inferior vena cava, and terminating in a large trunk situated upon the vertebral column, the thoracic duct. From the upper part of the trunk of the body on the left side, and from the left side of the head and neck, they also proceed to the thoracic duct. Those on the right side of the head and neck, right upper extremity, and right side of the thorax, form a distinct duct which terminates at the point of junction of the subclavian with the internal jugular vein on the right side of the root of the neck; The lacteals are the lymphatic vessels of the small intestines; they have received their distinctive appellation from conveying the milk- like product of digestion, the chyle, to the great centre of the lym- phatic system, the thoracic duct. They are situated in the mesen- tery, and pass through the numerous mesenteric glands in their course. Lymphatic vessels are very generally distributed through the ani- mal tissues; there are, nevertheless, certain structures in which they have never been detected, for example, the brain and spinal cord, the eye, bones, cartilages, tendons, the membranes of the ovum, the umbilical cord, and the placenta. The anastomoses between these vessels are less frequent than between arteries and veins; they are effected by means of vessels of equal size with the vessels which they connect, and no increase of calibre results from their junction. The lymphatic vessels are smallest in the neck, larger in the upper extremities, and larger still in the lower limbs. For the purpose of effecting the movement of their fluids in a pro- per direction, lymphatic vessels are furnished with valves, and it is to these that the appearance of constrictions around the cylinders of the vessels at short distances is due. Like the valves of veins, the valves of lymphatic vessels are each composed of two semilunar flaps attached by their convex border to the sides of the vessel and free by their concave border. This is the general character of the valves, but, as in veins, there are exceptions in their form and dispo- sition ; sometimes one flap is so small as to be merely rudimentary, while the other is large in proportion; sometimes the flap runs all the way round the tube, leaving a central aperture which can only be closed by a contractile power in the valve itself; and sometimes instead of being circular the aperture is elliptical, and the arrange- ment of the flaps like that of the ileo-coecal valve.* These peculiari- ties are most frequently met with at and near the anastomoses of the lymphatic vessels. The valves are most numeroufly met with near the lymphatic glands; next in frequency they are found in the neck and upper extremities w7here the vessels are small, and least numerously in the lower limbs where the lymphatics are larger. In the thoracic duct an interspace of two or three inches frequently occurs between the valves. Connected with the presence of valves in the lymphatic vessels, are two lateral dilatations or pouches, ana- logous to the valvular sinuses of veins. These sinuses are situated on the cardiac side of the valves; they receive the valves when the * Mr. Lane, loc. cit. 32* 378 LYMPHATICS OF THE HEAD AND NECK. latter are thrown back by the current of the blood; and when reflux occurs, they become distended with a body of fluid which makes pressure on the flaps. These pouch-like dilatations and the constric- tions corresponding with the line of attachment of the convex borders of the flaps are the cause of the knotted appearance of distended lymphatic vessels. Like arteries and veins, lymphatic vessels are composed of three coats, external, middle and internal. The external coat is cellulo- fibrous, like that of blood-vessels; it is thin but very strong, and serves to connect the vessel to surrounding tissues, at the same time that it forms a protective covering. The middle coat is thin and elastic, and consists of a layer of longitudinal fibres analogous to those of the innermost layer of the middle coat of arteries and veins. Some few circular fibres may be seen externally to these in the larger lym- phatic vessels. The internal coat js inelastic and more liable to rup- ture than the other coats. It is a serous layer continuous with the lining membrane of the veins, and is invested by an epithelium. The valves are composed of a very thin layer of fibrous tissue coated on its two surfaces by epithelium. The lymphatic glands (conglobate, absorbent) are small oval and somewhat flattened or rounded bodies, composed of a plexus of minute lymphatic vessels, associated with a plexus of blood-vessels, and enclosed in a thin cellular capsule. When examined on the sur- face they are seen to have a lobulated appearance, while the face of a section is cellular from the division of the numberless convolutions which are formed by the lymphatic vessels within its substance. The colour of the glands is a pale pink, excepting those of the lungs, the bronchial glands, which in the adult are more or less mottled with black, and are sometimes filled with a black pigment. Lymphatic glands are larger in the young subject than in the adult, and are smallest in old age; they as well as their vessels are supplied with arteries, veins and nerves, like other structures. I shall describe the lymphatic vessels and glands according to the arrangement adopted for the veins, commencing with those of the head and neck, and proceeding next to those of the upper extremity, lower extremity, and trunk. LYMPHATICS OF THE HEAD AND NECK. The Superficial lymphatic glands of the head and face are small, few in nurnfer, and isolated ; they are the occipital, which are situated near the origin of the occipito-frontalis muscle; posterior auricular, behind the ear; parotid, in the parotid gland; zygomatic, in the zygo- matic fossa; buccal, upon the buccinator muscle ; and submaxillary, beneath the margin of the lower jaw. There are no deep lymphatic glands within the cranium. The Superficial cervical lymphatic glands are few in number and small; they are situated in the course of the external jugular vein be- tween the sterno-mastoid and trapezius muscles, at the root of the neck, and about the larynx. The Deep cervical glands (glandulae concatenatae) are numerous LYMPHATICS OF THE UPPER EXTREMITY. 379 and of large size ; they are situated around the internal jugular vein and sheath of the carotid arteries, by the side of the pharynx, oeso- phagus, and trachea, and extend from the base of the skull to the root of the neck, where they are in communication with the lymphatic vessels and glands of the thorax. The Superficial lymphatic vessels of the head and face are disposed in three groups; occipital, which take the course of the occipital vein to the occipital and deep cervical glands; temporal, which follow the branches of the temporal vein to the parotid and deep cervical glands; and facial, which accompany the facial vein to the submaxillary lym- phatic glands. The Deep lymphatic vessels of the head are the meningeal and cere- bral ; the former are situated in connexion with the meningeal veins, and escape through foramina at the base of the skull, to join the deep cervical glands. The cerebral lymphatics, according to Fohmann, are situated upon the surface of the pia mater, none having yet been discovered in the substance of the brain. They pass most probably through the foramina at the base of the skull, to terminate in the deep cervical glands. The Deep lymphatic vessels of the face proceed from the nasal fossae, mouth, and pharynx, and terminate in the submaxillary and deep cer- vical glands. The Superficial and deep cervical lymphatic vessels accompany the jugular veins, passing from gland to gland, and at the root of the neck communicate with the thoracic lymphatic vessels, and termi- nate, on the right side, in the ductus lymphaticus dexter, and on the left, in the thoracic duct, near its termination. LYMPHATICS OF THE UPPER EXTREMITY. The Superficial lymphatic glands of the arm are not more than four or five in number, and of very small size. One or two are si- tuated near the median basilic and cephalic veins, at the bend of the elbow ; and one or two near the basilic vein, on the inner side of the upper arm, immediately above the elbow. The Deep glands in the fore-arm are excessively small and infre- quent ; two or three may generally be found in the course of the radial and ulnar vessels. In the upper arm there is a chain of small glands accompanying the brachial artery. The Axillary glands are numerous and of large size. Some are closely adherent to the vessels, others are dispersed in the loose areo- lar tissue of the axilla, and a small chain may be observed extending along the lower border of the pectoralis major to the mammary gland. Two or three subclavian glands are situated beneath the clavicle, and serve as the medium of communication between the axillary and deep cervical lymphatic glands. The Superficial lymphatic vessels of the upper extremity commence upon the fingers and take their course along the fore-arm to the bend of the elbow. The greater part reach their destination by passing along the dorsal surface of the fingers, wrist, and fore-arm, and then curving around the borders of the latter; but some few are met with 380 LYMPHATICS OF THE LOWER EXTREMITY. in the palm of the hand, which take the direction of the median vein. At the bend of the elbow the lymphatics arrange themselves into two groups; an internal and larger group, which communicates with a gland situated just above the inner condyle, and then accompanies the basilic vein upwards to the axilla to enter the axillary glands; and a small group which follows the course of the cephalic vein. Several of the vessels of this group cross the biceps muscle at its upper part to enter the axillary glands, while the remainder, two or three in number, ascend with the cephalic vein in the interspace of the deltoid and pectoralis major; they usually join a small gland in this space, and then cross the pectoralis minor muscle to become con- tinuous with the subclavian lymphatics. Besides the lymphatic vessels of the arm, the axillary glands re- ceive those from the integument of the chest, its anterior, posterior, and lateral aspect, and the lymphatics of the mammary gland. The Deep lymphatics accompany the vessels of the upper extremity, and communicate occasionally with the superficial lymphatics. They enter the axillary and subclavian glands, and at the root of the neck terminate on the left side in the thoracic duct, and on the right side in the ductus lymphaticus dexter. LYMPHATICS OF THE LOWER EXTREMITY. The Superficial lymphatic glands of the lower extremity are those of the groin, the inguinal; and one or two situated in the superficial fascia of the posterior aspect of the thigh, just above the popliteal region. The Inguinal glands are divisible into two groups; a superior group of small size, situated along the course of Poupart's ligament, and receiving the lymphatic vessels from the parietes of the abdo- men, gluteal region, perineum, and genital organs; and an inferior group of larger glands clustered around the internal saphenous vein near its termination, and receiving the superficial lymphatic vessels from the lower extremity. The Deep lymphatic glands are the anterior tibial, popliteal, deep inguinal, gluteal, and ischiatic. The Anterior tibial is generally a single gland, placed on the inter- osseous membrane, by the side of the anterior tibial artery in the upper part of its course. The Popliteal glands, four or five in number and small, are embed- ded in the loose areolar tissue and fat of the popliteal space. The Deep inguinal glands, less numerous and smaller than the su- perficial, are situated near the femoral vessels in the groin, beneath the fascia lata. The Gluteal and ischiatic glands are placed near the vessels of that name, above and below the pyriformis muscle at the great ischiatic foramen. The Superficial lymphatic vessels are divisible into two groups, in- ternal and external; the internal and principal group commencing on the dorsum and inner side of the foot, ascend the leg by the side of the internal saphenous vein, and passing behind the inner condyle of LYMPHATICS OF THE TRUNK. 381 the femur, follow the direction of that vein to the groin, where they join the saphenous group of superficial inguinal glands. The greater part of the efferent vessels from these glands pierce the cribriform fascia of the saphenous opening and the sheath of the femoral vessels to join the lymphatic gland situated in the femoral ring, which serves to establish a communication between the lymphatics of the lower extremity and those of the trunk. The other efferent vessels pierce the fascia lata to join the deep glands. The vessels which pass up- wards from the outer side of the dorsum of the foot, ascend upon the outer side of the leg, and curve inwards just below the knee, to unite with the lymphatics of the inner side of the thigh. The external group consists of a few lymphatic vessels which commence upon the outer side of the foot and posterior part of the ankle, and accompany the external saphenous vein to the popliteal region, where they enter the popliteal glands. The Deep lymphatic vessels accompany the deep veins, and com- municate with the various glands in their course. After joining the deep inguinal glands they pass beneath Poupart's ligament, to com- municate with the numerous glands situated around the iliac vessels. The deep lymphatics of the gluteal region follow the course of the branches of the gluteal and ischiatic arteries. The former join the glands situated upon the upper border of the pyriformis muscle, and the latter, after communicating with the lymphatics of the thigh, enter the ischiatic glands. LYMPHATICS OF THE TRUNK. The lymphatics of the trunk may be arranged under three heads, superficial, deep, and visceral. The Superficial lymphatic vessels of the upper half of the trunk pass upwards and outwards on each side, and converge, some to the axil- lary glands, and others to the glands at the root of the neck. The lymphatics from the mammary glands follow the lower border of the pectoralis major, communicating, by means of a chain of lymphatic glands, with the axillary glands. The superficial lymphatic vessels of the lower half of the trunk, of the gluteal region, perineum, and external organs of generation, converge to the superior group of super- ficial inguinal glands. Some small glands are situated on each side of the dorsal vein of the penis, near the suspensory ligament; from these, as from the superficial lymphatics, the efferent vessels pass into the superior group of superficial inguinal glands. The Deep lymphatic glands of the thorax are the intercostal, internal mammary, anterior mediastinal, and posterior mediastinal. The Intercostal glands are of small size, and are situated on each side of the vertebral column, near the articulations of the heads of the ribs, and in the course of the intercostal arteries. The Internal mammary glands also very small, are placed in the intercostal spaces, by the side of the internal mammary arteries. The Anterior mediastinal glands occupy the loose areolar tissue of the anterior mediastinum, resting some on the diaphragm, but the greater number upon the large vessels at the root of the heart. 382 LYMPHATICS OF THE VISCERA. The Posterior mediastinal glands are situated along the course of the aorta and oesophagus in the posterior mediastinum, and communi- cate above with the deep cervical glands, on each side with the inter- costal and below with the abdominal glands. The Deep lymphatic vessels of the thorax are the intercostal, internal mammary, and diaphragmatic. The Intercostal lymphatic vessels follow the course of the arteries of the same name; and reaching the vertebral column curve down- wards, to terminate in the thoracic duct. The Internal mammary lymphatics commence in the parietes of the abdomen, communicating with the epigastric lymphatics. They as- cend by the side of the internal mammary vessels, being joined in their course by the anterior intercostals, and terminate at the root of the neck, on the right side in the tributaries of the ductus lymphaticus dexter, and on the left in the thoracic duct. The diaphragmatic lym- phatics pursue the direction of their corresponding veins, and terminate some in front in the internal mammary vessels, and some behind, in the posterior mediastinal lymphatics. The Deep lymphatic glands of the abdomen are the lumbar glands; they are very numerous, and are sealed around the common iliac vessels, the aorta and vena cava. The deep lymphatic glands of the pelvis are the external iliac, inter- nal iliac and sacral. The External iliac are placed around the external iliac vessels, being in continuation by one extremity with the femoral lymphatics, and by the other with the lumbar glands. The Internal iliac glands are situated in the course of the internal iliac vessels, and the sacral glands are supported by the concave sur- face of the sacrum. The Deep lymphatic vessels are continued upwards from the thigh, beneath Poupart's ligament, and along the external iliac vessels to the lumbar glands, receiving in their course the epigastric, circumflexa ilii, and ilio-lumbar lymphatic vessels. Those from the parietes of the pelvis, and from the gluteal, ischiatic, and obturator vessels, follow the course of the internal iliac arteries, and unite with the lumbar lym- phatics. And the lumbar lymphatic vessels, after receiving all the lymphatics from the lower extremities, pelvis, and loins, terminate by several large trunks in the receptaculum chyli. LYMPHATICS OF THE VISCERA. The Lymphatic vessels of the lungs are of large size, and are distri- buted over every part of the surface, and through the texture of these organs ; they converge to the numerous glands situated around the bifurcation of the trachea and roots of the lungs, the bronchial glands. Some of these glands of small size, may be traced in connexion with the bronchial tubes for some distance into the lungs. The efferent vessels from the bronchial glands unite with the tracheal and oesopha- geal glands, and terminate principally in the thoracic duct at the root of the neck, and partly in the ductus lymphaticus dexter. The bron- chial glands, in the adult, present a variable tint of brown, and in old LYMPHATICS OF THE VISCERA. 383 age a deep black colour. In infancy they have none of this pigment, and are not to be distinguished from lymphatic glands in other situa- tions. The Lymphatic vessels of the heart originate in the subserous areolar tissue of the surface, and in the deeper tissues of the organ, and follow the course of the vessels, principally, along the right border of the heart to the glands situated around the arch of the aorta and the bronchial glands, whence they proceed to the root of the neck, and terminate in the thoracic duct. The Pericardiac and thymic lymphatic vessels proceed to join the anterior mediastinal and bronchial glands. The Lymphatic vessels of the liver are divisible into the deep and superficial. The former take their course through the portal canals, and through the right border of the lesser omentum, to the lymphatic glands situated in the course of the hepatic artery and along the lesser curve of the stomach. The superficial lymphatics are situated in the areolar structure of the proper capsule, over the whole surface of the liver. Those of the convex surface are divided into two sets;— 1. Those which pass from before backwards; 2. Those which advance from behind forwards. The former unite to form trunks, which enter between the folds of the lateral ligaments at the right and left extremities of the organ, and of the coronary ligament in the middle. Some of these pierce the diaphragm and join the posterior mediastinal glands; others converge to the lymphatic glands situated around the inferior cava. Those which pass from behind forwards consist of two groups: one ascends between the folds of the broad ligament, and perforates the diaphragm, to terminate in the anterior mediastinal glands; the other curves around the anterior margin of the liver to its concave surface, and from thence to the glands in the right border of the lesser omentum. The lymphatic vessels of the concave surface are variously distributed, according to their position; those from the right lobe terminate in the lumbar glands; those from the gall-bladder which are large and form a remarkable plexus, enter the glands in the right border of the lesser omentum; and those from the left lobe converge to the lymphatic glands, situated along the lesser curve of the stomach. The Lymphatic glands of the spleen are situated around its hilus, and those of the pancreas in the course of the splenic vein. The lymphatic vessels of these organs pass through their respective glands, and join the aortic glands, previously to terminating in the thoracic duct. The Lymphatic glands of the stomach are of small size, and are situated along the lesser and greater curves of that organ. The lymphatic vessels, as in other viscera, are superficial and deep, the former originating in the subserous and the latter in the submucous tissue; they pass from the stomach in four different directions: some ascend to the glands situated along the lesser curve, others descend to those occupying the greater curve, a third set passes outwards to the splenic glands, and a fourth to the glands situated near the pylo- rus and to the aortic glands. 384 THORACIC DUCT. The Lymphatic glands of the small intestine are situated between the layers of the mesentery, in the meshes formed by the superior mesenteric artery, and are thence named mesenteric glands. These glands are most numerous and largest, superiorly, near the duode- num ; and, inferiorly, near the termination of the ileum. The Lymphatic vessels of the small intestines are of two kinds: those of the structure of the intestines, which run upon its surface previously to entering the mesenteric glands; and those which com- mence in the villi, upon the surface of the mucous membrane, and are named lacteals. The Lacteals, according to Henle, commence in the centre of each villus as a ccecal tubulus, which opens into a fine network, situated in the submucous tissue. From this areolar network the lacteal vessels proceed to the mesenteric glands, and from thence to the thoracic duct, in which they terminate. The Lymphatic glands of the large intestines are situated along the attached margin of the intestine, in the meshes formed by the arteries previously to their distribution. The lymphatic vessels take their course in two different directions; those of the ccecum, ascend- ing and transverse colon, after traversing their proper glands, pro- ceed to the mesenteric, and those of the descending colon and rec- tum to the lumbar glands. The Lymphatic vessels of the kidney follow the direction of the blood-vessels to the lumbar glands situated around the aorta and inferior vena cava; those of the supra-renal capsules, which are very large and numerous, terminate in the renal lymphatics. The Lymphatic vessels of the viscera of the pelvis terminate in the sacral and lumbar glands. The Lymphatic vessels of the testicle take the course of the sper- matic cord in which they are of large size; they terminate in the lumbar glands. THORACIC DUCT. The thoracic duct* commences in the abdomen, by a considera- ble and somewhat triangular dilatation, the receptaculum chyli, which is situated upon the front of the body of the second lumbar vertebra, behind and between the aorta and inferior vena cava, and close to the tendon of the right crus of the diaphragm. From the upper part of the receptaculum chyli the thoracic duet ascends through the aortic opening of the diaphragm, and along the front of the vertebral column, lying between the thoracic aorta and vena azygos, to the fourth dorsal vertebra. It then inclines to the left side, passes behind the arch of the aorta, and ascends by the side of the oesophagus and behind the perpendicular portion of the left subclavian artery to the root of the neck opposite the seventh cervical vertebra, where it makes a sudden curve forwards and downwards, and terminates at * The thoracic duct was discovered by Eustachius, in 1563, in the horse : he regarded it as a vein, and called it the vena alba thoracis. The lacteals were first seen by Asellius in 1622, in the dog; and within the next ten years by Veslingius in man. THORACIC DUCT. 385 Fig. 163.* the point of junction of the left subclavian with the left internal jugu- lar vein. The thoracic duct is equal in size to the diameter of a goose-quill at its commencement from the receptacu- lum chyli, diminishes considerably in dia- meter towards the middle of the posterior mediastinum, and again becomes dilated near its termination. At about the middle of its course it frequently divides into two branches of equal size, which reunite after a short course; and sometimes it gives off several branches, which assume a plexiform arrangement in this situation. Occasionally the thoracic duct bifurcates at the upper part of the thorax into two branches, one of which opens into the point of junction between the right subclavian and jugular veins, while the other proceeds to the nor- mal termination of the duct on the left side. In rare instances the duct has been found to terminate in the vena azygos, which is its normal destination in some Mammalia. The thoracic duct presents fewer valves in its course than lymphatic vessels ge- nerally; at its termination it is provided with a pair of semilunar valves, which prevent the admission of venous blood into its cylinder. Branches.—The thoracic duct receives at its commencement four or five large lymphatic trunks, which unite to form the receptaculum chyli: it next receives the trunks of the lacteal vessels. Within the thorax it is joined by a large lymphatic trunk from the liver, and in its course through the posterior mediastinum, receives the lymphatic vessels both from the viscera and from the parietes of the thorax. At its curve forwards in the neck it is joined by the lymphatic trunks * The course and termination of the thoracic duct. 1. The arch of the aorta. 2. The thoracic aorta. 3. The abdominal aorta; showing its principal branches divided near their origin. 4. The arteria innominata, dividing into the right carotid and right subcla- vian arteries. 5. The left carotid. 6. The left subclavian. 7. The superior cava, formed by the union of 8, the two venae innominata ; and these by the junction 9, of the internal jugular and subclavian vein at each side. 10. The greater vena azygos. 11. The ter- mination of the lesser in the greater vena azygos. 12. The receptaculum chyli; several lymphatic trunks are seen opening into it. 13. The thoracic duct, dividing opposite the middle of the dorsal vertebra into two branches which soon reunite; the course of the duct behind the arch of the aorta and left subclavian artery is shown by a dotted line. 14. The duct making its turn at the root of the neck and receiving several lymphatic trunks previously to terminating in the posterior aspect of the junction of the internal jugular and subclavian vein. 15. The termination of the trunk of the ductus lymphaticus dexter. 33 386 ON THE NERVOUS SYSTEM. from the left side of the head and neck, left upper extremity, and from the upper part of the thorax, and thoracic viscera. The Ductus lymphaticus dexter is a short trunk which receives the lymphatic vessels from the right side of the head and neck, right upper extremity, right side of the thorax, right lung, and one or two branches from the liver, and terminates at the junction of the right subclavian with the right internal jugular vein, at the point where these veins unite to form the right vena innominata. It is provided at its termination with a pair of semilunar valves, which prevent the entrance of blood from the veins. CHAPTER IX. ON THE NERVOUS SYSTEM. The nervous system consists of a central organ, the cerebro-spinal centre or axis, and of numerous rounded and flattened white cords, the nerves, which are connected by one extremity with the cerebro- spinal centre, and by the other are distributed to all the textures of the body. The sympathetic system is an exception to this descrip- tion ; for in place of one it has many small centres which are called ganglia, and which communicate very freely with the cerebro-spinal axis and with its nerves. The cerebro-spinal axis consists of two portions, the brain, an organ of large size, situated within the skull, and the spinal cord, a lengthened portion of the nervous centre continuous with the brain, and occupying the canal of the vertebral column. The most superficial examination of the brain and spinal cord shows them to be composed of fibres, which in some situations are ranged side by side or collected into bundles or fasciculi, and in other situations are interlaced at various angles by cross fibres. The fibres are connected and held together by a delicate areolar web, which forms the bond of support to the entire organ. It is also observed that the cerebro-spinal axis presents two substances differing from each other in density and colour; a gray or cineritious or cortical substance, and a white or medullary substance. The gray substance forms a thin lamella over the entire surface of the convolutions of the cerebrum, and the laminae of the cerebellum : hence it has been named cortical; but the gray substance is not confined to the surface of the brain, as this term would imply; it is likewise situated in the centre of the spinal cord its entire length, and may be thence traced through the medulla oblongata, crura cerebri, thalami optici, and corpora striata; it enters also into the composition of the locus perfo- ratus, tuber cinereum, commissura mollis, pineal gland, pituitary gland, and corpora rhomboidea. The fibres of the cerebro-spinal axis are arranged into two classes, diverging and converging. The diverging fibres proceed from the NERVOUS SYSTEM—DEVELOPEMENT. 387 medulla oblongata, and diverge to every part of the surface of the brain ; while the converging commence upon the surface, and proceed inwards towards the centre so as to connect the diverging fibres of opposite sides. In certain parts of their course the diverging fibres are separated by the gray substance, and increase in number so as to form a body of considerable size, which is called a ganglion. The position and mutual relations of these fibres and ganglia may be best explained by reference to the mode of developement of the cerebro- spinal axis in animals and in man. The centre of the nervous system in the lowest animals possessed of a lengthened axis, presents itself in the form of a double cord. A step higher in the animal scale, and knots or ganglia are developed upon one extremity of this cord; such is the most rudimentary con- dition of the brain in the lowest forms of vertebrata. In the lowest fishes the anterior extremity of the double cord displays a. succession of five pairs of ganglia. The higher fishes and amphibia appear to have a different disposition of these primitive ganglia. The first two have become fused into a single ganglion, and then follow only three pairs of symmetrical ganglia. But if the larger pair be unfolded after being hardened in alcohol, it will then be seen that the whole number of ganglia exist, but that four have become concealed by a thin covering that has spread across them. This condition of the brain carries us upwards in the animal scale even to Mammalia ; e. g., in the dog or cat we find, first a single ganglion, the cerebellum; then three pairs following each other in succession; and if we unfold the middle pair, we shall be at once convinced that it is composed of two pairs of primitive ganglia concealed by an additional developement. Again it will be observed, that the primitive ganglia of opposite sides, at first separate and disjoined, become connected by means of transverse fibres of communication (commissures; commissura, a join- ing). The office of these commissures is the association in function of the two symmetrical portions. Hence we arrive at the general and important conclusion, that the brain among the lower animals consists of primitive cords, primitive ganglia upon those cords, and commissures which connect the substances of the adjoining ganglia, and associate their functions. In the developement of the cerebro-spinal axis in man, the earliest indication of the spinal cord is presented under the form of a pair of minute longitudinal filaments placed side by side. Upon these, towards the anterior extremity, five pairs of minute swellings are observed, not disposed in a straight line as in fishes, but curved upon each other so as to correspond with the direction of the future cranium. The posterior pair soon become cemented upon the middle line, forming a single ganglion ; the second pair also unite with each other; the third and fourth pairs, at first distinct, are speedily veiled by a lateral developement, which arches backwards and conceals them; the anterior pairs, at first very small, decrease in size and become almost lost in the increased developement of the preceding pairs. We see here a chain of resemblances corresponding with the pro- 3S8 NERVOUS SYSTEM—STRUCTURE. gressive developement observed in the lower animals; the human brain is passing through the phases of improving developement, which distinguish the lowest from the lower creatures: and we are naturally led to the same conclusion with regard to the architecture of the human brain, that we were led to establish as the principle of deve- lopement in the inferior creatures, namely, that it is composed of primitive cords, primitive ganglia upon those cords, commissures to connect those ganglia, and developements from those ganglia. In the adult, the primitive longitudinal cords have become cemented together, to form the spinal cord. But, at the upper extremity, they separate from each other under the name of crura cerebri. The first pair of ganglia developed from the primitive cords, have grown into the cerebellum ; the second pair (the optic lobes of animals) have be- come the coryora quadrigemina of man. The third pair, the optic thalami, and the fourth, the corpora striata, are the basis of the hemi- spheres, which, the merest lamina in the fish, have become the largest portion of the brain in man. And the fifth pair (olfactory lobes), so large in the lowest forms, have dwindled into the olfactory bulbs of man. The white substance of the brain and spinal cord when examined with the microscope, is found to consist of fibres embedded in gra- nular matter. The fibres vary in diameter from j^„ to yj^o of an inch; the former is the measurement of the fibres where the white substance is accumulated in any quantity; the latter, where the fibres enter the gray substance, and between the admeasurements every in- termediate size occurs. The fibres are composed of a thin, transpa- rent, and structureless neurilemma, con- taining in the living body a pellucid, co- lourless, oil-like fluid (neurine). After death the nervous fluid coagulates, and then presents the appearance of a white, opaque, curd-like matter, which aggre- gates in masses when the fibres are pressed or stretched, and gives to the nervous fibre a varicose form. The disposition of the nervous fibre to take on the varicose form bears a close re- lation to the thinness of the neurilemma ; hence in the fibres of the brain and spi- nal cord, and also in those of the olfactory, optic, and auditory nerves, where the neurilemma is very thin, this character is most remarkable. * Minute structure of nerve. 1. The mode of termination of nerve-fibres in loops; three of these loops are simple, the fourth is convoluted. The latter is found in situations where an exalted degree of sensation exists. 2. A nerve-fibre from the brain, showing the vari- cose appearance produced by traction or pressure. 3. A nerve-fibre enlarged to show its structure,—namely, a tubular envelope, and a contained substance, neurine. 4. A nerve- cell, sliowing its composition of a granular-looking capsule and granular contents. 5. Its nucleus containing a nucleolus. 6. A nerve-cell from which several caudate processes are given off. It contains, like the preceding, a nucleolated nucleus. 7. The third con- stituent of the medullary masses, namely, granules, or rather minute cells. These are dispersed among the cerebral fibres in great numbers; they present every variety of size and are many of them nucleated. ' Fig. 164* CLASSIFICATION OF NERVES. 389 The nervous fibres of the brain terminate in the gray substance by form- ing loops, as do the peripheral nerves in nearly all parts of the body. The gray substance of the brain is composed of globular cells em- bedded in a soft granular matter, which serves as a bond of connexion between them. The cells vary in size from T^n to j^'^ of an inch in diameter; they are of a reddish-gray colour, and are composed of a moderately thick capsule, containing a soft granular pulp and a nu- cleolated nucleus adherent to the inner surface of the investing cap- sule. The contents of the nucleus are similar to those of the parent cell, and the nucleolus may be either single or granular. Besides the constituents of the nerve-cell, there are pigment granules in va- riable number, sometimes dispersed generally through the pulp, and sometimes collected into small clusters, and giving to the cell a va- rious tint of gray. It is to these pigment-bearing cells, collected together in greater or smaller numbers, that different parts of the brain owe their relative degrees of intensity of gray. The general form of the nerve-cells is globular, but there are found mingled with the globular cells others of different shape. Some of these latter are oval oblong, or flattened, but the most remarkable form is that which is termed caudate, from its sending off from its periphery one or more coecal processes of variable length. From the capsules of the nerve-cells filaments are frequently given off, which serve to connect the cells together, and the number and arrangement of the cells offer many peculiarities in different parts of the cerebro-spinal mass. Two kinds of gray substance are described by Rolando as existing in the spinal cord; the one (substantia cinerea spongiosa vasculosa) is the ordinary gray matter of the cord, and the other (substantia cinerea gelatinosa) forms part of the posterior cornua. The former resembles in structure the gray matter of the brain, while the latter is composed of small bodies resembling the blood corpuscles of the frog. The nerves are divisible into two great classes ; those which pro- ceed directly from the cerebro-spinal axis, the cranial and spinal nerves, and constitute the system of animal life; and those which originate from a system of nervous centres, independent of the cere- bro-spinal axis, but closely associated with that, centre by numerous communications, the sympathetic system, or system of organic life. The division of nerves into cranial and spinal is purely arbitrary, and depends upon the circumstance of the former passing through the foramina of the cranium, and the latter through those of the verte- bral column. With respect to origin, all the cranial nerves, with the exception of the first, olfactory, proceed from the spinal cord, or from its immediate prolongation into the brain. The spinal nerves arise by two roots; anterior, which proceeds from the anterior segment of the spinal cord, and possesses a motor function ; and posterior, which is connected with the posterior segment, and bestows the faculty of sensation. The motor nerves of the cranium are shown by dissec- tion to be continuous with the motor portion of the cord, and form one system with the motor roots of the spinal cord; while the nerves of sensation, alwavs excepting the olfactory, are in like manner 33* 390 ORIGIN OF NERVES. traced to the posterior segment of the cord, and form part of the system of sensation. To these two systems a third was added by Sir Charles Bell, the respiratory system, which consists of nerves asso- ciated in the function of respiration, and arising from the side of the upper part of the spinal cord in one continuous line, which he thence named the respiratory tract. The microscope has succeeded in making no structural distinction between the anterior and posterior roots of the spinal nerves; but the latter are remarkable from pos- sessing a ganglion near their attachment with the cord. This gan- glion is observed upon the posterior roots of all the spinal nerves, and also upon the corresponding root of the fifth cranial nerve, which is thence considered a spinal cranial nerve. Upon others of the cranial nerves a ganglion is found, which associates them in their function with the nerves of sensation, and establishes an analogy with the spinal nerves. The researches of Mr. Grainger have made an important addition to our knowledge of the mode of connexion of the nerves with the spinal cord; he has shown that both roots of the spinal nerves, as well as most of the cerebral, divide into two sets of filaments upon entering the cord, one set being connected to the gray substance, while the other is continuous with the white or fibrous part of the cord. The former he considers to be the agents of the excito-motory system of Dr. Marshall Hall; and the latter, the communication with the brain, and the medium for the transmission of sensation and voli- tion. He has not been able to trace the fibres which enter the gray substance to their termination; but he thinks it probable that the ulti- mate filaments of the posterior root join those of the anterior root; or in the words of Dr. Marshall Hall's system, that the incident fibres (sensitive) are continuous with the reflex (motor). The connexion of a nerve with the cerebro-spinal axis is called, for convenience of description, its origin: this term must not, however, be received literally, for each nerve is developed in the precise situa- tion which it occupies in the body, and with the same relations that it possesses in after life. Indeed, we not unfrequently meet with in- stances in anencephalous foetuses where the nerves are beautifully and completely formed, while the brain and spinal cord are wanting. The word "origin" must therefore be considered as a relic of the darkness of preceding ages, when the cerebro-spinal axis was looked upon as the tree from which the nerves pushed forth as branches. In their distribution, the spinal nerves for the most part follow the course of the arteries, particularly in the limbs, where they lie almost constantly to the outer side and superficially to the vessels, as if for the purpose of receiving the first intimation of danger, and of com- municating it to the muscles, that the latter may instantly remove the arteries from impending injury. The microscopic examination of a cerebro-spinal nerve shows it to be composed of minute fibres, resembling those of the brain, and con- sisting of a neurilemma enclosing a pellucid fluid during life, and an opaque, white, curd-like substance after death. The chief difference between the fibres of the nerves and the cerebral fibres, is the larger NERVES—STRUCTURE-COMMUNICATIONS. 391 size (sAu t0 Wos of an inch) of the former, the greater thickness of their neurilemma, and a consequent indisposition to the formation of varicose enlargements upon compression. The primitive fibres, or filaments, are assembled into small bundles, and enclosed in'a distinct sheath, constituting a funiculus; the funiculi are collected into larger bundles, or fasciculi, and a single fasciculus or a number of fasciculi, connected by fibro-cellular tissue, and invested by a membranous sheath, constitute a nerve. The funiculi, when freshly exposed, pre- sent a peculiar zigzag line across their cylinder, which is most pro- bably produced by a wrinkling of the neurilemma, as it is destroyed by making extension upon the nerve. Communications between nerves take place either by means of the funiculi composing a single nerve, or of the fasciculi in a nervous plexus. In these communications there is no fusion of nervous sub- stance, the cord formed by any two funiculi is constantly enlarged, and corresponds accurately with their combined bulk. Microscopic examination substantiates this observation, and shows that the primi- tive fibre passes unchanged from one funiculus to the other, so that the primitive fibre is single, and uninterrupted from its connexion with the cerebro-spinal axis to its terminal distribution. A nervous plexus consists in a communication between the fasciculi and funi- culi composing the nerves which are associated in their supply of a limb or of a certain region of the body. During this communication there is an interchange of funiculi, and with the funiculi an inter- change of fibres. The Sympathetic system consists of numerous ganglia, of commu- nicating branches passing between the ganglia, of others passing be- tween the ganglia and the cerebro-spinal axis, and of branches of distribution which are remarkable for their frequent and plexiform communications. The sympathetic nerves also differ from other nerves in their colour, which is of a grayish pearly tint. Examined with the microscope, they are seen to be composed of an admixture of gray and white fibres; the white fibres belong to the cerebro- spinal system: the gray are much smaller than the white, less trans- parent, and the neurilemma is less easily distinguishable from its con- tents : some of the nerves are composed of gray fibres only, without any admixture of white. The sympathetic ganglia contain the nerve-cells observed in the gray substance of the brain; they are firmer in structure and enclosed in a strong investing capsule, the latter being made up of nucleated corpuscles. The fasciculi of fibres entering the ganglion become divided, and form a plexus around the globules; they then converge to constitute one or more fasciculi, by which they quit the ganglion. The termination of nerves takes place by a separation of the fas- ciculi into their primitive nervous fibrils, and by the distribution of the latter to the various tissues and surfaces of the body in the form of loops. In the muscles these terminal loops surround the ultimate fas- ciculi, in the skin thev enter into the composition of the papillae, and in very thin membranes they are modified so as to constitute a net- work. The nerves of special sense offer other modifications in the 392 BRAIN—MEMBRANES. mode of termination of the primitive fibres; thus, in the olfactory nerve, the termination is by loops; in the auditory nerve, partly by loops, and partly by free extremities; and in the optic nerve by free rounded extremities alone. The capillary vessels of nerves are very minute. They run pa- rallel with the nervous fasciculi, and every here and there are con- nected by transverse communications, so as to give rise to a network composed of oblong meshes very similar to the capillary system of muscles. The nervous system may be divided for convenience of descrip- tion into 1. The brain. 2. The spinal cord. 3. The cranial nerves. 4. The spinal nerves. 5. The sympathetic system. the brain. The brain is a collective term which signifies those parts of the nervous system, exclusive of the nerves themselves, which are con- tained within the cranium; they are the cerebrum, cerebellum, and medulla oblongata. These are invested and protected by the mem- branes of the brain, and the whole together constitute the encephalon (sv xsytxkri, within the head). MEMBRANES OF THE ENCEPHALON. Dissection.—To examine the encephalon with its membranes, the upper part of the skull must be removed, by sawing through the ex- ternal table and breaking the internal table with the chisel and ham- mer. After the calvarium has been loosened all round, it will require a considerable degree of force to tear the bone away from the dura mater. This adhesion is particularly firm at the sutures, where the dura mater is continuous with a membranous layer interposed between the edges of the bones; in other situations, the connexion results from numerous vessels which permeate the inner table of the skull. The adhesion subsisting between the dura mater and bone is greater in the young subject and in old persons than in the adult. Upon being torn away, the internal table will present numerous deeply grooved and ramified channels, corresponding with the branches of the arteria meningea media. Along the middle line will be seen a groove corresponding with the superior longitudinal sinus, and on either side maybe frequently observed some depressed fossae, corresponding with the Pacchionian bodies. The membranes of the encephalon are the dura mater, arachnoid membrane, and pia mater. The Dura Mater* is the firm, whitish or grayish laver which is brought into view when the calvarium is removed. It is a strong fibrous membrane, somewhat laminated in texture, and composed of white fibrous tissue. Lining the interior of the cranium, it serves as the internal periosteum of that cavity ; it is prolonged also into the spinal column, under the name of the theca vertebralis, but is not ad- * So named from a supposition that it was the source of all the fibrous membranes of the body. DURA MATER—PROCESSES. 