iu.i' ■f$i %0* ,/ '^ ^ J THE LONDON DISSECTOR; OR, SYSTEM OF DISSECTION, practised in the Hospitals and Lecture Rooms of the Metropolis; EXPLAINED BT THE CLEAREST RULES, FOR THE USE OF STUDENTS; COMPRISING A DESCRIPTION OF THE MUSCLES, VESSELS, NERVES, AND VISCERA, OF THE HUMAN BODY, AS THEY APPEAR ON DISSECTION; WITH D1HECTIOXS FOB THEIR DEMONSTRATION. IRST AMERICAN, FROM THE FIFTH LONDON EDITION. \ ytifa PHILADELPHIA: ^UBIISHED BT JAMES WEBSTER, NO. 24, SOUTH EIGHTH STREET. William Brown, Printer. /AN/V/e* i /WaT>G*&k/, PREFACE. The Writer of the following pages, having frequently witnessed the difficulties which at- tend the pursuit of Practical Anatomy, conceiv- ed that some assistance might be derived from a Compendium, describing the various parts of the Human Body as they come into view under the knife of the Dissector. With this intention the present performance is offered to the Public. The muscles are demonstrated in the order < " their situation, this being the only method that can be pursued in actual Dissection. The relative situation of the several parts is minutely attended to, and, at the same time, re- petitions are avoided, as far as the nature of the arrangement adopted would allow. Should this work in any degree facilitate the progress of the Anatomical Student, the object of the Author will be attained. CONTENTS. Page GENERAL Rules for Dissection - ... 1 Chap. I. Dissection of the Abdomen. Sect. I. Muscles of the Abdomen .... 5 Obliquus Descendens Externus ib. Obliquus Ascendens Internus v - - 10 Cremaster -.......11 Transversalis Abdominis - - - 12 Fascia Transversalis ..... ib- Rectus Abdominis .... 13 Pyramidalis - - - 14 Sect. II. Dissection of the Cavitt of the Abdomen ib. General Situation of the Viscera - - 15 Peritoneum, and its Reflections - - 16 Liver - - .....18 Gall-bladder......19 Stomach - ib. Intestines ....... ib. Spleen - ... 21 Pancreas ... - . 22 Kidneys........ib. Renal Capsules .... 23 Diaphragm - -.....ib. Psoas Parvus - - - - - 25 Psoas Magnus - - - - - ib. Iliacus Internus 26 Fascia Iliaca - - - - - ib. Quadratus Lumborum - - - - ib. Of the Vessels and Nerves situated behind the Pe- ritoneum - - - - 27 Aorta and its Ramifications - - ib. Vena Cava Abdominalis ... 31 Vena Portarum - - - - 32 Par Vagum - - - - 33 Anterior Intercostal Nerve - - - ib. Posterior Intercostal - - - - ib. Thoracic Duct ... . - 34 a 2 VI CONTENTS. Pagt Cbaf. II. Dissection of the Perineum and Organs of Ge- neration in the Male. General Remarks - - - . - - 35 Erector Penis - -,.....36 Accelerator Urinae - - - ' ?^ Transversus Perinei - - - - ib. Sphincter Ani - - - - - 38 Levator Ani - .... - ib. Coccygeus.....- -39 Connection of the Bladder and Rectum - ib. Prostate Gland - ... 40 Urethra - -.....ib. Corpus Spongiosum, and Bulb of the Urethra ib. Glandulae Anteprostatae - . ib. Vesiculae Seminales •*. - ib. Vasa Deferentia ... ... 41 Corpora Cavernosa Penis .... ib. Bladder - - - - - - ib. Rectum, &c - - - - 42 Vessels and Nerves contained within the Pelvis 43 Internal Iliac Artery and its Branches - - ib. Internal Iliac Vein and its Branches 44 Nerves of the Pelvis - - - - ib. Course of the Anterior Crural Nerve - - 45 Course of the Obturator Nerve - - ib. Course of the Great Sciatic Nerve - - - ib. Of the Scrotum ... - ib. Chap. III. Dissection of the Organs of Generation in the Female. Mons Veneris ... .47 Labia Externa - - - - ib. Clitoris - - - - - ib. Perineum ... .... 48 Nymphae - - - - . - ib. Vestibulum - - - - - ib. Hymen, and Carunculae Myrtiformis - - i&. Vagina and os Tincae ... 49 Erector Clitoridis - * - - « - 50 Transversus Perinei ib. Sphincter Vaginae - - - ib. Sphincter Am - " - - - ib. Levator Ani - - - -'.