393 herent to the bones in that canal as in the cranium. From the inter- nal surface of the dura mater, processes are directed inwards for the support and protection of parts of the brain; while from its exterior, other processes are prolonged outwards to form sheaths for the nerves as they quit the skull and spinal column. Its external surface is rough and fibrous, and corresponds with the internal table of the skull. The internal surface is smooth, and lined by the thin varnish-like lamella of the arachnoid membrane. The latter is a serous membrane. Hence the dura mater becomes a fibro-serous membrane, being com- posed of its own proper fibrous structure, and the serous layer derived from the arachnoid. There are two other instances of fibro-serous membrane in the body, formed in the same way, namely the pericar- dium and tunica albuginea of the testicle. On the external surface of the dura mater the branches of the middle meningeal artery may be seen ramifying; and in the middle line is a depressed groove, formed by the subsidence of the upper wall of the superior longitudinal sinus. If the sinus be opened along its course, it will be found to be a triangular channel, crossed at its lower angle by numerous white bands, called chordae Willisii ;* granular bodies are also occasionally seen in its interior, these are glandulae Pacchioni. The Glandula Pacchioni^ are small, round, whitish granulations, occurring singly or in clusters, and forming small groups of various size along the margin of the longitudinal fissure of the hemispheres, but more particularly on the middle of this border. These bodies would seem to be of morbid origin; they are absent in infancy, increase in numbers in adult life, and are abundant in the aged. They are generally associated with opacity of the arachnoid around their bases, but in some instances are wanting even in the adult. They have their point of attachment in the pia mater, from which they seem to spring, carrying with them the arachnoid membrane, and then, in proportion to their size, producing various effects upon contiguous parts. For example, when small they remain free or constitute a bond of adhe- sion between the visceral and parietal layer of the arachnoid; when of larger size they produce absorption of the dura mater, and as the degree of absorption is greater or less, they protrude through that membrane, and form depressions on the inner surface of the cra- nium, or simply render the dura mater thin and cribriform. Some- times they cause absorption of the wall of the longitudinal sinus, and projecting into its cavity give rise to the granulations described in re- lation to that channel. If the student cut through one side of the dura mater, in the direc- tion of his incision through the skull, and turn it upwards towards the middle line, he will observe the smooth internal surface of this membrane. He will perceive also the large veins of the hemispheres filled with dark blood, and passing from behind forwards to open into * Willis lived in the seventeenth century; he was a great defender of the opinions of Harvey. t These bodies are incorrectly described as conglobate glands by Pacchioni, in an epistolary dissertation, " De Glandulis conglobatis Dura? Meningis indequeortis Lympha- ticis ad Piam Matrem productis," published in Rome, in 1705. 394 DURA MATER—PROCESSES. the superior longitudinal sinus; and the firm connexion, by means of these veins and the Pacchionian bodies, between the opposed sur- faces of the arachnoid membrane. If he separate these adhesions with his scalpel, he will see a vertical layer of dura mater descend- ing between the hemispheres; and if he draw one side of the brain a little outwards, he will be enabled to perceive the extent of the pro- cess of membrane which is called the falx cerebri. The processes of dura mater which are sent inwards towards the interior of the skull, are the falx cerebri, tentorium cerebelli, and falx cerebelli. The Falx cerebri (falx, a sickle), so named from its sickle-like appearance, narrow in front, broad behind, and forming a sharp curved edge below, is attached in front to the crista galli process of the ethmoid bone, and behind to the tentorinm cerebelli. The Tentorium cerebelli (tentorium, a tent) is a roof of dura mater, thrown across the cerebellum and attached at each side to the mar- gin of the petrous portion of the temporal bone; behind to the trans- verse ridge of the occipital bone, which lodges the lateral sinuses; and to the clinoid processes in front. It supports the posterior lobes of the cerebrum and prevents their pressure* on the cerebellum, leaving only a small opening anteriorly, for the transmission of the crura cerebri. The Falx cerebelli is a small process, generally double, attached to the vertical ridge of the occipital bone beneath the lateral sinus, and to the tentorium. It is received into the indentation between the two hemispheres of the cerebellum. The layers of the dura mater separate in several situations, so as to form irregular channels which receive the venous blood. These are the sinuses of the dura mater, which have been described at page 362. The student cannot see the tentorium and falx cerebelli until the brain is removed; but he should consider the attachments of the for- mer upon the dried skull, for he will have to incise it in the removal of the brain. He should now proceed to that operation, for which purpose the dura mater is to be incised all round, on a level with the section through the skull, and the scissors are to be carried deeply between the hemispheres of the brain in front, to cut through the anterior part of the falx; then draw the dura mater backwards, and leave it hanging by its attachment to the tentorium. Raise the ante- rior lobes of the brain carefully with the hand, and lift the olfactory bulbs from the cribriform fossae with the handle of the scalpel. Then cut across the two optic nerves and internal carotid arteries. Next divide the infundibulum and third nerve, and carry the knife along the margin of the petrous bone at each side, so as to divide the tentorium near its attachment. Cut across the fourth, fifth, sixth, seventh, and eighth nerves in succession with a sharp knife, and pass the scalpel as far down as possible into the vertebral canal, to sever the spinal cord, cutting first to one side and then to the other, in * In leaping animals, as the feline and canine genera, the tentorium forms tent. ARACHNOID MEMBRANE. 395 order to divide the vertebral arteries and first cervical nerves. Then let him press the cerebellum gently forwards with the fingers of the right hand, the hemispheres being supported with the left, and the brain will roll into his hand. The Arteries of the dura mater are the anterior meningeal from the ethmoidal, ophthalmic, and internal carotid. The middle menin- geal and meningea parva from the internal maxillary. The inferior meningeal from the ascending pharyngeal and occipital arteries; and the posterior meningeal from the vertebral. Its Nerves are derived from the nervi molles and vertebral plexus of the sympathetic, from the Casserian ganglion, the ophthalmic nerve, and sometimes from the fourth. The branches from the two last are given off while those nerves are situated by the side of the sella turcica; they are recurrent, and pass backwards between the layers of the tentorium, to the lining membrane of the lateral sinus. Arachnoid Membrane. The Arachnoid (fyayyy sfdo^, like a spider's web), so named from its extreme tenuity, is the serous membrane of the cerebro-spinal centre, and, like other serous membranes, a shut sac. It envelopes the brain and spinal cord (visceral layer) and is reflected upon the inner surface of the dura mater (parietal layer), giving to that mem- brane its serous investment. On the upper surface of the hemispheres the arachnoid is transpa- rent, but may be demonstrated as it passes across the sulci from one convolution to another by injecting, with a blow-pipe, a stream of air beneath it. At the base of the brain the membrane is opalescent and thicker than in other situations, and more easily demonstrable from the circumstance of its stretching across the interval between the middle lobes of the hemispheres. The space which is included between this layer of membrane and those parts of the base of the brain which are bounded by the optic commissure and fissures of Sylvius in front, and the pons Varolii behind, is termed the anterior sub-arachnoidean space. Another space formed in a similar manner, between the under part of the cerebellum and the medulla oblongata, is the posterior sub-arachnoidean space; and a third space, situated upon the corpora quadrigemina, may be termed the superior sub- arachnoidean space. These spaces communicate freely with each other, the anterior and posterior across the crura cerebelli, the ante- rior and the middle around the crura cerebri, and the latter and the posterior across the cerebellum in the course of the vermiform pro- cesses. They communicate also with a still larger space formed by the loose disposition of the arachnoid around the spinal cord, the spinal sub-arachnoidean space. The whole of these spaces, with the slighter spaces between the convolutions of the hemispheres, consti- tute one large and continuous cavity which is filled with a limpid, serous secretion, the sub-arachnoidean fluid,* a fluid which is neces- * The presence of a serous fluid beneath the arachnoid has given rise to the conjecture that a sub-arachnoid serous membrane may exist in that situation. Such a supposition is quite unnecessary to explain the production of the secretion, since the pia mater is fully adequate to that function. 396 PIA MATER—CEREBRUM. sary to the maintenance and protection of the cerebro-spinal mass. The quantity of the sub-arachnoidean fluid is determined by the relative size of the cerebro-spinal axis and that of the containing cavity, and is consequently very variable. It is smaller in youth than in old age, and in the adult has been estimated at about two ounces. The visceral layer of the arachnoid is connected to the pia mater by a delicate areolar tissue, which in the sub-arachnoidean spaces is loose and filamentous. The serous secretion of the true cavity of the arachnoid is very small in quantity as compared with the sub-arachnoidean fluid. The arachnoid does not enter into the ventricles of the brain, as imagined by Bichat, but is reflected inwards upon the venae Galeni for a short distance only, and returns upon those vessels to the dura mater of the tentorium. It surrounds the nerves as they originate from the brain, and forms a sheath around them to their point of exit from the skull. It is then reflected back upon the inner surface of the dura mater. There are no vessels apparent in the arachnoid, and no nerves have been traced into it. Pia Mater. The Pia mater is a vascular membrane composed of innumerable vessels held together by a thin layer of fibro-cellular tissue. It in- vests the whole surface of the brain, dipping into the sulci between the convolutions, and forming a fold in its interior called velum inter- positum. It also forms folds in other situations, as in the third and fourth ventricles, and in the longitudinal grooves of the spinal cord. This membrane differs very strikingly in its structure in different parts of the cerebro-spinal axis. Thus, on the surface of the cere- brum, in contact with the soft gray matter of the brain, it is exces- sively vascular, forming remarkable loops of anastomoses in the interspaces of the convolutions, and distributing multitudes of minute straight vessels to the gray substance. In the substantia perforata, again, and locus perforatus, it gives off tufts of small arteries, which pierce the white matter to reach the gray substance in the interior. But upon the crura cerebri, pons Varolii, and spinal cord, its vascular character seems almost lost. It has become a dense fibrous mem- brane, difficult to tear off, and forming the proper sheath of the spinal cord. The pia mater is the nutrient membrane of the brain, and derives its blood from the internal carotid and vertebral arteries. Its Nerves are the minute filaments of the sympathetic, which ac- company the branches of the arteries. CEREBRUM. The Cerebrum is divided superiorly into two hemispheres by the great longitudinal fissure, which lodges the falx cerebri, and marks the original developement of the brain by two symmetrical halves. Each hemisphere, upon its under surface, admits of a division into CEREBRUM-CORPUS CALLOSUM. 397 three lobes, anterior, middle, and posterior. The anterior lobe rests upon the roof of the orbit, and is separated from the middle by the fissure of Sylvius.* The middle lobe is received into the middle fossa of the base of the skull, and is separated from the posterior by a slight impression produced by the ridge of the petrous bone. The posterior lobe is supported by the tentorium. If the upper part of one hemisphere, at about one-third from its summit, be removed with a scalpel, a centre of white substance will be observed, surrounded by a narrow border of gray, which follows the line of the sulci and convolutions, and presents a zigzag form. This section, from exhibiting the largest surface of medullary sub- stance demonstrable in a single hemisphere, is called centrum ovale minus; it is spotted by numerous small red points (puncta vasculosa) which are produced by the escape of blood from the cut ends of minute arteries and veins. Now separate carefully the two hemispheres of the cerebrum, and a broad band of white substance (corpus callosum) will be seen to connect them; it will be seen also that the surface of the hemisphere, where it comes into contact with the corpus callosum, is bounded by a large convolution (gyrus fornicatus) which lies horizontally on that body, and may be traced forwards and backwards to the base of the brain, terminating by each extremity at the fissure of Sylvius. The sulcus between this convolution and the corpus callosum has been termed, very improperly, the " ventricle of the corpus callosum," and some longitudinal fibres (striae longitudinales laterales), which are brought into view when the convolution is raised, were called by Reil the " covered band." If, now, the upper part of each hemi- sphere be removed to a level with the corpus callosum, a large ex- panse of medullary substance, surrounded by a zigzag line of gray substance, corresponding with the convolutions and sulci of the two hemispheres, will be seen; this is the centrum ovale majus of Vieussens. The Corpus callosum (callosus, hard) is a thick layer of medullary fibres, passing transversely between the two hemispheres, and con- stituting their great commissure. It is situated in the middle line of the centrum ovale majus, but nearer to the anterior than to the pos- terior part of the brain, and terminates anteriorly in a rounded border (genu), which may be traced downwards to the base of the brain, in front of the commissure of the optic nerves. Posteriorly, it forms a thick rounded fold (splenium), which is continuous with the fornix. The breadth of the corpus callosum is about four inches. Beneath the posterior rounded border of the corpus callosum is the transverse fissure of the cerebrum, which extends between the hemi- spheres and crura cerebri from very near the fissure of Sylvius on one side, to the same point on the opposite side of the brain. It is through this fissure that the pia mater communicates with the velum * James Dubois, a celebrated professor of anatomy in Paris, where he succeeded Vidius in 1550, although known much earlier by his works and discoveries, but particu- larly by his violence in the defence of Galen. His name was Latinized to Jacobus Sylvius. 34 398 CEREBRUM—LATERAL VENTRICLES, interpositum. And it was here that Bichat conceived the arachnoid to enter the ventricles; hence it is also named the fissure of Bichat. Along the middle line of the corpus callosum is the raphe, a linear . depression between two slightly elevated longitudinal bands (chordae longitudinales Lancisii); and on either side of the raphe may be seen the linea transversa, which mark Fi£-165-* the direction of the fibres of which the corpus callosum is composed. These fibres may be traced into the hemispheres on either side, and they will be seen to be crossed at about an inch from the raphe by the longi- tudinal fibres of the covered band of Reil. Anteriorly and posteriorly, the fibres of the corpus callosum curve into their corresponding lobe. If, now, a superficial incision be made through the corpus callosum on either side of the raphe, two irregular cavities will be opened, which extend from one extremity of the hemispheres to the other: these are the lateral ventricles. To expose them completely, their upper boundary should be removed with the scissors. In making this dissection, the thin and diaphanous membrane of the ventricles may frequently be seen. Lateral Ventricles.—Each lateral ventricle is divided into a central cavity, and three smaller cavities called cornua. The ante- rior cornu curves forwards and outwards in the anterior lobe; the middle cornu descends into the middle lobe; and the posterior cornu passes backwards in the posterior lobe, converging towards its fellow of the opposite side. The central cavity is triangular in its form, being bounded above (roof) by the corpus callosum; internally, by the septum lucidum, which separates it from the opposite ventricle; * The lateral ventricles of the cerebrum. 1,1. The two hemispheres cut down to a level with the corpus callosum so as to constitute the centrum ovale majus. The surface is seen to be studded with the small vascular points—puncta vasculosa ; and surrounded by a narrow margin which represents the gray substance. 2. A small portion of the anterior extremity (genu) of the corpus callosum. 3. Its posterior boundary (splenium); the intermediate portion forming the roof of the lateral ventricles has been removed so as to completely expose those cavities. 4. A part of the septum lucidum, showing an inter- space between its layers—the fifth ventricle. 5. The anterior cornu of one side. 6. The commencement of the middle cornu. 7. The posterior cornu. 8. The corpus striatum of one ventricle. 9. The tenia semicircularis covered by the vena corporis striata and tenia Tarini. 10. A small part of the thalamus opticus. 11. The dark fringe-like body to the left of the numeral is the choroid plexus. This plexus communicates with that of the opposite ventricle through the foramen of Monro, or foramen commune anterius ; a bristle is passed through this opening, and its extremities are seen resting on the corpus striatum at each side. The figure 11 rests upon the edge of the fornix, upon that part of it which is called the corpus fimbriatum. 12. The fornix. 13. The commencement of the hippo- campus major descending into the middle cornu. The rounded oblong body in the pos- terior cornu of the lateral ventricle, directly behind the figure 13, is the hippocampus minor. CORPUS STRIATUM—CHOROID PLEXUS. 399 and below (floor) by the following parts, taken in their order of posi- tion from before backwards:— Corpus striatum, Choroid plexus, Tenia semicircularis, Corpus fimbriatum, Thalamus opticus, Fornix. The Corpus striatum is named from the striated lines of white and gray matter which are seen upon cutting into its substance. It is gray on the exterior, and of a pyriform shape. The broad end, directed forwards, rests against the corpus striatum of the opposite side: the small end, backwards, is separated from its fellow by the interposition of the thalami optici. The corpora striata are the supe- rior ganglia of the cerebrum. The Tenia semicircularis (tenia, a fillet) is a narrow band of me- dullary substance, extending along the posterior border of the corpus striatum, and serving as a bond of connexion between that body and the thalamus opticus. The tenia is partly concealed by a large vein (vena corporis striati), formed by small vessels from the corpus stria- tum and thalamus opticus, which terminates in the vena Galeni of its own side. The vein is overlaid by a yellowish band, a thickening of the lining membrane of the ventricle. This was first noticed and described by Tarinus, under the name of the horny band. We may therefore term it, tenia Tarini.* The Thalamus opticus (thalamus, a bed) is an oblong body, having a thin coating of white substance on its surface; it has received its name from giving origin to one root of the optic nerve. It is the inferior ganglion of the cerebrum. Part only of the thalamus is seen in the floor of the lateral ventricle; we must, therefore, defer its further description until we can examine it in its entire extent. The Choroid plexus (x°'?'°v> sfSoz, resembling the chorion)f is a vas- cular fringe extending obliquely across the floor of the lateral ventri- cle, and sinking into the middle cornu. Anteriorly, it is small and tapering, and communicates with the choroid plexus of the opposite ventricle, through a large oval opening, the foramen of Monro, or foramen commune anterius. The foramen may be distinctly seen by pulling slightly on the plexus, and pressing aside the septum lucidum with the handle of the knife. It is situated between the under surface of the fornix, and the anterior extremities of the thalami optici, and forms a communication transversely between the lateral ventricles, and perpendicularly with the third ventricle. The choroid plexus presents upon the surface a number of minute vascular processes, which are termed villi. They are invested by a very delicate epithelium, surmounted by cilia, which have been seen in active movement in the embryo. In their interior the plexuses not unfrequently contain particles of calcareous matter, and they are sometimes covered by small clusters of serous cysts. The Corpus fimbriatum is a narrow white band, which is situated * Peter Turin, a French anatomist: his work, entitled " Adversaria Anatomica," was published in 1750. t See the note appended to the description of the choroid coat of the eyeball. 400 CEREBRUM—CORNUA. immediately behind the choroid plexus, and extends with it into the descending cornu of the lateral ventricle. It is in fact the lateral thin edge of the fornix, and being attached to the hippocampus major in the descending horn of the lateral ventricle, is also termed, tenia hippocampi. The Fornix is a white layer of medullary substance, of which a portion only is seen in this view of the ventricle. The Anterior' cornu is triangular in its form, sweeping outwards, and terminating by a point in the anterior lobe of the brain, at a short distance from its surface. The Posterior cornu or digital cavity curves inwards, as it extends back into the posterior lobe of the brain, and likewise terminates near the surface. An elevation corresponding with a deep sulcus between two convolutions projects into the area of this cornu, and is called the hippocampus minor. The Middle or descending cornu, in descending into the middle lobe of the brain, forms a very considerable curve, and alters its di- rection several times as it proceeds. Hence it is described as pass- ing backwards and outwards and downwards, and then turning for- wards and inwards. This complex expression of a very simple curve has given birth to a symbol formed by the primary letters of these various terms; and by means of this the student recollects with ease the course of the cornu, bodfi. It is the largest of the three cornua, and terminates close to the fissure of Sylvius, after having curved around the crus cerebri. The middle cornu should now be laid open, by inserting the little finger into its cavity, and making it serve as a director for the scalpel in cutting away the side of the hemisphere, so as to expose it com- pletely. The Superior boundary of the middle cornu is formed by the under surface of the thalamus opticus, upon which are the two projections called corpus genieulatum internum and externum; and the inferior wall by the various parts which are often spoken of as the contents of the middle cornu: these are the— Hippocampus major, Choroid plexus, Pes hippocampi, Fascia dentata, Pes accessorius, Transverse fissure. Corpus fimbriatum, The Hippocampus major or cornu Ammonis, so called from its re- semblance to a ram's horn, the famous crest of Jupiter Ammon, is a considerable projection from the inferior wall, and extends the whole length of the middle cornu. Its extremity is likened to the foot of an animal, from its presenting a number of knuckle-like elevations upon the surface, and is named pes hippocampi. The hippocampus major is the internal surface of the convolution (gyrus fornicatus) of the la- teral edge of the hemisphere, the convolution which has been pre- viously described as lying upon the corpus callosum and extending downwards to the base of the brain to terminate at the fissure of Sylvius. If it be cut across, the section will be seen to resemble the CORPUS FIMBRIATUM. 401 extremity of a convoluted scroll, consisting of alternate layers of white and gray substance. The hippocampus major is continuous superiorly with the fornix and corpus callosum, deriving from the latter its medullary layer. The Pes accessorius is a swelling somewhat resembling the hippo- campus major, but smaller in size; it is situated on the outer wall of the cornu, and is frequently absent. The Corpus fimbriatum (tenia hippocampi) is the narrow white band which is prolonged from the central cavity of the ventricle, and is attached along the inner border of the hippocampus major. It is lost inferiorly on the hippocampus. Fascia dentata :—If the corpus fimbriatum be carefully raised, a narrow serrated band of gray substance, the margin of the gray sub- stance of the middle lobe, will be seen beneath it; this is the fascia dentata. Beneath the corpus fimbriatum will be likewise seen the transverse fissure of the brain, which has been before described as extending from near the fissure of Sylvius on one side, across to the same point on the opposite side of the brain. It is through this fissure that the pia mater com- municates with the cho- roid plexus, and the latter obtains its supply of blood. The fissure is bounded on one side by the corpus fim- briatum, and on the other by the under surface of the thalamus opticus. The internal boundary of the lateral ventricle is the septum lucidum. The septum is thin and semi- transparent, and consists of two laminae of cerebral substance attached above to the under surface of the corpus callosum at its anterior part, and below to the * The mesial surface of a longitudinal section of the brain. The incision has been carried along the middle line ; between the two hemispheres of the cerebrum, and through the middle of the cerebellum and medulla oblongata. 1. The inner surface of the left hemisphere. 2. The divided surface of the cerebellum, showing the arbor vita;. 3. The medulla oblongata. 4. The corpus callosum, curving downwards in front to terminate at the base of the brain ; and rounded behind, to become continuous with 5, the fornix. 6. One of the crura of the fornix descending to 7, one of the corpora albicantia. 8. The sep- tum lucidum. 9. The velum interpositum, communicating with the pia mater of the convolutions through the fissure of Bichat. 10. Section of the middle commissure situated in the third ventricle. 11. Section of the anterior commissure. 12. Section of the poste- rior commissure ; the commissure is somewhat above and to the left of the numeral. Ihe interspace between 10 and 11 is the foramen commune anterius, in which the crus of the fornix (6) is situated. The interspace between 10 and 12 is the foramen commune pos- terius. 13. The corpora quadrigemina, upon which is seen resting the pineal gland, 14 15. The iter a tertio ad quartum ventriculum, or aqueduct of Sylvius lb. the fourth ventricle. 17. The pons Varolii, through which are seen passing the diverging fibres of the corpora pyramidalia. 18. The crus cerebri of the left side, with the third nerve arising from it. 19. The tuber cinereum, from which projects the infundibulum having the pitui- tary gland appended to its extremity. 20. One of the optic nerves. 21. Ihe left olfac tory nerve terminating anteriorly in a rounded bulb. 402 CEREBRUM—FORNIX. fornix. Between the two layers is a narrow space, the fifth ventricle, which is lined by a proper membrane. The fifth ventricle may be shown,by snipping through the septum lucidum transversely with the scissors. The corpus callosum should now be cut across towards its anterior extremity, and the two ends carefully dissected away. The anterior portion will be retained only by the septum lucidum, but the posterior will be found incorporated with the white layer beneath, which is the fornix. Fornix.—The fornix (arch) is a triangular lamina of white sub- stance, broad behind, and extending into each lateral ventricle: nar- row in front, where it terminates in two crura, which arch down- wards to the base of the brain. The two crura descend in a curved direction to the base of the brain, embedded in gray substance in the lateral walls of the third ventricle, and lying directly behind the an- terior commissure. At the base of the brain they make a sudden curve upon themselves and constitute the corpora albicantia, from which they may be traced upwards to their origin in the thalami op- tici. Opening transversely beneath these two crura, just as they are about to arch downwards, is the foramen of communication between the lateral and the third ventricles, the foramen of Monro; or foramen commune anterius. The choroid plexuses communicate, and the veins of the corpora striata pass through this opening. The lateral thin edges of the fornix are continuous posteriorly with the concave border of the hippocampus major at each side, and form the narrow white band called corpus fimbriatum (posterior crus of the fornix). In the middle line the fornix is continuous with the corpus callosum, and at each side writh the hippocampus major and minor. Upon the under surface of the fornix towards its posterior part, some transverse lines are seen passing between the diverging corpora fim- briata: this appearance is termed the lyra (corpus psalloides), from a fancied resemblance to the strings of a harp. The fornix may now be removed by dividing it across anteriorly, and turning it backwards, at the same time separating its lateral con- nexions with the hippocampi. If the student examine its under sur- face, he will perceive the lyra above described. Beneath the fornix is the velum interpositum, a duplicature of pia mater introduced into the interior of the brain, through the transverse fissure. The velum is continuous at each side with the choroid plexus, and contains in its inferior layer, two large veins (the vena Galeni) which receive the blood from the corpora striata and choroid plexuses, and terminate posteriorly, after uniting into a single trunk, in the straight sinus. Upon the under surface of the velum interpositum are two fringe-like bodies, which project into the third ventricle. These are the choroid plexuses of the third ventricle; posteriorly these fringes enclose the pineal gland. If the velum interpositum be raised and turned back, an operation which must be conducted with care, particularly at its posterior part where it invests the pineal gland, the thalami optici and the cavity of the third ventricle will be brought into view. Thalami Optici.—The thalami optici are two oblong, square-shaped THIRD VENTRICLE. 403 bodies, of a white colour superficially, inserted between the two diverg- ing portions of the corpora striata. In the middle line a fissure exists between them, which is called the third ventricle. Posteriorly and in- feriorly, they form the superior wall of the descending cornu, and pre- sent two rounded elevations called corpus geniculatum externum and internum. The corpus geniculatum externum is the larger of the two, and of a grayish colour; it is the principal origin of the optic nerve. Anteriorly, the thalami are connected with the corpora albicantia by means of two white bands, which appear to originate in the white substance uniting the thalami to the corpora striata. Externally they are in relation with the corpora striata and hemispheres. In their in- terior the thalami are composed of white fibres mixed with gray sub- stance. They are essentially the inferior ganglia of the cerebrum. Third Ventricle.—The third ventricle is the fissure between the two thalami optici. It is bounded above by the under surface of the velum interpositum, from which are suspended the choroid plexuses of the third ventricle. Its floor is formed by the gray substance of the anterior termination of the corpus callosum, called lamina cinerea, the tuber cinereum, corpora albicantia, and locus perforatus. Laterally it is bounded by the thalami optici; anteriorly by the anterior commissure and crura of the fornix; an& posteriorly by the posterior commissure and the iter a tertio ad quartum ventriculum. The third ventricle is cross- ed by three commissures, the anterior, middle, and posterior; and between these are two spaces, called foramen commune anterius and foramen commune posterius. The Anterior commissure is a small rounded white cord, which en- ters the corpus striatum at either side, and spreads out in the substance of the hemispheres; the middle or soft commissure consists of gray mat- ter, which is continuous with the gray lining of the ventricle, it connects the adjacent sides of the thalami optici; the posterior commissure, smaller than the anterior, is a rounded white cord, connecting the two thalami optici posteriorly. The space between the anterior and middle commissure is called the foramen commune anterius, and is that to which Monro has given his name (foramen of Monro). It is the medium of communication be- tween the lateral and third ventricles and it transmits superiorly the choroid plexus and the venae corporum striatorum. The foramen com- mune anterius is also termed, iter ad infundibulum, fromleading down- wards to the funnel-shaped cavity of the infundibulum. The crura of the fornix are embedded in the lateral walls of the foramen commune, and are concealed from view in this situation by the layer of gray sub- stance which lines the interior of the third ventricle. If the crura be slightly separated, the anterior commissure will be seen crossing from one corpus striatum to the other, immediately in front of them. The space between the middle and posterior commissure is the foramen commune posterius; it is much shallower than the preceding, and is the origin of a canal, the aqueduct of Sylvius or iter a tertio ad quartum ventriculum, which leads backwards beneath the posterior commissure and through the base of the corpora quadrigemina to the upper part of the fourth ventricle. 404 CEREBRUM—FOURTH VENTRICLE. Corpora Quadrigemina.—The corpora quadrigemina, or optic lobes, are situated immediately behind the third ventricle and posterior com- missure; and beneath the posterior border of the corpus callosum. They form, indeed, at this point, the inferior boundary of the trans- verse fissure of the hemispheres, the fissure of Bichat. The anterior pair of these bodies are gray in colour, and are named nates: the posterior pair are white and much smaller than the anterior; they are termed testes. From the nates may be traced a rounded process (brachium anterius) which passes obliquely outwards into the thala- mus opticus ; and from the testes a similar but smaller process (bra- chium posterius) which has the same destination. The corpus geni- culatum internum lies in the interval of these two processes where they enter the thalamus, and behind the brachium posterius is a pro- minent band (laqueus) which marks the course of the superior divi- sion of the fasciculus olivaris. The corpora quadrigemina are per- forated longitudinally through their base by the aqueduct of Sylvius; they are covered in partly by the pia mater and partly by the velum interpositum, and the nates form the base of support of the pineal gland. Pineal Gland.—The pineal gland is a small reddish gray body o f a conical form (hence its synonym conarium), situated on the anterior part of the nates and invested by a duplicature of pia mater derived from the under part of the velum interpositum. The pineal gland, when pressed between the fingers is found to contain a gritty matter (acervulus) composed chemically of phosphate and carbonate of lime, and is sometimes hollow in the interior. It is connected to the brain by means of two medullary cords called peduncles and a thin lamina derived from the posterior commissure; the peduncles of the pineal gland are attached to the thalami optici and may be traced along the upper and inner margin of those bodies to the crura of the fornix with which they become blended. From the close connexion sub- sisting between the pia mater and the pineal gland and the softness of texture of the latter, the gland is liable to be torn away in the re- moval of the pia mater. Behind the corpora quadrigemina is the cerebellum, and beneath the cerebellum the fourth ventricle. The student must therefore di- vide the cerebellum down to the fourth ventricle, and turn its lobes aside to examine that cavity. Fourth Ventricle.—The fourth ventricle (sinus rhomboidalis) is the ventricle of the medulla oblongata, upon the posterior surface of which, and of the pons Varolii, it is placed. It is a lozenge-shaped cavity, bounded on each side by a thick cord passing between the cerebellum and corpora quadrigemina, called the processus e cerebello ad testes, and by the corpus restiforme. It is covered in behind by the cerebellum, and by a thin lamella of medullary substance, stretched between the two processus e cerebello ad testes, termed the valve of Vieussens.* That portion of the cerebellum which forms the posterior boundary of the fourth ventricle, presents four small prominences or lobules, and * Raymond Vieussens, a great discoverer in the anatomy of the brain and nervous system. His " Neurographia Universalis" was published at Lyons, in 1685. LINING MEMBRANE OF THE VENTRICLES. 405 a thin layer of medullary substance, the velum medullare posterius. Of the lobules two are placed in the middle line, the nodulus and uvula, the former being before the latter; the remaining two are named amygdala, or tonsils, and are situated one on either side of the uvula. They all project into the cavity of the fourth ventricle, and the velum medullare posterius is situated in front of them. The valve of Vieussens or velum medullare anterius is an extremely thin lamella of medullary substance, prolonged from the white matter of the cere- bellum to the testes, and attached on each side to the processus e ce- rebello ad testes. This lamella is overlaid for a short distance by a thin, transversely-grooved lobule of gray substance (linguetta lami- nosa) derived from the anterior border of the cerebellum, and its junction with the testes is strengthened by a narrow slip given off by the commissure of those bodies, the franulum veli medullaris anteri- oris. The anterior wall, orfloor of the fourth ventricle is formed by two slightly convex bodies, processus teretes or posterior pyramids, separated by a longitudinal groove which is continuous inferiorly with the sulcus longitudinalis posterior of the spinal cord. The pro- cessus teretes are crossed transversely by several white and gray fasciculi (linea transversa) the origin of the auditory nerves. And upon the lower part of the floor of this ventricle is an impression resembling the point of a pen and hence named calamus scriptorius; the lateral boundaries of. the calamus are the processus clavati of the posterior median columns of the spinal cord. Above, the fourth ven- tricle is bounded by the corpora quadrigemina and aqueduct of Syl- vius ; and below by a layer of pia mater and arachnoid, called the valve of the arachnoid. It is by rupture of this latter that a commu- nication is established between the ventricles of the brain and the sub-arachnoidean space. Within the fourth ventricle and lying against the uvula and tonsils are two small vascular fringes formed by the pia mater, the choroid plexuses of the fourth ventricle. The fourth ventricle is lined by gray matter derived from the interior of the spinal cord, the gray matter being partly concealed by a thin expan- sion of white substance. LINING MEMBRANE OF THE VENTRICLES. The lining membrane of the ventricles is a serous layer distinct from the arachnoid ; it lines the whole of the interior of the lateral ventricles, and is connected above and below with the attached border of the choroid plexus, so as to exclude all communication between the ven- tricles and the exterior of the brain. From the lateral ventricles it is reflected through the foramen of Monro on each side, into the third ventricle, which it invests throughout. From the third it is conducted into the fourth ventricle, through the iter a tertio ad quartum ventri- culum, and lines its interior, together with the layer of pia mater which forms its inferior boundary. In this manner a perfect com- munication is established between all the ventricles, with the excep- tion of the fifth, which has its own proper membrane. It is this membrane which gives them their polished surface, and transudes the secretion which moistens their interior. When the fluid accumu- 406 CEREBELLUM. lates to an unnatural degree, it may then break down this layer and the layer of pia mater at the bottom of the fourth ventricle, and thus make its way into the sub-arachnoidean space; but in the normal condition it is doubtful whether a communication exists between the interior of the ventricles and the serous cavity of the sub-arachnoidean space. CEREBELLUM. The Cerebellum, seven times smaller than the cerebrum, is situated beneath the posterior lobes of the latter, being lodged in the posterior fossa of the base of the cranium and protected from the superincum- bent pressure of the cerebrum by the tentorium cerebelli. Like the cerebrum, it is composed of gray and white substance, the former occupying the surface, the latter the interior, and its surface is formed of parallel laminae separated by sulci, and here and there by deeper sulci. In form, the cerebellum is oblong and flattened, its greater diameter being from side to side, its two surfaces looking upwards and downwards, and its borders being anterior, posterior, and lateral. In consideration of its shape the cerebellum admits of a division into two hemispheres, into certain processes termed processes and lobules, and into certain divisions of its substance called lobes, formed upon the hemispheres by the deeper sulci above referred to. The two he- mispheres are separated from each other on the upper surface of the cerebellum by a longitudinal ridge which is termed the superior ver- miform process and which forms a commissure between them. On the anterior border of the organ there is a semilunar notch, incisura cerebelli anterior, which encircles the corpora quadrigemina poste- riorly. On the posterior border there is another notch, incisura cere- belli posterior, which receives the upper part of the falx cerebelli; and upon the under surface is a deep fissure corresponding with the me- dulla oblongata, and termed the vallecula (valley). Each hemisphere of the cerebellum is divided by means of a fissure (sulcus horizontalis) which runs along its free border, into an upper and a lower portion, and upon each of these portions certain lobes are marked out. Thus on the upper portion there are two such lobes separated by a sulcus, somewhat more strongly marked than the rest, and extending deeper into the substance of the cerebrum; they are the lobus superior anterior and lobus superior posterior. Upon the under portion of the hemisphere there are three such lobes, namely, lobus inferior anterior, medius, and posterior, and two addi- tional ones of peculiar form, the lobus inferior internus or tonsil, and the flocculus. The tonsil (amygdala), is situated on the side of the vallecula and projects into the fourth ventricle. The flocculus or pneumogastric lobule, long and slender, extends from the side of the vallecula around the corpus restiforme to the crus cerebelli, lying behind the filaments of the eighth pair of nerves. The commissure between the two hemispheres is termed the worm (vermis); that portion of the worm which occupies the upper sur- face of the cerebellum as far back as the horizontal fissure, being the processus vermiformis superior, and that which is lodged within the CEREBELLUM. 407 vallecula being the processus vermiformis inferior. The superior vermiform process is a prominent longitudinal ridge, extending from the incisura anterior to the incisura posterior cerebelli. In imitation of the hemispheres it is divided into lobes of which three have received names namely, the lobulus centralis, which is a small lobe situated in the incisura anterior; the monticulus cerebelli, a longer lobe, having its peak and declivity; and a small lobe near the inci- sura posterior, the commissufa simplex. The lobes of the inferior- vermiform process are four in number, namely,—the commissura brevis, situated in the incisura posterior, below the horizontal fissure; the pyramid, a small, obtusely-pointed eminence; a larger promi- nence, the uvula, situated between the tonsils, and connected with them by means of a commissure; and in front of the uvula, the nodulus. In front of the nodulus is a thin lamina of medullary sub- stance, consisting of a central and two lateral portions, the velum medullare posterius (valvula Tarini), and between this velum in front, and the nodulus and uvula behind, is a deep fossa which is known as the swallow's nest (nidus hirundinis). The velum medullare ante- rius is the valve of Vieussens, described with the fourth ventricle; both these vela proceed from the same point in the roof of that ven- tricle and separate from each other at an angle, the one passing obliquely forwards, the other obliquely backwards. When a vertical incision is made into the cerebellum that appear- ance is seen which has been denominated arbor vita cerebelli; the white substance in the centre of such a section resembles the trunk of a tree from which branches are given off, and from the branches branchlets and leaves, the two latter being coated by a moderately thick and uniform layer of gray substance. If the incision be made somewhat nearer to the commissure than to the lateral border of the organ, a yellowish gray dentated line enclosing medullary substance, traversed by the openings of numerous vessels, will be seen in the centre of a white substance. This is the ganglion of the cerebellum, the corpus rhomboideum or dentatum, from which the peduncles of the cerebellum proceed. The gray line is dense and horny in struc- ture, and is the cut edge of a thin capsule, open towards the medulla oblongata. The cerebellum is associated with the rest of the encephalon by means of three pairs of rounded cords or peduncles, superior, middle, and inferior. The superior peduncles, or processus e cerebello ad testes, proceed from the cerebellum forwards and upwards to the testes, in which they are lost. They form the anterior part of the lateral boundaries of the fourth ventricle and give attachment by their inner borders to the valve of Vieussens which is stretched between them. At their junction with the testes they are crossed by the fourth pair of nerves. The middle peduncles, or crura cerebelli ad pontem, the largest of the three, issue from the cerebellum through the anterior extremity of the sulcus horizontalis, and are lost in the pons Varolii. The inferior peduncles, or crura ad medullam oblon- gatam, are the corpora restiformia which descend to the posterior 408 BASE OF THE BRAIN. part of the medulla oblongata, and form the inferior portion of the lateral boundaries of the fourth ventricle. BASE OP THE BRAIN. The student should now prepare to study the base of the brain: for this purpose the organ should be turned upon its incised surface; and if the dissection have hitherto been conducted with care, he will find the base perfectly uninjured. The arachnoid membrane, some parts of the pia mater, and the circle of Willis, must be carefully cleared away in order to expose all the parts to be examined. These he will find arranged in the following order from before backwards:— Longitudinal fissure, Olfactory nerves, Fissure of Sylvius, Substantia perforata, Commencement of the verse fissure, Optic commissure, Tuber cinereum, The Longitudinal fissure is the space separating the two hemi- spheres ; it is continued downwards to the base of the brain, and divides the two anterior lobes. . In this fissure the anterior cerebral arteries ascend towards the corpus callosum ; and, if the two lobes be slightly drawn asunder, the anterior border (genu) of the corpus cal- losum will be seen descending to the base of the brain. Arrived at the base of the brain, the corpus callosum terminates by a concave border which is prolonged to the commissure of the optic nerves by a thin layer of gray substance, the lamina cinerea. The lamina cinerea is the anterior part of the inferior boundary of the third ventricle. On each side of the lamina cinerea the corpus callosum is continued into the substantia perforata and crura cerebri, and upon the latter forms a narrow medullary band lying externally to, and slightly over- lapping the optic tract, the medulla innominata. Upon the under surface of each anterior lobe, on either side of the longitudinal fissure, is the olfactory nerve, with its bulb. The Fissure of Sylvius bounds the anterior lobe posteriorly, and separates it from the middle lobe; it lodges the middle cerebral artery. If this fissure be followed outwards, a small isolated cluster of five or six convolutions will be observed ; these constitute the island of Reil. The island of Reil, together with the substantia perforata, form the base of the corpus striatum. The Substantia perforata is a triangular plane of white substance, situated at the inner extremity of the fissure of Sylvius. It is named perforata, from being pierced by a number of openings for small ar- teries, which enter the brain in this situation to supply the gray sub- stance of the corpus striatum. Passing backwards on each side beneath the edge of the middle lobe, is the commencement of the great transverse fissure, which ex- Infundibulum, Corpora albicantia, Locus perforatus, Crura cerebri, trans- Pons Varolii, Crura cerebelli, Medulla oblongata. BASE OF THE BRAIN. 409 tends beneath the hemisphere of one side to the same point on the op- posite side. A probe passed into this fissure between the crus cere- bri and middle lobe would enter the middle cornu of the lateral ven- tricle. The Optic commissure is situated on the middle line; it is the point of communication between the two optic nerves. The Tuber cinereum is an eminence of gray substance situated im- mediately behind the optic commissure, and in front of the corpora mammillaria. From its centre there projects a small conical body of gray substance, apparently a prolongation of the tuber cinereum, the infundibulum. The infundibulum is hollow in its interior, enclosing a short coecal canal, which communicates with the cavity of the third ventricle, and below the termi- nation of the canal the conical Fls-167-* process becomes connected with the pituitary gland. The infun- dibulum and tuber cinereum form part of the floor of the third ventricle. The Pituitary gland (hypo- physis cerebri), is a small, flat- tened, reddish-gray body situ- ated in the sella turcica, and closely retained in that situa- tion by the dura mater and arachnoid. It consists of two lobes, closely pressed together, the anterior lobe being the larger of the two and oblong in shape, the posterior round. Both lobes are connected with the infundibulum, but the latter is so soft in texture as to be ge- nerally torn through in the re- moval of the brain. Indeed, for the purposes of the student, it is * The under surface or base of the brain. 1. The anterior lobe of one hemisphere of the cerebrum. 2. The middle lobe. 3. The posterior lobe almost concealed by (4) the hemisphere of the cerebellum. 5. The pyramidal lobe of the inferior vermiform process of the cerebellum. 6. The pneumogastric lobule. 7. The longitudinal fissure. 8. The olfactory nerves, with their bulbous expansions. 9. The substantia perforata at the inner termination of the fissure of Sylvius; the three roots of the olfactory nerve are seen upon the substantia perforata. The commencement of the transverse fissure on each side is concealed by the inner border of the middle lobe. 10. The commissure of the optic nerves; the numeral is placed between the optic nerves as they diverge from the commis- sure, and rests upon the lamina cinerea of the corpus callosum. 11. The tuber cinereum, from which the infundibulum is seen projecting. 12. The corpora albicantia. 13. Phe locus pcrforatus, bounded on each side by the crura cerebri, and by the third nerve. 14. The pons Varolii. 15. The crus cerebelli of one side. 16. The fifth nerve emerging from the anterior border of the crus cerebelli; the small nerve by its side is the fourth. 17. The sixth pair of nerves. 18. The seventh pair of nerves consisting of the auditory and facial. 19. The corpora pyramidalia of the medulla oblongata; the corpus ohvare and part of the corpus rcstiforme are seen at each side. Just below the numeral is the decus- sation of the fibres of the corpora pyramidalia. 20. The eighth pair of nerves. 21. Ihe ninth or hypoglossal nerve. 22. The anterior root of the first cervical spinal nerve. oo 410 MEDULLA OBLONGATA. better to effect this separation with the knife, and leave the pituitary body in situ, to be examined with the ba-se of the cranium. The Corpora albicantia (mammillaria, pisiformia, bulbi fornicis), are two white convex bodies, having the shape and size of peas, situ- ated behind the tuber cinereum, and between the crura cerebri. They are a part of the crura of the fornix, which after their origin from the thalami optici descend to the base of the brain, and making a sudden curve upon themselves previously to their ascent to the lateral ventricles constitute the corpora albicantia. When divided by sec- tion, these bodies will be found to be composed of a capsule of white substance, containing gray matter, the gray matter of the two cor- pora being connected by means of a commissure. The Locus perforatus is a layer of whitish gray substance, connect- ed in front with the corpora albicantia, behind with the pons Varolii, and on each side with the crura cerebri, between which it is situated. It is perforated by several thick tufts of arteries, which are distributed to the thalami optici and third ventricle, of which it assists in forming the floor. It is sometimes called the pons Tarini. The Crura cerebri are two thick white cords which issue from the anterior border of the pons Varolii, and diverge to each side to enter the thalami optici. By their outer side the crura cerebri are continu- ous with the corpora quadrigemina, and above they constitute the lower boundary of the aqueduct of Sylvius. In their interior they contain gray matter, which has a semilunar shape when the crus is divided transversely, and has been termed the locus niger. The third nerve will be observed to arise from the inner side of each, and the fourth nerves wind around their outer border from above. The Pons Varolii* (protuberantia annularis, nodus encephali), is the broad transverse band of white fibres, which arches like a bridge across the upper part of the medulla oblongata ; and, contracting on each side into a thick rounded cord, enters the substance of the cere- bellum under the name of crus cerebelli. There is a groove along its middle which lodges the basilar artery. The pons Varolii is the com- missure of the cerebellum, and associates the two lateral lobes in their common function. Resting upon the pons, near its posterior border, is the sixth pair of nerves. On the anterior border of the crus cere- belli, at each side, is the thick bundle of filaments belonging to the fifth nerve, and, lying on its posterior border, the seventh pair of nerves. The upper surface of the pons forms a part of the floor of the fourth ventricle. MEDULLA OBLONGATA. The medulla oblongata (bulbus rhachidicus,) is the upper enlarged portion of the spinal cord. It is somewhat conical in shape, and a little more than an inch in length, extending from the pons Varolii to * Constant Varolius, Professor of Anatomy in Bologna ; died in 1578. He dissected the brain in the course of its fibres, beginning from the medulla oblongata; a plan which has since been perfected by Vieussens, and by Gall and Spurzheim. The work contain. ing his mode of dissection, " De Resolutione Corporis Humani," was published after his death, in 1591. MEDULLA OBLONGATA. 411 a point corresponding wilh the upper border of the atlas. On the middle line, in front and behind, the medulla oblongata is marked by two vertical fissures, the fissura longitudinalis anterior and posterior, which divide it superficially into two symmetrical lateral cords or columns; whilst each lateral column is subdivided by minor grooves into three smaller cords, namely, the corpora pyramidalia, corpora olivaria, and corpora restiformia. The Corpora pyramidalia are two narrow convex cords, tapering slightly from above downwards, and situated one on either side of the sulcus longitudinalis anterior. At about an inch below the pons the corpora pyramidalia communicate very freely across the sulcus by a decussation of their fibres, and at their point of entrance into the pons they are constricted into round cords. The fissura longitudinalis is somewhat enlarged by this constriction, and the enlarged space has received the name of foramen ccecum of the medulla oblongata. The Corpora olivaria (named from some resemblance to the shape of an olive), are two oblong, oval-shaped, convex bodies, of about the same breadth with the corpora pyramidalia, about half an inch in length, and somewhat larger above than below. The corpus olivare is 'situated immediately external to the corpus pyramidale, from which. and from the corpus restiforme, it is separated by a well-marked groove. In this groove some longitudinal fibres are seen which en- close the base of the corpus olivare, and have been named funiculi siliqua, those which lie to its inner side being the funiculus internus, and those to its outer side the funiculus externus. Besides these there are other fibres which cross the corpus olivare obliquely, these are the fibra arciformes. When examined by section, the corpus olivare is found to be a ganglion deeply embedded in the medulla oblongata, and meeting its fellow at the middle line behind the corpus pyramidale. The ganglion of the corpus olivare (corpus dentatum, nucleus olivse), like that of the cerebellum, is a yellowish-gray dentated capsule, open behind, and containing medullary substance from which a fasciculus of fibres proceeds upwards to the corpora quadrigemina and thalami optici. The nervous filaments which spring from the groove on the inner side of the corpus olivare, are those of the hypoglossal nerve; and those on its outer side are the glosso-pharyngeal and pneumo- gastric. The Corpora restiformia, (restis, a rope), comprehend the whole of the posterior half of each lateral column of the medulla oblongata. They are separated from the corpora olivaria by the grooves already spoken of; posteriorly they are divided from each other by the fissura longitudinalis posterior and by the fourth ventricle, and superiorly they diverge and curve backwards to enter the cerebellum, and con- stitute its inferior peduncles. Along the posterior border of each corpus restiforme, and marked off from that body by a groove, is a narrow white cord, separated from its fellow by the fissura longitu- dinalis posterior. This pair of narrow cords are termed the posterior median columns or fasciculi (funiculi graciles). Each fasciculus forms an enlargement (processus clavatus) at its upper end, and is then lost in the corresponding corpus restiforme. The processus clavati are 412 FIBRES OF THE BRAIN. the lateral boundaries of the nib of the calamus scriptorius. The corpus restiforme is crossed near its entrance into the cerebellum, by the auditory nerve, the choroid plexus of the fourth ventricle, and the pneumogastric lobule. The remaining portion of the medulla oblongata, visible from the exterior, are the two slightly convex columns which enter into the formation of the floor of the fourth ventricle. These columns are the funiculi teretes or posterior pyramids. Diverging Fibres.—The fibres composing the columns of the me- dulla oblongata have a special arrangement on reaching the upper part of that body, those of the corpora pyramidalia and olivaria enter the pons Varolii, and are thence prolonged through the crura cerebri, thalami optici, and corpora striata to the cerebral hemi- spheres ; but those of the cor- pora restiformia are reflected backwards into the cerebellum and form its inferior peduncles. From pursuing this course, and spreading out as they ad- vance, these fibres have been termed by Gall the diverging fibres. While situated within the pons the fibres of the cor- pus pyramidale and olivare se- parate and spread out, and have gray substance interposed be- tween them ; and they quit the pons much increased in num- ber and bulk, so as to form the crus cerebri. The fibres of the crus cerebri again are sepa- rated in the thalamus opticus, and are intermingled with gray matter, and they also quit that body greatly increased in num- ber and bulk. Precisely the same change takes place in the corpus * The base of the brain, upon which several sections have been made, showing the distribution of the diverging fibres. 1. The medulla oblongata. 2. One half of the pons Varolii. 3. The crus cerebri crossed by the optic nerve (4), and spreading out into the hemisphere to form the corona radiata. 5. The optic nerve near its origin; the nerves about the crus cerebri and cerebelli are the same as in the preceding figure. 6. The olfactory nerve. 7. The corpora albicantia. On the right side a portion of the brain has been removed to show the distribution of the diverging fibres. 8. The fibres of the corpus pyramidale passing through the substance of the pons Varolii. 9. The fibres passing through the thalamus opticus. 10 The fibres passing through the corpus striatum. 11. Their distribution to the hemispheres. 12. The fifth nerve : its two roots may be traced the one forwards to the fibres of the corpus pyramidale, the other backwards to the fasci- culi teretes. 13. The fibres of the corpus pyramidale which pass outwards with the corpus restiforme into the substance of the cerebellum: these are the arciform fibres of Solly. The fibres referred to are those below the numeral, the numeral itself rests upon the corpus olivare. 14. A section through one of the hemispheres of the cerebellum sliowing the corpus rhomboideum iu the centre of its white substance; the arbor vitee is also beautifully seen. 15. The opposite hemisphere of the cerebellum. FIBRES OF THE BRAIN. 413 striatum, and the fibres are now so extraordinarily multiplied as to be capable of forming a large proportion of the hemispheres. Observing this remarkable increase in the white fibres, apparently from the admixtureof gray substance, Gall and Spurzheim considered the latter as the material of increase or formative substance to the white fibres, and they are borne out in this conclusion by several collateral facts, among the most prominent of which is the great vas- cularity of the gray substance; and the larger proportion of the nu- trient fluid circulating through it, is fully capable of effecting the in- creased growth and nutrition of the structures by which it is sur- rounded. For a like reason the bodies in which this gray substance occurs, are called by the same physiologists "ganglia of increase," and by other authors simply ganglia. Thus the thalami optici and corpora striata are the ganglia of the cerebrum; or, in other words, the formative ganglia of the hemispheres. The fibres of the corpora pyramidalia are not all of them destined to the course above described; several fasciculi curve outwards to reach the corpora restiformia, some passing in front and some behind the corpus olivare on each side. These are the arciform fibres, and they are distinguished by Mr. Solly into the superficial and deep cere- bellar fibres. In the pons Varolii the continued or cerebral fibres (Solly) of the corpus pyramidale are placed between the superficial and deep layers of transverse fibres, and escaping from the pons, con- stitute the inferior and inner segment of the crus cerebri. From the crus cerebri they pass for the most part beneath the thalami optici into the corpora striata. The fibres which enclose the corpus olivare, under the name of fasciculi siliquae, are separated by that body into two bands; the innermost of the two bands, funiculus siliqua internus, accompanies the fibres of the corpus pyramidale into the crus cerebri. The funi- culus siliqua externus unites with a fasciculus proceeding from the nucleus olivae and the combined column ascending behind the crus cerebelli divides into a superior and an inferior band. The inferior band proceeds with a fasciculus presently to be described, the fasci- culus innominatus, into the upper segment of the crus cerebri. The superior band (laqueus) ascends by the side of the processus e cerebello ad testes, and crossing the latter obliquely enters the corpora quad- rigemina, in which many of its fibres are distributed, while the rest are continued onwards into the thalamus opticus. The corpora restiformia derive their fibres from the anterior as well as from the posterior columns of the medulla oblongata; they diverge as they approach the cerebellum, and leaving between them the cavity of the fourth ventricle enter the substance of the cerebellum, under the form of two rounded cords. These cords envelope the corpora rhomboidea, or ganglia of increase, and then expand on all sides so as to constitute the cerebellum. Besides the fibres here described, there are in the interior of the medulla oblongata behind the corpora olivaria, and more or less appa- rent between these bodies and the corpora restiformia, two large bun- dles of fibres, the fasciculi innominati. These fasciculi ascend behind 35* 414 CONVERGING FIBRES. the deep transverse fibres of the pons Varolii and become apparent in the floor of the fourth ventricle, under the name of fasciculi teretes or posterior pyramids. From this point they are prolonged upwards beneath the corpora quadrigemina into the crura cerebri, of which they form the upper and outer segment, and are thence continued through the thalami optici and corpora striata into the hemispheres. The locus niger of the crus cerebri is a septum of gray matter inter- posed between these fasciculi and those of the corpora pyramidalia. Converging Fibres.—In addition to the diverging fibres which are thus shown to constitute both the cerebrum and cerebellum, by their increase and developement, another set of fibres are found to exist, which have for their office the association of the symmetrical halves, and distant parts of the same hemispheres. These are called from their direction converging fibres, and from their office commissures. The commissures of the cerebrum and cerebellum are the— Corpus callosum, Middle commissure, Fornix, Posterior commissure, Septum lucidum, Peduncles of the pineal gland, Anterior commissure, Pons Varolii. The Corpus callosum is the commissure of the hemispheres. It is therefore of moderate thickness in the middle, where its fibres pass directly from one hemisphere to the other; thicker in front, where the anterior lobes are connected; and thickest behind, where the fibres from the posterior lobes are assembled. The fibres which curve back- wards into the posterior lobes from the posterior border of the corpus callosum have been termed forceps, those which pass directly out- wards into the middle lobes from the same point, tapetum, and those which curve forwards and inwards from the anterior border to the anterior lobes, forceps anterior. The Fornix is an antero-posterior commissure, and serves to con- nect a number of parts. Below it is associated with the thalami op- tici ; on each side, by means of the corpora fimbriata, with the mid- dle lobes of the brain; and, above, with the corpus callosum, and consequently with the hemispheres. The Septum lucidum is a perpendicular commissure between the fornix and corpus callosum. The Anterior commissure traverses the corpus striatum, and con- nects the anterior and middle lobes of opposite hemispheres. The Middle commissure is a layer of gray substance, uniting the thalami optici. The Posterior commissure is a white rounded cord, connecting the thalami optici. The Peduncles of the pineal gland must also be regarded as com- missures, assisted in their function by the gray substance of the gland. The Pons Varolii is the commissure to the two hemispheres of the cerebellum. It consists of transverse fibres, which are split into two layers by the passage of the fasciculi of the corpora pyramidalia and SPINAL CORD. 415 olivaria. These two layers, the superior and inferior, are collected together on each side, in the formation of the crura cerebelli. SPINAL CORD. The dissection of the spinal cord requires that the spinal column should be opened throughout its entire length by sawing through the lamina; of the vertebrae, close to the roots of the transverse processes, and raising the arches with a chisel; the muscles of the back having been removed as a preliminary step. The Spinal column contains the spinal cord, or medulla spinalis; the roots of the spinal nerves; and the membranes of the cord, viz. the dura mater, arachnoid, pia mater, and membrana dentata. The Dura mater spinalis (theca vertebralis) is a cylindrical sheath of fibrous membrane, identical in structure with the dura mater of the skull, and continuous with that membrane. At the margin of the occipital foramen it is closely adherent to the bone; by its anterior surface it is attached to the posterior common ligament, and below by means of its pointed extremity to the coccyx. In the rest of its extent it is comparatively free, being connected, by a very loose areolar tissue only, to the walls of the spinal canal. In this areolar tissue there exists a quantity of reddish, oily, adipose substance, somewhat analogous to the marrow of long bones. On either side and below, the dura mater forms a sheath for each of the spinal nerves, to which it is closely adherent. Upon its inner surface it is smooth, being lined by the arachnoid; and on its sides may be seen double openings for the two roots of each of the spinal nerves. The Arachnoid is a continuation of the serous membrane of the brain. It encloses the cord very loosely, being connected to it only by long slender filaments of fibro-cellular tissue, and by a longitudi- nal lamella which is attached to the posterior aspect of the cord. The fibro-cellular tissue is most abundant in the cervical region, and diminishes in quantity from above downwards; and the longitudinal lamella is complete only in the dorsal region. The arachnoid passes off on either side with the spinal nerves, to which it forms a sheath; and is then reflected upon the dura mater, to constitute its serous surface. A connexion exists in several situations between the arach- noid of the cord and that of the dura mater. The space between the arachnoid and the spinal cord is identical with that already described as existing between the same parts in the brain, the sub-arachnoidean space. It is occupied by a serous fluid, sufficient in quantity to expand the arachnoid, and fill completely the cavity of the theca vertebralis. The sub-arachnoidean fluid keeps up a con- stant and gentle pressure upon the entire surface of the brain and spinal cord, and yields with the greatest facility to the various move- ments of the cord, giving to those delicate structures the advantage of the principles so usefully applied by Dr. Arnott in the hydro- static bed. The Pia mater is the immediate investment of the cord; and, like the other membranes, is continuous with that of the brain. It is not, however, like the pia mater cerebri, a vascular membrane; but is 416 SPINAL CORD. dense and fibrous in its structure, and contains few vessels. It invests the cord closely, and sends a duplicature into the fissura longitudi- nalis anterior, and another, extremely delicate, into the fissura longi- tudinalis posterior. It forms a sheath for each of the filaments of the nerves, and for the nerves themselves; and, inferiorly, at the conical termination of the cord, is prolonged downwards as a slender ligament (filum terminale), which descends through the centre of the cauda equina, and is attached to the dura mater lining the canal of the coccyx. This attachment is a rudiment of the original extension of the spinal cord into the canal of the sacrum and coccyx. The Membrana dentata (ligamentum dentatum) is a thin process of pia mater sent off from each side of the cord throughout its entire length, and separating the anterior from the posterior roots of the spinal nerves. The number of serrations on each side is about twenty, the first being situated on a level with the occipital foramen, and having the vertebral artery and hypoglossal nerve passing in front and the spinal accessory nerve behind it, and the last opposite the first or second lumbar vertebra. Below this point the membrana dentata is lost in the filum terminale of the pia mater. The use of this membrane is to maintain the position of the spinal cord in the midst of the fluid by which it is surrounded. The Spinal cord of the adult extends from the pons Varolii to opposite the first or second lumbar vertebra, where it terminates in a rounded point; in the child, at birth, it reaches to the middle of the third lumbar vertebra, and in the embryo is prolonged as far as the coccyx. It presents a difference of diameter in different parts of its extent, and exhibits three enlargements. The uppermost of these is the medulla oblongata; the next corresponds with the origin of the nerves destined to the upper extremities; and the lower enlargement is situated near its termination, and corresponds with the attachment of the nerves which are intended for the supply of the lower limb. In form, the spinal cord is a flattened cylinder, and presents on its anterior surface a fissure, which extends into the cord to the depth of one third of its diameter. This is the fissura longitudinalis anterior. If the sides of the fissure be gently separated, they will be seen to be connected at the bottom by a layer of medullary substance, the ante- rior commissure. On the posterior surface another fissure exists, which is so narrow as to be hardly perceptible without careful examination. This is the fissura longitudinalis posterior. It extends more deeply into the cord than the anterior fissure, and terminates in the gray substance of the interior. These two fissures divide the medulla spinalis into two lateral cords, which are connected to each other by the white com- missure which forms the bottom of the anterior longitudinal fissure, and by a commissure of gray matter situated behind the former. On either side of the fissura longitudinalis posterior i a slight line, which bounds on each side the posterior median columns. These columns are most apparent at the upper part of the cord, near the fourth ventricle, where they are separated by the point of the calamus SPINAL CORD. 417 scriptorius, and where they form a bulbous enlargement at each side, called the processus clavatus. Two other lines are observed on the medulla, the anterior and pos- terior lateral sulci, corresponding with the attachment of the anterior and posterior roots of the spinal nerves. The anterior lateral sulcus is a mere trace, marked only by the attachment of the filaments of the anterior roots. The posterior lateral sulcus is more evident, and is a narrow grayish line derived from the gray substance of the in- terior. Although these fissures and sulci indicate a division of the spinal cord into three pairs of columns, namely, anterior, lateral, and poste- rior, the posterior median columns being regarded as a part of the posterior columns, it is customary to consider each half of the spinal cord as consist- ing of two columns only, the anterolateral and the posterior. The anterolate- ral columns are the columns of motion, and comprehend all that part of the cord situated between the fis- sura longitudinalis anterior and the posterior lateral sulcus, the gray line of origin of the poste- rior roots of the spinal nerves. The posterior columns are the co- lumns of sensation. If a transverse section of the spinal cord be made, its internal struc- ture may be seen and examined. It would then appear to be com- posed of two hollow cylinders of white matter, placed side by side, and connected by a narrow white commissure. Each cylinder is filled with gray substance, which is connected by a commissure of the same matter. The form of the gray substance, as observed in the section, is that of two half moons placed back to back, and joined by a trans- verse band. The horns of the moons correspond to the sulci of origin of the anterior and posterior roots of the nerves. The anterior horns, larger than the posterior, do not quite reach this surface; but the posterior appear upon the surface, and form a narrow gray line, the sulcus lateralis posterior. The white substance of the spinal cord is composed of parallel fibres which are collected into longitudinal laminae and extend through- out the entire length of the cord. These laminae are various in breadth, and are arranged in a radiated manner; one border being thick and corresponding with the surface of the cord, while the other is thin and lies in contact with the gray substance of the interior. * Sections of the spinal marrow in different portions of its length. 1. Opposite the 11th dorsal vertebra. 2. Opposite the 10th dorsal. 3. Opposite the 8th dorsal. 4. Oppo- site the 5th dorsal. 5. Opposite the 7th cervical. 6. Opposite the 4th cervical. 7. Oppo- site the 3d cervical. 8. Section of medulla oblongata through the corpora olivaria. 418 CRANIAL NERVES. According to Rolando the white substance constitutes a simple ner- vous membrane, which is folded into longitudinal plaits, having the radiated disposition above described. The anterior commissure, ac- cording to his description, is merely the continuation of this nervous membrane from one lateral cord across the middle line to the other. Moreover, Rolando considers that a thin lamina of pia mater is re- ceived between each of the folds from the exterior, while a layer of the gray substance is prolonged between them from within. Cruveil- hier is of opinion that each lamella is completely independent of its neighbours, and he believes this statement to be confirmed by patho- logy, which shows that a single lamella may be injured or atrophied, and at the same time be surrounded by others perfectly sound. CRANIAL NERVES. There are nine pairs of cranial nerves. Taken in their order from before, backwards, they are as follows:— 1st. Olfactory. 2d. Optic. 3d. Motores oculorum. 4th. Pathetici (trochleares). 5th. Trifacial (trigemini). 6th. Abducentes. 7 , ( Facial (portio dura), ( Auditory (portio mollis). ( Glosso-pharyngeal, 8th. < Pneumogastric (vagus, par vagum). ( Spinal accessory. 9th. Hypoglossal (lingual). Functionally or physiologically the cranial nerves admit of divi- sion into three groups, namely, nerves of special sense, nerves of motion, and compound nerves, that is, nerves which contain fibres both of sensation and motion. The nerves belonging to these groups are the following:— 1st. Olfactory. 2d. Optic. 7th. Auditory. 3d. Motores oculorum. 4th. Pathetici. 6th. Abducentes. 7th. Facial. 9th. Hypoglossal. 5th. Trifacial. 8th. Glosso-pharyngeal. Pneumogastric. Spinal accessory. The fourth, facial and eighth nerves were considered by Sir Charles Bell to form a system apart from the rest, and to be allied in the func- Special sense Motion Compound OLFACTORY NERVE. 419 tions of expression and re- Fis-17°* spiration. In consonance with this view he termed them respiratory nerves, and he gave to that part of the medulla oblongata from which they arise the name of respiratory tract. First Pair. Olfac- tory. — The olfactory nerve arises by three roots; an inner root from the substantia perforata, a middle root from a papilla of gray matter (caruncula mammillaris) embedded in the anterior lobe, and an external root, which may Fig.l7l.-t be traced as a white streak along the fissure of Sylvius into the cor- pus striatum, where it is continu- ous with some of the fibres of the anterior commissure. The ner- vous cord formed by the union of these three roots is soft in tex- ture, prismoid in shape, and em- bedded in a sulcus between two convolutions on the under surface of each anterior lobe of the brain, lying between the pia mater and the arachnoid. As it passes for- wards it increases in breadth and swells at its extremity into an ob- long mass of gray and white sub- stance, the bulbus olfactorius, which rests upon the cribriform lamella of the ethmoid bone. From the under surface of the bulbus olfactorius are given off the nerves which pass through the cribriform foramina and supply the mu- * A view of the 1st pair or olfactory, with the nasal branches of the 5th. 1. Frontal sinus. 2. Sphenoidal sinus. 3. Hard palate. 4. Bulb of the olfactory nerve. 5. Branches of the olfactory on the superior and middle turbinated bones. 6. Spheno-pala- tine nerves from the 2d of the 5th. 7. Internal nasal nerve from the 1st of the 5th. 8. Branches of 7, to Schneiderian membrane. 9. Ganglion of Cloquet in the foramen inci- sivum. 10. Anastomosis on the inferior turbinated bone of the branches of the 5th pair. t A view of the 2d pair or optic, and the origins of seven other pairs. 1,1. Globe of the eye, the one on the left hand is perfect, but that on the right has the sclerotic and cho- roid removed to show the retina. 2. The chiasm of the optic nerves. 3. The corpora albicantia. 4. The infundibulum. 5. The pons Varolii. 6. The medulla oblongata. The figure is on the right corpus pyramidale. 7. The 3d pair, motores oculi. 8. 4th pair, pathetici. 9. 5th pair, trigemini. 10. 6th pair, abducentes. 11. 7th pair, auditory and racial. 12. 8th pair, pneumogastric, spinal accessory, and glosso-pharyngeal. 13. 9th pair, hypoglossal. 420 OPTIC—MOTORES OCULORUM. cous membrane of the nares; they are arranged into two groups, an inner group reddish in colour, and soft, which spread out upon the sep- tum naritTm, and an outer group, whiter and more firm, which descend through bony canals in the outer wall of the nares, and are distri- buted upon the superior and middle turbinated bones. Second Pair. Optic—The optic nerve, a nerve of large size, arises from the corpora geniculata on the posterior and inferior aspect of the thalamus opticus and from the nates. Proceeding from this origin it winds around the crus cerebri as a flattened band, under the name of tractus opticus, and joins with its fellow in front of the tuber cinereum to form the optic commissure (chiasma). The tractus op- ticus is united with the crus cerebri and tuber cinereum, and is co- vered in by the pia mater; the commissure is also connected with the tuber cinereum, from which it receives fibres, and the nerve be- yond the commissure diverges from its fellow, becomes rounded in form, and is enclosed in a sheath derived from the arachnoid. In pass- ing through the optic foramen the optic nerve receives a sheath from the dura mater, which splits at this point into two layers ; one, which becomes the periosteum of the orbit; the other, the one in question, which forms the sheath for the nerve, and is lost in the sclerotic coat of the eyeball. After a short course within the orbit the optic nerve pierces the sclerotic and choroid coats and expands into the nervous membrane of the eyeball, the retina. Near the globe, the nerve is pierced by a small artery, the arteria centralis retinae, which runs through the central axis of the nerve and reaches the internal surface of the retina, to which it distributes branches. The commissure rests upon the processus olivaris of the sphenoid bone; it is bounded by the lamina cinerea of the corpus callosum in front, by the substantia perforata on each side, and by the tuber cine- reum behind. Within the commissure the innermost fibres of the optic nerves cross each other to pass to opposite eyes, while the outer fibres continue their course uninterruptedly to the eye of the corre- sponding side. The neurilemma of the commissure, as well as that of the nerves, is formed by the pia mater. Third Pair. Motores Oculorum.—The motor oculi, a nerve of moderate size, arises from the inner side of the crus cerebri, close to the pons Varolii, and passes forward between the posterior cerebral and superior cerebellar artery. It pierces the dura mater immediately in front of the posterior clinoid process; descends obliquely along the external wall of the cavernous sinus; and divides into two branches which enter the orbit between the two heads of the external rectus muscle. The superior branch ascends, and supplies the superior rectus and levator palpebrae. The inferior sends a branch beneath the optic nerve to the internal rectus, another to the inferior rectus, and a long branch to the inferior oblique muscle. From the latter a short thick branch is given off to the ciliary ganglion, forming its inferior root. The fibres of origin of this nerve may be traced into the gray sub- PATHETIC—TRIFACIAL. 421 stance of the crus cerebri,* into the motor tract,f and as far as the superior fibres of the crus cerebri.J In the cavernous sinus it receives one or two filaments from the cavernous plexus, and one from the ophthalmic nerve. Fourth Pair. Pathetici (trochlearis).—The fourth is the smallest cerebral nerve; it arises from the valve of Vieussens close to Fis-172.5 the testis, and winding around the crus cerebri to the extremity of the petrous portion of the tem- poral bone, pierces the dura ma- ter near the oval opening for the fifth nerve, and passes along the outer wall of the cavernous sinus to the sphenoidal fissure. In its course through the sinus it is situ- ated at first below the motor oculi, but afterwards ascends and becomes the highest of the nerves which enter the orbit through the sphenoidal fissure. Upon enter- ing the orbit the nerve crosses the levator palpebrae muscle near its origin, and is distributed upon the orbital surface of the superior oblique or trochlearis muscle; hence its synonym trochlearis. Branches.—While in the cavernous sinus the fourth nerve gives off a recurrent branch, some filaments of communication to the ophthalmic nerve, and a branch to assist in forming the lachrymal nerve; the recurrent branch, which consists of sympathetic filaments derived from the carotid plexus, passes backwards between the layers of the tentorium, and divides into two or three filaments, which are dis- tributed to the lining membrane of the lateral sinus. This nerve is sometimes a branch of the ophthalmic, and occasionally proceeds directly from the carotid plexus. Fifth Pair. Trifacial (trigeminus).—The fifth nerve, the great sensitive nerve of the head and face, and the largest cranial nerve, is analogous to the spinal nerves in its origin by two roots, from the anterior and posterior columns of the spinal cord, and in the existence of a ganglion on the posterior root. It arises|| from a tract of yel- * Mayo. t Solly. t Grainger. § A view of the 3d, 4th, and 6th pairs of nerves. 1. Ball of the eye, the rectus externus muscle being cut and hanging down from its origin. 2. The superior maxilla. 3. The third pair or motor oculi distributed to all the muscles of the eye except the supe- rior oblique and external rectus. 4. The 4th pair or patheticus going to the superior oblique muscle. 5. One of the branches of the 5th. 6. The 6th pair or motor externus distributed to the external rectus muscle. 7. Spheno-palatine ganglion and branches. 8. Ciliary nerves from the lenticular ganglion, the short root of which is seen to connect it with the 3d pair. || I have adopted the origin of this nerve, given by Dr. Alcock, of Dublin, as the result of his dissections, in the Cycloptedia of Anatomy and Physiology. Mr. Mayo also traces the anterior root of the nerve to a similar origin. 36 422 OPHTHALMIC NERVE. lowish-white matter situated in front of the floor of the fourth ven- tricle and the origin of the auditory nerve, and behind the crus cere- belli. This tract divides inferiorly into two fasciculi which may be traced downwards into the spinal cord, one being continuous with the fibres of the anterior column, the other with the posterior column. Proceeding from this origin the two roots of the nerve pass forward, and issue from the brain upon the anterior part of the crus cerebelli, where they are separated by a slight interval. The anterior is much smaller than the posterior, and the two together constitute the fifth nerve, which in this situation consists of seventy to a hundred fila- ments held together by pia mater. The nerve then passes through an oval opening in the border of the tentorium, near the extremity of the petrous bone, and spreads out into a large semilunar ganglion, the Casserian. If the ganglion be turned over, it will be seen that the anterior root lies against its under surface without having any connexion with it, and may be followed onwards to the inferior maxillary nerve. The Casserian ganglion divides into three branches, the ophthalmic, superior maxillary, and inferior maxillary. The Ophthalmic Nerve is a short trunk, being not more than three quarters of an inch in length; it arises from the upper angle of the Casserian ganglion, beneath the dura mater, and passes forwards through the outer wall of the cavernous sinus, lying externally to the other nerves; it divides into three branches. Previously to its divi- sion it receives several filaments from the carotid plexus, and gives off a small recurrent nerve, that passes backwards with the recurrent branch of the fourth nerve between the two layers of the tentorium to the lining membrane of the lateral sinus. The Branches of the ophthalmic nerve are, the— Frontal, Lachrymal, Nasal. The Frontal nerve mounts above the levator palpebrae, and runs forward, resting upon that muscle, to the supra-orbital foramen, through which it escapes upon the forehead, with the supra-orbital artery. It supplies the conjunctiva and upper eyelid, and the integu- ment of the cranium as far as the vertex. The frontal nerve gives off but one small branch, the supra-troch- lear, which passes inwards above the pulley of the superior oblique muscle, and ascends along the middle line of the forehead, distributing filaments to the integument, to the inner angle of the eye and root of the nose, and to the conjunctiva. The Lachrymal nerve, the smallest of the three branches of the ophthalmic, receives a filament from the fourth nerve in the cavernous sinus, and passes outwards along the upper border of the external rectus muscle, and in company with the lachrymal artery, to the lachrymal gland, where it divides into two branches. The superior branch passes along the upper surface of the gland and through a foramen in the malar bone, and is distributed upon the temple and cheek, communicating with the subcutaneus malae and facial nerves. The inferior branch supplies the lower surface of the gland and con- FIFTH PAIR OF NERVES. 423 Fig. 173.* junctiva, and terminates in the integument of the upper lid communi- cating with the facial nerve. The Nasal nerve (naso-ciliaris) passes forwards between the two heads of the external rectus muscle, crosses the optic nerve in company with the ophthalmic artery, and enters the anterior ethmoidal fora- men immediately above the internal rectus. It then traverses the upper b] part of the ethmoid bone to the cri- briform plate, and passes down- wards through the slit-like opening by the side of the crista galli into the nose, where it divides into two bran- ches—an internal branch supplying the mucous membrane, near the an- terior openings of the nares; and an external branch which passes be- tween the fibro-cartilages, and is distributed to the integument at the extremity of the nose. The Branches of the nasal nerve within the orbit are, the gan- glionic, ciliary, and infra-trochlear; in the nose it gives off one or two filaments to the anterior ethmoidal cells and frontal sinus. The gan- glionic branch passes obliquely forwards to the superior angle of the ciliary ganglion, forming its superior long root. The ciliary branches are two or three filaments which are given off by the nasal as it crosses the optic nerve. They pierce the posterior part of the sclerotic, and pass between that tunic and the choroid to be distributed to the iris. The infra-trochlear is given off just as the nerve is about to enter the anterior ethmoidal foramen. It passes along the superior border of the internal rectus to the inner angle of the eye, where it communicates with the supra-trochlear nerve, and supplies the lachrymal sac, caruncula lachrymalis, conjunctiva, and inner angle of the orbit. * A view of the distribution of the trifacial or 5th pair.—1. Orbit. 2. Antrum of High- more. 3. Tongue. 4. Lower maxilla. 5. Root of 5th pair forming the ganglion of Casser. 6. 1st branch, Ophthalmic. 7. 2d branch, Superior maxillary. 8. 3d branch, Inferior maxillary. 9. Frontal branch, dividing into external and internal frontal at 14. 10. Lachrymal branch, dividing before entering the lachrymal gland. 11. Nasal branch. Just under the figure is the long root of the lenticular or ciliary ganglion, and a few of the ciliary nerves. 12. Internal nasal, disappearing through the anterior ethmoidal fora- men. 13. External nasal. 14. External and internal frontal. 15. Infraorbitary nerve. 16. Posterior dental branches. 17. Middle dental branch. 18. Anterior dental nerve. 19. Terminating branches of infra-orbital, called labial and palpebral. 20. Subcutaneus malte or orbitar branch. 21. Pterygoid or recurrent, from Meckel's ganglion. 22. Five anterior branches of 3d of 5th, being nerves of motion, and called masseter, temporal, pterygoid and buccal. 23. Lingual branch joined at an acute angle by the chorda tym- pani. 24. Inferior dental nerve terminating in, 25. Mental branches. 26. Superficial temporal nerve. 27. Auricular branches. 28. Mylo-hyoid branch. 424 SUPERIOR MAXILLARY NERVE. The Superior Maxillary Nerve, larger than the preceding, pro- ceeds from the middle of the Casserian ganglion; it passes forwards through the foramen rotundum, crosses the spheno-maxillary fossa, and enters the canal in the floor of the orbit, along which it runs to the infra-orbital foramen. Emerging on the face, beneath the levator labii superioris muscle, it divides into a number of branches, which are distributed to the lower eyelid and conjunctiva, and to the mus- cles and integument of the upper lip, nose, and cheek, forming a plexus with the facial nerve. The Branches of the superior maxillary nerve are divisible into three groups:—1. Those which are given off in the spheno-maxillary fossa. 2. Those in the infra-orbital canal; and 3. Those on the face. They may be thus arranged :— I Orbital, Spheno-maxillary fossa, 1 Two from Meckel's ganglion, f Posterior dental. T j. 7-, 7 7 { Middle dental, Infra-orbital canal, , Anterior dental. n A , I Muscular, On the face, j Cutaneous. The Orbital branch (n. subcutaneus malae) enters the orbit through the spheno-maxillary fissure, and divides into two branches, temporal and malar; the temporal branch ascends along the outer wall of the orbit, and, after receiving a branch from the lachrymal nerve, passes through a canal in the malar bone and enters the temporal fossa; it then pierces the temporal muscle and fascia and is distributed to the integument of the temple and side of the forehead, communicating with the facial and anterior auricular nerve. In the temporal fossa it communicates with the deep temporal nerves. The malar, or inferior branch, takes its course along the lower angle of the outer wall of the orbit, and emerges upon the cheek through an opening in the malar bone, passing between the fibres of the orbicularis palpebrarum mus- cle. It communicates with branches of the infra-orbital and facial nerves. The Two branches from Meckel's ganglion ascend from that body to join the nerve, as it crosses the spheno-maxillary fossa. The Posterior dental branches pass through small foramina, in the posterior surface of the superior maxillary bone, and running for- wards in the base of the alveolus, supply the posterior teeth and gums. The Middle and anterior dental branches descend to the corre- sponding teeth and gums; the former beneath the lining membrane of the antrum, the latter through distinct canals in the walls of the bone. Previously to their distribution, the dental nerves form a plexus (supe- rior maxillary plexus) in the outer wall of the superior maxillary bone immediately above the alveolus. From this plexus the filaments are given off which supply the pulps of the teeth, the gums, the mu- cous membrane of the floor of the nares, and the palate. Some gangliform masses have been described in connexion with this plexus, INFERIOR MAXILLARY NERVE. 