-»"•' ib. Coccygeus - - - - - -- - ". ib. Plexus Retiformis - - - 51 Vagina - - - - - ib. Uteni9 ----- ib. Fallopian Tubes - - - - 52 Ovaria ... . . - . ib. Bladder ... ib. CONTENTS. vis Page Chap. III. Urethra.......52 Ureter - - - - - - ib. Chap. IV. Dissection of the Thigh. Sect. I. Of the anterior part of the Thigh. § 1. Of the Fascia of the Thigh, Cutaneous Vessels and Nerves, &c. ... - 53 § 2. Muscles situated on the Fore part and Inside of the Thigh - - ... -55 Tensor Vaginae Femoris . - - - - ib. Sartorius.......56 Rectus Femoris - - '- - - ib. Vastus Externus - - -57 Vastus Internus - - - - 58 Cruralis - - - - - 59 Gracilis - - - - ib. Pectinalis ...... 60 Triceps Adductor Femoris - - ib. § 3. Of the Vessels and Nerves situated on the Fore part and Inside of the Thigh - - 62 Femoral Artery, and its Branches - - ib. Obturator Artery - - - 64 Femoral Vein .... - ib. Obturator Vein ..... ib. Anterior Crural Nerve - - - ib. Obturator Nerve .... - 65 Sect. II. Of the Posterior Part of the Thigh. § 1. Of the Fascia, &c. - - - - ib. § 2. Of the Muscles on the Back part of the Thigh ib. Gluteus Maximus - - • - - - 66 Gluteus Medius - - 67 Gluteus Minimus .... - ib. Pyriformis .... 68 Gemini - ... . ib. Obturator Internus - - - - -69 Quadratus Femoris ... ib. Obturator Externus - - - - 70 Biceps Flexor Cruris ... - ib. Semitendinosus ... - - 71 Semimembranosus ... 72 § 3. Of the Vessels and Nerves on the Posterior part of the Thigh ... 73 -, "* Arteria Glutea - - - ib. Arteria Sciatica - - - - - ib. Veins ----- ib. Nervus Sciaticus.....ib. ^ECT. III. Dissection of the Ham and Fascia on the Back Part of the Leg - " - 74 Of the Fascia - .... ib. Sciatic Nerre - - - - ib. VU1 CONTENTS. Page Chap. IV. Popliteal Vein.....74 Popliteal Artery ... . . 75 Chap. V. Dissection of the Leg and Foot. Sect. I. Of the Fore part of the Leg and Foot - 77 Of the Fascia, Cutaneous Vessels, Nerves, &c. ib. Of the Muscles situated on the Fore part and Out- side of the Leg1 .... - 78 Tibialis Anticus .... - ib. Extensor Longus Digitorum Pedis 79 Peroneus Tertius - ib. Extensor Proprius Pollicis Pedis - - 80 Peroneus Longus ..... ib.' Peroneus Brevis - . - - 81 Of the Muscles on the Upper Part of the Foot 82 Extensor Brevis Digitorum Pedis - ib. Of the Vessels and Nerves situated on the Forepart of the Leg and Foot - - - - 83 Anterior Tibial Artery . - - - ib. Anterior Tibial Vein .... 84 Anterior Tibial Nerve - - . ib. Sect. II. Dissection of the Posterior Part of the Leg. Muscles situated on the Posterior part of the Leg 85 Gastrocnemius Externus, seu Gemellus - ib. Soleus - - - - - ib. Plantaris - - . - . 87 Popliteus - - - . ib, Flexor Longus Digitorum Pedis - - 88 Flexor Longus Pol^cis Pedis - . 89 Tibialis Posticus - - - - ib. Vessels and Nerves of the Back Part of the Leg 90 Posterior Tibial Artery, and Ramifications ib. Posterior Tibial Vein - - 92 Posterior Tibial Nerve - . - ib Sect. III. Dissection of the Sole of the Foot - . 93 Aponeurosis Plantaris . . - ib First Order of Muscles in the Sole of the Foot ib. Abductor Pollicis Pedis . . - 94 Abductor Minimi Digiti Pedis ... '^b. Flexor Brevis Digitorum Pedis . . ib' Second Order of Muscles in the Sole of the Foot 95 Tendon of the Flexor Digitorum Longus ib. Tendon of the Flexor Longus Pollicis - ib! Flexor Digitorum Accessorius - . - ib' Lumbricales Pedis - . . ■< ' Third Order of Muscles in the Sole of the Foot ib Flexor Brevis Pollicis Pedis - . jb Adductor Pollicis Pedis . . - 96 Flexor Brevis Minimi Digiti - . - " ib " Transversalis Pedis - . . '. ij7' CONTENTS. IX Pafe CflAF. V. Tendon of the Tibialis Posticus - - 97 Fourth Order of Muscles in the Sole of the Foot ib. Tendon of the Peroneus Longus - - ib. Interossei Tnterni - - - - 98 Interossei Externi - - - ib. Chap. VI. Dissection of the Head. Sect. I. Of the External Parts of the Head 99 Integuments ... ... ib. Occipito-frontalis - - - - ib. Muscles of the Ear ..... 