425 one being placed over the canine, and another over the second molar tooth. The Muscular and cutaneous branches are the terminating filaments of the nerve; they supply the muscles, integument, and mucous mem- brane of the cheek, nose, and lip, and form an intricate plexus with branches of the facial nerve. The Inferior Maxillary Nerve proceeds from the inferior angle of the Casserian ganglion; it is the largest of the three divisions of the fifth nerve, and is augmented in size by the anterior or motor root, which passes behind the ganglion, and unites with the inferior maxillary as it escapes through the foramen ovale. Emerging at the foramen ovale the nerve divides into two trunks, external and internal, which are separated from each other by the external pterygoid muscle. The External trunk, into which may be traced nearly the whole of the motor root, immediately divides into five branches which are distributed to the muscles of the temporo-maxillary region ; they are— The Masseteric, which crosses the sigmoid notch with the masse- teric artery to the masseter muscle. It sends a small branch to the temporal muscle, and a filament to the temporo-maxillary articu- lation. Temporal; two branches passing between the upper border of the external pterygoid muscle and the temporal bone to the temporal muscle. Two or three filaments from these nerves pierce the tempo- ral fascia, and communicate with the lachrymal, subcutaneus ma- lae, auricular and facial nerve. Buccal; a large branch which pierces the fibres of the external pterygoid, to reach the buccinator muscle. This nerve sends fila- ments to the temporal and external pterygoid muscle, to the mucous membrane and integument of the cheek, and communicates with the facial nerve. Internal pterygoid; a long and slender branch, which passes in- wards to the internal pterygoid muscle, and gives filaments in its course to the tensor palati and tensor tympani. This nerve is re- markable from its connexion with the otic ganglion, to which it is attached. The Internal trunk divides into three branches— Gustatory, Inferior dental, Anterior auricular. The Gustatory Nerve descends between the two pterygoid muscles to the side of the tongue, where it becomes flattened, and divides into numerous filaments, which are distributed to the papillae and mucous membrane. Relations. — It lies at first between the external pterygoid muscle and the pharynx, next between the two pterygoid muscles, then be- tween the internal ptervgoid and ramus of the jaw, and between the 36* 426 INFERIOR DENTAL NERVE—ABDUCENS. stylo-glossus muscle and the submaxillary gland; lastly, it runs along the side of the tongue, resting upon the hyo-glossus muscle, and covered in by the mylo-hyoideus and mucous membrane. The gustatory nerve, while between the two pterygoid muscles, receives a branch from the inferior dental; lower down it is joined at an acute angle by the chorda tympani which passes downwards in the sheath of the gustatory to the submaxillary gland, where it unites with the submaxillary ganglion. On the hyo-glossus muscle some branches of communication are sent to the hypoglossal, and in the course of the nerve several small branches to the mucous membrane of the fauces, to the tonsils, submaxillary gland, Wharton's duct, and sublingual gland. The Inferior Dental Nerve passes downwards with the inferior dental artery, at first between the two pterygoid muscles, and then between the internal lateral ligament and the ramus of the lower jaw, to the dental foramen. It then runs along the canal in the infe- rior maxillary bone, distributing branches (inferior maxillary plexus) to the teeth and gums, and divides into two terminal branches, inci- sive and mental. The incisive branch passes forwards, to supply the incisive teeth: the mental branch escapes through the mental fora- men, to be distributed to the muscles and integument of the chin and lower lip, and to the mucous membrane of the latter, communicating with the facial nerve. The inferior dental nerve gives off but one branch, the mylo- hyoidean, which leaves the nerve just as it is about to enter the dental foramen. This branch pierces the insertion of the internal lateral ligament, and descends along a groove in the bone to the in- ferior surface of the mylo-hyoid muscle, to which, and to the anterior belly of the digastricus, it is distributed. The Anterior Auricular Nerve originates by two roots, between which the arteria meningea media takes its course, and passes di- rectly backwards behind the articulation of the lower jaw, against which it rests. In this situation it divides into two branches, which reunite, and form a kind of plexus. From the plexus two branches are given off—ascending and descending. The ascending or tempo- ral branch sends one or two considerable branches of communication to the facial nerve, and then ascends in front of the ear to the tempo- ral region, upon which it is distributed in company with the branches of the temporal artery. In its course it sends filaments to the tem- poro-maxillary articulation, to the pinna and meatus of the ear, and to the integument in the temporal region. It communicates on the temple with branches of the facial, supra-orbital, lachrymal, and sub- cutaneus malae nerve. The descending branch enters the parotid gland, to which it sends numerous branches; it communicates with the inferior dental and auricularis magnus nerve, and supplies the external ear, the meatus auditorius, and the temporo-maxillary arti- culation, and sends one or two filaments into the tympanum. Sixth Pair. Abducentes. — The abducens nerve, about half the size of the motor oculi, arises by several filaments from the upper constricted part of the corpus pyramidale close to the pons Varolii. FACIAL NERVE. 427 Proceeding forwards from this origin it lies parallel with the basilar artery, and, piercing the dura mater upon the clivus Blumenbachii of the sphenoid bone, ascends beneath that membrane to the cavernous sinus. It then runs forwards along the inner wall of the sinus below the other nerves, and, resting against the internal carotid artery, passes between the two heads of the external rectus, and is distri- buted to that muscle. As it enters the orbit, it lies upon the ophthal- mic vein, from which it is separated by a lamina of dura mater. In the cavernous sinus it is joined by several filaments from the carotid plexus, by one from Meckel's ganglion, and one from the ophthalmic nerve. Mr. Mayo traced the origin of this nerve between the fasci- culi of the corpora pyramidalia to the posterior part of the medulla oblongata; and Mr. Grainger pointed out its connexion with the gray substance of the spinal cord. Seventh Pair.—The seventh pair consists of two nerves which lie side by side on the posterior border of the crus cerebelli. The smaller and most internal of these, and, at the same time, the most FlS-174-* dense in texture, is the facial nerve or portio dura. The ex- ternal nerve, which is soft and pulpy, and often grooved by contact with the preceding, is the auditory nerve or portio mollis of the seventh pair. Soemmering makes the audi- tory nerve the eighth pair; but, retaining the classifica- tion of Willis, we regard it as a part of the seventh with the facial. Facial Nerve (portio dura).—The facial nerve arises from the upper part of the groove between the corpus olivare and corpus resti- forme, close to the pons Varolii, from which point its fibres may be traced deeply into the corpus restiforme. The nerve then passes for- wards, resting upon the crus cerebelli, and comes into relation with the auditory nerve, with which it enters the meatus auditorius inter- nus, lying at first to the inner side of, and then upon that nerve. At the bottom of the meatus it enters the canal expressly intended for it, the aqueductus Fallopii, and directs its course forwards towards the hiatus Fallopii, where it forms a gangliform swelling (intumescentia gangliformis), and receives the petrosal branch of the Vidian nerve. It then curves backwards towards the tympanum, and descends along the inner wall of that cavity to the stylo-mastoid foramen. Emerg- ing at the stylo-mastoid foramen it passes forwards within the parotid gland, crossing the external jugular vein and external carotid artery, • A view of the origin and distribution of the portio mollis of the 7th pair or auditory nerve. 1. The medulla oblongata. 2. The pons Varolii. 3, and 4. The crura cerebelli of the right side. 5. 8th pair. 6. 9th pair. 7. The auditory nerve distributed to the cochlea and labyrinth. 8. The 6th pair. 9. The portio dura of the 7th pair. 10. The 4th pair. 11. The 3d pair. 428 FACIAL NERVE. and at the ramus of the lower jaw divides into two trunks, temporo- facial and cervicofacial. These trunks at once split into numerous branches which, after forming a number of looped communications (pes anserinus) with each other over the masseter muscle, spread out upon the side of the face, from the temple to the neck, to be distri- buted to the muscles of this extensive region. The communications which the facial nerve maintains in its course are the following: in the meatus auditorius, it sends one or two filaments to the auditory nerve; the intumescentia gangliformis receives the nervus petrosus superficialis major and minor, and sends a twig back to the auditory nerve; behind the tympanum the nerve receives one or two twigs from the auricular branch of the pneumogastric; at its exit from the stylo-mastoid foramen it receives a twig from the glosso-pharyngeal, and in the parotid gland one or two large branches from the anterior auricular nerve. Besides these, the facial nerve has numerous peri- pheral communications, with the branches of the fifth nerve on the face, and of the cervical nerves in the parotid gland and neck. The numerous communications of the facial nerve obtained for it the desig- nation of nervus sympatheticus minor. The Branches of the facial nerve are— lie, tympani. r auricular, o-facial, -facial. The Tympanic branch is a small filament distributed to the stapedius muscle. The Chorda tympani quits the facial just before that nerve emerges from the stylo-mastoid foramen, and ascends by a distinct canal to the upper part of the posterior wall of the tympanum, where it enters that cavity through an opening situated between the base of the pyramid and the attachment of the membrana tympani, and becomes invested by mu- cous membrane. It then crosses the tympanum be- tween the handle of the * The distribution of the facial nerve and the branches of the cervical plexus. 1. The facial nerve, escaping from the stylo-mastoid foramen, and crossing the ramus of the lower jaw; the parotid gland has been removed in order to see the nerve more distinctly. Within the aqueductus { Tympar Fallopii. ( Chorda nr. • . ., ( Posterio After emerging at the \ ^ , , stylo-mastoid foramen, ) tV \< * J (D gastri On the face, \ n P J ( Cervico Fig. 175.* FACIAL NERVE. 429 malleus and long process of the incus to the anterior inferior angle of the cavity, and escapes through a distinct opening in the fissura Glaseri, and joins the gustatory nerve at an acute angle between the two pterygoid muscles. Enclosed in the sheath of the gusta- tory nerve, it descends to the submaxillary gland, where it unites with the submaxillary ganglion. The Posterior auricular nerve ascends behind the ear, between the meatus and mastoid process, and divides into an anterior and a poste- rior branch. The anterior branch receives a filament of communi- cation from the auricular branch of the pneumogastric nerve, and distributes filaments to the retrahens and attollens aurem muscles and to the pinna. The posterior branch communicates with the auricularis magnus and occipitalis minor, and is distributed to the posterior belly of the occipito-frontalis. The Stylo-hyoid branch is distributed to the stylo-hyoid muscle. The Digastric branch supplies the posterior belly of the digastricus muscle, and communicates with the glosso-pharyngeal and pneumo- gastric nerve. The Temporofacial gives off a number of branches which are dis- tributed over the temple and upper half of the face, supplying the muscles of this region, and communicating with the branches of the auricular, the subcutaneus malae, and the supra-orbital nerve. The inferior branches, which accompany Stenoh's duct, and form a plexus with the terminal branches of the infra-orbital nerve. The Cervicofacial divides into a number of branches that are dis- tributed to muscles on the lower half of the face and upper part of the neck. The cervical branches form a plexus with the superficialis colli nerve over the submaxillary gland, and are distributed to the platysma myoides. Auditory Nerve (portio mollis).—The auditory nerve takes its origin in the lineae transversae (striae medullares) of the anterior wall or floor of the fourth ventricle, and winds around the corpus resti- forme, from which it receives fibres, to the posterior border of the crus cerebelli. It then passes forwards upon the crus cerebelli in company with the facial nerve, which lies in a groove on its superior surface, and enters the meatus auditorius internus, and at the bottom of the meatus it divides into two branches, cochlear and vestibular. The auditory nerve is soft and pulpy in texture, and receives in the meatus auditorius several filaments from the facial nerve. Eighth Pair.—The eighth pair consists of three nerves, glosso- 2. The posterior auricular branch; the digastric and stylo-mastoid filaments are seen near the origin of this branch. 3. Temporal branches, communicating with (4) the branches of the frontal nerve. 5. Facial branches, communicating with (6) the infra- orbital nerve. 7. Facial branches, communicating with (8) the mental nerve. 9. Cer- vico-facial branches, communicating with (10) the superficialis colli nerve, and forming a plexus (11) over the submaxillary gland. The distribution of the branches of the facial in a radiated direction over the side of the face and their looped communications constitute the pes anserinus. 12. The auricularis magnus nerve, one of the ascending branches of the cervical plexus. 13. The occipitalis minor, ascending along the posterior border of the sterno-mastoid muscle. 14. The superficial and deep descending branches of the cervical plexus. 15. The spinal accessory nerve, giving off a branch to the external sur- face of the trapezius muscle. 16. The occipitalis major nerve, the posterior branch of the second cervical nerve. 430 GLOSSO-PHARYNGEAL NERVE. pharyngeal, pneumogastric, and spinal accessory; these are the ninth, tenth, and eleventh pairs of Soemmering. Glosso-pharyngeal Nerve.—The glosso-pharyngeal nerve arises by five or six filaments from the groove between the corpus olivare and restiforme, and escapes from the skull at the innermost extremity of the jugular foramen through a distinct opening in the dura mater, lying an- teriorly to the sheath of the pneumogastric and spinal accessory nerves, and internally to the jugular vein. It then passes forwards between the jugular vein and internal carotid artery, to the stylo-pharyngeus muscle, and descends along the inferior border of that muscle to the hyo-glossus, beneath which it curves to be distributed to the mucous membrane of the base of the tongue and fauces, to the mucous glands of the mouth, and to the tonsils. While situated in the jugular fossa, the nerve presents two gangliform swellings; one superior (ganglion jugulare of Miiller) of small size, and involving only the posterior fibres of the nerve ; the other inferior, nearly half an inch below the prece- ding, of larger size and occupying the whole diameter of the nerve, the ganglion of Andersch* (ganglion petrosum). The fibres of origin of this nerve may be traced through the fasci- culi of the corpus restiforme to the gray substance in the floor of the fourth ventricle. The Branches of the glosso-pharyngeal nerve are— Communicating branches with the Facial, Pneumogastric, Spinal accessory, Sympathetic. Tympanic, Muscular, Pharyngeal, Lingual, Tonsillitic. The Branches of communication proceed from the ganglion and from the upper part of the trunk of the nerve, and are common to the facial, eighth pair, and sympathetic; they form a complicated plexus at the base of the skull. The Tympanic branch (Jacobson's nerve) proceeds from the gang- lion of Andersch, or from the trunk of the nerve immediately above the ganglion: it enters a small bony canal in the jugular fossa (page 72) and divides into six branches, which are distributed upon the inner wall of the tympanum, and establish a plexiform communication (tym- panic plexus) with the sympathetic and fifth pair of nerves. The branches of distribution supply the fenestra rotunda, fenestra ovalis, and Eustachian tube: those of communication join the carotid plexus, the petrosal branch of the Vidian nerve, and the otic ganglion. The Muscular branch divides into filaments, which are distributed to the stylo-pharyngeus and to the posterior belly of the digastricus and stylo-hyoideus muscle. * Charles Samuel Andersch. " Tractatus Anatomico-Physiologicus de Nervis Corporis Humani Aliquibus, 1797." PNEUMOGASTRIC NERVE. 431 The Pharyngeal branches are two or three filaments which are distributed to the pharynx and unite with the pharyngeal branches of the pneumogastric and sympathetic nerve to form the pharyngeal plexus. The Lingual branches enter the substance of the tongue beneath the hyo-glossus and stylo-glossus muscle, and are distributed to the mucous membrane of the side and base of the tongue, and to the epi- glottis and fauces. The Tonsillitic branches proceed from the glosso-pharyngeal nerve near its termination; they form a plexus (circulus tonsillaris) around the base of the tonsil, from which numerous filaments are given off to the mucous membrane of the fauces and soft palate, communicating with the posterior palatine branches of Meckel's ganglion. Pneumogastric Nerve (vagus).—The pneumogastric nerve arises by ten or fifteen filaments from the groove between the corpus olivare and corpus restiforme, immediately below the glosso-pharyngeal, and passes out of the skull through the inner extremity of the jugular fora- men in a distinct canal of the dura mater. While situated in this canal it presents a small rounded ganglion (ganglion jugulare); and having escaped from the skull, a gangliform swelling (plexus gangli- formis), nearly an inch in length, and surrounded by an irregular plexus of white nerves, which communicate with each other, with the* other divisions of the eighth pair, and with the trunk of the pneumo- gastric below the ganglion. The plexus gangliformis (ganglion of the superior laryngeal branch, of Sir Astley Cooper), is situated, at first, behind the internal carotid artery, and then between that vessel and the internal jugular vein. The pneumogastric nerve then descends the neck within the sheath of the carotid vessels, lying behind and be- tween the artery and vein, to the root of the neck. Here the course of the nerve at opposite sides becomes different. On the right side it passes between the subclavian artery and vein to the posterior mediastinum, then behind the root of the lung to the oesophagus, which it accompanies to the stomach, lying on its poste- rior aspect. On the left it enters the chest parallel with the left subclavian ar- tery, crosses the arch of the aorta, and descends behind the root of the lung, and along the anterior surface of the oesophagus, to the stomach. The fibres of origin of the pneumogastric nerve, like those of the glosso-pharyngeal, may be traced through the fasciculi of the corpus restiforme into the gray substance of the floor of the fourth ventricle. The Branches of the pneumogastric nerve are the following:— Communicating branches with the Facial, Glosso-pharyngeal, Spinal accessory, Hypo-glossal, Sympathetic. Auricular, Pharyngeal, 432 SUPERIOR LARYNGEAL NERVE. Fig. 176.* Superior laryngeal, Cardiac, Inferior or recurrent laryngeal, Pulmonary anterior, Pulmonary posterior, (Esophageal, Gastric. The Branches of communication form part of the complicated plexus at the base of the skull. The branches to the ganglion of Andersch are given off by the superior ganglion in the jugular fossa. The Auricular nerve is given off from the lower part of the jugular ganglion, or from the trunk of the nerve immediately below, and receives immediately after its origin a small branch of communication from the glosso-pharyngeal. It then passes outwards behind the jugular vein, and on the outer side of that vessel enters a small canal (page 72) in the petrous portion of the temporal bone near the stylo-mastoid foramen. Guided by this canal it reaches the descending part of the aqueductus Fal- lopii and joins the facial nerve. In the aqueductus Fallopii the auricular nerve gives off two small filaments, one of which communicates with the posterior auricular branch of the facial, while the other is dis- tributed to the pinna. The Pharyngeal nerve arises from the pneumogastric, immediately above the gan- gliform plexus, and descends behind the in- ternal carotid artery to the upper border of the middle constrictor, upon which it forms the pharyngeal plexus assisted by branches from the glosso-pharyngeal, superior la- ryngeal, and sympathetic. The pharyngeal plexus is distributed to the muscles and mucous membrane of the pharynx. The Superior laryngeal nerve arises from the gangliform plexus of the pneumogastric, of which it appears to be almost a continu- ation ; hence this plexus was named by Sir Astley Cooper the "ganglion of the superior laryngeal branch." The nerve descends behind the internal carotid artery to the opening in the thyro-hyoidean membrane, through which it passes with the superior la- * Origin and distribution of the eighth pair of nerves. 1, 3, 4. The medulla oblongata. 1. Is the corpus pyramidale of one side. 3. The corpus olivare. 4. The corpus resti- SUPERIOR LARYNGEAL NERVE. 433 ryngeal artery, and is distributed to the mucous membrane of the larynx and arytenoideus muscle. On the latter, and behind the cri- coid cartilage, it communicates with the recurrent laryngeal nerve. Behind the internal carotid it gives off the external laryngeal branch, which sends a twig to the pharyngeal plexus, and then descends to supply the inferior constrictor and crico-thyroid muscles and thyroid gland. This branch communicates inferiorly with the recurrent la- ryngeal and sympathetic nerve. Mr. Hilton of Guy's Hospital, concludes from his dissections* that the superior laryngeal nerve is the nerve of sensation to the larynx, being distributed solely (with the exception of its external laryngeal branch and a twig to the arytenoideus) to the mucous membrane. If this fact be taken in connexion with the observations of Sir Astley Cooper, and the dissections of the origin of the nerve- by Mr. Edward Cock, we shall have ample evidence, both in the ganglionic origin of the nerve and in its distribution, of its sensitive function. The recur- rent, or inferior laryngeal nerve, is the proper motor nerve of the larvnx, and is distributed to its muscles. The Cardiac branches, two or three in number, arise from the pneumogastric in the lower part of the neck, and cross the lower part of the common carotid, to communicate with the cardiac branches of the sympathetic, and with the great cardiac plexus. The Recurrent laryngeal, or inferior laryngeal nerve, curves around the subclavian artery on the right, and the arch of the aorta on the left side. It ascends in the groove between the trachea and oesopha- gus, and piercing the lower fibres of the inferior constrictor muscle enters the larynx close to the articulation of the inferior cornu of the thyroid with the cricoid cartilage. It is distributed to all the muscles of the larynx with the exception of the crico-thyroid, and communi- cates on the arytenoideus muscle with the superior laryngeal nerve. As it curves around the subclavian artery and aorta it gives branches to the heart and root of the lungs; and as it ascends the neck it dis- tributes filaments to the oesophagus and trachea, and communicates with the external laryngeal nerve and sympathetic. The Anterior pulmonarybranches are distributed upon the anterior aspect of the root of the lungs, forming, with branches from the great cardiac plexus, the anterior pulmonary plexus. The Posterior pulmonary branches, more numerous than the ante- rior, are distributed upon the posterior aspect of the root of the lungs, and are joined by branches from the great cardiac plexus, forming the posterior pulmonary plexus. forme. 2. The pons Varolii. 5. The facial nerve. 6. The origin of the glosso-pharyn- geal nerve. 7. The ganglion of Andersch. 8. The trunk of the nerve. 9. The spinal accessory nerve. 10.^The ganglion of the pneumogastric nerve. 11. Its plexiform gan- glion. 12 Its trunk. 13. Its pharyngeal branch forming the pharyngeal plexus (14), assisted by a branch from the glosso-pharyngeal (8), and one from the superior laryngeal nerve (15) 16 Cardiac branches. 17. Recurrent laryngeal branch. 18. Anterior pul- monary branches. 19. Posterior pulmonary branches. 20 (Esophageal plexus. 21 Gastric branches. 22. Origin of the spinal accessory nerve. 23. Its branches distributed to the sterno-mastoid muscle. 21. Its branches to the trapezius muscle. » Guy's Hospital Reports, vol. ii. 37 434 SPINAL ACCESSORY NERVE. Upon the oesophagus the two nerves divide into numerous branches which communicate with each other and constitute the oesophageal plexus which completely surrounds the cylinder of the oesophagus, and accompanies it to the cardiac orifice of the stomach. The Gastric branches are the terminal filaments of the two pneumo- gastric nerves; they are spread out upon the anterior and posterior surfaces of the stomach, and are likewise distributed to the omentum, spleen, pancreas, liver, and gall-bladder, and communicate, particu- larly the right nerve, with the solar plexus. Spinal Accessory Nerve.—The spinal accessory nerve arises by several filaments from the side Fis-177-* of the spinal cord as low down as the fourth or fifth cervical nerve, and ascends behind the ligamentum denticulatum, and between the anterior and poste- rior roots of the spinal nerves, to the foramen lacerum poste- rius. It communicates in its course with the posterior root of the first cervical nerve, and entering the foramen lacerum becomes applied against the pos- terior aspect of the ganglion jugu- lare of the pneumogastric, being contained in the same sheath of dura mater. In the jugular fossa it divides into two branches; the smaller joins the pneumogastric immediately below the jugular ganglion, and contributes to the formation of the pharyngeal nerve; the larger or true con- tinuation of the nerve passes backwards behind the internal jugular vein, and descends obliquely to the upper part of the sterno-mastoid * The anatomy of the side of the neck, showing the nerves of the tongue. 1. A frag- ment of the temporal bone containing the meatus auditorius externus, mastoid, and styloid process. 2. The stylo-hyoid muscle. 3. The stylo-glossus. 4. The stylo-pharyngeus. 5. The tongue. 6. The hyo-glossus muscle; its two portions. 7. The genio-hyo glossus muscle. 8. The genio-hyoideus; they both arise from the inner surface of the symphysis of the lower jaw. 9. The sterno-hyoid muscle. 10. The sterno-thyroid. 11. The thyro- hyoid, upon which the thyro-hyoidean branch of the hypoglossal nerve is seen ramifying. 12. The omo-hyoid crossing the common carotid artery (13), and internal jugular vein (14). 15. The external carotid giving off its branches., 16. The internal carotid. 17. The gustatory nerve giving off a branch to the submaxillary ganglion (18), and commu- nicating a little further on with the hypoglossal nerve. 19. The submaxillary, or Whar- ton's duct, passing forwards to the sublingual gland. 20. The glosso-pharyngeal nerve, passing in behind the hyo-glossus muscle. 21. The hypoglossal nerve curving around the occipital artery. 22. The deseendens noni nerve, forming a loop with (23) the com- municans noni, which is seen to be arising by filaments from the upper cervical nerves. 24. The pneumogastric nerve, emerging from between the internal jugular vein and common carotid artery, and entering the chest. 25. The facial nerve, emerging from the stylo-mastoid foramen, and crossing the external carotid artery. HYPOGLOSSAL NERVE. 435 muscle. It pierces the sterno-mastoid, and then passes obliquely across the neck, communicating with the second, third, and fourth cervical nerves, and is distributed to the trapezius. The spinal ac- cessory sends numerous twigs to the sterno-mastoid in its passage through that muscle, and in the trapezius the nervous filaments may be traced downwards to its lower border. The pneumogastric and spinal accessory nerves together (nervus vagus cum accessorio) resemble a spinal nerve, of which the former with its ganglion is the posterior and sensitive root, the latter the anterior and motor root. Ninth Pair.* Hypoglossal Nerve (lingual.) The hypoglossal nerve arises from the groove between the corpus pyramidale and corpus olivare by ten or fifteen filaments, which being collected into two bundles, escape from the cranium through the anterior condyloid foramen. The nerve then passes forwards between the internal carotid artery and internal jugular vein, and descends along the anterior and inner side of the vein to a point parallel with the angle of the lower jaw. It next curves inwards around the occipital artery, with which it forms a loop, and crossing the lower part of the hyo- glossus muscle to the genio-hyo-glossus, sends filaments onwards with the anterior fibres of that muscle as far as the tip of the tongue. It is distributed to the muscles of the tongue, and principally to the genio-hyo-glossus. While resting on the hyo-glossus muscle it is flattened, and beneath the mylo-hyoideus it communicates with the gustatory nerve. At its origin the hypoglossal nerve sometimes communicates with the posterior root of the first cervical nerve. The Branches of the hypoglossal nerve are:— Communicating branches with the Pneumogastric, Spinal accessory, First and second cervical nerves, Sympathetic. Deseendens noni, Thyro-hyoidean branch, Communicating filaments with the gustatory nerve. The Communications with the pneumogastric and spinal accessory take place through the medium of a plexiform interlacement of branches at the base of the skull, behind the internal jugular vein. The communications with the sympathetic nerve are derived from the superior cervical ganglion. The Deseendens noni is a long and slender twig, which quits the hypoglossal just as that nerve is about to form its arch around the occipital artery, and descends upon the sheath of the carotid vessels. Just below the middle of the neck it forms a loop with a long branch (communicans noni) from the second and third cervical nerves. From the convexity of this loop branches are sent to the sterno-hyoi- deus, sterno-thyroideus, and both bellies of the omo-hyoideus; some- * The twelfth pair according to the arrangement of Soemmering. 436 SPINAL NERVES. times also a twig is given off to the cardiac plexus, and occasionally one to the phrenic nerve. If the deseendens noni be traced to its origin it will be found to be formed by a branch from the hypoglos- sal, and one from the first and second cervical nerves; occasionally it receives also a filament from the pneumogastric. The Thyro-hyoidean nerve is a small branch, distributed to the thyro-hyoideus muscle. It is given off from the trunk of the hypoglos- sal near the posterior border of the hyoglossus muscle, and descends obliquely over the great cornu of the os hyoides. The Communicating filaments, with the gustatory nerve, are several small twigs, which ascend upon the hyoglossus muscle near its anterior border, and form a kind of plexus with filaments sent down by the gustatory nerve. SPINAL NERVES. There are thirty-one pairs of spinal nerves, each arising by two roots, an anterior or motor root, and a posterior or sensitive root. The anterior roots proceed from a narrow white line, anterior lateral sulcus, on the antero-lateral column of the spinal cord, and gradually approach towards the anterior longitudinal fissure as they descend. The posterior roots, more regular than the anterior, proceed from the posterior lateral sulcus, a narrow gray stria, formed by the internal gray substance of the cord. They are larger, and the filaments of origin more numerous than those of the anterior roots. In the inter- vertebral foramina there is a ganglion on each of the posterior roots. The first cervical nerve forms an exception to these characters; its posterior root is smaller than the anterior; it often joins in whole or in part with the spinal accessory nerve and sometimes with the hypo- glossal : there is frequently no ganglion upon it, and when the ganglion exists it is often situated within the dura mater, the latter being the usual position of the ganglia of the last two pairs of spinal nerves. After the formation of a ganglion, the two roots unite and constitute a spinal nerve, which escapes through the intervertebral foramen and divides into an anterior branch for the supply of the front aspect of the body, and a posterior branch for the posterior aspect. In the first cervical and two last sacral nerves this division takes place within the dura mater and in the upper four sacral nerves externally to that cavity, but within the sacral canal. The anterior branches, with the exception of the first two cervical nerves, are larger than the posterior; an arrangement which is proportioned to the larger extent of surface they are required to supply. The Spinal nerves are divided into— Cervical.....8 pairs. Dorsal......12 Lumbar ..... 5 Sacral . .... 6 The cervical nerves pass off transversely from the spinal cord ; the dorsal are oblique in their direction; and the lumbar and sacral verti- CERVICAL PLEXUS. 437 cal ; the latter form the large assemblage of nerves at the termination of the cord called cauda equina. cervical nerves. The cervical nerves increase in size from above dowrnwards; the first (sub-occipital) passes out of the spinal canal between the occi- pital bone and the atlas; and the last, between the last cervical and first dorsal vertebra. Each nerve, at its escape from the intervertebral foramen, divides into an anterior and a posterior branch. The anterior branches of the four upper cervical nerves form the cervical plexus; the posterior branches, the posterior cervical plexus. The anterior branches of the four inferior cervical together with the first dorsal form the brachial plexus. Anterior Cervical Nerves.—The anterior branch of the first cer- vical nerve escapes from the vertebral canal through the groove upon the posterior arch of the atlas which supports the vertebral artery, be- neath which it lies. It then descends in front of the transverse process of the atlas, sends several twigs to the rectus lateralis and recti antici, and forms an anastomotic loop by communicating with an ascending branch of the second nerve. The anterior branch of the second cervical nerve at its exit from the intervertebral foramen between the atlas and the axis, gives twigs to the rectus anticus major, scalenus posticus and levator anguli scapulae muscles and divides into three branches, viz. an ascending branch, which completes the arch of communication with the first nerve; and two descending branches, which communicate with the third nerve. The anterior branch of the third cervical nerve, double the size of the preceding, divides at its exit from the intervertebral foramen into numerous branches, some of which are distributed to the rectus major, longus colli, and scalenus posticus muscles, while others communicate and form loops and anastomoses with the second and fourth nerve. The anterior branch of the fourth cervical nerve, of the same size with the preceding, sends twigs to the rectus major, longus colli, and levator anguli scapulae, communicates by anastomosis with the third, and sends a small branch downwards to the fifth nerve. Its principal branches pass downwards and outwards across the posterior triangle of the neck, towards the clavicle and acromion. The anterior branches of the fifth, sixth, seventh, and eighth cervi- cal nerves will be described with the brachial plexus, of which they form a part. cervical plexus. The cervical plexus is constituted by the loops of communication, and by the anastomoses which take place between the anterior branches of the four first cervical nerves. The plexus rests upon the levator anguli scapulae, posterior scalenus, and splenius muscle, and is covered in by the sterno-mastoid and platysma. The Branches of the cervical plexus may be arranged into three groups, superficial ascending, superficial descending; and deep— 37* 438 CERVICAL PLEXUS. ( Superficialis colli. Ascending, < Auricularis magnus, ( Occipitalis minor. Superfical j ^ I Acromiales, ( Claviculares. Communicating branches, , Muscular, l Communicans noni, Phrenic. The Superficialis colli is formed by communicating branches from the second and third cervical nerves; it curves around the posterior border of the sterno-mastoid and crosses obliquely behind the exter- nal jugular vein to the anterior border of that muscle, where it di- vides into an ascending and a descending branch; the descending branch is distributed to the integument on the side and front of the neck, as low down as the clavicle ; the ascending branch passes up- wards to the submaxillary region, and divides into four or five fila- ments, some of which pierce the platysma myoides and supply the integument as high up as the chin and lower part of the face, while others form a plexus with the descending branches of the facial nerve beneath the platysma. One or two filaments from this nerve accom- pany the external jugular vein. The Auricularis magnus, the largest of the three ascending branches of the cervical plexus, also proceeds from the second and third cer- vical nerve ; it curves around the posterior border of the sterno-mas- toid and ascends upon that muscle, lying parallel with the external jugular vein, to the parotid gland, where it divides into an anterior and a posterior branch. The anterior branch is distributed to the integument over the parotid gland, to the gland itself, communicating with the facial nerve, and to the external ear. The posterior branch pierces the parotid gland and crosses the mastoid process, where it divides into branches which supply the posterior part of the pinna and the integument of the side of the head, and communicate with the posterior auricular branch of the facial and with the occipitalis minor. Previously to its division the auricularis magnus nerve sends off several facial branches which are distributed to the cheek. The Occipitalis minor arises from the second cervical nerve; it curves around the posterior border of the sterno-mastoid above the preceding and ascends upon that muscle, parallel with its posterior border, to the lateral and posterior side of the head. It is distributed to the integument and to the muscles of this region, namely, to the occipito-frontalis, attollens and attrahens aurem, and communicates with the occipitalis major, auricularis magnus and posterior auricular branch of the facial. The Acromiales and Claviculares are two or three large nerves which proceed from the fourth cervical nerve and divide into nume- rous branches which pass downwards over the clavicle, and are dis- tributed to the integument of the upper and anterior part of the chest from the sternum to the shoulder. POSTERIOR CERVICAL NERVES. 439 The Communicating branches are filaments which arise from the loop between the first and second cervical nerve, and pass inwards to communicate with the sympathetic, the pneumogastric, and the hypo- glossal nerve. The three first cervical nerves send branches to the first cervical ganglion ; the fourth sends a branch to the trunk of the sympathetic, or to the middle cervical ganglion. From the second cervical nerve a large branch is given off which goes to join the spinal accessory nerve. The Muscular branches proceed from the third and fourth cervical nerves; they are distributed to the trapezius, levator anguli scapulae, and rhomboidei muscles. The Comrnunicans noni is a long slender branch formed by fila- ments from the first, second, and third cervical nerves; it descends upon the outer side of the internal jugular vein, and forms a loop with the deseendens noni over the sheath of the carotid vessels. The Phrenic nerve (internal respiratory of Bell) is formed by fila- ments from the third, fourth, and fifth cervical nervee, receiving also a branch from the sympathetic. It descends to the root of the neck, rest- ing upon the scalenus anticus muscle, then crosses the first portion of the subclavian artery, and enters the chest between it and the subclavian vein. Within the chest it passes through the middle mediastinum, between the pleura and pericardium, and in front of the root of the lung to the diaphragm to which it is distributed, some of its filaments reaching the abdomen through the openings for the oesophagus and vena cava, and communicating with the phrenic and solar plexus, and on the right side with the hepatic plexus. The left phrenic nerve is rather longer than the right, from the inclination of the heart to the left side. Posterior Cervical Nerves.—The posterior division of the first cervical nerve (sub-occipital), larger than the anterior, escapes from the vertebral canal through the opening for the vertebral artery, lying posteriorly to that vessel, and emerges into the triangular space formed by the rectus posticus major, obliquus superior, and obliquus inferior. It is distributed to the recti and obliqui muscles, and sends one or two filaments downwards to communicate with the second cervical nerve. The posterior branch of the second cervical nerve is three or four times greater than the anterior branch, and is larger than the other posterior cervical nerves. The posterior branch of the third cervical nerve is smaller than the preceding, but larger than the fourth ; and the other posterior cervical nerves go on progressively decreasing to the seventh. The posterior branches of the fourth, fifth, sixth, seventh and eighth nerves pass inwards between the muscles of the back in the cervical and upper part of the dorsal region, and reaching the surface near the middle line, are reflected outwards, to be distributed to the integument. The fourth and fifth are nearly transverse in their course, and lie between the semispinalis colli and complexus. The sixth, seventh, and eighth are directed nearly vertically down- wards ; they pierce the aponeurosis of origin of the splenius and tra- pezius. 410 BRACHIAL PLEXUS. Posterior Cervical Plexus.—This plexus is constituted by the suc- cession of anastomosing loops and communications wrhich pass be- tween the posterior branches of the first, second, and third cervical nerves. It is situated between the complexus and semispinalis colli, and its branches are the— Musculo-cutaneous, Occipitalis major. The Musculo-cutaneous branches pass inwards between the com- plexus and semispinalis colli to the ligamentum nuchae, distributing muscular filaments in their course. They then pierce the aponeurosis of the trapezius and become subcutaneous, sending branches outwards to supply the integument of the posterior aspect of the neck, and up- wards to the posterior region of the scalp. The Occipitalis major is the direct continuation of the second cer- vical nerve; it ascends obliquely inwards, between the obliquus in- ferior and complexus, pierces the complexus and trapezius after pass- ing for a short distance between them, and ascends upon the posterior aspect of the head between the integument and occipito-frontalis, in company with the occipital artery. The occipitalis major sends numerous branches to the muscles of the neck, and is dis- tributed to the integument of the scalp, as far forwards as the middle of the vertex of the head. Its branches communicate with those of the occipitalis minor. Fig. 178.* BRACHIAL PLEXUS. The plexus or axillary is formed by Brachial of nerves communications between the an terior branches of the four last cervical and first dorsal nerve. These nerves are all similar in size, and their mode of disposi- tion in the formation of the plexus is the following: the fifth and sixth nerves unite to form a common trunk, which soon di- vides into two branches; the last cervical and first dorsal also unite immediately upon their exit from the intervertebral foramina, and the common trunk resulting from their union after a short course also * A view of the brachial plexus of nerves and branches of arm. 1, 1. The scalenus anticus muscle, in front of which are the roots of the plexus. 2, 2. The median nerve. 3. The ulnar nerve. 4. The branch to the biceps muscle. 5. The nerves of Wrisbere 6. The phrenic nerve from the 3d and 4th cervical. BRACHIAL PLEXUS—BRANCHES. 441 divides into two branches; the seventh nerve passes outwards be- tween the common trunks of the two preceding, and opposite the clavicle divides into a superior branch which unites with the inferior division of the superior trunk, and an inferior branch which commu- nicates with the superior division of the inferior trunk: from these divisions and communications the brachial plexus results. The bra- chial plexus communicates with the cervical plexus by means of a branch sent down from the fourth to the fifth nerve, and by the infe- rior branch of origin of the phrenic nerve, and also sends filaments of communication to the sympathetic. The plexus is broad in the neck, narrows as it descends into the axilla, and again enlarges at its lower part where it divides into its six terminal branches. Relations.—The brachial plexus is in relation in the neck with the two scaleni muscles, between which its nerves issue; lower down it is placed between the clavicle and subclavius muscle above, and the first rib and first serration of the serratus magnus muscle below. In the axilla, it is situated at first to the outer side and then behind the axillary artery, resting by its outer border against the tendon of the subscapularis muscle. At this point it completely surrounds the artery by means of the two cords which are sent off to form the median nerve. Its Branches may be arranged into two groups, humeral and de- scending,— Humeral Branches. Descending Branches. Superior muscular, External cutaneous, Short thoracic, Internal cutaneous, Long thoracic, Lesser internal cutaneous, Supra-scapular, Median, Subscapular, Ulnar, Inferior muscular. Musculo-spiral, Circumflex. The superior Muscular nerves are several large branches which are given off by the fifth cervical nerve above the clavicle; they are, a subclavian branch to the subclavius muscle, which usually sends a communicating filament to the phrenic nerve; a rhomboid branch to the rhomboidei muscles; and frequently an angular branch to the levator anguli scapulae. The Short thoracic nerves (anterior) are two in number; they arise from the brachial plexus at a point parallel with the clavicle, and are divisible into an anterior and a posterior branch. The anterior' branch passes forwards between the subclavius muscle and the subclavian vein, and is distributed to the pectoralis major muscle, entering it by its costal surface. In its course it sends one or two twigs to the deltoid muscle and gives off a branch which forms a loop of com- munication with the posterior branch. The posterior branch passes forward beneath the axillary artery and unites with the communicat- ing branch of the preceding to form a loop, from which numerous branches are given off to the pectoralis major and pectoralis minor. 442 INTERNAL CUTANEOUS NERVE. The Long thoracic nerve (posterior thoracic, external respiratory of Bell) is a long and remarkable branch arising from the fourth and fifth cervical nerves, immediately after their escape from the inter- vertebral foramina. It passes down behind the plexus and axillary vessels, resting on the scalenus posticus muscle; it then descends along the side of the chest upon the serratus magnus muscle to its lowest serration. It sends numerous filaments to this muscle in its course. The Supra-scapular nerve arises above the clavicle from the fifth cervical nerve and descends obliquely outwards to the supra-scapular notch; it then passes through the notch, crosses the supra-spinous fossa beneath the supra-spinatus muscle, and passing in front of the concave margin of the spine of the scapula enters the infra-spinous fossa. It is distributed to the supra-spinatus and infra-spinatus muscle. The Subscapular nerves are two in number; of which one arises from the brachial plexus above the clavicle, the other from the pos- terior aspect of the plexus within the axilla. They are distributed to the subscapularis muscle. The Inferior muscular nerves are tw7o or three branches which proceed from the lower and back part of the brachial plexus, and are distributed to the latissimus dorsi and teres major. The former of these is the longer, and follows the course of the subscapular artery. The terminal branches of the plexus are arranged in the following order: the external cutaneous, and one head of the median to the outer side of the artery; the other head of the median, internal cuta- neous, lesser internal cutaneous, and ulnar, upon its inner side; and the circumflex and musculo-spiral behind. The External Cutaneous Nerve (musculo-cutaneous, perforans Casserii) arises from the brachial plexus in common with the exter- nal head of the median; it pierces the coraco-brachialis muscle and passes between the biceps and brachialis anticus, to the outer side of the bend of the elbow, where it perforates the fascia, and divides into an external and internal branch. The branches pass behind the median cephalic vein, the external, the larger of the two, taking the course of the radial vein and communicating with the branches of the radial nerve on the back of the hand; the internal and smaller following the direction of the supinator longus, communicating with the internal cutaneous, and at the lower third of the fore-arm sending off a twig, which accompanies the radial artery to the wrist, and distributes filaments to the synovial membranes of the joint. The external cutaneous nerve supplies the coraco-brachialis, biceps and brachialis anticus in the upper arm, and the integument of the outer side of the fore-arm as far as the wrist and hand. The Internal Cutaneous Nerve is one of the internal and smaller of the branches of the axillary plexus; it arises from the plexus in common with the ulnar and internal head of the median, and passes down the inner side of the arm in company with the basilic vein, MEDIAN NERVE. 443 Fig. 179. giving off several cutaneous filaments in its course. At about the middle of the upper arm it pierces the deep fascia by the side of the basilic vein and divides into two branches, anterior and posterior. The anterior branch, the larger of the two, divides into several branches which pass in front of, and sometimes behind, the median basilic vein at the bend of the elbow, and descends in the course of the palmaris longus muscle to the wrist, distributing filaments to the integument in their course and communicating with the anterior branch of the external cutaneous on the outer side, and its own pos- terior branch on the inner side of the fore-arm. The posterior branch sends off several twigs to the integument over the inner con- dyle and olecranon, and then descends the fore-arm in the course of the ulnar vein as far as the wrist, supplying the integument on the inner side of the fore-arm and communicating with the anterior branch of the same nerve in front, and the dorsal branch of the ulnar nerve on the wrist. The Lesser Internal Cutaneous Nerve, or nerve of Wrisberg, the smallest of the bran- ches of the brachial plexus, is very irregular in point of origin. It is a long and slender nerve, and usually arises from the common trunk of the last cervical and first dorsal nerve. Passing downwards into the axillary space it communicates with the external branch of the first intercosto-humeral nerve, and descends on the inner side of the internal cutaneous nerve, to the middle of the pos- terior aspect of the upper arm, where it pierces the fascia and is distributed to the integument of the elbow, communicating with filaments of the posterior branch of the internal cutaneous and with the spiral cuta- neous. In its course it gives off two or three cutaneous filaments to the integument of the inner and anterior aspect of the upper arm. The Median Nerve has received its name from taking a course along the middle of the fore-arm to the palm of the hand ; it is, therefore, intermediate in position between the radial and ulnar nerves. It commences by two heads, which embrace the axillary artery; lies at first to the outer side of the brachial artery, which it crosses at its middle; and descends on its inner side to the bend of the elbow. It then passes between the two heads of the pronator radii teres and * Nerves of front of forearm. 1. Median nerve. 2. Anterior branch of musculo-spiral or radial nerve. 3. Ulnar nerve. 4. Division of median nerve in the palm to the thumb 1st, 2d, and radial side of 3d finger. 5. Division of ulnar nerve to ulnar side of 6i and both sides of 4th finger. 444 ULNAR NERVE. flexor sublimis digitorum muscles, and runs down the fore-arm, be- tween the flexor sublimis and profundus, and beneath the annular ligament, into the palm of the hand. The Branches of the median nerve are,— Muscular, Superficial palmar, Anterior interosseous, Digital. The Muscular branches are given off by the nerve at the bend of the elbow; they are distributed to all the muscles on the anterior aspect of the fore-arm, with the exception of the flexor carpi ulnaris, and to the periosteum. The branch to the pronator radii teres sends off reflected branches to the elbow-joint. The Anterior interosseous is a large branch accompanying the an- terior interosseous artery, and supplying the deep layer of muscles in the fore-arm. It passes beneath the pronator quadratus muscle, and pierces the interosseous membrane near the wrist. On reaching the posterior aspect of the wrist it joins a large and remarkable ganglion which gives off a number of branches for the supply of the joint. The Superficial palmar branch arises from the median nerve at about the lower fourth of the fore-arm : it crosses the annular liga- ment, and is distributed to the integument over the ball of the thumb and in the palm of the hand. The median nerve at its termination in the palm of the hand is spread out and flattened, and divides into six branches, one muscular and five digital. The muscular branch is distributed to the muscles of the ball of the thumb. The digital branches send twigs to the lum- bricales muscles and are thus arranged: two pass outwards to the thumb to supply its borders ; one to the radial side of the index finger; one subdivides for the supply of the adjoining sides of the index and middle fingers; and the remaining one, for the supply of the adjoining sides of the middle and ring fingers. The digital nerves in their course along the fingers are situated to the inner side of the digital arteries. Opposite the base of the first phalanx each nerve gives off a dorsal branch which runs along the border of the dorsum of the finger. Near the extremity of the finger the digital nerve divides into a palmar and a dorsal branch ; the former supplying the sentient extremity of the finger, and the latter the structures around and be- neath the nail. The digital nerve maintains no communication with its fellow of the opposite side. The Ulnar Nerve is somewhat smaller than the median, behind which it lies, gradually diverging from it in its course. It arises from the brachial plexus in common with the internal head of the median and the internal cutaneous nerve, and runs down the inner side of the arm, to the groove between the internal condyle and olecranon, rest- ing upon the internal head of the triceps, and accompanied by the in- ferior profunda artery. At the elbow it is superficial, and supported by the inner condyle, against which it is easily compressed, giving rise to the thrilling sensation along the inner side of the fore-arm and little finger, ascribed to striking the "funny bone." It then passes MUSCULO-SPIRAL NERVE. 445 between the two heads of the flexor carpi ulnaris and descends along the inner side of the fore-arm, crosses the annular ligament, and di- vides into two branches, superficial and deep pal-mar. At the com- mencement of the middle third of the fore-arm, it becomes applied against the artery, and lies to its ulnar side, as far as the hand. The Branches of the ulnar nerve are,— Muscular in the upper arm, Articular, Muscular in the fore-arm, Anastomotic, Dorsal branch, Superficial palmar, Deep palmar. Fig. 180.* The Muscular branches in the upper arm are a few filaments distributed to the triceps. The Articular branches are several fila- ments to the elbow-joint, which are given off from the nerve as it lies in the groove between the inner condyle and the olecranon. The Muscular branches in the fore-arm are distributed to the flexor carpi ulnaris and flexor profundus digitorum muscle. The Anastomotic branch (n. cutaneus palma- ris ulnaris) is a small nerve which arises from the ulnar at about the middle of the fore-arm, and divides into a deep and a superficial branch; the former accompanies the ulnar artery, the latter pierces the deep fascia and is distributed to the integument, communi- cating with the posterior branch of the inter- nal cutaneous nerve. The Dorsal branch passes backwards be- neath the tendon of the flexor carpi ulnaris, at the lower third of the fore-arm, and divides into branches which supply the integument and two fingers and a half on the posterior aspect of the hand, communicating with the internal cutaneous and radial nerve. The Superficial palmar branch divides into three filaments, which are distributed, one to the ulnar side of the little finger, one to the ad- joining borders of the little and ring fingers, and a communicating branch to join the median nerve. The Deep palmar branch passes between the abductor and flexor minimi digiti, to the deep palmar arch, supplying the muscles of the little finger, and the interossei and other deep structures in the palm of the hand. The Musculo-spiral Nerve, the largest branch of the brachial * A view of the nerves on the dorsal aspect of the fore-arm and hand. 1, 1. The ulnar nerve. 2, 2. The posterior interosseous nerve. 3. Termination of the nervus cutaneus humeri. '4. The dorsalis carpi, a branch of the radial nerve. 5, 5. A back view of the digital nerves. 6. Dorsal branch of the ulnar nerve. * 38 446 CIRCUMFLEX NERVE. plexus, arises from the posterior part of the plexus by a common trunk with the circumflex nerve. It passes downwards from its origin in front of the tendons of the latissimus dorsi and teres major muscle, and winds around the humerus in the spiral groove, accom- panied by the superior profunda artery, to the space between the brachialis anticus and supinator longus, and thence onwards to the bend of the elbow, where it divides into two branches, the posterior interosseous and radial nerve. The Branches of the musculo-spiral nerve are,— Muscular, Spiral cutaneous, Radial, Posterior interosseous. The Muscular branches are distributed to the triceps, to the supi- nator longus, and to the extensor carpi radialis longior. The Spiral cutaneous nerve pierces the deep fascia immediately below the insertion of the deltoid muscle, and passes down the outer side of the fore-arm as far as the wrist. It is distributed to the inte- gument. The Radial nerve runs along the radial side of the fore-arm to the commencement of its lower third; it then passes beneath the tendon of the supinator longus, and at about two inches above the wrist-joint pierces the deep fascia and divides into an external and an internal branch. The external branch, the smaller of the two, is distributed to the outer border of the hand and thumb, and communicates with the posterior branch of the external cutaneous nerve. The internal branch crosses the direction of the extensor tendons of the thumb and divides into several filaments for the supply of the ulnar border of the thumb, the radial border of the index finger, and the adjoining bor- ders of the index and middle fingers. It communicates on the back of the hand with the dorsal branch of the ulnar nerve. In the upper third of the fore-arm the radial nerve lies beneath the border of the supinator longus muscle. In the middle third it is in relation with the radial artery lying to its outer side. It then quits the artery, and passes beneath the tendon of the supinator longus, to reach the back of the hand. The Posterior interosseous nerve, somewhat larger than the radial, separates from the latter at the bend of the elbow, pierces the supi- nator brevis muscle, and emerges from its lower border on the pos- terior aspect of the fore-arm, where it divides into branches which supply the whole of the muscles on the posterior aspect of the fore- arm. One branch, longer than the rest, descends to the posterior part of the wrist, and forms a large gangliform swelling (the common character of nerves which supply joints), from which numerous branches are distributed to the wrist-joint. The Circumflex Nerve arises from the posterior part of the bra- chial plexus by a common trunk with the musculo-spiral nerve. It passes downwards over the border of the subscapularis muscle, winds around the neck of the humerus with the posterior circumflex artery, and terminates by dividing into numerous branches which supply the deltoid muscle. The Branches of the circumflex nerve are muscular and cuta- INTERCOSTAL NERVES. 447 neous. The Muscular branches are distributed to the subscapularis, teres minor, teres major, latissimus dorsi, and deltoid. The cuta- neous branches pierce the deltoid muscle and are distributed to the inte- gument of the shoulder. One of these cutaneous branches (cutaneus brachii superior), larger than the rest, winds around the posterior bor- der of the deltoid, and divides into filaments which pass in a radiating direction across the shoulder and are distributed to the integument. dorsal nerves. The dorsal nerves are twelve in number on each side; the first appears between the first and second dorsal vertebrae, and the last between the twelfth dorsal and first lumbar. They are smaller than the lower cervical nerves, and diminish gradually in size from the first to the tenth, and then increase to the twelfth. Each nerve, as soon as it has escaped from the intervertebral foramen, divides into two branches; a dorsal branch and the true intercostal nerve. The Dorsal branches pass directly backwards between the trans- verse processes of the vertebrae, lying internally to the anterior costo- transverse ligament, where each nerve divides into an anterior or muscular and a posterior or musculo-cutaneous branch. The muscular branch enters the substance of the muscles in the direction of a line corresponding with the interval of separation between the longissi- mus dorsi and sacro-lumbalis, and is distributed to the muscles of the back, its terminal filaments reaching to the integument. The musculo-cutaneous branch passes inwards, crossing the semispinalis dorsi to the spinous processes of the dorsal vertebrae, giving off mus- cular branches in its course; it then pierces the aponeurosis of origin of the trapezius and latissimus dorsi, and divides into branches which are inclined outwards beneath the integument to which they are distributed. The dorsal branch of the first dorsal nerve resembles in its mode of distribution the dorsal branches of the last cervical. The dorsal branches of the last four dorsal nerves pass obliquely downwards and outwards into the substance of the erector spinae in the situation of the interspace between the sacro-lumbalis and longissimus dorsi. After supplying the erector spinae and communicating freely with each other they approach the surface along the outer border of the sacro-lumbalis, where they pierce the aponeuroses of the transver- salis, internal oblique, serratus posticus inferior, and latissimus dorsi, and divide into internal branches which supply the integument in the lumbar region upon the middle line, and external branches which are distributed to the integument upon the side of the lumbar and in the gluteal region. Intercostal Nerves.—The Intercostal nerves receive one or two filaments from the adjoining ganglia of the sympathetic, and pass forwards in the intercostal space with the intercostal vessels, lying below the veins and artery, and supplying the intercostal muscles in their course. At the termination of the intercostal spaces near the sternum, the nerves pierce the intercostal and pectoral muscles, and incline downwards and outwards to be distributed to the integument of the mamma and front of the chest. Those which are situated 448 LUMBAR NERVES. between the false ribs pass behind the costal cartilages, and between the transversalis and obliquus internus muscles, and supply the rectus and the integument on the front of the abdomen. The first and last dorsal nerves are exceptions to this distribution. The anterior branch of the first dorsal nerve divides into two branches; a smaller, which takes its course along the under surface of the first rib to the sternal extremity of the first intercostal space; and a larger, which crosses obliquely the neck of the first rib to join the brachial plexus. The last dorsal nerve, next in size to the first, sends a branch of commu- nication to the first lumbar nerve, to assist in forming the lumbar plexus. The Branches of each intercostal nerve are, a muscular twig to the intercostal and neighbouring muscles, and a cutaneous branch which is given off at about the middle of the arch of the rib. The first intercostal nerve has no cutaneous branch. The cutaneous branches of the second and third intercostal nerves are named, from their origin and distribution, intercosto-humeral. The First Intercosto-humeral Nerve is of large size; it pierces the external intercostal muscle of the second intercostal space, and divides into an internal and an external branch. The internal branch is distributed to the integument of the inner side of the arm. The external branch communicates with the nerve of Wrisberg, and divides into filaments which supply the integument upon the inner and posterior aspect of the arm as far as the elbow. This nerve sometimes takes the place of the nerve of Wrisberg. The Second Intercosto-humeral Nerve is much smaller than the preceding; it emerges from the external intercostal muscle of the third intercostal space between the serrations of the serratus magnus muscle, and divides into filaments which are distributed to the integument of the shoulder. One of these filaments may be traced inwards to the integument of the mamma. The two intercosto- humeral nerves not unfrequently communicate previously to their distribution. The cutaneous branches of the fourth and fifth intercostal nerve send anterior twigs to the integument of the mammary gland and posterior filaments to the scapular region of the back. The cutaneous branches of the remaining intercostal nerves reach the surface between the serrations of the serratus magnus muscle above and the external oblique below, and each nerve divides into an anterior and a posterior branch ; the former being distributed to the integument of the antero- lateral, and the latter to that of the lateral part of the trunk. The cutaneous branch of the last dorsal nerve is remarkable for its size (n. clunium superior anticus); it pierces the internal and exter- nal oblique muscles, crosses the anterior part of the crest of the ilium, and is distributed to the integument of the gluteal region as low down as the trochanter major. LUMBAR NERVES. There are five pairs of lumbar nerves, of which the first makes its appearance between the first and second lumbar vertebrae, and the LUMBAR PLEXUS. 449 last between the fifth lumbar and the base of the sacrum. The anterior branches increase in size from above downwards. They communicate at their origin with the lumbar ganglia of the sympa- thetic, and pass obliquely outwards behind the psoas magnus or between its fasciculi, sending twigs to that muscle and to the quad- ratus lumborum. In this situation each nerve divides into two branches, a superior branch which ascends to form a loop of com- munication with the nerve above, and an inferior branch which descends to join in like manner the nerve below, the communications and anastomoses which are thus established constituting the lumbar plexus. The posterior branches diminish in size from above downwards; they pass backwards between the transverse processes of the corre- sponding vertebrae, and each nerve divides into an internal and an external branch. The internal branch, the smaller of the two, passes inwards to be distributed to the multifidus spinae and interspinales, and becoming cutaneous supplies the integument of the lumbar region on the middle line. The external branches communicate with each other by several loops and, after supplying the deeper muscles, pierce the sacro-lumbalis to reach the integument to which they are distri- buted. The external bran- ches of the three lower lum- Fig. 181.* bar nerves (nervi clunium su- periores postici) descend over the superior part of the crest of the ilium, and are distri- buted to the integument of the gluteal region. LUMBAR PLEXUS. The Lumbar plexus is formed by the communica- tions and anastomoses which take place between the ante- rior branches of the five lum- bar nerves, and between the latter and the last dorsal. It is narrow above and increases in breadth inferiorly, and is situated between the trans- verse processes of the lumbar vertebrae and the quadratus lumborum behind, and the psoas magnus muscle in front. * A view of the lumbar and ischiatic plexus and the branches of the former. 14. The bodies of the lumbar vertebra. 13. The psoas magnus muscle. 11. The iliacus internus muscle. 15. The quadratus lumborum muscle. 6. Ihe diaphragm. 12. 1 he three broad muscles of the abdomen. 17. The sartorius. 1. The lumbar plexus. 2. The ischiatic plexus. 3, 3. Abdomino-crural nerves. 4. External cutaneous nerve (ingumo-cutancous, 5, 6, 7. Cutaneous branches from (8). The anterior crural nerve 9. I he genito-crural nerve or spermatids externus. 10, 10. The lower termination of the great sympathetic. 38*' 450 EXTERNAL CUTANEOUS NERVE. The Branches of the lumbar plexus are the— Musculo-cutaneous, Crural, External-cutaneous, Obturator, Genito-crural, Lumbo-sacral. The Musculo-cutaneous Nerves, two in number, superior and in- ferior, proceed from the first lumbar nerve. The superior musculo- cutaneous nerve (ilio-scrotal, ilio-hypogastricus), passes outwards be- tween the posterior fibres of the psoas magnus, and crossing obliquely the quadratus lumborum to the middle of the crest of the ilium, pierces the transversalis muscle, and gives off a cutaneous branch. It then winds along the crest of the ilium between the transversalis and in- ternal oblique, and divides into two branches, abdominal and scrotal. The abdominal branch is continued forwards parallel with the last in- tercostal nerve to near the rectus muscle, to which it sends branches and perforates the aponeuroses of the internal and external oblique to be distributed to the integument of the mons pubis and groin. The scrotal branch, opposite the anterior superior spinous process of the ilium, communicates with the inferior musculo-cutaneous nerve, and passes forward to the external abdominal ring. It then pierces the cremaster muscle and accompanies the spermatic cord in the male, and the round ligament in the female, to be distributed to the integu- ment of the scrotum or external labium. The inferior musculo-cuta- neous nerve (ilio-inguinal) also arises from the first lumbar nerve. It is much smaller than the preceding, crosses the quadratus lumborum below it, and curves along the crest of the ilium to the anterior su- perior spinous process, resting in its course upon the iliac fascia. It there pierces the transversalis fascia and muscle, communicates with the scrotal branch of the ilio-scrotal nerve, and passes along the sper- matic canal with the spermatic cord to be similarly distributed. The External Cutaneous Nerve (inguino-cutaneous) proceeds from the second lumbar nerve. It pierces the posterior fibres of the psoas muscle; and crossing the iliacus obliquely, lying upon the iliac fascia, to the anterior superior spinous process of the ilium, passes into the thigh beneath Poupart's ligament. It then pierces the fascia lata at about two inches below the anterior superior spine of the ilium, and divides into two branches, anterior and posterior. The posterior branch crosses the tensor vaginae femoris muscle to the outer and posterior side of the thigh, and supplies the integument in that region. The anterior nerve divides into two branches which are distributed to the integument upon the outer border of the thigh, and to the articu- lation of the knee. The Genito-crural proceeds also from the second lumbar nerve. It traverses the psoas magnus from behind forwards, and runs down on the anterior surface of that muscle and beneath its fascia to near Poupart's ligament, where it divides into a genital and a crural branch. The genital branch (n. spermaticus seu pudendus externus) crosses the external iliac artery to the internal abdominal ring and descends CRURAL NERVE. 451 Fig. 182/ along the spermatic canal, lying behind the cord to the scrotum, where it divides into branches which supply the spermatic cord and cremaster in the male, and the round ligament and external labium in the female. At the internal abdominal ring this nerve sends off a branch which after supplying the lower border of the internal oblique and transver- salis, is distributed to the integument of the groin. The crural branch (lumbo-inguinalis), the most external of the two, descends along the outer border of the ex- ternal iliac artery and, crossing the origin of the circumflex ilii artery, enters the sheath of the femoral vessels in front of the femoral artery. It pierces the sheath below Poupart's liga- ment, and is distributed to the integument of the anterior aspect of the thigh as far as its middle. This nerve is often very small, and sometimes communicates with one of the cu- taneous branches of the crural nerve. The Crural, or Femoral Nerve, is the largest of the divisions of the lumbar plexus; it is formed by the union of branches from the second, third, and fourth lumbar nerves, and, emerging from beneath the psoas muscle, passes downwards in the groove between it and the iliacus, and beneath Poupart's liga- ment into the thigh, where it spreads out and divides into numerous branches. At Pou- part's ligament it is separated from the femo- ral artery by the breadth of the psoas muscle, which at this point is scarcely more than half an inch in diameter, and by the iliac fascia, beneath which it lies. Branches.—While situated within the pelvis the crural nerve gives off several muscular branches to the iliacus, and one to the psoas. On emerging from beneath Poupart's liga- ment the nerve becomes flattened and di- vides into numerous branches, which may be arranged into,— Cutaneous, Muscular, Branch to the femoral sheath, Short saphenous nerve, Long saphenous nerve. The Cutaneous nerves (middle cutaneous) two in number, proceed from the anterior part of the crural, and after perforating the sar- torius muscle to which they give filaments, pierce the fascia lata and are distributed to the integument of the middle and lower part of the * A view of the anterior crural nerve and branches. 1. Place of emergence of the nerve under Poupart's ligament. 2. Division of the nerve into branches. 3. Femoral artery. 4. Femoral vein. 5. Branches of obturator nerve. 6. Nervus saphenus. 452 SAPHENOUS NERVES. thigh and of the knee. The most external of these nerves perforates the upper part of the sartorius, communicates with the crural branch of the genito-crural, divides into two branches at about the middle of the thigh, and gives off numerous filaments to the anterior and outer aspect of the limb as far as the patella. The internal nerve perforates the muscle at about its middle, pierces the fascia lata at the lower third of the thigh, descends to the inner condyle, and curves forward to the front of the knee, supplying the integument by many filaments. Besides these another cutaneous branch derived from the muscular branch to the vastus externus is found on the outer side of the lower third of the thigh. The Muscular branches are several large twigs which are distri- buted to the muscles of the anterior aspect of the thigh. One of these is sent to the rectus; one to the vastus externus, which gives off a cutaneous twig to the outer aspect of the thigh; one to the cruraeus, and one large and long branch to the vastus internus. From the two latter, filaments are distributed to the periosteum and knee-joint. The sartorius receives its supply of nerves from the cutaneous nerves by which it is perforated. The Branch to the femoral sheath is a small nerve wrhich passes in- wards to the sheath of the femoral vessels at the upper part of the thigh, and divides into several filaments which surround the femoral and profunda vessels. Two of these filaments, one from the front, and the other from the posterior part of the sheath, unite to form a small nerve which escapes from the saphenous opening and passes downwards with the saphenous vein. Other filaments are distributed to the adductor muscles, and communicate with the long saphenous nerve. The Short saphenous nerve (n. cutaneus internus) inclines inwards to the sheath of the femoral vessels, and divides into a superficial and a deep branch. The superficial branch passes downwards along the inner border of the sartorius muscle to the lower third of the thigh; it then pierces the fascia lata, joins the internal saphenous vein, and accompanies that vessel to the knee-joint, where it terminates by communicating with the long saphenous nerve. The deep branch de- scends on the outer side of the sheath of the femoral vessels, and crosses the sheath at its lower part to a point opposite the termi- nation of the femoral artery, where it divides into several filaments which constitute a plexus by their communication with other nerves. One of these filaments communicates with the descending branch of the obturator nerve, another with the long saphenous nerve, and two or three are distributed to the integument upon the internal and pos- terior aspect of the thigh. The Long saphenous nerve (n. cutaneus internus longus) inclines inwards to the sheath of the femoral vessels, and entering the sheath accompanies the femoral artery to the aponeurotic canal formed by the adductor longus and vastus internus muscles. It then quits the artery, and, passing between the tendons of the sartorius and gracilis, descends along the inner side of the leg with the internal saphenous OBTURATOR NERVE. 453 vein, crosses in front of the inner ankle, and is distributed to the in- tegument on the inner side of the foot as far as the great toe. The internal saphenous nerve receives from the obturator nerve two branches of communication, one near its upper part, which passes through the angle of division of the femoral artery, and the other at the internal condyle. The branches which it gives off in its course are, a femoral cutaneous branch, at about the middle of the thigh, distributed to the integument of the inner and posterior aspect of the limb, and communicating with other cutaneous filaments from the saphenous below the knee; a tibial cutaneous branch proceeding from the nerve a little above the internal condyle, passing between the sartorius and gracilis and descending the inner aspect of the leg to the ankle; an articular branch of small size, proceeding from the nerve while in the aponeurotic canal of the femoral artery, and passing directly to the knee-joint to supply the synovial membrane; an ante- rior cutaneous branch proceeding from the saphenous at the inner condyle, perforating the sartorius, and dividing into a number of fila- ments which supply the integument over the patella and around the joint, and the integument of the front and outer aspect of the leg as far as the ankle; lastly, cutaneous filaments below the knee to supply the inner side and front of the leg and foot, and articular branches to the ankle-joint. The Obturator Nerve is formed by a branch from the third, and another from the fourth lumbar nerve. It passes downwards among the fibres of the psoas muscle, through the angle of bifurcation of the common iliac vessels, and along the inner border of the brim of the pelvis, to the obturator foramen, where it joins the obturator artery. Having escaped from the pelvis it gives off two small twigs to the obturator externus muscle and divides into four branches, three ante- rior, which pass in front of the adductor brevis, supplying that muscle, the pectineus, the adductor longus, and the gracilis ; and a posterior branch which passes downwards behind the adductor brevis, and ramifies in the adductor magnus. From the branch which supplies the adductor brevis, a communi- cating filament passes outwards through the angle of bifurcation of the femoral vessels to unite with the long saphenous nerve. From the branch to the adductor longus a long cutaneous nerve proceeds, which issues from beneath the inferior border of that muscle, sends filaments of communication to the plexus of the short saphenous nerve, and descends to the inner side of the knee, where it pierces the fascia and communicates with the long saphenous nerve. It is distributed to the integument upon the inner side of the leg. From the posterior branch an articular branch is given off which pierces the adductor magnus muscle, accompanies the popliteal artery, and is distributed to the synovial membrane of the knee-joint on its posterior aspect. The Lumbo-sacral Nerve.—The anterior division of the fifth lum- bar nerve, conjoined with a branch from the fourth, constitutes the lumbo-sacral nerve, which descends over the base of the sacrum into the pelvis, and assists in forming the sacral plexus. 454 SACRAL PLEXUS. Fig. 183.* SACRAL NERVES. There are six pairs of sacral nerves; the first escape from the ver- tebral canal through the first sacral foramina, and the two last between the sacrum and coccyx. The posterior sacral nerves are very small and diminish in size from above downwards; they communicate with each other immediately after their escape from the posterior sacral foramina, and divide into external and internal branches. The external branches pierce the gluteus maximus, to which they give fila- ments, and are distributed to the integument of the posterior part of the gluteal region (n. cutanei clunium posteriores). The internal supply the integument over the sacrum and coccyx. The anterior sacral nerves diminish in size from above downwards; the first is large and unites with the lumbo-sacral nerve; the second, of equal size, unites with the preceding; the third, which is scarcely one-fourth so large as the third, also joins with the preceding nerves in the formation of the sacral plexus. The fourth anterior sacral nerve is about one-third the size of the preceding sacral nerve ; it di- vides into several branches, one of which is sent to the sacral plexus, a second to join the fifth sacral nerve, a third to the viscera of the pelvis communicating with the hypogastric plexus, and a fourth to the coccygeus muscle, and to the integument around the anus. The fifth anterior sacral nerve presents about half the size of the fourth; it divides into two branches, one of which communicates with the fourth, the other with the sixth. The sixth sacral nerve (coccygeal) is exceedingly small; it gives off an ascending filament which is con- tinuous with the communicating branch of the fifth; and a descending filament which passes downwards by the side of the coccyx and traverses the fibres of the great sacro- ischiatic ligament to be distributed to the gluteus maximus and to the integument. All the anterior sacral nerves receive branches from the sacral ganglia of the sympathetic at their emergence from the sacral foramina. SACRAL PLEXUS. The Sacral plexus is formed by the lumbo-sacral, and by the ante- rior branches of the four upper sacral nerves. The plexus is trian- gular in form, the base corresponding with the whole length of the sacrum, and the apex with the lower part of the great ischiatic fora- * A view of the branches of the ischiatic plexus to the hip and back of the thigh. 1, 1. Posterior sacral nerves. 2. Nervi glutei. 3. The internal pudic nerve, (nervus pudenda. lis longus superior). 4. The lesser ischiatic nerve, giving off the perineal cutaneous (pudendalis longus inferior), and 5. The ramus femoralis cutaneus posterior. The refer- ence to the great ischiatic has been omitted. It is seen to the right of 3. GLUTEAL NERVE. 455 men. It is in relation behind with the pyriformis muscle, and in front with the pelvic fascia, which latter separates it from the branches of the internal iliac.artery, and from the viscera of the pelvis. The Branches of the sacral plexus are divisible into the internal and the external; they may be thus arranged:— Internal. External. Visceral, Muscular, • Muscular. Gluteal, Internal pudic, Lesser ischiatic, Greater ischiatic. The Visceral nerves are three or four large branches which are derived from the fourth and fifth sacral nerves: they ascend upon the side of the rectum and bladder; in the female upon the side of the rectum, the vagina and the bladder ; and interlace with the branches of the hypogastric plexus, sending in their course numerous filaments to those viscera. The Muscular branches given off within the pelvis are one or two twigs to the levator ani; an obturator branch ; which curves around the spine of the ischium to reach the internal surface of the obturator internus muscle; a coccygeal branch; and an haemorrhoidal nerve which passes through the two ischiatic openings and descends to the termination of the rectum to supply the sphincter and the integument. The Muscular branches supplied by the sacral plexus externally to the pelvis are, a branch to the pyramidalis; a branch to the gemellus superior; and a branch of moderate size which descends between the gemelli muscles and the ischium, and is distributed to the gemellus inferior, the quadratus femoris, and the capsule of the hip-joint. The Gluteal Nerve (superior gluteal) is a branch of the lumbo- sacral ; it passes out of the pelvis with the gluteal artery, through the great sacro-ischiatic foramen, and divides into a superior and an in- ferior branch. The superior branch follows the direction of the su- perior curved line of the ilium, accompanying the deep superior branch of the gluteal artery, and sending filaments to the gluteus medius and minimus. The inferior passes obliquely downwards and forwards between the gluteus medius and minimus, distributing nume- rous filaments to both, and terminates in the tensor vaginae femoris muscle. The Internal Pudic Nerve arises from the lower part of the sa- cral plexus, passes out of the pelvis through the great sacro-ischiatic foramen below the pyriformis muscle, and takes the course of the internal pudic artery." While situated beneath the obturator fascia it lies below that vessel and divides into a superior and an inferior branch. The Superior nerve (dorsalis penis) ascends upon the posterior surface of the ramus of the ischium, pierces the deep perineal fascia and accompanies the arteria dorsalis penis to the glans, to which k is 456 GREAT ISCHIATIC NERVE. distributed. At the root of the penis this nerve gives off a cutaneous branch which runs along the side of the organ, gives filaments to the corpus cavernosum, and with its fellow of the opposite side sup- plies the integument of the upper two-thirds of the penis and prepuce. The Inferior or perineal nerve pursues the course of the internal pu- dic artery in the perineum and sends off three principal branches, an external perineal branch, which ascends upon the outer side of the crus penis, and supplies the scrotum; a superficial perineal branch, which accompanies the artery of that name and distributes filaments to the scrotum, to the integument of the under part of the penis and to the prepuce; and, thirdly, the bulbo-urethral branch, which sends twigs to the sphincter ani, transversus perinei, and accelerator urinae, and terminates by ramifying in the corpus spongiosum. In the female the internal pudic nerve is distributed to the parts analogous to those of the male. The superior branch supplies the clitoris; and the inferior the vulva and parts in the perineum. The Lesser Ischiatic Nerve passes out of the pelvis through the great sacro-ischiatic foramen below the pyriformis muscle, and di- vides into muscular and cutaneous branches. The muscular branches, inferior gluteal, are distributed to the gluteus maximus ; some as- cending in the substance of that muscle to its upper border, and others descending. The cutaneous branches are, several ascending fila- ments to the integument over the gluteus maximus (n. cutanei clunium inferiores), perineal cutaneous, and middle posterior cutaneous. The Perineal cutaneous nerve (pudendalis longus inferior), curves around the tuberosity of the ischium and ascends in a direction parallel to the ramus of the ischium and os pubis to the scrotum, where it communicates with the superficial perineal nerve, and divides into an internal and an external branch. The internal branch passes down upon the inner side of the testis to the scrotum; the ex- ternal branch to its outer side, and both terminate in the integument of the under border of the penis. The Middle posterior cutaneous nerve crosses the tuberosity of the ischium and pierces the deep fascia at the lower border of the gluteus maximus. It then passes downwards along the middle of the poste- rior aspect of the thigh and of the popliteal region, and is distributed to the integument as far as the middle of the calf of the leg. In its course the nerve gives off several cutaneous branches to the integu- ment of the inner and outer side of the thigh, and in the popliteal region a communicating branch which pierces the fascia of the leg and unites with the external saphenous nerve. The Great Ischiatic Nerve is the largest nervous cord in the body ; it is formed by the sacral plexus, or rather is a prolongation of the plexus, and at its exit from the great sacro-ischiatic foramen be- neath the pyriformis muscle measures three quarters of an inch in breadth. It descends through the middle of the space between the trochanter major and tuberosity of the ischium, and along the poste- rior part of the thigh to about its lower third, where it divides into POSTERIOR TIBIAL NERVE. 457 two large terminal branches, popliteal and peroneal. This division sometimes takes place at the plexus, and the two nerves descend to- gether side by side ; occasionally they are separated at their com- mencement by a part or the whole of the pyriformis muscle. The nerve in its course down the thigh rests upon the gemellus superior, tendon of the obturator internus, gemellus inferior, quadratus femoris, and adductor magnus muscle, and is covered in by the gluteus maxi- mus, biceps, semi-tendinosus, and semi-membranosus. The Branches of the great ischiatic nerve, previously to its divi- sion, are muscular and articular. The muscular branches are given off from the upper part of the nerve and supply both heads of the biceps, the semi-tendinosus, semi-membranosus, and adductor magnus. The articular branch descends to the upper part of the external con- dyle of the femur, and divides into filaments which are distributed to the fibrous capsule and to the synovial membrane of the knee-joint. The Popliteal Nerve passes through the middle of the popliteal spare, from the division of the great ischiatic nerve to the lower border of the popliteus muscle, accompanies the artery beneath the arch of the soleus, and becomes the posterior tibial nerve. It is superficial in the whole of its course, and lies externally to the vein and artery. The Branches of the popliteal nerve are muscular or sural, and ar- ticular, and a cutaneous branch the communicans poplitei. The Muscular branches, of considerable size, and four or five in number, are distributed to the two heads of the gastrocnemius, to the soleus, plantaris, and popliteus. The Articular nerve pierces the ligamentum posticum Winslowii, and supplies the interior of the knee-joint. It usually sends a twig to the popliteus muscle. The Communicans poplitei (communicans tibialis) is a large nerve which arises from the popliteal at about the middle of its course, and descends between the two heads of the gastrocnemius, and along the groove formed by the two bellies of that muscle; at a variable dis- tance below the articulation of the knee it receives a large branch, the communicans peronei, from the peroneal nerve, and the two toge- ther constitute the external saphenous nerve. The External saphenous nerve pierces the deep fascia below the fleshy part of the gastrocnemius muscle, and continues its course down the leg, lying along the outer border of the tendo Achillis and by the side of the external saphenous vein which it accompanies to the foot. At the lower part of the leg it winds around the outer malleolus, and is distributed to the outer side of the foot and little toe, communicating with the external peroneal cutaneous nerve, and sending numerous filaments to the integument of the heel and sole of the foot. The Posterior Tibial Nerve is continued along the posterior aspect of the leg from the lower border of the popliteus muscle to the posterior part of the inner ankle, where it divides into the internal oJ 458 INTERNAL PLANTAR NERVE. and external plantar nerve. In the upper part of its course it lie s to the outer side of the posterior tibial artery ; it then becomes placed superficially to that vessel, and at the ankle is again situated to its outer side ; in the lower third of the leg it lies parallel with the inner border of the tendo Achillis. Fig. 184.* Fi?.185.t W^i The Branches of the posterior tibial nerve are three or four mus- cular twigs to the deep muscles of the posterior aspect of the leg, the branch to the flexor longus pollicis accompanies the fibular artery; one or two filaments which entwine around the artery and then ter- minate in the integument ;J and two or three plantar cutaneous branches which pass downwards upon the inner side of the os calcis and are distributed to the integument of the heel. The Internal Plantar Nerve, larger than the external, crosses * A view of some of the branches of the popliteal nerve. 1. The popliteal nerve. 2, 3. The terminations of the ramus femoralis cutaneus posterior. 4, 5. The saphenous nerve. 6, 6. The external saphenous or communicans tibia?. t A view of the posterior tibial nerve in the back of the leg. 1 and 2, indicate its course, the upper part of the peroneal nerve being seen to the right. t It is extremely interesting in a physiological point of view, to observe the mode of distribution of these filaments. I have traced them in relation with several, and I have no doubt that they exist in connexion with all the superficial arteries. They seem to be the direct monitors to the artery of the presence or approach of danger. PERONEAL NERVE. 459 the posterior tibial vessels to enter the sole of the foot, where it lies in the interspace between the abductor pollicis and flexor brevis digitorum; it then enters the Fig. 186.