100 1. Common :— Attollens Aurem ... - ib. Anterior Auris - - - - - ib. Retrahentis Auris ... - ib. 2. Proper:— Helicis Major ... - - ib. Helicis Minor .... - 101 Tragicus - - - - ib, Antitragicus - - - - ib. Transversus Auris - - - ib. 3. Internal .-— Laxator Tympani.....ib. Tensor Tympani ... - 102 Stapedius......ib. Sect. II. Of the Contents of the Cranium, or of the Brain and its Membranes - - 103 Dura Mater - - - - - ib. Pia Mater -.....i05 Cerebrum ..... 106 Cerebellum - - - 112 Medulla Oblongata, and Nerves of the Brain 117 Medulla Spinalis and Nervi Spinales - 118 Course of the great Sympathetic Nerve 121 Course of the Par Vagum - - - ib. Vessels of the Brain - - - 122 Chap. VII. Dissection of the Anterior Part of the Neck. Sect, I. Of the Muscles .... - 12*> Platysma Myoides - - 124 Sterno-cleido-mastoideus - - ib. Os Hyoides, Larynx, Trachea - - 125 Sterno-hyoideus - - - - ib. Omo-hyoideus - - - - ib. Sterno-thyroidcus - - - - 126 Thyro-hyoideus.....ib. Crico-thyroideus - - - - ib. Digastricus......127 Stylo-hyoideus ... - - ib. Stylo-glossus .... 128 Stylo-pharyngeus ... - ib. CONTENTS. Pa/?e Chap. VII. Mylo-hyoideus ... - - 128 Genio-hyoideus - - - 129 Genio-hyo-glossus - - - - ib- Ilyo-glossus - ..-- - 130 Lingualis .... - ib. Sect. II. Of the Vessels and Nerves seen in the Dissec- tion of the Neck - - - - 131 Carotid Artery and its Ramifications - ib. Internal Jugular Vein and its Branches * 133 Eighth Pair of Nerves, or Par Vagum - ib. Intercostal, or Great Sympathetic Nerve 134 Ninth Pair, or Lingual Nerve - - 135 Lingual Branch of the Fifth Pair - ib. Spinal Accessory Nerve - - - ib. Cervical Nerves - - 336 Phrenic Nerve - - - - ib. Recurrent Nerve - - - - ib. Chap. VIII. Dissection of the Thorax Sect. I. Of the Muscles which lie upon the Outside of the Thorax.....137 Pectoralis Major - - ib. Pectoralis Minor - - • - - - 138 Subclavius .... 139 Sect. H. Of the Parts contained within the Cavitt of the Thorax .... - ib. ' General Appearances - - - ib. Pleura........ 140 Lungs - - ... 141 Pericardium - - . - ib. Heart ----- ib. Sect. III. Of the Great Vessels of the Heart - - 142 Vena Cava Superior ... . ib. Vena Cava Inferior .... 143 Aorta and Ramifications - - - ib. Thymus * - - - . - - - ib. Course of the Subclavian Artery and Branches 144 Course of the Subclavian Vein - - 146 Course of the Brachial Plexus of Nerves - ib. Scalenus Anticus . - - ib. Scalenus Medius ..... ib. Scalenus Posticus .... 147 Sect. IV. Disskction of the Axilla or Arm-Pit - ib. Axillary Vein .... . 143 Axillary Artery .... - ib. Axillary Plexus of Nerves . . 149 Sect. V. Dissection of the Posterior Mediastinum, and of the Nerves and Vessels which have their Course through the Thorax - 151 Course of the Phrenic Nerve through the Thorax ib. CONTENTS. XI CHAr. VIII. Trachea -......^ Course of the Intercostal, or Great Sympathetic Nerve 152 Vena Azygos ... - - ib Aorta, and its Ramifications in the Th >rax 153 Thoracic Duct 154 OZsophagus - . . - - ib Course of the Par Vagum in the Thorax - 155 Dorsal Nerves......;D Sect. VI. Dissection of the Heart, when rkmoved from the Body......J5g Chap. IX. Dissection of the Pace. Sect. I. Of the Muscles ...... J5g Orbicularis Palpebrarum ... jb. Corrugator Supercilii - ... 16O Compressor Naris.....ib. Levator Labii Superioris Alacque Nasi - 161 Zygomaticus Minor - - . - - ib. Zygomaticus Major - . 162 Levator Anguli Oris - . - ib. Depressor Anguli Oris - - - . ib. Depressor Labii Inferioris - - - ib. Buccinator......153 Orbicularis Oris.....ib. Depressor Labii Superioris Alaeque Nasi . 164 Levator Labii Inferioris - - ib. Masseter - . ... 165 Temporalis - . . . ;b. Pterygoideus Externus - . - 166 Pterygoideus Internus - . - ib. Parotid Gland - - - - . - 167 Sect. II. Of the Vessels avu Nerves ... 168 External Maxillary Artery - - ib. External Carotid Artery and Ramifications ib. Frontal Artery - - - . 169 Veins - . . . 