* sheath of the latter muscle, and divides oppo- site the bases of the metatarsal bones into three digital branches ; one to supply the ad- joining sides of the great and second toe; the second the adjoining sides of the second and third toe; and the third the corresponding sides of the third and fourth toes. This dis- tribution is precisely similar to that of the di- gital branches of the median nerve. In its course the internal plantar nerve gives off cutaneous branches to the integument of the inner side and sole of the foot; muscular branches to the muscles forming the inner and middle group of the sole; a digital branch to the inner border of the great toe; and arti- cular branches to the articulations of the tarsal and metatarsal bones. The External Plantar Nerve, the smaller of the two, follows the course of the external plantar artery to the outer border of the mus- culus accessorius, beneath which it sends seve- ral large muscular branches to supply the adductor pollicis and the articulations of the tarsal and metatarsal bones. It then gives bran- ches to the integument of the outer border and sole of the foot, and sends forward two digital branches to supply the little toe and one half the next. The Peroneal Nerve is one-half, smaller than the popliteal; it passes downwards by the side of the tendon of the biceps, crossing the inner head of the gastrocnemius and the origin of the soleus, to the neck of the fibula, where it pierces the origin of the peroneus longus muscle, and divides into two branches, the anterior tibial and musculo-cutaneous. The Branches of the peroneal nerve previously to its division are, the communicans peronei, cutaneous, articular, and muscular. The communicans peronei, much smaller than the communicans poplitei, crosses the external head of the gastrocnemius to the middle of the leg. It there sends a large branch to join the communicans poplitei and constitute the external saphenous nerve, and descends very much reduced in size with the external saphenous vein to the side of the external ankle, to which and to the integument of the heel it distri- butes filaments. The cutaneous branch passes down the outer side of the leg, supplying the integument. The articular is a small branch * A view of the termination of the posterior tibial nerve in the sole of the foot. 1. In- side of the foot. 2. Outer side. 3. Heel. 4. Internal plantar nerve. 5. External plantar nerve. 6. Branch to flexor brevis. 7. Branch to outside of little toe. 8. Branch to space between 4th and 5th toes. 9, 9, 9. Digital branches to remaining spaces. 10. Branch to internal side of great toe. 460 PERONEAL NERVE—BRANCHES. distributed to the knee-joint. The muscular branches are twigs to the short head of the biceps, peroneus longus, and tibialis anticus. The Anterior Tibial Nerve commences at the bifurcation of the peroneal, upon the head of the fibula, and passes beneath the upper part of the extensor longus digitorum, to reach the outer side of the anterior tibial artery, just as that vessel has Fig. 187* emerged through the opening in the interosseous membrane. It descends the anterior aspect of the leg with the artery; lying at first to its outer side, and then in front of it, and near the ankle becomes again placed to its outer side. Reaching the ankle, it passes beneath the annular ligament; accom- panies the dorsalis pedis artery, supplies the ad- joining sides of the great and second toes, and com- municates with the internal peroneal cutaneous nerve. The Branches given off by the anterior tibial nerve are, muscular to the muscles in its course, and on the foot a tarsal branch which passes be- neath the extensor brevis digitorum, and distributes filaments to the interossei muscles and to the arti- culations of the tarsus and metatarsus. The Musculo-cutaneous Nerve passes down- wards in the direction of the fibula, in the sub- stance of the peroneus longus; it then passes for- wards to get between the peroneus longus and brevis, and at the lower third of the leg pierces the deep fascia, and divides into two peroneal cu- taneous branches. In its course it gives off several branches to the peronei muscles. The Peroneal cutaneous nerves pass in front of the ankle-joint, and are distributed to the integu- ment of the foot and toes; the external supplying three toes and a half, and the internal one and a half. They communicate with the saphenous and anterior tibial nerves. The external saphenous nerve frequently supplies the fifth toe and the adjoining side of the fourth. SYMPATHETIC NERVES. The Sympathetic system consists of a series of ganglia, extending along each side of the vertebral column from the head to the coccyx, communicating with all the other nerves of the body, and distributing branches to all the internal organs and viscera. * A view of the anterior tibial nerve. 1. The peroneal nerve. 2, 3. The anterior tibial nerve accompanying the artery of the same name. CRANIAL GANGLIA. 461 It communicates with the other nerves immediately at their exit from the cranium and vertebral canal. The fourth and sixth nerves, however, form an exception to this rule; for with these it unites in th(| cavernous sinus; and with the olfactory, optic, and auditory, at their ultimate expansions. The branches of distribution accompany the arteries which supply the different organs, and form communications around them, which are called plexuses, and take the name of the artery with which they are associated: thus we have the mesenteric plexus, hepatic plexus, splenic plexus, &c. All the internal organs of the head, neck, and trunk are supplied with branches from the sympathetic, and some of them exclusively; hence it is considered a nerve of organic life. It is called the ganglionic nerve from the circumstance of being formed by a number of ganglia; and from the constant disposition which it evinces in its distribution, to communicate and form small knots or ganglia. There are five sympathetic ganglia in the head; viz., the ganglion of Ribes; the ciliary or lenticular; the spheno-palatine, or Meckel's; the otic, or Arnold's; and the submaxillary: three in the neck; supe- rior, middle, and inferior: twelve in the dorsal region; four in the lumbar region; and four or five in the sacral region. Each ganglion may be considered as a distinct centre giving off branches in four different directions, viz., superior or ascending, to communicate with the ganglion above; inferior or descending, to communicate with the ganglion below; external, to communicate with the spinal nerves; and internal, to communicate with the sym- pathetic filaments of the opposite side, and to be distributed to the viscera. CRANIAL GANGLIA. Ganglion of Ribes, Ciliary, or lenticular ganglion, Spheno-palatine, or Meckel's ganglion, Otic, or Arnold's ganglion, Submaxillary ganglion. The Ganglion of Ribes is a small ganglion situated upon the ante- rior communicating artery, and formed by the union of the sympa- thetic filaments which accompany the ramifications of the two anterior cerebral arteries. These filaments are derived from the carotid plexus at each side; and through their intervention, the ganglion of Ribes is brought into connexion with the carotid plexus, and with the other ganglia of the sympathetic. This ganglion, though of very small size, is interesting, as being the superior point of union between the sym- pathetic chains of opposite sides of the body. The Ciliary Ganglion (lenticular) is a small quadrangular and flattened ganglion situated within the orbit, between the optic nerve and the external rectus muscle; it is in close contact with the optic nerve, and is surrounded by adipose tissue, which renders its dissec- tion somewhat difficult. 39* 462 CILIARY GANGLION. Its branches of distribution are the ciliary, which arise from its anterior angles by two groups: the upper group, consisting of about four filaments; and the lower, of five or six. They accompany the Fig. 188.* • ciliary arteries in a waving course, and divide into a number of fila- ments which pierce the sclerotic around the optic nerve, and supply the tunics of the eyeball. A small filament is said by Tiedemann, to accompany the arteria centralis retinae into the centre of the globe of the eye. Its branches of communication are three, one, the long root, which proceeds from the posterior superior angle to the nasal branch of the ophthalmic nerve; a short thick branch, the short root, from the pos- terior inferior angle to the inferior division of the third nerve; and a slender filament, the sympathetic root, which passes backwards to the cavernous sinus, and communicates with the carotid plexus. Occasionally the ciliary ganglion receives also a filament of commu- * The cranial ganglia of the sympathetic nerve. 1. The ganglion of Ribes. 2. The filament by which it communicates with the carotid plexus (3). 4. The ciliary or lenti- cular ganglion, giving off ciliary branches for the supply of the globe of the eye. 5. Part of the inferior division of the third nerve, receiving a short thick branch (the short root) from the ganglion. 6. Part of the nasal nerve, receiving a longer branch (the long root) from the ganglion. 7. A slender filament (the sympathetic root) sent directly back- wards from the ganglion to the carotid plexus. 8. Part of the sixth nerve in the caver- nous sinus, receiving two branches from the carotid plexus. 9. Meckel's ganglion (spheno-palatine). 10. Its ascending branches, communicating with the superior maxil- lary nerve. 11. Its descending or palatine branches. 12. Its internal branches, spheno- palatine or nasal. 13. The naso-palatine branch, one of the nasal branches. * The naso- palatine ganglion. 14. The posterior branch of the ganglion, the Vidian nerve. 15. Its carotid branch (n. petrosus profundus) communicating with the carotid plexus. 16. Its petrosal branch (n. petrosus superficialis minor), joining the intumescentia gangliformis of the facial nerve. 17. The facial nerve. 18. The chorda tympani nerve, which descends to join the gustatory nerve. 19. The gustatory nerve. 20. The submaxillary ganglion, receiving the chorda tympani, and other filaments from the gustatory. 21. The superior cervical ganglion of the sympathetic. SPHENOPALATINE GANGLION. 463 nication (middle root) from the spheno-palatine ganglion; and it sometimes sends a twig to the abducens nerve. The Spheno-palatine Ganglion (Meckel's) the largest of the cranial ganglia of the sympathetic, is very variable in its dimensions. It is situated in the spheno-maxillary fossa. Its branches are divisible into four groups; ascending, descend- ing, internal, and posterior. The branches of distribution are the internal and the descending. The internal branches are the nasal and the naso-palatine. The nasal or spheno-palatine nerves, four or five in number, enter the nasal fossa through the spheno-palatine foramen, and are distributed to the mucous membrane of the superior meatus, and superior and middle spongy bones. Besides these, several branches issue through small openings in the palate and sphenoid bone and supply the mucous membrane of the upper part of the pharynx and the Eusta- chian tube. The naso-palatine nerve (Scarpa) enters the nasal fossa with the nasal nerves, and crosses the roof of the nares to reach the septum, to which it gives several filaments. It then curves downwards and forwards to the naso-palatine canal, and enters the anterior palatine canal, where it joins with its fellow of the opposite side and receives filaments from the anterior dental and palatine nerves. By this junc- tion an enlargement is formed, the naso-palatine ganglion (Cloquet's), which distributes filaments to the mucous membrane of the palate, immediately behind the incisor teeth. The descending branches are the three palatine nerves, anterior, middle, and posterior. The anterior palatine nerve, the largest of the three, descends from the ganglion through the posterior palatine canal, and emerges at the posterior palatine foramen. It then passes forwards in the substance of the hard palate to which it is distributed, and commu- nicates with the naso-palatine ganglion and with its branches. While in the posterior palatine canal this nerve gives off several branches which enter the nose through openings in the palate bone, and are distributed to the middle and inferior meatus, the inferior spongy bone, and the antrum. The middle palatine nerve descends through the same canal to the posterior palatine foramen, and distributes branches to the tonsil, soft palate, and uvula. The posterior palatine nerve, the smallest of the three, quits the other nerves to enter a distinct canal, from which it emerges by a separate opening behind the posterior palatine foramen. It is distri- buted to the hard palate and gums near the point of its emergence, and to the tonsil and soft palate. The branches of communication are the ascending and the poste- rior. The ascending branches are, one or two to join the superior maxillary nerve; one to the abducens nerve; one to the ciliary gan- glion constituting its middle root; and occasionally two filaments to 464 OTIC GANGLIOX. the optic nerve within the orbit. The posterior branch is the Vidian or pterygoid nerve. The Vidian* nerve passes directly backwards from the spheno- palatine ganglion, through the pterygoid or Vidian canal, to the fora- men lacerum basis cranii, where it divides into two branches, the carotid and petrosal. The carotid branch (n. petrosus profundus) crosses the foramen lacerum, surrounded by the ligamentous sub- stance which closes that opening and enters the carotid canal by several filaments to join the carotid plexus. The petrosal branch (n. petrosus superficialis major) enters the cranium through the foramen lacerum basis cranii, piercing the ligamentous substance of the latter, and passes backwards beneath the Casserian ganglion and dura mater, embedded in a groove upon the anterior surface of the petrous bone, to the hiatus Fallopii. In the hiatus Fallopii the petrosal branch of the Vidian receives a twig from Jacobson's nerve and terminates in the intumescentia gangliformis of the facial nerve. While in the pterygoid canal the Vidian nerve sends off a minute branch which passes through an opening in the sphenoid bone and joins the otic ganglion. The Otic Ganglion (Arnold's)! is a small oval-shaped and flattened ganglion, resting against the inner surface of the inferior maxillary nerve, immediately below the foramen ovale ; it is in relation exter- nally with the trunk of the inferior maxillary nerve, just at the point of union of the motor root; internally it rests against the cartilage of the Eustachian tube and tensor palati muscle; and posteriorly it is in contact with the arteria meningea media. It is closely adherent to the internal pterygoid nerve, and appears like a swelling upon that branch. The branches of the otic ganglion are seven in number; two of distribution, and five of communication. The branches of distribution are, a small filament to the tensor tympani muscle, and one to the tensor palati muscle; the latter is usually derived from the internal pterygoid nerve, at the point where that nerve is enclosed by the ganglion. The branches of communication are, two or three filaments to the outer portion of the inferior maxillary nerve; one or two filaments to the auricular nerve; a filament to the chorda tympani; filaments to the arteria meningea media to communicate with the nervi molles; a filament which enters the cranium through the foramen spinosum with the arteria meningea media and accompanies the nervus petro- sus superficialis minor to the hiatus Falopii, where it joins the intu- mescentia gangliformis of the facial nerve; a filament which enters the cranium through a small canal behind the foramen rotundum to join the Casserian ganglion; a filament which enters a small canal near the foramen ovale to communicate with the Vidian nerve ; and * Guido Guidi, latinized into Vidus Vidius, was professor of anatomy and medicine in the College of France in 1542. His work is posthumous, and was published in 1611. t Frederick Arnold, " Dissertatio Inauguralis de Parte Cephalica Nervi Sympathetici " Heidelberg, 1826; and " Ueber den Ohrknoten," 1828. CAROTID PLEXUS. 465 the nervus petrosus superficialis minor. The latter nerve ascends from the ganglion to a small canal situated between the foramen ovale and foramen spinosum, and passes backwards on the petrous bone to the hiatus Falopii, where it divides into two filaments. One of these filaments enters the hiatus and joins the intumescentia gan- gliformis of the facial; the other passes to a minute foramen nearer the base of the petrous bone and enters the tympanum, where it com- municates with a branch of Jacobson's nerve. The Submaxillary Ganglion is a small round or triangular gan- glion, situated upon the submaxillary gland, in close relation with the gustatory nerve and near the posterior border of the mylo-hyoideus muscle. Its branches of distribution, six or eight in number, divide into many filaments, which supply the substance of the submaxillary gland and Wharton's duct. Its branches of communication are, two or three from and to the gustatory nerve; one from the chorda tympani; and one or two fila- ments which pass to the facial artery and communicate with the nervi molles from the cervical portion of the sympathetic. Carotid Plexus.—The ascending branch of the superior cervical ganglion enters the carotid canal with the internal carotid artery, and divides into two branches, which form several loops of communica- tion with each other around the artery. These branches, together with those derived from the petrosal branch of the Vidian, constitute the carotid plexus. They also form frequently a small gangliform swelling upon the under part of the artery, which is called the carotid ganglion. The latter, however, is not constant. The continuation of the carotid plexus onwards with the artery by the side of the sella turcica, is called the cavernous plexus. The carotid plexus is the centre of communication between all the .cranial ganglia; and being derived from the superior cervical gan- glion, between the cranial ganglia and those of the trunk, it also com- municates with the greater part of the cerebral nerves, and distributes filaments with each of the branches of the internal carotid, which accompany those branches in all their ramifications. Thus, the Ganglion of Ribes is formed by the union of the filaments which accompany the anterior cerebral arteries, and which meet on the anterior communicating artery. The ciliary ganglion communi- cates with the plexus by means of the long branch which is sent back to join it in the cavernous sinus. The spheno-palatine, and with it the naso-palatine ganglion, joins the plexus by means of the carotid branch of the Vidian. The submaxillary ganglion is brought into connexion with it by means of the otic ganglion, and the otic ganglion by means of the tympanic nerve and the Vidian. It communicates with the third nerve in the cavernous sinus, and through the ciliary ganglion ; frequently with the fourth in the for- mation of the nerve of the tentorium ; with the Casserian ganglion ; with the ophthalmic division of the fifth in the cavernous sinus, and by 466 CERVICAL GANGLIA. means of the ciliary ganglion; with the superior maxillary, through the spheno-palatine ganglion ; and with the inferior maxillary, through the otic ganglion. It sends two branches directly to the sixth nerve, which unite* with it as it crosses the cavernous sinus; it communi- cates with the facial and auditory nerves, through the medium of the petrosal branch of the Vidian; and with the glosso-pharyngeal by means of two filaments to the tympanic nerve. CERVICAL GANGLIA. The Superior cervical ganglion is long and fusiform, of a grayish colour, smooth, and of considerable thickness, extending from within an inch of the carotid foramen in the petrous bone to opposite the lower border of the third cervical vertebra. It is in relation in front with the sheath of the internal carotid artery and internal jugular vein; and behind with the rectus anticus major muscle. Its branches, like those of all the sympathetic ganglia in the trunk, are divisible into superior, inferior, external, and internal; to which may be added, as proper to this ganglion, anterior. The superior (carotid nerve) is a single branch which ascends by the side of the internal carotid, and divides into two branches; one lying to the outer side, the other to the inner side of that vessel. The two branches enter the carotid canal, and by their communica- tions with each other and with the petrosal branch of the Vidian, constitute the carotid plexus. The inferior or descending branch, sometimes two, is the cord of communication with the middle cervical ganglion. The external branches are numerous, and may be divided into two sets: those which communicate with the glosso-pharyngeal, pneumo- gastric, and hypoglossal nerves; and those which communicate with the three first cervical nerves. The internal branches are three in number: pharyngeal, to assist in forming the pharyngeal plexus; laryngeal, to join the superior laryn- geal nerve and its branches; and the superior cardiac nerve, or nervus superficialis cordis. The anterior branches accompany the carotid artery with its branches, around which they form intricate plexuses, and here and there small ganglia; they are called, from the softness of their tex- ture, nervi molles, and from their reddish hue, nervi subrufi. The Middle cervical ganglion (thyroid ganglion) is of small size, and sometimes altogether wanting. It is situated opposite the fifth cervical vertebra, and rests upon the inferior thyroid artery. This relation is so constant, as to have induced Haller to name it the " thyroid ganglion." Its superior branch, or branches, ascend to communicate with the superior cervical ganglion. Its inferior branches descend to join the inferior cervical ganglion; * Panizza, in his " Experimental Researches on the Nerves," denies this communica- tion, and states very vaguely that " they are merely lost and entwined around it."__Edin- burgh Medical and Surgical Journal, January 1836. CARDIAC NERVES. 467 one of these frequently passes in front of the subclavian artery, the other behind it. Its external branches communicate with the third, fourth, and fifth cervical nerves. Its internal branches arc, filaments which accompany the inferior thyroid artery, the inferior thyroid plexus; and the middle cardiac nerve, nervus cardiacus magnus. The Inferior cervical ganglion (vertebral ganglion) is much larger than the preceding, and is constant in its existence. It is of a semi- lunar form, and is situated upon the base of the transverse process of the seventh cervical vertebra,immediately behind the vertebral artery: hence its title to the designation "vertebralganglion." Its superior branches communicate with the middle cervical gan- glion. The inferior branches pass some before and some behind the sub- clavian artery, to join the first thoracic ganglion. The external branches consist of two sets; one which communi- cates with the sixth, seventh, and eighth cervical and first dorsal nerve; and one which accompanies the vertebral artery along the vertebral canal, forming the vertebral plexus. This plexus sends filaments to all the branches given off by the artery, and communicates in the cranium with the filaments of the carotid plexus accompanying the branches of the internal carotid artery. The internal branch is the inferior cardiac nerve, nervus cardiacus minor. Cardiac Nerves.*—The superior cardiac nerve (nervus superficia- lis cordis) arises from the lower part of the superior cervical ganglion; it then descends the neck behind the common carotid artery and pa- rallel with the trachea, crosses the inferior thyroid artery, and running by the side of the recurrent laryngeal nerve for a short distance, passes behind the arteria innominata to the concavity of the arch of the aorta, wrhere it joins the cardiac ganglion. In its course it receives branches from the pneumogastric nerve, and sends filaments to the thyroid gland and trachea. The Middle cardiac nerve (nervus cardiacus magnus) proceeds from the middle cardiac ganglion, or, in its absence, from the cord of communication between the superior and inferior. It is the largest of the three nerves, and lies nearly parallel with the recurrent laryn- geal. At the root of the neck it divides into several branches, which pass some before and some behind the subclavian artery; it commu- nicates with the superior and inferior cardiac, and with the pneumo- gastric and recurrent nerves, and descends to the bifurcation of the trachea, to the great cardiac plexus. The Inferior cardiac nerve (nervus cardiacus minor) arises from the inferior cervical ganglion, communicates freely with the recurrent » There is no constancy with regard to the origin and course of these nerves ; there- fore the student must not be disappointed in finding the description in discord with his dissection. 468 CARDIAC NERVES. Fig. 189.* laryngeal and middle cardiac nerves, and descends to the front of the bifurcation of the trachea, to join the great car- diac plexus. The Cardiac ganglion is a ganglionic enlargement of va- riable size, situated beneath the arch of the aorta, to the right side of the ligament of the ductus arteriosus. It re- ceives the superior cardiac nerves of opposite sides of the neck and a branch from the pneumogastric, and gives off numerous branches to the car- diac plexuses. The Great cardiac plexus is situated upon the bifurcation of the trachea, above the right pulmonary artery, and behind the arch of the aorta. It is formed by the convergence of the middle and inferior cardiac neves, and by branches from the pneumogastric and deseen- dens noni nerve, and first tho- racic ganglion. The Anterior cardiac plexus is situated in front of the as- cending aorta, near its origin. It is formed by the commu- nications of filaments that pro- ceed from three different sources, namely, from the su- perior cardiac nerves, cross- ing the arch of the aorta; from the cardiac ganglion be- neath the arch ; and from the great cardiac plexus, passing * A view of the great sympathetic nerve. 36. The cavity of the cranium. 34. The globe of the eye. 33. The septum of the nose. 32. The incisor teeth. 31. The submaxillary gland. 30. The larynx 29. The heart. 28. The left lung. *. The cceliac axis. 27. The ascending vena cava. 26. The kidney. 25. The crista of the ilium. 23. The bladder. 22. The rectum. 24. The pubes. 1. Plexus on the carotid artery in the carotid foramen. 2, Sixth nerve, (motor externus). 3. 1st of the fifth or ophthalmic nerve. 4. Branch on the septum narium, connecting Meckel's ganglion with Cloquet's in the incisive foramen. 5. Immediately above the figure is the recurrent branch or Vidian nerve, dividing into the carotid and petrosal branches. 6. Posterior palatine branches. 7. Lingual nerve joined by the chorda tympani. 8. The portio dura of the seventh pair or facial nerve. 9. The superior cervical ganglion. 10. The middle cervical ganglion. 11. The inferior cervical ganglion. 12. The roots of the great splanchnic nerve, arising from the dorsal THORACIC GANGLIA. 469 between the ascending aorta and the right auricle. The anterior cardiac plexus supplies the anterior aspect of the heart, distributing numerous filaments with the left coronary artery, which form the anterior coronary plexus. The Posterior cardiac plexus is formed by numerous branches from the great cardiac plexus, and is situated upon the posterior part of the ascending aorta, near its origin. It divides into two sets of branches: one set accompanying the right coronary artery in the auriculo-ventricular sulcus; the other set joining the artery on the posterior aspect of the heart. They both together constitute the pos- terior coronary plexus. The great cardiac plexus likewise gives branches to the auricles of the heart, and others to assist in forming the anterior and posterior pulmonary plexuses. THORACIC GANGLIA. The Thoracic ganglia are twelve in number on each side. They are flattened and triangular, or irregular in form, and present the pe- culiar gray colour and pearly lustre of the other sympathetic gan- glia ; they rest upon the heads of the ribs, and are covered in by the pleura costalis. The two first ganglia and the last are usually the largest. Their branches are superior, inferior, external, and internal. The superior and inferior are prolongations of the substance of the ganglia rather than branches ; the former to communicate with the ganglion above, the latter with that below. The external branches, two or three in number, communicate with both roots of each of the spinal nerves. The internal branches of the five upper ganglia are pulmonary to join the pulmonary plexuses; asophageal to the oesophageal plexus and aortic to the thoracic aorta and its branches ; the first thoracic ganglion moreover sends branches to the cardiac plexuses. The branches of the lower ganglia are aortic, and several large cords which unite to form the two splanchnic nerves. The Great splanchnic nerve arises from the sixth dorsal ganglion, and receives branches from the seventh, eighth, ninth, and tenth, which augment it to a nerve of considerable size. It descends in front of the vertebral column, within the posterior mediastinum, pierces the diaphragm immediately to the outer side of each crus, and terminates in the semilunar ganglion. The Lesser splanchnic nerve (renal) is formed by filaments from the tenth, eleventh, and sometimes from the twelfth dorsal ganglion It pierces the diaphragm, and descends to join the renal plexus. The Semilunar ganglion is a large, irregular, gangliform body, pierced by numerous openings, and appearing like the aggregation of a number of smaller ganglia, having spaces between them. It is situ- ated by the side of the coeliac axis, and communicates with the gan- ganglia. 13. The lesser splanchnic nerve. 14. The renal plexus. 15. The solar plexus. 16 The mesenteric plexus. 17. The lumbar ganglia. 18. The sacral ganglia. 19. The vesical plexus. 20. The rectal plexus. 21. The lumbar plexus, (cerebro-spinal.) 40 470 LUMBAR GANGLIA. glion of the opposite side, both above and below that trunk, so as to form a gangliform circle, from which branches pass off in all direc- tions, like rays from a centre. Hence the entire circle has been named the solar plexus. The Solar plexus receives the great splanchnic nerves; part of the lesser splanchnic nerves; the termination of the right pneumogastric nerve; some branches from the right phrenic nerve; and sometimes one or two filaments from the left. It sends numerous filaments, which accompany, under the name of plexuses, all the branches given off by the abdominal aorta. Thus, we have derived from the solar plexus the— Phrenic plexuses, Renal plexuses, Gastric plexus, Superior mesenteric plexus, Hepatic plexus, Spermatic plexuses, Splenic plexus, Inferior mesenteric plexus. Supra-renal plexuses, The Renal plexus is formed chiefly by the lesser splanchnic nerve, but receives many filaments from the solar plexus. The Spermatic plexus is formed principally by the renal plexus. The Inferior mesenteric plexus receives filaments from the aortic plexus. LUMBAR. GANGLIA. The Lumbar ganglia are four in number on each side, of the pecu- liar pearly gray colour, fusiform, and situated upon the anterior part of the bodies of the lumbar vertebrae. The superior and inferior branches of the lumbar ganglia are branches of communication with the ganglion above and below, as in the dorsal region. The external branches, two or three in number, communicate with the lumbar nerves. The internal branches consist of two sets; of which the upper pass inwards in front of the abdominal aorta, and form around that trunk a plexiform interlacement, which constitutes the lumbar aortic plexus; the lower branches cross the common iliac arteries, and unite over the promontory of the sacrum, to form the hypogastric plexus. The Lumbar aortic plexus is formed by branches from the lumbar ganglia, and receives filaments from the solar and superior mesenteric plexuses. It sends filaments to the inferior mesenteric plexus, and terminates in the hypogastric plexus. The Hypogastric plexus is formed by the termination of the aortic plexus, and by the union of branches from the lower lumbar ganglia. It is situated over the promontory of the sacrum, between the two common iliac arteries, and bifurcates inferiorly into two lateral por- tions, which communicate with branches from the fourth and fifth sacral nerves. It distributes branches to all the viscera of the pelvis, and sends filaments which accompany the branches of the internal iliac artery. NOSE AND NASAL FOSSAE. 471 SACRAL GANGLIA. The Sacral ganglia are four or five in number on each side. They are situated upon the sacrum, close to the anterior sacral foramina, and resemble the lumbar ganglia in form and mode of connexion, although much smaller in size. The superior and inferior branches communicate with the ganglia above and below. The external branches communicate with the sacral nerves. The internal branches communicate very freely with the lateral divisions of the hypogastric plexus, and are distributed to the pelvic viscera. The last pair of sacral ganglia give off branches which join a small ganglion, situated on the first bone of the coccyx, called the ganglion impar, or azygos. This ganglion resembles in its position and function the ganglion of Ribes, serving to connect the inferior extremity of the sympathetic system, as does the former ganglion its upper extremity. It gives off a few small branches to the coccyx and rectum. CHAPTER IX. ORGANS OF SENSE. The organs of sense, the instruments by which the animal frame is brought into relation with surrounding nature, are five in number. Four of these organs are situated within the head, viz., the apparatus of smell, sight, hearing, and taste, and the remaining organ, of touch, is resident in the skin, and distributed over the surface of the body. THE NOSE AND NASAL FOSSi). The organ of smell consists essentially of two parts: one external, the nose; the other internal, the nasal fossa. The nose is the triangular pyramid projecting from the centre of the face, immediately above the upper lip. Superiorly, it is connected with the forehead, by means of a narrow bridge; inferiorly, it presents two openings, the nostrils, which overhang the mouth, and are so con- structed that the odour of all substances must be received by the nose before they can be introduced within the lips. The septum between the openings of the nostrils is called the columna. Their entrance is guarded by a number of stiff hairs (vibrissa) which project across the openings, and act as a filter in preventing the introduction of foreign substances, such as dust or insects, with the current of air intended for respiration. The anatomical elements of which the nose is composed are,—1. Integument. 2. Muscles. 3. Bones. 4. Fibro-cartilages. 5. Mucous membrane. 6. Vessels and nerves. 1. The Integument forming the tip (lobulus) and wings (ala) of the 472 STRUCTURE OF THE NOSE. nose is extremely thick and dense, so as to be with difficulty separated from the fibro-cartilage. It is furnished with an abundance of seba- ceous follicles, which by their oily secretion, protect the extremity of the nose in excessive alternations of temperature. The sebaceous mat- ter of these follicles becomes of a dark colour upon the surface, from the attraction of the carbonaceous matter floating in the atmosphere; hence the spotted appearance which the tip of the nose presents in large cities. When the integument is firmly compressed, the inspis- sated sebaceous secretion is squeezed out from the follicles, and, taking the cylindrical form of their excretory ducts, has the appearance of small white maggots with black heads. 2. The Muscles are brought into view by reflecting the integument: they are the pyramidalis nasi, compressor nasi, dilatator naris, levator labii superioris alaeque nasi, and depressor labii superioris alaeque nasi. They have been already described with the muscles of the face. 3. The Bones of the nose are the nasal, and nasal processes of the superior maxillary. 4. The Fibro-cartilages give form and stability to the outwork of the nose, providing at the same time, by their elasticity, against injuries. They are five in number, namely, the— Fibro-cartilage of the septum, Two lateral fibro-cartilages, Two alar fibro-cartilages. The Fibro-cartilage of the septum, somewhat triangular in form, divides the nose into its two nostrils. It is con- nected above with the nasal bones and lateral fibro-cartilages; behind, with the ethmoidal sep- tum and vomer; and below, with the palate pro- cesses of the superior maxillary bones. The alar fibro-cartilages and columna move freely upon the fibro-cartilage of the septum, being but loosely conpected with it by perichondrium. The Lateral fibro-cartilages are also triangular: they are connected, in front with the fibro-carti- lage of the septum ; above with the nasal bones; behind with the nasal processes of the superior maxillary bones; and below with the alar fibro- id cartilages. Alar fibro-cartilages.—Each of these cartilages is curved in such a manner as to correspond with the opening of the nostril, to which it forms a kind of rim. The inner portion is loosely connected with the same part of the op- posite cartilage, so as to form the columna. It is expanded and thickened at the point of the nose to constitute the lobe; and upon the side forms a curve corresponding with the form of the ala. This * The fibro-cartilages of the nose. 1. One of the nasal bones. 2. The fibro-cartilage of the septum. 3. The lateral fibro-cartilage. 4. The alar fibro-cartilage. 5. The central portions of the alar fibro-cartilages which constitute the columna. 6. The appendix of the alar fibro-cartilage. 7. The nostrils. NASAL FOSSiE. 473 curve is prolonged downwards and forwards in the direction of the posterior border of the ala by three or four small fibro-cartilaginous plates, which are appendages to the alar fibro-cartilage. The whole of these fibro-cartilages are connected with each other, and to the bones, by perichondrium, which, from its membranous structure, permits of the freedom of motion existing between them. 5. The Mucous membrane, lining the interior of the nose, is conti- nuous with the skin externally, and with the pituitary membrane of the nasal fossae within. Around the entrance of the nostrils it is pro- vided with numerous vibrissa. 6. Vessels and Nerves.—The arteries of the nose are the lateralis nasi from the facial, and the nasalis septi from the superior coronary. Its Nerves are the facial, infra-orbital, and nasal branch of the ophthalmic. NA SAL FOSSAE. To obtain a good view of the nasal fossa, the face must be divided through the nose by a vertical incision, a little to one side of the middle line. The Nasal fossa are two irregular, compressed cavities, extending backwards from the nose to the pharynx. They are bounded supe- riorly by the lateral cartilage and by the nasal, sphenoid and ethmoid bones ; inferiorly by the hard palate; and in the middle line they are separated from each other by a bony and fibro-cartilaginous septum. A plan of the boundaries of the nasal fossae will be found at page 97. Upon the outer wall of each fossa, in the dried skull, are three projecting processes, termed spongy bones. The two superior be- long to the ethmoid, the inferior is a separate bone. In the fresh fossae these are covered with mucous membrane, and serve to in- crease its surface by their prominence and by their convoluted form. The space intervening between the superior and middle spongy bone is the superior meatus ; the space between the middle and inferior the middle meatus; and that between the inferior and the floor of the fossa the inferior meatus. These meatuses are passages which extend from before backwards, and it is in rushing through and amongst these that the atmosphere deposits its odorant particles upon the mucous membrane. There are several openings into the nasal fossae: thus, in the superior meatus are the openings of the sphenoidal and posterior ethmoidal cells; in the middle the anterior ethmoid cells, the frontal sinuses, and the an- trum maxillare; and, in the inferior meatus, the termination of the nasal duct. In the dried bone there are two additional openings, the spheno-palatine and the anterior palatine foramen; the former being situated in the superior, and the latter in the inferior meatus. The Mucous membrane of the nasal fossae is called pituitary, or Schneiderian* The former name being derived from its secretion, the latter from Schneider, who was the first to show that the secre- * Conrad Victor Schneider, professor of Medicine at Wittenberg. His work, entitled De Catarrhis, &c, was published in 1661. 40* 474 EYE—SCLEROTIC COAT. tion of the nose proceeded from the mucous membrane, and not from the brain, as was formerly imagined. It is continuous with the general gastro-pulmonary mucous membrane, and may be traced through the openings in the meatuses, into the sphenoidal and eth- moidal cells; into the frontal sinuses; into the antrum maxillare; through the nasal duct to the surface of the eye, where it is continu- ous with the conjunctiva; along the Eustachian tubes into the tym- panum and mastoid cells, to which it forms the lining membrane; and through the posterior nares into the pharynx and mouth, and thence through the lungs and alimentary canal. The surface of this membrane is furnished with a columnar epithe- lium supporting innumerable vibratile cilia. Vessels and Nerves.—The Arteries of the nasal fossae are the ante- terior and posterior ethmoidal, from the ophthalmic artery; and the spheno-palatine and pterygo-palatine from the internal maxillary. The Nerves are, the olfactory, the spheno-palatine branches from Meckel's ganglion, and the nasal branch of the ophthalmic. The ultimate filaments of the olfactory nerve terminate in minute papillae. THE EYE, WITH ITS APPENDAGES. The form of the eyeball is that of a sphere, of about one inch in diameter, having the segment of a smaller sphere ingrafted upon its anterior surface, which increases its antero-posterior diameter. The axes of the two eyeballs are parallel with each other, but do not cor- respond with the axes of the orbits, which are directed outwards. The optic nerves follow the direction of the orbits, and therefore enter the eyeballs to their nasal side. The Globe of the Eye is composed of tunics and of refracting media called humours. The tunics are three in number, the 1. Sclerotic and Cornea, 2. Choroid, Iris, and Ciliary processes, 3. Retina and Zonula ciliaris. The humours are also three— Aqueous, Crystalline (lens), Vitreous. First Tunic.—The Sclerotic and Cornea form the external tunic of the eyeball, and give it its peculiar form. Four-fifths of the globe are invested by the sclerotic, the remaining fifth by the cornea. The Sclerotic (tfxX^te, hard) is a dense fibrous membrane, thicker behind than in front. It is continuous, posteriorly, with the sheath of the optic nerve, which is derived from the dura mater, and is pierced by that nerve as well as by the ciliary nerves and arteries. Anteriorly it presents a bevelled edge which receives the cornea in the same way that a watch-glass is received by the groove in its case. Its anterior surface is covered in by a thin layer, the tunica albuginea, derived from the expansion of the tendons of the four recti muscles. By its posterior surface it gives attachment to the two oblique mus- STRUCTURE OF THE CORNEA. 475 cles. The tunica albuginea is covered, for a part of its extent, by the mucous membrane of the front of the eye, the conjunctiva; and, by reason of the brilliancy of its whiteness, gives occasion to the com- mon expression, "the white of the eye." At the entrance of the optic nerve the sclerotic forms a thin cribriform lamella (lamina cribrosa), which is pierced by a number of minute openings for the passage of the nervous filaments. One of these openings, larger than the rest, and situated in the centre of the lamella, is the porus opticus, through which the arteria centralis retinae enters the eyeball. The Cornea (corneus, horny) is the transparent projecting layer that constitutes the ante- rior fifth of the globe of Fig.i9i* the eye. In its form it is circular, concavo-con- vex, and resembles a watch-glass. It is re- ceived by its edge, which is sharp and thin, a within the bevelled bor- der of the sclerotic, to which it is very firmly attached, and it is some- what thicker than the anterior portion of that tunic. When examined from the exterior, its vertical diameter is seen to be about one sixteenth shorter than the transverse, in con- sequence of the overlapping above and below, of the margin of the sclerotica; on the interior, however, its outline is perfectly circular. The cornea is composed of four layers, namely, of the conjunc- tiva ; of the cornea proper, which consists of several thin lamella connected together by an extremely fine areolar tissue; of the cor- nea elastica, a " fine, elastic, and exquisitely transparent membrane, exactly applied to the inner surface of the cornea proper;" and of the lining membrane of the anterior chamber of the eyeball. The cornea elastica is remarkable for its perfect transparency, even when submitted for many days to the action of water or alcohol; while the cornea proper is rendered opaque by the same immersion. * A longitudinal section of the globe of the eye. 1. The sclerotic, thicker behind than in front. 2. The cornea, received within the anterior margin of the sclerotic, and con- nected with it by means of a bevelled edge. 3. The choroid, connected anteriorly with (4) the ciliary ligament, and (5) the ciliary processes. 6. The iris. 7. The pupil. 8. The third layer of the eye, the retina, terminating anteriorly by an abrupt border at the com- mencement of the ciliary processes. 9. The canal of Petit, which encircles the lens (12); the thin layer in front of this canal is the zonula ciliaris, a prolongation of the vascular layer of the retina to the lens. 10. The anterior chamber of the eye, containing the aqueous humour: the lining membrane by which the humour is secreted is represented in the diagram. 11. The posterior chamber. 12. The lens, more convex behind than be- fore, and enclosed in its proper capsule. 13. The vitreous humour enclosed in the hyaloid membrane, and in cells formed in its interior by that membrane. 14. A tubular sheath of the hyaloid membrane, which serves for the passage of the artery of the capsule of the lens. 15. The neurilemma of the optic nerve. 16. The arteria centralis retinae, embedded in the centre of the optic nerve. 476 STRUCTURE OF THE CORNEA. To expose this membrane, Dr. Jacob suggests that the eye should be placed in water for six or eight days, and then that all the opaque cornea should be removed layer after layer. Another character of the cornea elastica is its great elasticity, which causes it to roll up when divided or torn, in the same manner as the capsule of the lens. The use of this layer, according to Dr. Jacob, is to " preserve the requisite permanent correct curvature of the flaccid cornea proper." The opacity of the cornea, produced by pressure on the globe, results from the infiltration of fluid into the areolar tissue connect- ing its layers. This appearance cannot be produced in a sound living eye. Dissection.—The sclerotic and cornea are now to be dissected away from the second tunic; this, with care, may be easily per- formed, the only connexions subsisting between them being at the circumference of the iris, the entrance of the optic nerve, and the perforation of the ciliary nerves and arteries. Pinch up a fold of the sclerotic near its anterior circumference, and make a small opening into it, then raise the edge of the tunic, and with a pair of fine scissors, having a probe point, divide the entire circumference of the sclerotic, and cut it away bit by bit. Then separate it from its attachment around the circumference of the iris by a gentle pres- sure with the edge of the knife. The dissection of the eye must be conducted under water. In the course of this dissection the ciliary nerves and long ciliary arteries will be seen passing forwards between the sclerotic and choroid, to be distributed to the iris. Second Tunic—The second tunic of the eyeball is formed by the choroid, ciliary ligament and iris, the ciliary processes being an appendage developed from its inner surface. The Choroid* is a vascular membrane of a rich chocolate-brown colour upon its external surface, and of a deep black colour within. It is connected to the sclerotic, externally, by an extremely fine areolar tissue, and by nerves and vessels. Internally it is in simple contact with the third tunic of the eye, the retina. It is pierced posteriorly for the passage of the optic nerve, and is connected ante- riorly with the iris, ciliary processes, and with the line of junction of the cornea and sclerotic, by a dense white structure, the ciliary ligament, which surrounds the circumference of the iris like a ring. The choroid membrana is composed of three layers:—An external or venous layer, wmich consists principally of veins arranged in a peculiar manner: hence they have been named vena voriicosa. The * The word choroid has been very much abused in anatomical language ; it was origi- nally applied to the membrane of the foetus called chorion from the Greek word ^6§*oi', domicilium, that membrane being, as it were, the abode or receptacle of the foetus. Xo^iov comes from ^a-gsa, to take or receive. Now it so happens that the chorion in the ovum is a vascular membrane of peculiar structure. Hence the term choroid, ^og/ov i'tS'os, like the chorion, has been used indiscriminately to signify vascular structures, as in the choroid membrane of the eye, the choroid plexus, &c, and we find Cruveilhier in his admirable work on Anatomy, vol. iii. p. 463, saying in a note, " Choro'ide est synonyme de vasculeuse." IRIS—CILIARY PROCESSES. 477 marking upon the surface of the membrane produced by these veins, resembles so many centres, to which a number of curved lines con- verge. It is this layer which is connected with the ciliary ligament. The middle or arterial layer (tunica Ruyschiana*) is formed princi- pally by the ramifications of minute arteries. It is reflected inwards at its junction with the ciliary ligament, so as to form the ciliary pro- cesses. The internal layer is a delicate membrane (membrana pig- menti) composed of several laminae of nucleated hexagonal cells, which contain the granules of pigmentum nigrum, and are arranged so as to resemble a tessellated pavement. In animals the pigmentum nigrum, upon the posterior wall of the eyeball, is replaced by a layer of considerable extent, and of metallic brilliancy, called the tapetum. The Ciliary ligament, or circle, is the bond of union between the external and middle tunics of the eyeball, and serves to connect the cornea and sclerotic, at their line of junction, with the iris and exter- nal layer of the choroid. It is also the point to which the ciliary nerves and vessels proceed previously to their distribution, and it re- ceives the anterior ciliary arteries through the anterior margin of the sclerotic. A minute vascular canal is situated within the ciliary liga- ment, called the ciliary canal, or the canal of Fontana,f from its dis- coverer. The Iris (iris, a rainbow,) is so named from its variety of colour in different individuals: it forms a septum between the anterior and posterior chambers of the eye, and is pierced somewhat to the nasal side of its centre by a circular opening, which is called the pupil. By its periphery it is connected with the ciliary ligament, and by its inner circumference forms the margin of the pupil; its anterior sur- face looks towards the cornea, and the posterior towards the ciliary processes and lens. The iris is composed of two layers, an anterior or muscular, con- sisting of radiating fibres which converge from the circumference towards the centre, and have the power of dilating the pupil; and circular, which surround the pupil like a sphincter, and by their action produce contraction of its area. The posterior layer is of a deep purple tint, and is thence named uvea, from its resemblance in colour to a ripe grape. The Ciliary processes may be seen in two ways, either by remov- ing the iris from its attachment to the ciliary ligament, when a front view of the processes will be obtained, or by making a transverse section through the globe of the eye, when they may be examined from behind, as in fig. 192. The ciliary processes consist of a number of triangular folds, formed apparently by the plaiting of the middle and internal layer of * Ruysch was born at the Hague in 1638, and was appointed professor of Anatomy at Amsterdam in 1665. His whole life was employed in making injected preparations, for which he is justly celebrated, and he died at the advanced age of ninety-three years. He came to the conclusion that the body was entirely made up of vessels. t Felix Fontana, an anatomist of Tuscany. His " Description of a New Canal in the Eye," was published in 1778, in a Letter to the Professor of Anatomy in Upsal. 478 RETINA—STRUCTURE. the choroid. According to Zinn, they are about sixty in number, and may be divided into large and small, the latter being situated in the spaces between the former. Their pe- Fis-192-* riphery is connected with the ciliary ligament, and is continuous with the middle and internal layer of the cho- roid. The central border is free, and rests against the circumference of the lens. The anterior surface corresponds with the uvea; the posterior receives the folds of the zonula ciliaris between its processes, and thus establishes a con- nexion between the choroid and the third tunic of the eye. The ciliary pro- cesses are covered with a thick layer of pigmentum nigrum, which is more abundant upon them, and upon the an- terior part of the choroid, than upon the posterior. When the pig- ment is washed off, the processes are of a whitish colour. Third Tunic—The third tunic of the eye is the retina, which is prolonged forwards to the lens by the zonula ciliaris. Dissection.—If after the preceding dissection the choroid membrane be carefully raised and removed, the eye being kept under water, the retina may be seen very distinctly. The Retina is composed of three layers:— External, or Jacob's membrane, Middle, Nervous membrane, Internal, Vascular membrane. Jacob's membrane is extremely thin, and is seen as a flocculent film when the eye is suspended in water. Examined by the microscope, it is found to be composed of cells having a tessellated arrangement. Dr. Jacob considers it to be a serous membrane. The Nervous membrane is the expansion of the optic nerve, and forms a thin semi-transparent bluish white layer, which envelopes the vitreous humour, and extends forwards to the commencement of the ciliary processes, where it terminates by an abrupt scalloped margin. According to Treviranus, this layer is composed of cylindrical fibres, which proceed from the optic nerve and bend abruptly inwards, near their termination, to form the internal papillary layer, which lies in contact with the hyaloid membrane ; each fibre constituting by its extremity a distinct papilla. The Vascular membrane consists of the ramifications of a minute artery, the arteria centralis retinae, and its accompanying vein; the artery pierces the optic nerve, and enters the globe of the eye through * The anterior segment of a transverse section of the globe of the eye, seen from within. 1. The divided edge of the three tunics; sclerotic, choroid (the dark layer), and retina. 2. The pupil. 3. The iris, the surface presented to view in this section being the uvea. 4. The ciliary processes. 5. The scalloped anterior border of the retina. ZONULA CILIARIS. 479 Fig. 1934 the porus opticus, in the centre of the lamina cribrosa. This artery may be seen very distinctly by making a transverse section of the eyeball. Its branches are continuous anteriorly with the zonula cili- aris. The vascular layer forms distinct sheaths for the nervous pa- pillae, which constitute the inner surface of the retina. In the centre of the posterior part of the globe of the eye the retina presents a circular spot, which is called the foramen of Soemmering ;* it is surrounded by a yellow halo, the limbus luteus, and is frequently obscured by an elliptical fold of the retina, which, from its constancy of appearance, has been regarded as a normal condition of the mem- brane. The term foramen is misapplied to this spot, for the vascular layer and the membrana Jacobi are continued across it; the nervous substance alone appearing to be deficient. It exists only in animals having the axis of the eyeballs parallel with each other, as man, quadrumana, and some saurian reptiles, and is said to give passage to a small lymphatic vessel. The Zonula ciliaris (zonula of Zinn)f is a thin vascular layer, which connects the anterior margin of the retina with the anterior surface of the lens near its circumference. It pre- sents upon its surface a number of small folds corresponding with the ciliary pro- cesses, between which they are received. These processes are arranged in the, form of rays around the lens, and the spaces between them are stained by the' pigmentum nigrum of the ciliary pro- cesses. They derive their vessels from the vascular layer of the retina. The under surface of the zonula is in contact with the hyaloid membrane, and around the lens forms the anterior fluted wall of the canal of Petit. The connexion between these folds and the ciliary processes may be very easily demonstrated by dividing an eye transversely into two portions, then raising the anterior half, and allowing the vitreous humour to separate from its attachment by its own weight. The folds of the zonula will then be seen to be drawn out from between the folds of the ciliary processes. * Samuel Thomas Soemmering is celebrated for the beautiful and accurate plates which accompany his works. The account " De Foramine Centrali Retinse Humana?, Limbo Luteo cincto," was published in 1779, in the Commentationes Soc. Reg. Sclent. Gottingensis. . . . t John Gottfried Zinn, professor of Anatomy in Gottingen; his "Descriptio Anatomica Oculi Humani," was published in 1755 ; with excellent plates. It was republished by Wrisberg in 1780. . /.,,,», * X The posterior segment of a transverse section of the globe of the eye, seen from within. 1. The divided edge of the three tunics. The membrane covering the whole in- ternal surface is the retina. 2. The entrance of the optic nerve with the arteria centralis retinee piercing its centre. 3, 3. The ramifications of the arteria centralis. 4. The fora- men of Soemmering, in the centre of the axis of the eye; the shade from the sides of the retina obscures the limbus luteus which surrounds it. 5. A fold of the retina, which generally obscures the foramen of Soemmering after the eye has been opened. C�8B 480 AQUEOUS HUMOUR—CRYSTALLINE HUMOUR. Humours.—The Aqueous humour is situated in the anterior and posterior chambers of the eye ; it is a weakly albuminous fluid, having an alkaline reaction, and a specific gravity very little greater than distilled water. According to Petit, it scarcely exceeds four or five grains in weight. The anterior chamber is the space intervening between the cornea in front, and the iris and pupil behind. The posterior chamber is the narrow space, less than half an inch in depth,* bounded by the poste- rior surface of the iris and pupil in front, and by the ciliary processes, zonula ciliaris, and lens behind. The two chambers are lined by a thin layer, the secreting membrane of the aqueous humour. The Vitreous humour forms the principal bulk of the globe of the eye. It is an albuminous fluid resembling the aqueous humour, en- closed in a delicate membrane, the hyaloid, which sends processes into its interior, forming areolae in which the humour is retained. A small artery may sometimes be traced through the centre of the vitreous humour to the capsule of the lens; it is surrounded by a tubular sheath of the hyaloid membrane. This vessel is easily injected in the foetus. The Crystalline humour or lens is situated immediately behind the pupil, and is surrounded by the ciliary processes which slightly over- lap its margin. It is more convex on the posterior than on the anterior surface, and is embedded in the anterior part of the vitreous humour, from which it is separated by the hyaloid membrane. It is invested by a peculiarly transparent and elastic membrane, the cap- sule of the lens, which contains a small quantity of fluid called liquor Morgagni,-\ and is retained in its place by the attachment of the zonula ciliaris. Dr. Jacob is of opinion that the lens is connected to its capsule by means of areolar tissue, and that the liquor Morgagni is the result of a cadaveric change. The lens consists of concentric layers, of which the external are soft, the next firmer, and the central form a hardened nucleus. These layers are best demonstrated by boiling, or by immersion in alcohol, when they separate easily from each other. Another division of the lens takes place at the same time: it splits into three triangular segments, which have the sharp edge directed towards the centre, and the base towards the circumference. The concentric lamellae are composed of minute parallel fibres, which are united with each other by means of scalloped borders; the convexity on the one border fit- ting accurately the concave scallop upon the other. Immediately around the circumference of the lens is a triangular canal, the canal of Petit,% about a line and a half in breadth. It is * Winslow and Lieutaud thought the iris to be in contact with the lens; it frequently adheres to the capsule of the latter in iritis. The depth of the posterior chamber is greater in old than in young persons. t John Baptist Morgagni was born in 1682. He was appointed Professor of Medicine in Bologna, and published the first part of his "Adversaria Anatomica," in 1706. He died in 1771. X John Louis Petit, a celebrated French surgeon: he published several surgical and anatomical Essays, in the early part of the 18th century. He died in 1750. v J APPENDAGES OF THE EYE. 4SI bounded in front by the flutings of the zonula ciliaris; behind by the hyaloid membrane; and within by the border of the lens. The Vessels of the globe of the eye are the long, and short, and anterior ciliary arteries, and the arteria centralis retinae. The long ciliary arteries, two in number, pierce the posterior part of the scle- rotic, and pass forward on each side, between that membrane and th*e choroid, to the ciliary ligament, where they divide into two branches, which are distributed to the iris. The short ciliary arteries pierce the posterior part of the sclerotic coat, and are distributed to the middle layer of the choroid membrane. The anterior ciliary are branches of the muscular arteries. They enter the eye through the anterior part of the sclerotic, and are distributed to the iris. It is the increased number of these latter arteries in iritis that gives rise to the peculiar red zone around the circumference of the cornea. The arteria centralis retina enters the optic nerve at about half an inch from the globe of the eye, and passing through the porus opticus is distributed upon the inner surface of the retina, forming its vascular layer; one branch pierces the centre of the vitreous humour, and supplies the capsule of the lens. The Nerves of the eyeball are the optic, two ciliary nerves from the nasal branch of the ophthalmic, and the ciliary nerves from the ciliary ganglion. Observations.—The sclerotic is a tunic of protection, and the cor- nea a medium for the transmission of light. The choroid supports the vessels destined for the nutrition of the eye, and by its pig- mentum nigrum absorbs all loose and scattered rays that might con- fuse the image impressed upon the retina. The iris, by means of its powers of expansion and contraction, regulates the quantity of light admitted through the pupil. If the iris be thin, and the rays of light pass through its substance, they are immediately absorbed by the uvea; and if that layer be insufficient, they are taken up by the black pigment of the ciliary processes. In Albinoes, where there is an absence of pigmentum nigrum, the rays of light traverse the iris and even the sclerotic, and so^overwhelm the eye with light, that sight is destroyed, except in the dimness of evening or at night. In the manufacture of optical instruments care is taken to colour their interior black with the same object, the absorption of scattered rays. The transparent lamellated cornea and the humours of the eye have for their office the refraction of the rays in such proportion as to direct the image in the most favourable manner upon the retina. Where the refracting medium is too great, as in over-convexity of the cornea and lens, the image falls short of the retina (myopia, near- sightedness) ; and where it is too little, the image is thrown beyond the nervous membrane (presbyopia, far-sightedness). These condi- tions are rectified by the use of spectacles, which provide a differ- ently refracting medium externally to the eye, and thereby correct the transmission of light. APPENDAGES OF THE EYE. The Appendages of the eye (tutamina oculi) are the eyebrows, eye- 482 EYEBROWS—EYELIDS. lids, eyelashes, conjunctiva, caruncula lachrymalis, and the lachrymal apparatus. The Eyebrows (supercilia) are two projecting arches of integu- ment covered with short thick hairs, which form the upper boundary of the orbits. They are connected beneath with the orbiculares, r3ccipito-frontales, and corrugatores superciliorum muscles; their use is to shade the eyes from a too vivid light, or protect them from par- ticles of dust and moisture floating over the forehead. The Eyelids (palpebra) are two valvular layers placed in front of the eye, serving to defend it from injury by their closure. When drawn open they leave between them an elliptical space, the angles of which are called canthi. The outer canthus is formed by the meeting of the two lids at an acute angle. The inner canthus is prolonged for a short distance inwards towards the nose, and a tri- angular space is left between the lids in this situation, which is called the lacus lachrymalis. At the commencement of the lacus lachry- malis upon each of the two lids is a small angular projection, the lachrymal papilla or tubercle; and at the apex of each papilla a small orifice (punctum lachrymale), the commencement of the lachrymal canal. The eyelids have, entering into their structure, integument, orbicu- laris muscle, tarsal cartilages, Meibomian glands, and conjunctiva. The tegumentary areolar tissue of the eyelids is remarkable for its looseness and for the entire absence of adipose substance ; it is parti- cularly liable to serous infiltration. The fibres of the orbicularis muscle covering the eyelids, are extremely thin and pale. The Tarsal cartilages are two thin lamellae of fibro-cartilage about an inch in length, which give form and support to the eyelids. The superior is of a semilunar form, about one-third of an inch in breadth at its middle, and tapering to each extremity. Its lower border is broad and flat, its upper is thin, and gives attachment to the levator palpebrae and to the fibrous membrane of the lids. The Inferior fibro-cartilage is an elliptical band, narrower than the superior, and situated in the substance of the lower lid. Its upper border is flat, and corresponds with the flat edge of the upper carti- lage. The lower is held in its place by the fibrous membrane. At the inner canthus the tarsal cartilages terminate at the commence- ment of the lacus lachrymalis, and are attached to the margin of the orbit by the tendo oculi. At their outer extremity they terminate at a short distance from the angle of the canthus, and are retained in their position by means of a decussation of the fibrous structure of the broad tarsal ligament, called the external palpebral ligament. The Fibrous membrane of the lids is firmly attached to the perios- teum, around the margin of the orbit, by its circumference, and to the tarsal cartilages by its central margin. It is thick and dense on the outer half of the orbit, but becomes thin to its inner side. Its use is to retain the tarsal cartilages in their place, and give support to the lids ; hence it has been named the broad tarsal ligament. The Meibomian glands* are embedded in the internal surface of * Henry Meibomius, " de Vasis Palpebrarum Novis," 1666. CONJUNCTIVA. 483 the cartilages, and are very distinctly seen on examining the inner aspect of the lids. They have the appearance of parallel strings of pearls, about thirty in number in the upper cartilage, and somewhat fewer in the lower; they open by minute foramina upon the edges of the lids. They correspond in length with the breadth of the carti- lage, and are consequently longer in the upper than in the lower lid. Each gland consists of a single lengthened follicle or tube, into which a number of small clustered follicles open; the latter are so numerous as almost to conceal the tube by which the secretion is poured out upon the margin of the lids. Occasionally an arch is formed between two of them, and produces a very graceful appear- ance. The edges of the eyelids are furnished with a triple row of long thick hairs, which curve upwards from the upper lid, and down- wards from the lower, so that they may not interlace with each other in the closure of the eyelids, and prove an impediment to the opening of the eyes. These are the eyelashes (cilia), important organs of defence to the sensitive surface of so delicate an organ as the eye. The Conjunctiva is the mucous membrane of the eye. It covers the whole of its anterior surface, and is then reflected upon the lids so as to form their internal layer. The duplicatures formed between the globe of the eye and the lids are called the superior and inferior palpebral sinuses, of which the former is much deeper than the infe- rior. Where it covers the cornea the conjunctiva is very thin and closely adherent, and no vessels can be traced into it. Upon the sclerotica it is thicker and less adherent, but upon the inner surface of the lids is very closely connected, and is exceedingly vascular. It is continuous with the general gastro-pulmonary mucous mem- brane and sympathizes in its affections, as may be observed in various diseases. From the surface of the eye it may be traced through the lachrymal ducts into the lachrymal gland; along the edges of the lids it is continuous with the mucous lining of the Meibomian glands, and at the inner angle of the eye may be followed through the lachrymal canals into the lachrymal sac, and thence downwards through the nasal duct into the inferior meatus of the nose. The Caruncula lachrymalis is the small reddish body which occu- pies the lacus lachrymalis at the inner canthus of the eye. In health it presents a bright pink tint; in sickness it loses its colour, and be- comes pale. It consists of an assemblage of follicles similar to the Meibomian glands, embedded in a fibro-cartilaginous tissue, and is the source of the whitish secretion which so constantly forms at the inner angle of the eye. It is covered with minute hairs, which are sometimes so long as to be distinctly visible to the naked eye. Immediately to the outer side of the caruncula is a slight duplica- ture of the conjunctiva, called plica semilunaris, which contains a minute plate of cartilage, and is the rudiment of the third lid of ani- mals, the membrana nictitans of birds. Vessels and Nerves. — The palpebrae are supplied internally with arteries from the ophthalmic, and externally from the facial and 484 LACHRYMAL APPARATUS. transverse facial. Their nerves are branches of the fifth and of the facial. LACHRYMAL APPARATUS. The Lachrymal apparatus consists of the lachrymal gland with its excretory ducts; the puncta lachrymalia, and lachrymal canals; the achrymal sac and nasal duct. The Lachrymal gland is situated at the upper and outer angle of the orbit, and consists of two portions, orbital and palpebral. The orbital portion, about three quarters of an inch in length, is flattened and oval in shape, and occupies the lachrymal fossa in the orbital plate of the frontal bone. It is in contact, superiorly, with the peri- osteum, with which it is closely connected by its upper and convex surface; by its inferior or concave surface it is in relation with the globe of the eye, and the superior and external rectus; and by its anterior border with the broad tarsal ligament. By its posterior border it receives its vessels and nerves. The palpebral portion, smaller than the preceding, is situated in the upper eyelid, extending downwards to the superior margin of the tarsal cartilage. It is con- tinuous with the orbital portion above, and is enclosed in an invest- ment of dense fibrous membrane. The secretion of the lachrymal gland is conveyed away by ten or twelve small ducts, which run for a short distance beneath the conjunctiva, and open upon its surface by a series of pores about one-twentieth of an inch apart, situated in a curved line a little above the upper border of the tarsal cartilage. Lachrymal Canals.—The lachrymal canals commence at the mi- nute openings, puncta lachrymalia, seen upon the lachrymal papillae of the lids at the outer extremity of the lacus lachrymalis, and proceed inwards to the lachrymal sac, where they terminate beneath a val- vular semilunar fold of the lining membrane of the sac. The supe- rior duct at first ascends, and then turns suddenly inwards towards the sac, forming an abrupt angle. The inferior duct forms the same kind of angle, by descending at first, and then turning abruptly in- wards. They are dense and elastic in structure, and remain con- stantly open, so that they act like capillary tubes in absorbing the tears from the surface of the eye. The two fasciculi of the tensor tarsi muscle are inserted into these ducts, and serve to draw them inwards. The Lachrymal sac is the upper extremity of the nasal duct, and is scarcely more dilated than the rest of the canal. It is lodged in the groove of the lachrymal bone, and is often distinguished inter- nally from the nasal duct by a semilunar or circular valve. The sac consists of mucous membrane, but is covered in and retained in its place by a fibrous expansion, derived from the tendon of the orbicu- laris, which is inserted into the ridge on the lachrymal bone; it is also covered by the tensor tarsi muscle, which arises from the same ridge, and in its action upon the lachrymal canals may serve to com- press the lachrymal sac. The Nasal duct is a short canal about three quarters of an inch in length, directed downwards, backwards, and a little outwards to the ORGAN OF HEARING. 485 inferior meatus of the nose, where it terminates by an expanded orifice. It is lined by mucous membrane, which is continuous with the conjunctiva above, and with the pituitary membrane of the nose below. Obstruction from inflammation and suppuration of this duct constitutes the disease called fistula lachrymalis. Vessels and Nerves.—The lachrymal gland is supplied with blood by the lachrymal branch of the ophthalmic artery, and with nerves by the lachrymal branch of the ophthalmic and orbital branch of the superior maxillary. THE ORGAN OF HEARING. The apparatus of hearing is composed of three parts; the external ear, middle ear or tympanum, and internal ear or labyrinth. 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Chapman on Fevers, Gout, Dropsy, &c. &c, 1 vol. 8vo., 450 pages. Colombat de L'Isere on P'emales, translated and edited by Meigs, 1 vol. 8vo., 720 pages, cuts. Condie on the Diseases of Children, 2d edition, 1 vol. 8vo., 658 pages. Churchill on the Diseases of Females, by Huston, 4th edition, 1 vol. 8vo., 604 pages. Clymer and others on Fevers, a complete work in 1 vol. 8vo. 600 pages. Dewees on Children, 9th ed., 1 vol. 8vo., 548 pp. Dewees on Females, 8th edition, 1 vol.Svo., 532 pages, with plates. Dunglison's Practice of Medicine, 2d edition, 2 vols. 8vo., 1322 pages. Esquirol on Insanity, by Hunt, 8vo. 496 pages. Thomson on the Sick Room, &c, 1 vol. large 12mo., 360 pages, cuts. Watson's Principles and Practice of Physic, 2d edition by Condie, 1 vol. 8vo., 1060 large pages. SURGERY. Brodie on Urinary Organs, 1 vol. 8vo., 214 pages. Brodie on the Joints, 1 vol. 8vo. 216 pages. Brodie's Lectures on Surgery, 1 vol.Svo., 350 pp. Chelius' System of Surgery, by South and Norris, in 3 large 8vo. vols., near 2000 pages, or in 17 parts at 50 cents each. Cooper on Dislocations, and Fractures, 1 vol. Svo. 500 pages, many cuts. Cooper on Hernia, 1 vol. imp. 8vo., 428 pp., pl'ts. Cooper on the Testis and Thymus Gland, 1 vol. imperial 8vo. many plates. Cooper on the Anatomy and Diseases ofthe Breast, Surgical Papers, &c. &c, 1 vol. imp.8vo., pl'ts. Druitt's Principles and Practice of Modern Sur- gery, 3d ed., 1 vol. 8vo.,534 pages, many cuts. Durlacher on Corns, Bunions, &c. 12mo., 134 pp. Fergusson's Practical Surgery, 1 vol. 8vo., 2d edition, 640 pages, many cuts. Guthrie on the Bladder, 8vo., 150 pages. Harris on the Maxillary Sinus, 8vo., 166 pp. Jones' (Wharton) Ophthalmic Medicine and Sur- gery, by Hays, 1 vol. royal 12mo.,529 pages, many cuts, and plates plain or colored. Liston's Lectures on Surgery, by MUtter, 1 vol. Svo., 566 pages, many cuts. Lawrence on the Eve, by Hays, new edition, much improved, 863 pages, many cuts & plates. Lawrence on Ruptures, 1 vol. 8vo. 480 pages. Miller's Principles of Surgery, 1 vol. 8vo., 526 pp LEA & BLANCHARD'S PUBLICATIONS. 5 Miller's Practice of Surgery, 1 vol. 8vo., 496 pp. Maury's Dental Surgery, 1 vol. 8vo., 286 pages, many plates and cuts. Robertson on the Teeth, 1 vol. 8vo., 230 pp. pts. MATERIA MEDIC A AND THERAPEUTICS. Dunglison's Materia Medica and Therapeutics, a new ed., with cuts, 2 vols. 8vo., 986 pages. Dunglison on New Remedies, 5th ed., 1 vol.8vo., 653 pages. Ellis' Medical Formulary, 8th ed., much improv- ed, 1 vol. 8vo., 272 pages. Griffith's Medical Botany, a new work, 1 large vol. 8vo., with over 350 illustrations. Pereira's Materia Medica and Therapeutics, by Carson, 2d edition, 2 vols. Svo., 1580 very large pages, nearly 300 wood-cuts. Royle's Materia Medica and Therapeutics, by Carson, 1 vol. 8vo., 689 pages, many cuts. OBSTETRICS. Churchill's Theory and Practice of Midwifery, by Huston, 2d ed., 1 vol. 8vo., 520 pp., many cuts. Dewees' System of Midwifery, 11th ed., 1 vol. 8vo. 660 pages, with plates. Rigby's System of Midwifery, 1 vol. Svo. 492 pp. Ramsbotham on Parturition, with many plates, 1 large vol. imperial 8vo., new and improved edition, 520 pages. CHEMISTRY AND HYGIENE. Brighamon Excitement,&c, 1 vol. 12mo.,204 pp. Dunglison on Human Health, 2d ed.,8vo., 464 pp. Fowne's Elementary Chemistry for Students, 1 vol. royal 12mo., 460 large pages, many cuts. Graham's Elements of Chemistry, 1 vol. 8vo., 750 pages, many cuts. Griffith's Chemistry of the Four Seasons, 1 vol. royal 12mo., 451 pages, many cuts. Practical Organic Chemistry, 18mo., paper, 25 cts. Simon's Chemistry of Man, 8vo., 730 pp., plates. MEDICAL JURISPRUDENCE, EDUCATION, &c* Bartlett's Philosophy of Medicine, 1 vol. 8vo., 312 pages. Dunglison's Medical Student, 2d ed.l2mo.,312 pp. Man's Power over himself to Prevent or Control Insanity, 18mo. paper, price 25c<»nts. Taylor's Medical Jurisprudence, b/ Griffith, 1 vol. 8vo., 540 pages. Traill'sMedical Jurisprudence,! vol.Svo. 234pp. NATURAL SCIENCE, &c. Arnott's Elements of Physics, new edition, 1 vol. 8vo., 484 pages, many cuts. Brewster's Treatise on Optics, I vol. 12mo., 423 pages, many cuts. Babbage's " Fragment." 1 vol. 8vo., 250 pages. Buckland's Geology and Mineralogy, 2 vols. 8vo., with numerous plates and maps. Bridgewater Treatises, with many plates, cuts, maps, &c, 7 vols. 8vo., 3287 pages. Carpenter's Popular Vegetable Physiology, 1 vol. royal 12mo., many cuts. Hale's Ethnography and Philology of the U. S. Exploring Expedition, in 1 large imp. 4to. vol. Herschell's Treatise on Astronomy, 1 vol. 12mo. 417 pages, numerous plates and cuts. Introduction to Vegetable Physiology, founded on the works of De Candolle, Lindley, &c, 18mo., paper, 25 cents. Kirby on Animals, plates, 1 vol.8vo., 520 pages. Kirby and Spence's Entomology, from 6th Lon- don ed., 1 vol. 8vo., 600 large pages; plates, plain or colored. Philosophy in Sport made Science in Earnest, 1 vol. royal 18mo., 430 pages, many cuts. Roget's Animal and Vegetable Physiology, with 400 cuts, 2 vols. Svo., 872 pages. Trimmer's Geology and Mineralogy, 1 vol. 8vo., 528 pages, many cuts. VETERINARY MEDICINE. Claterand Skinner's Farrier, 1 vol. 12mo., 220 pp. Youatt's Great Work on the Horse, by Skinner, 1 vol. 8vo., 448 pages, many cuts. Youatt and Clater's Cattle Doctor, 1 vol. 12mo., 282 pages, cuts. Youatt on the Dog, by Lewis, 1 vol. demy 8vo., 403 pages, beautiful plates. NEW MEDICAL ASD SCIENTIFIC BOOKS. Lea 8? Blanchard have at press and preparing for publication thefollowing works. Carpenter's Comparative Anatomy and Physiology, revised by the author, with beautiful steel plates. A New Work on the Diseases and Surgery of the Ear, with illustrations. Bird's Natural Philosophy, from a new Lond. ed., in 1 vol. royal 12mo.r\vith wood-cuts. Youatt on the Pig, a new work with beautiful illustrations of all the different varieties. Maunder's Treasury of Natural History, a Popular Dictionary of Animated Nature, with illustrations. Dana on Corals, imp. 4to., with an Atlas of Maps, being vols. 8 and 9 of the U. S. Ex. Expedition. Churchill on the Management and more Important Diseases of Infancy and Childhood, in 1 vol.8vo. Solly on the Human Brain, its Structure, Physiology and Diseases. Spooner on Sheep, with numerous wood-cuts. Malgaigne's Operative Surgery, with numerous wood-cuts. Quain's Elements of Anatomy, by Dr. Sharpey, with many illustrations. De La Beche's new work on Geology, with numerous wood-cuts. Southwood Smith's Philosophy of Health. Kane's Elements of Pharmacy, with additions, in 1 vol. 12mo. The Universal Formulary and Pharmacy, by R. E. Griffith, M. D., in 1 vol. Svo. An Analytical Compend of the Various Branches of Practical Medicine, Surgery Anatomy, Mid- wifery, Diseases of Women and Children, Materia Medica and Therapeutics, Physiology, Chemistry and Pharmacy, by John Neill, M. D., and F. Gurney Smith, M.D., with numerous illustrations. Taylor's Manual of Toxicology, in 1 vol. Metcalf on Caloric, in one large 8vo. volume. The History, Diagnosis and Treatment of Typhoid, Typhus, Bilious Remittent, Congestive and Yellow Fever, by Elisha Bartlett, M. D., &c, being a new and extended ed. of his former work. A Cyclopedia of Anatomy and Physiology, based on the large work of Todd, in 2 vols, large Svo. The Universal Dispensatory, with many wood-cuts, in 1 large 8vo. volume. A New Work on Bandaging, and other Points of Minor Surgery, in 1 vol. 12mo., with wood-cuts. Elements of General Therapeutics, &c, by Alfred Stille, M.D., in 1 vol. 8vo. Coates' Popular Medicine, a new edition, fully revised and brought up, in 1 vol. large 12mo. Professor Meigs' New Work on Females j their Diseases and their Remedies, in a Series of Let- ters to his Class, in 1 vol. Svo. Together with various other works. 6 LEA & BLANCHARD'S PUBLICATIONS. NOW COMPLETE. THE GREAT SURGICAL LIBRARY. A SYSTEM "OF SURGERY. BY J. M. CHELIUS, Doctor in Medicine and Surgery, Public Professor of General and Ophthalmic Surgery, etc. etc. in the Uni- versity of Heidelberg. TRANSLATED FROM THE GERMAN, AND ACCOMPANIED WITH ADDITIONAL NOTES AND OBSERVATIONS, BY JOHN F. SOUTH, Surgeon to St. Thomas' Hospital. EDITED, WITH REFERENCE TO AMERICAN AUTHORITIES, BY GEORGE W. NORRIS, M. D. Now complete in three large octavo volumes of over six hundred pages each, or in 17 numbers, at fifty cents. This work has been delayed beyond the time originally promised for its completion, by the very extensive additions of the translator. In answer to numerous inquiries, the publishers now have the pleasure to pre- sent it in a perfect state to the profession, forming three unusually large volumes, bound in the best manner, and sold at a very low price. This excellent work was originally published in Germany, under the unpretending title of "Handbook to the Author's Lectures." In passing, however, through six successive editions, it has gradually increased in extent and importance, until it now presents a complete view of European Surgery in general, but more especially of English practice, and it is acknowledged to be well fitted to supply the admitted want of a com- plete and extended system of Surgery in all its branches, comprehending both the principles and the pracj tice' of this important branch of the healing art. Since Benjamin Bell's great work, first published in 1783, and now almost obsolete, no thorough and extended work has appeared in the English language, occupying the ground which this is so well calculated to cover. The fact of this work being carried to six editions in Germany, and translated into no less than eight lan- guages, is a sufficient evidence of the ability with which the author has carried out his arduous design. This translation has been undertaken with the concurrence and sanction of Professor Chelius. The trans- lator, Mr. John F. South, appears lo have devoted himself to it with singular industry and ardor, and to have brought it up almost to the very hour of publication His notes and additions are very numerous, embodying the results and opinions of all the dislinguished surgeons of the day, Continental, English and American. The leading opinions of John Hunter, on which Modern English Surgery has been raised, are set forth ; the results of the recent microscopical discoveries, especially in reference to inflammation, will be found here, together with many other practical observations, placing the work on a level with the present state of Sur- gery, and rendering it peculiarly useful, both to the student and practitioner. The labors of the English translator have been so numerous and important, that there is but little which remains to be supplied by the American editor. Dr. G. VV. Norris has consented, however, to superintend the passage of the work) through the press, and supply whatever may have been omitted in relation to the Surgical Literature ofthis country. The Medical Press and profession, both in England and in this country, have joined in praise of this great work.as being more complete than any other, and as affording a complete library of reference, equally suited to the practitioner and to the student. "We strongly recommend all surgical practitioners and students, who have not yet looked into this work, to provide themselves with it without delay, and study its pages diligently an3 deliberately."—The Edin- burgh Medical and, Surgical Journal. " Judging from a single number only of this work, we have no hesitation in saying that, if the remaining portions correspond at all wilh the first, it will be by fir the most complete and scientific System of Surgery in the English language. We have, indeed, seen no work which so nearly comes up to our idea of what such a production should be, both as a practical guide and as a work of reference, as this; and the fact that it has passed through six ediiions in Germany, and been translated into seven languages, is sufficiently.con- vincing proof of its value. It is methodical and concise, clear and accurate, omitting all minor details and fruitless speculations, it gives us all the information we want in the shortest and simplest form."—The New York Journal of" Medicine. '• Nor do these parts, in any degree, fall short of their predecessors, in the copiousness and value of their details. The work certainly forms an almost unique curiosity in medical literature, in the fact that the notes occupy a larger portion of the volume than the original matter, an arrangement which is constantly appearing to render the text subsidiary to its illustrations. Still this singularity of manner does not at all detract from the value of the matter thus disposed."—The London Medical Gazette. '•This work has long been the chief text-book on Surgery in the principal schools of Germany, and the publication of five editions of it in the original and of translations into no less than eight foreign languages, shows the high estimation in which it is held. Asa systematic work on Surgery it has merits of a high order, It is methodical and concise—and on the whole clear and accurate. The most necessary information is conveyed in the shortest and simplest form. Minor details and fruitless speculations are avoided. It is in fact, essentially a practical book. This work was first published nearly twenty years ago, and its solid and permanent reputation has no doubt led Mr. South to undertake the present translation of the latest edition of it, which. We are informed, is still passing through the press in Germany. We should have felt at a loss to select any one better qualified for the task than the translator of Otto's Compendium of Human and Com- parative Pathological Anatomy—a surgeon to a large hospital whose industry and opportunities have enabled him to keep pace wilh the improvements of his time." — The Medico-Chirurgical Review. '• Although Great Britain can boast of some of the most skillful surgeons, both among.her past and her present professors of that branch of medical science.no work professing to be a complete system of Surgery has been published in the British dominions-since that of Benjamin Bell, now more than half a century old. "This omission in English medical literature is fully and satisfactorily supplied by the translation of Profes- sor Chelius's System of Surgery by agentleman excellently fitted for the task, both by his extensive Teading, and the opportunities of practical experience which he has enjoyed for years as surgeon to one of our largest metropolitan hospitals. The fact of Professor Chelius's work having been translated into seven languages is sufficient proof of the estimation in which it is held by our continental brethren, and the English Edition, now in course of publication, loses none of the value of the original from the treatment received at the hands of its translator. The notes and additions of Professor South are numerous, and contain the opinions result- ing from his vast experience, and from that of his colleague."— The Medical Times. ■' It ably maintains the character formerly given, of being the 'most learned and complete systematic treatise now extant The descriptions of surgical diseases, and indeed the whole of the pathological depart- ment, are most valuable."—The Edinburgh Medical and Surgical Journal. (fj* Persons wishing this work sent to them by mail, in parts, can remit Ten Dollars, for which a set will be sent by the publishers, free of postage, together with a copy of "The Medical News and Library" for one year. LEA & BLANCHARD'S PUBLICATIONS. 7 CHELIUS'S SURGERY, CONTINUED. The publishers annex a very condensed summary of the contents of Chehus's Surgery, showing the complete and systematic manner in which the whole subject is divided and treated. I. Division.—Of Inflammation. 1. Of inflammation in general. 2. Of some peculiar kinds of inflammation. a. Of erysipelas; 6. Of burns ; c. Of frost- bite ; d. Of boils ; e. Of carbuncle. 3. Of inflammation in some special organs. a. Of inflammation of the tonsils ; 6. Of the parotid gland ; c. Of the breasts ; d. Of the urethra ; e. Of the testicle ; /. Of the muscles of the loins; g. Of the nail joints ; h. Of the joints, viz. a. Of the synovial membrane ; b. Of the car- tilages j c. Of the joint-ends of the bones, viz., aa. in the hip-joint; 66. in the shoulder-joint; cc. in the knee-joint; and so on. II. Division.—Diseases which consist in a dis- turbance of physical connexion. I. Fresh solutions of continuity. a. Wounds ; b. Fractures. II. Old solutions, A. Which do not suppurate, viz. a. False joints ; b. Hare-lip ; c. Cleft in the soft palate ; d. Old rupture of the female perineum. B. Which do suppurate, viz. i. Ulcers. 1. In general. 2. In particular. a. Atonic ; 6. Scorbutic ; c. Scrofulous ; d. Gouty ; e. Impetiginous ; /. Vene- real ; g. Bony ulcers or caries. ii. Fistulas. a. Salivary fistula ; 6. Biliary fistula ; c. Faecal fistula and artificial anus; d. Anal fistula; c. Urinary fistula. in. Solutions of continuity by changed position of parts. 1. Dislocations; 2. Ruptures; 3. Prolapses; 4. Distortions. IV. Solutions of continuity by unnatural distention. 1. In the arteries, aneurisms ; 2. In the veins, varices; 3. In the capillary-vascular sys- tem, teleangiectasis. III. Division.—Diseases dependent on the unna- tural adhesion of parts. 1. Anchylosis ofthe joint-ends of bones; 2. Grow- ing together and narrowing of the aperture ofthe nostrils ; 3. Unnatural adhesion ofthe tongue; 4. Adhesion of the gums to the cheeks; 5. Narrowing ofthe oesophagus; 6. Closing and narrowing of the rectum; 7. Growing together and narrowing ofthe pre- puce ; 8. Narrowing and closing of the ure- thra; 9. Closing and narrowing of the vagina and ofthe mouth ofthe womb. IV. Division.—Foreign bodies. 1. Foreign bodies introduced externally into our organism. a. Into the nose; 6. Into the mouth ; c. Into the gullet and intestinal canal; d. Into the wind-pipe. 2. Foreign bodies formed in our organism by the. retention of natural products. A. Retentions in their proper cavities and receptacles. a. Ranula; 6. Retention of urine; c. Retention ofthe fcetus in the womb or in the cavity ofthe belly, (Cesa- rean operation, section ofthe pubic symphysis, section ofthe belly.) B. Extravasation external to the proper cavi- ties or receptacles. a. Blood swellings on the heads of new- born children; 6. Hematocele; c. Collections of blood in joints. 3. Foreign bodies resulting from the accumulation of unnatural secreted fluids. a. Lymphatic swellings ; 6. Dropsy of joints ; c. Dropsy ofthe bursa? mucosa?; d. Wa- ter in the head, spina bifida; e. Water in the chest and empyema;/. Dropsy of the pericardium ; g. Dropsy of the belly; A. Dropsy ofthe ovary; i. Hy- drocele. 4. Foreign bodies produced from the concretion of. secreted fluids. V. Division.—Diseases which consist in the de- generation of organic parts, or in the produc~ tion of new structures. 1. Enlargement of the tongue; 2. Bronchocele ; 3. Enlarged clitoris ; 4. Warts; 5. Bunions ;? 6. Horny growths; 7. Bony growths ; S. Fun- gus of the dura mater; 9. Fatty swellings; 10. Encysted swellings; 11. Cartilaginous bodies in joints; 12. Sarcoma; 13. Medul- lary fungus ; 14. Polypus ; 15. Cancer. VI. Division.—Loss of organic parts. 1. Organic replacement of already lost parts, es- pecially ofthe face, according to the Taglia- cotian and Indian methods. 2. Mechanical replacement: Application of arti- ficial limbs, and so on. VII. Division.—Superfluity of organic parts. VIII. Division.—Display of the elementary ma- nagement of surgical operations. General surgical operations : Bleeding, cupping, application of issues, introduction of setons, amputations, resections, and so on. DRUITT'S SURGERY. New Edition—Now Ready, 1847. THE PRINCIPLES AND PRACTICE OF MOQEEN SUR8ERY. By ROBERT DRUITT, Surgeon. THIRD AMERICAN FROM THE THIRD LONDON EDITION Illustrated with one hundred and fifty-three wood engravings. WITH NOTES AND COMMENTS, BY JOSHUA B. FLINT, M.D., M. M., S. S., &c. &c. In One very neat Octavo Volume of about Five Hundred and Fifty Pages. In presenting this work to the American profession for the third time, but little need be said to solicit foT it a continuation of the favor with which it has been received. The merits which have procured it ths favor, its clearness, conciseness; and its excellent arrangement, will continue to render it the favorite test- • book ofthe student who wishes in a moderate space a compend ofthe principles and practice of Surgery. ''This work merits our warmest commendations, and we strongly recommend it to young surgeons as an admirable digest of the principles and practice of modern Surgery."—Medical Gazette. 8 LEA &, BLANCHARD'S PUBLICATIONS. NOW READY. KOYLE'S MATERIA MEDICA. MATERIA MEDICA AND THERAPEUTICS; INCLUDING THE PREPARATIONS OF THE PHARMACOPOEIAS OF LONDON, EDINBURGH, DUBLIN, AND OF THE UNITED STATES. WITH MANY NEW MEDICINES. BY J. FORBES ROYLE, M.D., F.R.S., Late of the Medical Staff in the Bengal Army, Professor of Materia Medica and Therapeutics, King's Col- lege, London, &c. &c. EDITED BY JOSEPH CARSON, M.D., Professor of Materia Medica in the Philadelphia College of Pharmacy, &c. &c. WITH NINETY-EIGHT ILLUSTRATIONS. fry See Specimen of the Cuts, but not of the Paper or Working-, on next Page. In one large octavo volume of about 700 pages. Being one of the most beautiful Medical works published in this Country. The want has been felt and expressed for some time, of a text-book on Materia Medica, which should occupy a place between the encyclopaedic works, such as Pereira, and the smaller treatises which present but a meagre outline of the science. It has been the aim of the author of the present work to fill this vacancy, and by the use of method and condensation, he has been enabled to present a volume to the student, which will be found to contain what is necessary in a complete and thorough text-book of the science, encumbered with few unnecessary details. The editor, Dr. Carson, has added whatever was wanted to adapt it to the Pharmacopoeia ofthe United States, and it is confidently recommended to the student and practitioner of medicine, as one of the best text-books on the subject, now before the profession.—Great care has been taken in its mechanical execution. " Dr. Royle's manual, while it has the convenience of being in a portable form, contains as much matter as would fill two octavo volumes in large type. Our readers will judge, from the remarks which we have already made, that we think highly of this work. The subject is well treated, the matter practical and well arranged, and we do not hesitate to recommend it as a most useful volume to the student and practitioner. It is a good specimen of typography, and the engravings are well executed."