170 Porlio Dura of the Seventh Pair, or Facial Nerve - - - - - - ib. Superior Cervical Nerve - - ib. Superior Maxillary Nerve - - - 171 Inferior Maxillary Nerve - - - ib. Frontal Nerve - - - - 172 Chap. X. Dissection of the Throat - - . 173 Sect. I. Muscles situated adout the Entry of the Fauces 174 Constrictor Isthmi Faucium - - ib. Palato-pharyngeus ... ib. Circumflexus, seu Tensor Palati - - 175 Levator palati - - - - - ib. Azygos Uvulae * . - 176 xu CONTENTS. Chap. x. r»£e Sect. II. Muscles situated on the Posterior Part of the Pharynx - - - 176 Constrictor Pharyngis Inferior - - ib. Constrictor Pharyngis Medius - - ib. Constrictor Pharyngis Superior - - 177 Sect. III. Muscles of the Larynx - - 178 Crico-arytaenoideus Posticus " - - ib. Crico arytaenoideus Lateralis ib ^Thyreo-arytaenoideus ... 1/9 Arytaenoideus Obliquus - - - ib. Arytaenoideus Transversus - - - ib. Thyreo-epiglottideus - - - ib. Arytaeno-epiglottideus ... . ib. Chap. XI. Dissection of the Orbit of the Eye. Sect. I. Muscles situated within the Orbit - - 181 Levator Palpebrae Superioris - - - ib. Levator Oculi - - - - 182 Depressor Oculi ... . . ib. Adductor Oculi - - ib. Abductor Oculi - - - - - 183 Obliquus Superior, seu Trochlearis t - ib. Obliquus Inferior - - - ib. Lacrymal Gland, Puncta, and Sac,— Caruncula Lacrymalis - - 183,184 Sect. II. Of the Vessels and Nerves met with in the Dis- section of the Orbit - - - 184 Ophthalmic Artery ... . jb. lnfra-orbita'y Artery - ... 185 Veins .... - ib. Optic Nerve ib. Nerve of the Third Pair, and its Ramifications ib. Nerve of the Fourth Pair - - - 186 First Branch of the Fifth Pair - . ib. Infra-orbitary Nerve ... - ib. Sixth Pair ' - - - - ib. Chaf. XII. Dissection of the Musoles situated on the Posterior Part of the Trunk and Neck. Trapezius, seu Cucullaris - - 187 Latissimus Dorsi ... . 188 » Rhomboideus t - - . 189 Levator Scapulae .... . 190 Serratus Magnus.....ib. Serratus Superibr Posticus - - 191 Splenius - - - . - ib. Serratus Posticus Inferior ... 192 Sacro-Lumbalis - - - . -193 Longissimus Dorsi.....ib. Spinalis Dorsi ... . 194 Cervicalis Descendens .... 195 CONTENTS. XUI ,-. , Paee Chap. XII. Transversalis Colli - - - 195 Trachelo mastoideus - - - - ib. Complexus......196 Semi-spinalis Colli .... ib. Semi spinalis Dorsi - - . - 197 Rectus Capitis Posticus Major - - ib. Rectus Capitis Posticus Minor - - ib. Obliquus Capitis Superior - - . - 198 Obliquus Capitis Inferior ... ib. Multifidus Spinae - - - - 199 Interspinals Colli, Dorsi, et Lumborum ib. Inter transversalis Colli, Dorsi, et Lumborum 2QQ Chap. XIII. Dissection of the Muscles situated between the Ribs and on the Inner Surface of the Sternum. Intercostales Externi, and Levatores Costarum 201 Intercostaleslnterni ... 202 Triangularis Sterni - - - - ib. Chaf. XIV. Dissection of the Muscles situated on the Anterior Part of the Neck, close to the Vertebrjb. Longus Colli - 203 Rectus Capitis Internus Major - " ib- Rectus Capitis Internus Minor - - lb. Rectus Capitis Lateralis - - - 204 Chap. XV. Dissection of the Superior Extremity. Sect. I. Of the Dissection of the Shoulder and Arm 205 Cutaneous Veins and Nerves, 205,206, 207 Muscles situated on the Shoulder and Arm 207 Deltoides ... - ib. Supra Spinatus - - 208 Infra-spinatus - - - - 209 Teres Minor - - - - ib. Teres Major - - - - 210 Subscapularis - - - - ib. Biceps Flexor Cubiti - - 211 Coraco Brachialis ... - ■ - 212 Brachialis Internus - - - 213 Triceps Extensor Cubiti - - ib. Sect. II Dissection of the Fascia and Muscles situat- ed on the Cubit or Foire-Arm - 215 Fascia - - - 216 Situation of the Vessels at the Bend of the Arm. ib j Muscles situated on the Fore part of the Cubit, and arising from the Inner Condyle of the Os Humeri - - ... 216 1. Superficial:— Pronator Radii Teres ... ib. Flexor Carpi Radialis - - - 217 b XIV CONTENTS. 222 Pag£ Chap. XV. Palmaris Longus - - - 218 Flexor Carpi Ulnaris . 