—Medical Gazette. In regard to the yet more essential constituent, the literary portion of the work, no one who is acquainted with the former productions of Dr. Royle, will doubt that the author has discharged his duties with the same skill as the artist. The work is, indeed, a most valuable one, and will till up an important gap that existed between Dr. Pereira's most learned and complete system of materia medica, and the class of productions at the other extreme, which are necessarily imperfect from their small extent. Such a work as this does not admit of analysis and scarcely of detailed critical examination. It would, however, be injustice to the learned author not to state that, in addition to what former works on the subject necessarily contained, the reader will find here not a little that is either original, or introduced for the first time, more especially in the details of botany and natural history, and in what may be termed the archaeology of drugs.—The British and Foreign Medical Review. Ofthe various works that have from time to time appeared on materia medica on the plan ofthe one before us, there is none more deserving of commendation. From the examination which we have given, accuracy and perspicuity seem to characterize it throughout, as a text book of refer- ence to the student of medicine, and especially of pharmacy in its application to medicine, none could be better. We think that every one who can afford it should possess this excellent work, the value of which has been greatly enhanced by the additions of Dr. Carson, than whom no one is more competent to estimate it correctly, and to make such additions as may adapt it for American service.__The Medical Examiner. We have sufficiently extended our notice of the manual of materia medica and therapeutics, to show that it possesses great merit, which will be a pretty sure guarantee of its acceptableness to the profession. The department of materia medica is now so extended, that the treatises recently issued from the press, partake ofthe nature of cyclopaedias. To the student, whether of pharmacy solely or medicine, an extended manual as the present cannot but be regarded with favor.__The American Journal of Pharmacyt We cannot, however, conclude without expressing our warm approbation of the volume as a whole. It will certainly not detract from the author's high reputation.—The Medico-Chirurgical Review. ZA Fig. 72. CONIUM MACULATUM. (Hemlock.) Fig 85. Fig. 46. DIOSMA CRENATA. (Rue.) MYRISTICA OFFICINALIS. (Nutmeg.) 10 LEA & BLANCHARD'S PUBLICATIONS. CHURCHILL'S MIDWIFERY. ON THE THEORY AND PRACTICE OF MIDWIFERY, BY FLEETWOOD CHURCHILL; M. D., M.R.I. A., Licentiate of the College of Physicians in Ireland; Physician lo the Western Lying-in-Hospital; Lecturer on Midwifery, &c, in the Richmond Hospital Medical School, Ac. &.C. WITH NOTES AND ADDITIONS, BY ROBERT HUSTON, M.D., Professor of Materia Medica and General Therapeutics, and formerly of Obstetrics and the Disease of Wo- men and Children iu the Jefferson Medical College of Philadelphia; President of the Philadelphia Medical Society, &c. &c. 'SECOND AMERICAN EDITION. WITH ONE HUNDRED AND TWENTY-EIGHT ILLUSTRATIONS, Engraved by Gilbert from Drawings by Bagg and others. In one beautiful octavo volume. In this age of books, when much is written in every department of the science of medicine, it is a matter of no small moment to the student, which of the many he shall choose for his study in pupilage, and guide in practice. In no department is the choice more difficult than in that of midwifery ; many excellent and truly valuable treatises in this department of medicine have, within a few years past, been written; of this character are those of Dewees. Velpeau. Meigs and Righy, with due respect to the authors ofthe works just cited, we are compelled lo admit, that to Mr. Churchill has been reserved the honorof presenting lothe profession, one more particularly adapted to the want and use of students, a work rich in statistics—clear in practice—and free in style—possessing no small claims to our confidence.—The New York Journal of Medicine. WILLIAMS' PATHOLOGY. PRINCIPLES OF MEDICINE, COMPRISING! GENERAL PATHOLOGY AND THERAPEUTICS, AND A GENERAL VIEW OF ETIOLOGY, NOSOLOGY, SEMEIOLOGY. DIAGNOSIS AND PROGNOSIS. BY CHARLES J. B. WILLIAMS, M.D., F.R.S., Fellow ofthe Royal College of Physicians, &c. WITH NOTES AND ADDITIONS, BY MEREDITH CLYMER, M.D., &c. In one volume, octavo. PEREIRA'S MATERIA MEDICA. Witb nearly Three Hundred Engravings on Wood. A NEW EDITION, LATELY PUBLISHED. THE ELEMENTS OF MATERIA MEDICA AND THERAPEUTICS. COMPREHENDING THE NATURAL HISTORY, PREPARATION, PROPERTIES, COMPO- SITION, EFFECTS AND USES OF MEDICINES. BY JONATHAN PEREIRA, M.D., F.R.S. and L.S. Member ofthe Society of Pharmacy of Paris; Examiner in Materia Medica and Pharmacy of the University of London; Lecturer on Materia Medica at the London Hospital. &c &c. Second American, from the last London Edition, enlarged and improved. WITH NOTES AND ADDITIONS BY JOSEPH CARSON, M.D. In two volumes, octavo, containing Fifteen Hundred very large pages, illustrated by Two Hundred and Seventy-five Wood-cuts. This encyclopedia of materia medica. for such it may justly be entitled, gives the fullest and most ample ex- fositipn of materia medica and ils associate branches of any work hitherto published in the English language. l abounds in research and erudition: its statements of facts are clear and methodically arranged, while its therapeutical explanations are philosophical, and in accordance with sound clinical experience. It is equally adapted as a text-book for students, or a work of reference for the advanced practitioner, and no one can consult its pages without profit. The editor has performed his task with much ability and judgment. In the first American edition, he adopted the Pharmacopoeia of the United States, and the formula set forth in that standard authority; in the present he has introduced an account of substances that have recently attracted at- tention by their therapeutic employment, together with the mode of forming the characters and uses of new pharmaceutic preparations, and ihe details of more elaborate and particular chemical investigations, with respect to the nature of previously known and already described elementary principles—all the important indigenous medicines of the United States heretofore known, are also described. The work, however, is loo well known to need any further remark. We have no doubt it will have a circulation commensurate wilh its extraordinary merits.— The New York Journal of Medicine. •■ An Encyclopaedia of knowledge in that department of medical science—by the common consent ofthe pro- fession the most elaborate and scientific Treatise on Materia Medica in our language."— Western Journal of Medicine and Surgery. LEA & BLANCHARD'S PUBLICATIONS. 11 WILSON'S ANATOMY. New Edition—Now Ready, 1847. A SYSTEM OF HUMAN ANATOMY, GENERAL AND SPECIAL. BY ERASMUS WILSON, M.D., Lecturer on Anatomy, London. THIRD AMERICAN FROM THE LAST LONDON EDITION. EDITED BY P. B. GODDARD, A. M., M.D., Professor of Anatomy in the Franklin Medical College of Philadelphia. WITH TWO HUNDRED AND THIRTY-FIVE ILLUSTRATIONS BY GILBERT. In one beautiful octavo volume of over SIX IIU.VlHtJCJt Large Page*, Strongly Bound and sold at a low price. Since the publication of the second American edition of this work, the author has issued a new edition in London, in which he has carefully brought up his work to a level with the most advanced science of the day. All the elementary chapters have been re-written, and such alterations made through the body ofthe work, by the introduction of all new facts of interest, illustrated by appro- priate engravings, as much increase its value. The present edition is a careful and exact reprint ofthe English volume, with the addition of such other illustrations as were deemed necessary to a more complete elucidation of the text; and the insertion of such ofthe notes appended to the last American edition as had not been adopted by the author and embodied in his text; together with such additional information as appeared calculated to enhance the value ofthe work. It may also be stated that the utmost care has been taken in the revision of the letter-press, and in obtaining clear and distinct impressions of the accompanying cuts. It will thus be seen, that every effort has been used to render this text-book worthy of a con- tinuance of the great favor with which it has been everywhere received. Professors desirous of adopting it for their classes may rely on being always able to procure editions brought up to the day. This book is well known for the beauty and accuracy of its mechanical execution. The present edition is an improvement over the last, both in the number and clearness of its embellishments ; it is bound in the best manner in strong sheep, and is sold at a price which renders it accessible to all. CONDIE ON CHILDREN.—New Edition, 1847. A PRACTICAL~TREATISE ON THE DISEASES OF CHILDREN. BY D. FRANCIS CONDIE, M. D, Fellow ofthe College of Physicians, Member ofthe American Philosophical Society, &c. In one large octavo volume. [Ty The publishers would particularly call the attention ofthe profession to an examination of this book. In the preparation of a new edition ofthe present treatise, every part of the work has been subjected to a careful revision: several portions have been entirely rewritten; while, throughout, numerous additions have been made, comprising all the more important facts, in reference to the nature, diagnosis, and treat- ment ofthe diseases of infancy and childhood, that have been developed since the appearance of the first edition. It is with some confidence that the author presents this edition as embracing a full and connected view of the actual stale ofthe pathology and therapeutics of those affections which most usually occur be- tween birth and puberty. This work is being introduced, as a text-book, very extensively throughout the Union. CHURCHILL ON FEMALES. New Edition, 1847.—Now Ready. THE DISEASEToF FEMALES, INCLUDING THOSE OF ' PREGNANCY AND CHILDBED. BY FLEETWOOD CHURCHILL, M D., Author of "Theory and Practice of Midwifery," &c. &c. FOURTH AMERICAN, FROM THE SECOND LONDON EDITION, WITH ILLUSTRATIONS. EDITED, WITH NOTES, BY ROBERT M. HUSTON, M.D., &c.&c. In one volume, 8vo. The rapid sale of three editions of this valuable work, stamp it so emphatically with the approbation of the profession of this country, that the publishers in presenting a fourth deem it merely necessary to observe, that every care has been taken, by the editor, to supply any deficiencies which may have existed in former impressions, and to bring the work fully up to the date of publication. 12 LEA & BLANCHARD'S PUBLICATIONS. LIBRARY OF OPHTHALMIC MEDICINE AND SURGERY. Brought up to 1847. A TREATISE ON THEllSEASES OF THE EYE, BY W. LAWRENCE, F.R.S., Surgeon Extraordinary to the Queen, Surgeon to St. Bartholomew's Hospital, &c. &c. A NEW EDITION, With many Modifications and Additions, and the Introduction of nearly two hundred Illustrations. BY ISAAC H AYS, M. D., Surgeon to Wills' Hospital, Physician to the Philadelphia Orphan Asylum, &c. &c. In one very large octavo volume of near 900 pages, with twelve plates and numerous wood-cuts through the text. This is among the largest and most complete works on this interesting and difficult branch of Medica Science. The early call for a new edition of this work, confirms the opinion expressed by the editor of its great value, and has stimulated him to renewed exertions to increase its usefulness to practitioners, by incorporat-' ing in it the recent improvements in Ophthalmic Practice. In availing himself, as he has freely done, of the observations and discoveries of his fellow-laborers in the same field, the editor has endeavored to do so with entire fairness, always awarding to others what justly belongs to them. Among the additions which have been made, may be noticed.—the descriptions of several affections not treated of in the original,—an account ofthe catoptric examination ofthe eye, and of its employment as a means of diagnosis.—one hun- dred and seventy-six illustrations, some of them from original drawings,— and a very full index. There have also been introduced in the several chapters on the more important diseases, the results of the editor's ex- perience in regard to their treatment, derived from more than a quarterof a century's devotion to the subject, during all of which period he has been attached to some public institution for the treatment of diseases ofthe eye. " We think there are few medical works which could be so generally acceptable as this one will be to the profession on this side ofthe Atlantic. The want of a scientific and comprehensive treatise on Diseases of the Eye, has been much deplored. That want is now well supplied. The reputation of Mr. Lawrence as an Oculist has been long since fully established; his great merit consists in the clearness of his style and the very practical tenor of his work. The value of the present beautiful edition is greatly enhanced, by the important additions made by the editor. Dr Hays has, for nearly a quarter of a century, been con- nected with public institutions for the treatment of Diseases of the Eye, and few men have made better im- provement than he has. of such extensive opportunities of acquiring a thorough knowledge ofthe subject. The wood-cuts are executed wilh great accuracy and beauty, and no man, who pretends to treat diseases ofthe eye, should be without this work."—Lancet. JONES ON THE EYE, Now Ready. THE PRINCIPLES AND PRACTICE OF OPHTHALMIC MEDICINE AND SURGERY. By T. WHARTON JONES, F.R.S., &c. &c. WITH ONE HUNDRED AND TEN ILLUSTRATIONS. EDITED BY ISAAC HAYS, M. D., &c. In One very neat Volume, large royal 12mo., with Four Plates, plain or colored, and Ninety- eight well executed Wood-cuts. This volume will be found to occupy a place hitherto unfilled in this department of medical science. The aim of the author has been to produce a work which should, in a moderate compass, be suffi- cient to serve both as a convenient text-book for students and as a book of reference for practitioners, suitable for those who do not desire to possess the larger and encyclopaedic treatises, such as Lawrence's. Thus, by great attention to conciseness of expression, a strict adherence to arrange- ment, and the aid of numerous pictorial illustrations, he has been enabled to embody in it the prin- ciples of ophthalmic medicine, and to point out their practical application more fully than has been done in any other publication of the same size. The execution of the work will be found to correspond with its merit. The illustrations have been engraved and printed with care, and the whole is confidently presented as in every way worthy the attention of the profession. " We are confident that the reader will find, on perusal, that the execution of the work amply fulfils the promise of the preface, and sustains, in every point, the already high reputation of the author as an ophthal- mic surgeon, as well as a physiologist and pathologist. The book is evidently the result of much labor and research, and has been written with the greatest care and attention ; it possesses that best quality which a general work, like a system, or manual, can show, viz :—the quality of having all the materials whenceso- ever derived, so thoroughly wrought up, and digested in the author's mind, as to come forth with the freshness and impressiveness of an original production. We regret that we have received the book at so late a period as precludes our giving more than a mere notice of it, as although essentially and necessarily a compilation, it contains many things which we should be glad lo reproduce in our pages, whether in the shape of new pathological views, of old errors corrected, or of sound principles of practice in doubtful cases clearly laid down. But we dare say most of our readers will shortly have an opportunityof seeing these in their original locality, as we entertain little doubt that this book will become what its author hoped it might become, a manual for daily reference and consultation by the student and the general practitioner. The work is marked by that correctness, clearness and precision of style which distinguish all the productions of the learned author.''—The British and Foreign Medical Review. LEA & BLANCHARD'S PUBLICATIOIsS. 13 NEW AND COMPLETE MEDICAL BOTANY. NOW READY. MEDICAL "BOTANY, OR, A DESCRIPTION OF ALL THE MORE IMPORTANT PLANTS USED IN MEDICINE, AND OF THEIR PROPERTIES, USES AND MODES OF ADMINISTRATION. BY R. EGLESFELD GRIFFITH, M.D. &c. &c. In one large octavo volume. With about three hundred and fifty Illustrations on Wood. Specimens of the Cuts are annexed, but not so well printed as in the work, nor on as good paper. This work is intended to supply a want long felt in this country, of some treatise present- ing correct systematic descriptions of medicinal plants, accompanied by representations ot the most important of them, and furnished at a price so moderate as to render it generally accessible and useful. In the arrangement, the author has treated more fully of those plants which are known to be of the greatest importance; and more especially of such as are of native origin; while others, rarely used, are briefly noticed or mentioned only by name. In all cases, the technical descriptions are drawn up in accordance with the existing state of botanical knowledge, and in order that these maybe fully appreciated, even by those not proficients in the science, an Introduction has been prepared, containing a concise view of Vegetable Physiology, and the Anatomy and Chemistry of Plants. Besides this, a very copious Glossaht of botanical terms has been appended, together with a most complete Iniikx, giving not only the scientific but also the common names of the species noticed in it It will thus be seen that the work presents a view not only of the properties and medical virtues ofthe various species of the vegetable world, but also of their organization, compo- sition and classification. ... To the student, who is really anxious to study Botany for those great purposes which ren- der it so necessary for the advancement of Medical Science, and who has been obliged to rest satisfied with such imperfect knowledge as can be obtained from the Afferent treatises on the Materia Medica, the present work will be of great utility as a text-book and guide in his researches, as it presents in a condensed form, all that is at present known respecting those vegetable substances which are employed to alleviate suffering and to minister to he wants of man. It will also be found extremely convenient to practitioners through the country, who are anxious to obtain a knowledge of the medicinal plants occurring in then- vicinity and who are unwilling to procure the scarce and high-priced works which are at present the only ones accessible on this important branch of medical knowledge. Great care has been taken to render the mechanical execution satisfactory. NOW PREPARING, AND TO BE READY BY AUGUST NEXT, AN ANALYTICAL COMPEND OF THE VARIOUS BRANCHES OF PRACTICAL MEDICINE, SURGERY, ANATOMY, MIDWIFERY, DISEASES OF WOMEN AND CHILDREN, Mattria Medica and Therapeutics, Physiology, ©HIBBC 118EST AS?© fflBIAISHIAfflT. BY JOHN NEILL, M.D., ' Demonstrator of Anatomy in the University of Pennsylvania, and F. GURNEY SMITH, M.D., Lecturer on Physiology in the Philadelphia Association for Medical Instruction. To make one large royal Duodecimo volume, with numerous Illustrations on Wood. It is the intention of the publishers to page this work in such a way, that it can be done up in separate divisions, and in paper to go by mail; no one division will cost over 50 cents, thus pre- senting separate MANUALS on the various branches of medicine, and at a very low price. Fig. 164. EH O 5 Ph PC? CORNUS FLORIDA. (Dogwood.) Fig. 51. Fig. 54. ACONITUM NAPELLUS. (Wolfsbanes HELLEBORUS NIGER. (Black Hellebore.) LEA & BLANCHARD'S PUBLICATIONS. 15 THE GREAT MEDICAL LIBRARY. THE CYCLOP/EDIA OF PRACTICAL MEDICINE; COMPRISING TREATISES ON THE NATURE AND TREATMENT OF DISEASES, MATERIA MEDICA AND THERAPEUTICS, DISEASES OE WOMEN AND CHILDREN, MEDICAL JURISPRUDENCE, &c. &c. EDITED BI JOHN FORBES, M. D., F.R.S., ALEXANDER TWEEDIE, M.D., F.R.S., AND JOHN CONOLLY, M.D. REVISED, WITH ADDITIONS, By ROBLEY DUNGLISON, M. D. THIS WORK IS NOW COMPLETE, AND FORMS FOUR LARGE SUPER-ROYAL, OCTAVO VOLUMES. CONTAINING THIRTY-TWO HUNDRED AND FIFTY-FOUR UNUSUALLY LARGE PAGES IN DOUBLE COLUMNS, PRINTED ON GOOD PAPER, WITH A NEW AND CLEAR TYPE. THE WHOLE WELL AND STRONGLY BOUND, WITH RAISED BANDS AND DOUBLE TITLES. Or, to he had in twenty-four parts, at Fifty Cents each. For a list of Articles and Authors, together with opinions of the press, see Supplement to the No- vember number of the Medical News and Library for 1845. This work having been completed and placed before the profession, has been steadily advancing in favor with all classes of physicians. The nu- merous advantages which it combines, beyond those of any other work ; the weight which each article carries with it, as being the production of some physician of acknowledged reputation who has devoted himself especially to the subject confided to him; the great diversity of topics treated of; the compendiousness with which everything of importance is digested into a comparatively small space ; the manner in which it has been brought up to the day, everything necessary to the American practitioner having been added by Dr. Dunglison; the neatness of its mechanical execution; and the extremely low price at which it is afTorded, combine to render it one of the most attractive works now before the profession. As a book for con- stant and reliable reference, it presents advantages which are shared by no other work of the kind. To country practitioners, especially, it is abso- lutely invaluable, comprising in a moderate space, and trifling cost, the matter for which they would have to accumulate libraries, when removed from public collections. The steady and increasing demand with which it has been favored since its completion, shows that its merits have been appreciated, and that it is now universally considered as the LIBRARY FOR CONSULTATION AND REFERENCE. a XMiAomrxcnrar aits cheap wopoi. SMITH & HORNER'S ANATOMICAL ATLAS, Just Published, Price Five Dollars in Parts. AN ANATOMICAL ATLAS ILLUSTRATIVE OF THE STRUCTURE OF THE HUMAN BODY. BY HENRY H. SMITH, M.D., Fellow ofthe College of Physicians, l(c. UNDER THE SUPERVISION OF WILLIAM E. HORNER, M.D., Professor of Anatomy in the University ofPennsylvania. In One large Volume, Imperial Octavo. This work is but just completed, having been delayed over the time intended by the great difficulty in giving 10 the illustrations the desired finish and perfection. It consists of five parts, whose contents are as follows: Part I. The Bones and Ligaments, with one hundred and thirty engravings. Part II. The Muscular and Dermoid Systems, with ninety-one engravings. Part HI. The Organs of Digestion and Generation, with one hundred and ninety-one engravings. Part IV. The Organs of Respiration and Circulation, with ninety-eight engravings. Part V. The Nervous System and the Senses, with one hundred and twenty-six engravings. Forming altogether a complete System of Anatomical Plates, of nearly SIX HUNDRED AND FIFrY FIGURES, executed in the best style of art, and making one large imperial ociavo volume. Those who do not want it in parts can have the work bound in extra cloth or sheep at an extra cost. This work possesses novelty both in the design and the execution. It is the first attempt to apply engraving on wood, on a large scale, to the illustration of human anatomy, and the beauty ofthe parts issued induces the publishers to flatter themselves with the hope of the perfect success of their undertaking. The plan of the work is at once novel and convenient. Each page is perfect in itself, the references being immediately under the figures, so that the eye takes in the whole at a glance, and obviates the necessity of continual reference backwards and forwards. The cuts are selected from the best and most accurate sources; and, where neces- sary, original drawings have been made from the admirable Anatomical Collection ofthe University of Penn sylvania. It embraces all the late beautiful discoveries arising from the use of the microscope in the investi- gation of tiie minute structure of the tissues. In tiie getting up of this very complete work, the publishers have spared neither pains nor expense, and they now present it lo the profession, with the full confidence that it will be deemed all that is wanted in a scientific and artistical point of view, while, at the same time, its very low price places it within the reach of all. Itis particularly adapted to supply the place of skeletons or subjects, as the profession will see by examining the list of plates "These figures are well selected, and present a complete and accurate representation of that wonderful fabric, the human body. The plan of this Atlas, which renders it so peculiarly convenient for the student, and its superb artistical execution, have been already pointed out. We must congratulate the student upon the completion of this atlas, as it is the most convenient work of the kind that has yet appeared; and, we must add, the very beautiful manner in which it is 'got up' is so creditable to the country as to be flattering to out national pride."—American Medical Journal. "This is an exquisite volume, and a beautiful specimen of art. We have numerous Anatomical Atlases, but we will venture to say that none equal it in cheapness, and none surpass it in faithfulness and spirit. We strongly recommend to our friends, both urban and suburban, the purchase of this excellent work, for which both editor and publisher deserve the thanks of the profession."—Medical Examiner. "We would strongly recommend it, not only to the student, but also to the working practitioner, who, although grown rusty iii the toils of his Harness still has the desire, and often the necessity, of refreshing Iks knowledge in this fundamental part of the science of medicine."—New York Journal of Medicine and Surg. " The plan of this Atlas is admirable, and its execution superior lo any thing of the kind before published m this country. It is a real labour-saving affair, and we regard its publication as the greatest boon that could be conferred on the student of anatomy. It will be equally valuable to the practitioner, by affording him an easy means of recalling the details learned in the dissecting room, and which are soon forgotten."—American Medi- cal Journal. " It is a beautiful as well as particularly useful design, which should be extensively patronized by physicians, Burgeons and medical students."—Boston Med. and Surg. Journal. il It has been the aim of the author of the Atlas to comprise in it the valuable points of all previous works, to embrace the latest microscopical observations on the anatomy of the tissues, and by placing it at a moderate price.to enable all to acquire it who may need its assistance in the dissecting or operating room, or other fieM of practice."—Western Journal of Med. and Surgery. " These numbers complete the series of this beautiful work, which fully merits the praise bestowed upon the earlier numbers. Wre regard all the engravings as possessing an accuracy only equalled by their beauty, and cordially recommend the work to all engaged in the study of anatomy."—Neio York Journal of Medicine and Surgery. " A more elegant work than the one before us could not easily be placed by a physician upon the table of his student."— Western Journal of Medicine and Surgery. "We were much pleased with Part I, but the Second Part gratifies us still more, both as regards the attract- ive nature of the subject, (The Dermoid and Musc-ulur Systems,) and the beautiful artistical execution of the .[lustrations. We have here delineated the most accurate microscopic views of some of the tissues, as, for instance, the cellular and adipose tissues, the epidermis, rete mucosum and cutis vera, the sebaceous and perspiratory organs of the skin, the perspiratory glands and hairs of the skin, and the hair and nails. Then follows the genera] anatomy of the muscles, and, lastly, their separate delineations. We would recommend llus Anaioinical Alias lo our readers in the very strongest temis.n—Airto York Journal of Medicine and Sur. giry. LEA & BLANCHARD'S PUBLICATIONS. 17 HORNER'S ANATOMY, NEW EDITION. SPECIAL ANATOMY" AND HISTOLOGY. BY WILLIAM E. HORNER, M. D., PROFESSOR OF ANATOMY IN THE UNIVERSITY OF PENNSYLVANIA, &C, &C. Seventh edition. Wilh many improvements and additions. In two octavo volumes, with illustrations on wood. This standard work has been so long hefore the profession, and has been so extensively used, that, in announcing the new edition, it is only necessary to state, that it has under- gone a most careful revision ; the author has introduced many illustrations relating to Mi- croscopical Anatomy, and has added a large amount of text on those various points of investigation that are rapidly advancing and attracting so much attention. This new edition has been arranged to refer conveniently to the illustrations in Smith and Horner's Anato- mical Atlas. "The name of Professor Horner is a sufficient voucher for the fidelity and accuracy of any work on anatomy, but if any further evidence could be required ofthe value ofthe pre- sent publication, it is afforded by the fact of its having reached a seventh edition. It is altogether unnecessary now to inquire into the particular merits of a work which has been so long before the profession, and is so well known as the present one, but in announcing a new edition, it is proper to state that it has undergone several modifications, and has been much extended, so as to place it on a level with the existing advanced state of anatomy.— The histological portion has been remodelled and rewritten since the last edition; numerous wood cuts have been introduced, and specific references are made throughout the work to the beautiful figures in the Anatomical Atlas, by Dr. H. H. Smith."—The American Medical Journal, for January, 1847. HORNER'S^ISSECTOR. THE UNITED STATES DISSECTOR, BEING A NEW EDITION, WITH EXTENSIVE MODIFICATIONS, AND ALMOST REWRITTEN, OF "WIORJVEIVS PUACTICJIIj AJ%\MTOJHI\» IN ONE VERY NEAT VOLUME, ROYAL 12mo. With many Illustrations on Wood. The numerous alterations and additions which this work has undergone, the improve- ments which have been made in it, and the numerous wood-cuts which have been intro- duced, render it almost a new work. It is the standard work for the Students in the University of Pennsylvania. Some such guide-book as the above is indispensable to the student in the dissecting room, and this, prepared by one ofthe most accurate of our anatomists, may claim to combine as many advantages as any other extant. It has been so favorably received that the publish- ers have issued the fourth edition, which comes forth embellished by various wood cuts.— The copy for which we are indebted to the publishers, although received by us a fortnight since, gives proof in its appearance that it has already seen service at the dissecting table, where students have found it a valuable guide.—The Western Journal of Medicine and Sur- gery- HOPE ON THE HEART. NEW_EDITION, JUST PUBLISHED. A TREATISE ON THE DISEASES OF THE HEART AND GREAT VESSELS, AND ON THE AFFECTIONS WHICH MAY BE MISTAKEN FOR THEM. Comprising the author's view of the Physiology of the Heart's Action and Sounds as demonstrated by his ex- periments on the Motions and Sounds in 1830. and on the Sounds in 1834—5. BY J. HOPE, M.D., F. R. S., &c. &c. Second American from the third London edition. With Notes and a Detail of Recent Experiments. BY C. W. PENNOCK, M.D., &c. In one octavo volume of nearly six hundred pages wilh thographic plates. 18 LEA & BLANCHARD'S PUBLICATIONS. WORKS BY PROFESSOR wTpTjDEWEES. NEW EDITIONS. DEWEES'S MIDWIFERY, A COMPREHENSIVE SYSTEM OP MIDWIFERY. CHIEFLY DESIGNED TO FACILITATE THE INQUIRIES OF THOSE WHO MAY BE PUR- SUING THIS BRANCH OF STUDY. ILLUSTRATED BY OCCASIONAL CASES AND MANY ENGRAVINGS. Eleventh Edition, with the Author's last Improvements and Corrections. BY WILLIAM P. DEWEES, M.D., LATE PROFESSOR OF MIDWIFERY IN THE UNIVERSITY OF PENNSYLVANIA, ETC. In one volume, octavo. " That this wofk, notwithstanding the length of time it has been before the profession, and the numerous treat- ises that have appeared since it was written, should have still maintained its ground, and passed to edition after edition, is sufficient proof that in it the practical talents of the author were fully placed before the profes- sion. Ofthe book itself it would be superfluous to speak, having been so long and so favorably known through- out the country as to have become identified with American Obstetrical Science. DEWEES ON FEMALES. A TREATISE ON THE "DISEASES OF FEMALES, BY WILLIAM P. DEWEES, M. D., &c, LATE PROFESSOR OF MIDWIFERY IN THE UNIVERSITY OF PENNSYLVANIA, ETC. EIGHTH EDITION, With the Author's last Improvements and Corrections. In one octavo volume, with plates. D E WEES ON CHILDR E N. A TREATISE ON THE PHYSICAL AND MEDICAL TREATMENT OF CHILDREN, BY WILLIAM P. DEWEES, M. D., LATE PROFESSOR OF MIDWIFERY IN THE UNIVERSITY OF PENNSYLVANIA, ETC. ETC. NINTH EDITION. In one volume octavo. This edition embodies the notes and additions prepared by Dr. Dewees before his death, and will be found much improved. The objects of this work are, 1st, to teach those who have the charge of children, either as parent ot guardian, the most app'roved methods of securing and improving their physical powers. This is attempted by pointing out the duties which the parent or the guardian owes for this purpose, to this interesting but helpless class of beings, and the manner by which their duties shall be fulfilled. And 2d, to render available a long experience to those objects of our affection when they become diseased. In attempting this, the author has avoided as much as possible, "technicality," and has given, if he does not flatter himself too much, to each disease of which he treats, its appropriate and designating characters, with a fidelity that will prevent any two being confounded together, with the best mode of treating them, that either his own experience or that of others has suggested. Physicians cannot too strongly recommend the use of this book in all families. ASHWELL ON THE DISEASES OF FEMALES. A PRACTICAL TREATISE ON THE DISEASES PECULIAR TO WOMEN. ILLUSTRATED BY CASES DERIVED FROM HSPOITAL AND PRIVATE PRACTICE. By SAMUEL ASHWELL, M.D., Member ofthe Royal College of Physicians j Obstetric Physician and Lecturer to Guy's Hospital, &c. Edited by PAUL BECK GODDARD, M. D. The whole complete in one large octavo volume. " The most able, and certainly the most standard and practical work on female diseases that we have yet seen."*-'Medico-Chirurgical Review. LEA & BLANCHARD'S PUBLICATIONS. 19 WATSON'S PRACTICE OF PHYSIC. NEW EDITION BY CONDIE. LECTURES ON THE RINCIPLES AND PRACTICE OF PHYSIC DELIVERED AT KING'S COLLEGE, LONDON, By THOMAS WATSON, M.D., &c. &c. Second American, from the Second London Edition. REVISED, WITH ADDITIONS, BY D. FRANCIS CONDIE, M. D., Author of a work on the "Diseases of Children," &c. In One Octavo Volume Cf nearly ELEVEN HUNDRED Large Pages, strongly bound with raised bands. The rapid sale of the first edition of this work is an evidence of its merits, and of its general favor with the American practitioner. To commend it still more strongly to the profession, the publishers have gone to a great expense in preparing this edition with larger type, finer paper, and stronger binding with raised bands. It is edited with reference particularly to American practice, by Dr. Condie; and with these numerous im- provements, the price is still kept so low as to be within the reach of all, and to render it among the cheapest ■works offered^to the profession. It has been received with the utmost favor by the medical press, both of this country and of England, a few of the notices of which, together with a letter from Professor Chapman, are submitted. Philadelphia, September 27th, 1844. Watson's Practice of Physic, in my opinion, is among the most comprehen- sive works on the subject extant, replete with curious and important matter, and written with great perspicuity and felicity of manner. As calculated to do much good, I cordially recommend it to that portion of the profession in this country who may be influenced by my judgment. N. CHAPMAN, M.D., Professor ofthe Practice and Theory of Medicine in the University of Pennsylvania. "We know of no work better calculated for being placed in the hands of the student, and for a text-book, and as such we are sure it will be very extensively adopted. On every important point the author seems to have posted up his knowledge to the day."—American Medical Journal. Oiie ofthe most practically useful books that ever was presented to the student—indeed a more admirable summary of general and special pathology, and of the application of therapeutics to diseases, we are free to say has not appeared for very many years. The lecturer proceeds through the whole classification of human ills, acapite adcalcem, showing atevery step an extensive knowledge of his subject, with the ability of commu- nicating his precise ideas in a style remarkable for its clearness and simplicity."—N. Y. Journal of Medi- cine and Surgery. " We are free to state that a careful examination of this volume has satisfied us that it merits all the com- mendation bestowed on it in this country and at home. It is a work adapted to the wants of young practi- tioners, combining as it does, sound principles and substantial practice. It is not too much to say that it is a representative of the actual state of medicine as taught and practised by the most eminent physicians of the present day, and as such we would advise everyone about embarking in the practice of physic lo provide him- self with a copy of it."—Western Journal of Medicine and Surgery. VOGEUS PATHOLOGICAL ANATOMY. THE PATHOLOGICAL ANATOMY OP THE HUMAN BODY. By JULIUS VOGEL, M.D., &c. TRANSLATED FROM THE GERMAN, WITH ADDITIONS, By GEORGE E. DAY, M.D., &c. KllustvatetJ bj uptoar/Bs of ©ne JfJunUreti $lafn anti Colore* SSnutabfrtQS. In One neat Octavo Volume. In our last number we gave a pretty full analysis of the original of this very valuable work, to which we must refer the reader. We have only to add here our opinion that the translator has performed his task in an excellent manner, and has enriched the work with many valuable additions.—The British and Foreign Medical Review. It is decidedly the best work on the subject of which it treats in the English language, and Dr. Day, whose translation is well executed, has enhanced its value by a judicious selection ofthe most important figures from the atlas, which are neatly engraved.—The London Medical Gazette. 20 LEA & BLANCHARD'S PUBLICATIONS. A NEW EDITION OP THE GREAT HESIdA L_L 23 Z I 0 0 IT. A Dictionary of MEDICAL SCIENCE, CONTAINING A CONCISE ACCOUNT OF THE VARIOUS SUBJECTS AND TERMS; WITH THE FRENCH AND OTHER SYNONYMES; NOTICES OF CLIMATES AND OF CELE- BRATED MINERAL WATERS; FORMULAE FOR VARIOUS OFFICINAL AND EMPIRICAL PREPARATIONS, &c. BY ROBLEY DUNGLISON, M. D., PROFESSOR OP THE INSTITUTES OF MEDICINE, ETC. IN JEFFERSON MEDICAL COLLEGE, PHILADELPHIA. Sixth edition, revised and greatly enlarged. In one royal octavo volume of over 800 very large pages, double columns. Strongly bound in the best leather, raised bands. "The most complete medical dictionary in the English language."— Western Lancet. " We think that ^the author's anxious wish to render the work a satisfactory and desirable—if not indispen- sable—Lexicon, in which the student may search without disappointment for every term that has been legitimated in the nomenclature of the science,' has been fully accomplished. Such a work is much needed by all medical students and young physicians, and will doubtless continue in extensive demand. It is a lasting monument ofthe industry and literary attainments ofthe author, who has long occupied the highest rank among the medical teachers of America."—The New Orleans Medical and Surgical Journal. "The simple announcement ofthe fact that Dr. Dunglison's Dictionary lias reached a sixth edition, is almost as high praise as could be bestowed upon it by an elaborate notice. It is one of those standard works that have been ' weighed in the balance and (not) been found wanting ' It has stood the test of experience, and the fre- quent calls for new editions, prove conclusively that it is held by the profession and by students in the highest estimation. The present edition is not a mere reprint of former ones; the author has for some time been laboriously engaged in revising and making such alterations and additions as are required by the rapid pro- gress of our science, and the introduction of new terms into our vocabulary. In proof of this it is stated ' that the present edition comprises nearly two thousand five hundred subjects and terms not contained in the last. Many of these had been introduced into medical terminology in consequence of the progress of the science, and others had escaped notice in previous revisions.' We think that the earnest wish of the author has been accomplished; and that he has succeeded in rendering the work'a satisfactory and desirable—if not indis- pensable—Lexicon, in which the student may search, without disappointment, for every term that has been legitimated in the nomenclature of the science.' This desideratum he has been enabled to attempt in suc- cessive editions, by reason of the work not being stereotyped; and the present edition.certainly offers stronger claims to the attention of the practitioner and student, than any of its predecessors. The work is got up in the usual good taste of the publishers, and we recommend it in full confidence to all who have not yet supplied themselves wilh so indispensable an addition to their libraries."—The New York Journal of Medicine. A NEW EDITION OF DUNGLISON'S HUMAN PHYSIOLOGY. HUMAN PHYSIOLOGY, WITH THREE HUNDRED AND SEVENTY ILLUSTRATIONS. BY ROBLEY DUNGLISON, M.D., PROFESSOR OFTHE INSTITUTES OF MEDICINE IN THE JEFFERSON MEDICAL COLLEGE, PHILADELPHIA, ETC.,BTC. Sixth edition, greatly improved.—In two large octavo volumes, containing nearly 1350 pages. "It is but necessary for the Author to say, that all the cares that were bestowed on the preparation of the fifth edition have been extended lo the sixth, and even to a greater amount. Nothing of importance that has been recorded since its publication, has, he believes, escaped his attention. Upwards of seventy illustrations have been added; and many of the former cuts have been replaced by others. The work, he trusts, will be found entirely on a level with the existing advanced stale of physiological science." In mechanical and artistical execution, this edition is far in advance of any former one. " i illustrations have been subjected to a thorough revision, many have been rejected and their places supplied with superior ones, while numerous new wood-cuts have been added wherever perspicuity or novelty seemed to require them. . "Those who have been accustomed to consult the former editions of this work, know with how much care and accuracy every fact and opinion of weight, on the various subjects embrnccd in a treatise on Physiology, are collected and arranged, so as to present the laiest and best account of the science. To such we need hardly say, that, in this respect, the present edition is not less distinguished than those which have preceded it. In the two years and a half which have elapsed since the last or fifth edition appeared, nothing of consequence that has been recorded seems to have been omitted. Upwards of seventy illustrations have been added, and many of the former cuts have been replaced by others of better execution. These mostly represent the minute structures as seen through the microscope, and are necessary for a proper comprehension of the modern discoveries in this department"—The Medical Examiner. The " Human Physiology" of Professor Dunglison has long since taken rank as one of the medical classics in our language. Edition after edition has been issued, each more perfect than the last, till now we have the sixth, with upwards of seventy new illustrations. To say that it is by far the best text-book of physiology ever published in this country, is but echoing the general voice of the profession. It is simple and concise in style, clear in illustration, and altogether on a level with the existing advanced state of physiological science. The additions to the present edition are extremely numerous and valuable; scarcely a fact worth naming which has a bearing upon the subject seems to have been omitted. All the recent writers on physiology, both in the French, German and English languages, have been consulted and freely used, and the facts lately revealed through the agency of organic chemistry and the microscope have received a due share of attention. As it is, we cordially recommend the work as in the highest degree indispensable both to students and practitioners of medicine.—New York Journal of Medicine. The most full and complete system of physiology in our language.— Western Lancet. LEA & BLANCHARD'S PUBLICATIONS. 21 DUNGLISON'S THERAPEUTICS. NEW AND MUCH IMPROVED EDITION. GENERAL THERAPEUTICS AND MATERIA MEDICA. With One Hundred and Twenty Illustrations. ADAPTED FOR A MEDICAL TEXT-BOOK. BY ROBLEY DUNGLISON, M.D., Professor of Institutes of Medicine, &c. in Jefferson Medical College; Late Professor of Materia Medica, kc. in the Universities of Virginia and Maryland, and in Jefferson Medical College. Third Edition, Revised and Improved, in two octavo volumes, well bound. In this edition much improvement will be found over the former ones The author has subjected it to a tho- rough revision, and has endeavored to so modify the work as to make it a more complete and exact exponent ofthe present state of knowledge on the important subjects of which it treats. The favor with which the former editions were received, demanded that the present should be rendered still more worthyof the patronage of the profession, and this alteration will be found not only in the matter ofthe volumes, but also in the numerous illustrations introduced, and the general improvement in the appearance ofthe work. "This is a revised and improved edition ofthe auihor's celebrated book, entitled ' General Therapeutics;' an account of the different articles of the Materia Medica having been incorporated with it. The work has, in fact, been entirely remodelled, so that it is now the most complete and satisfactory exponent ofthe existing state ot Therapeutical Science, within the moderate limits of a text-book, of any hitherto published. What gives the work a superior value, in our judgment, is the happy blending of Therapeutics and Matttria Medica as they are, or ou«ht to be taught in all our medical schools; going no farther into the nature and commercial history of drugs than is indispensable •for the medical student. This gives to the treatise a clinical and practical charac- ter, calculated to benefit in Ihe highest degree, both students and practitioners. We shall adopt it as a text- book for our classes, while pursuing this branch of medicine, and shall be happy to learn that it has been adopted as such, in all of our medical institutions."—The N. Y. Journal of Medicine. "Our junior brethren in America will find in these volumes of Professor Dunglison, a 'Thesaurus Medica- MlNUM,' more valuable than a large purse of gold."— London Medico-Chirurgical Review. DUNGLISON ON NEW REMEDIES. NEW EDITION, BROUGHT UP TO OCTOBER 1846. R3EW REMEDIES. BY ROBLEY DUNGLISON, M.D., &c. &c. Fifth edition, with extensive additions. In one neat octavo volume. The numerous valuable therapeutical agents which have of late years been introduced into the Materia Medica, render it a difficult matter for the practitioner to keep up wilh the advancement ofthe science, espe- cially as the descriptions of them are difficult of access, being scattered so wit. f J an ivnoixvn indiqiw jo uvim ivnouvn 3 n i o i a i w jo uvmii ivnouvn snoiqsw jo a a > ^> * <¥^¥> \j^\^SAY%i\ LIBRARY OF MEDICINE NATIONAL LIBRARY OF MEDICINE NATIONAL LIBRARY OF MEDICINE N A T I OH OF* LIBRARY OF MEDICINE N A T I O N A I I I B R A R Y O F M E D I C I N E N A T I O N A I I I B R A R Y O F M E D I C I N E N A T I 01':■