1D- Flexor Sublimis Perforatus - - 219 2. Deep-seated :— Flexor Profundans Perforans - - 22U Flexor Longus Pollicis - - - ib. Pronator Quadratus - 221 Muscles situated on the outer and back part of the fore-arm, and arising from the Outer Con- dyle of the Os Humeri 1. Superficial :— Supinator Radii Longus - - '^ Extensor Carpi Radialis Longior - - 22a Extensor Carpi Radialis Brevior - ib. Extensor Digitorum Communis - - 224 Extensor Carpi Ulnaris ... 225 Anconeus ...--- ib- 2. Deep-seated :— Supinator Radii Brevis ... - 226 Extensor Ossis Metacarpi Pollicis Manus ib. Extensor Primi Internodii Pollicis Manus 227 Extensor Secundi Internodii Pollicis Manus ib. Indicator .... 228 Sect. III. Dissection of the Palm of the Hand - 229 Fascia Palmaris - - ' - - ib. Palmaris Brevis ... . 230 Flexor Tendons - - - - ib. Lumbricales - - ... ib. Short Muscles of the Thumb and Fore-finger ib. Abductor Pollicis Manus - - 231 Flexor Ossis Metacarpi Pollicis - ib. Flexor Brevis Pollicis Manus - - ib. Adductor Pollicis Manus - - 232 Abductor Indicis - - - ib. Short Muscles of the Little Finger - 233 Abductor Minimi Digiti Manus - ib. Flexor Parvus Minimi Digiti Manus - ib. Abductor Metacarpi Minimi Digiti Manus ib. Interossei Interni .... 234 Interossei Externi - - - 235 Sect. IV. Of the Vessels and Nerves of the Superior Extremity .... 235 Brachial Artery and its Ramifications - 236 Venae Comites ib. Nerves of the Axillary Plexus - . - 241 COMPENDIUM OF PRACTICAL ANATOMY. GENERAL RULES FOR DISSECTION. DEXTERITY in the manual operation of dissection can only be acquired by practice; the observance, how- ever, of certain general rules, will facilitate the labour of the student. 1. The position of the hand in dissecting should be the same, as in writing or drawing; and the knife, held, like the pen or pencil, by the thumb and the two first fingers,' should be moved by means of them only; while the hand rests firmly on the two other fingers bent inwards as in writing, and on the wrist. The instrument can be gui- ded with much more steadiness and precision in this way, than when it is moved by means of the wrist, elbow, or shoulder, in the manner which young dissectors often fall into. 2. No more of the integuments should at any time be removed, than is necessary for the present dissection, as exposure to the air renders the parts dry and indistinct. 3. In dissecting muscular parts, the muscles should be extended; the cellular membrane, which connects 2 them to the integuments, should be placed on the stretch, and entirely removed with the skin ; the knife should be kept close to the muscles, and carried steadily in the di- rection of their fibres, separating a fasciculus at each stroke:—thus the exposed surface will appear clean, and the course of the fibres distinct. 4. When small vessels are to be demonstrated, another method is to be followed; the skin only must be remo- ved, and the cellular membrane cautiously and slowly dissected from the vessels. 5. During dissection, every little operation should be practised, which can give the dexterity of hand so essen- tial to the surgeon ; such are, the use of the catheter and probang, the introduction of a probe through the nose in- to the Eustachian tube, or nasal duct, and the cutting down to the various arteries, which may become the ob- ject of surgical operations; as the external iliac, femoral, anterior and posterior tibial, brachial, radial, and ulnar, &c. The grand object of the surgical student is to acquire a knowledge of the relative situation of parts. This should be kept in view in all his anatomical labours. Hence, when he is dissecting the muscles, he should carefully expose the chief blood-vessels and nerves; and attentive- ly consider their position with regard to each other, and to the surrounding parts. This species of knowledge will afford him the most essential assistance in his future operations on the living subject; in which indeed it is so necessary, that we are perfectly astonished to see per- sons rash enough to use the knife without possessing this information; but we view the hesitation, confusion, and blunders by which such operators betray their ignorance to the bystander, as the natural result, and the well merit- ed but too light punishment, of such criminal temerity. The smaller arteries and veins, and the minute nervous ramifications, will be more advantageously studied in sub- jects devoted to those purposes, and prepared by means of injection, immersion in spirits of wine, &c. 3 The reader will observe, that, in general, the mus- cles of one side of the body only are described, because all the muscles of the body have correspondent ones of the opposite side, with a few exceptions which are point- ed out. To the description of each muscle are subjoined the synonyma of the best myological writers, and the names* proposed by professor Dumas of Montpellier, in his new Nomenclature. * These names will be distinguished by being placed last among the synonyma of each muscle; their terminations, as adapted to the French language, are retained. The following is the list of the changes made in the names of the bones, on which the new no- menclature of Dumas is founded. Sus-Jlcromien is the name given to the edge of the clavicle placed above the acromion of the scapula. Sous Acromion to the edge of the same bone situated under- neath. Scapulum to the scapula. Trochiter to the greater protuberance near the head of the os humeri. Trochanter to the great trochanter of the os femoris. Trochin to the lesser protuberance near the head of the os humeri. Trochantin to the lesser trochanter of the os femoris. Epitrochlee to the internal condyle of the os humeri. Epicondyle to the external condyle of the os humeri. Phalange to the first phalanx of the fingers or toes. Phalangine to the second phalanx. Phalangette to the third phalanx. Sits, above—sous, below—pre, before. The synonyma, however, are rather to be considered as a mat- ter of curiosity, than as names that have any chance of coming into general use. Being intended to convey a sort of anatomical descrip- tion of the muscles, a great proportion of them are by far too long for names. The disadvantages of that nomenclature are pointed out by Or. Barclay of Edinburgh, in a late work on the subject, a work which discovers abilities of the first order. From the specimens which this anatomist has already given, it is to be expected, that he will soon present the world with a complete list of names, much bettt r adapted to general use, than any that have hitherto been employed. New terms, however, ought first to be given in the Latin language. They would thus be more easily adopted by ana- tomists of all countries, and might afterwards, if necessary, be translated into the various modern languages, in such a manner as would best suit the genius of each. 4 #' The Bursa; Mucosa met with in the dissection of the muscles are not regularly enumerated; but it is to be understood, that wherever tendons are described as rub- bing on bones, muscles or other tendons, a sac is formed by the surrounding cellular membrane, secreting syno- via, to lubricate the parts in motion. 5 CHAP. I. DISSECTION OF THE ABDOMEN. IN dissecting a subject, it is usual to begin with the Muscles of the Abdomen. SECT. I. MUSCLES of the abdomen, and the parts connect- ed WITH THEM IN DISSECTION. These muscles are ten in number, five on each side. An incision should be made through the integuments, from the sternum to the os pubis ; and this should be crossed by another passing immediately below the umbi- licus: dissect off the flaps; this will lav bare. 1. The Obliquus Descendens Externus.—Ori- gin: By eight triangular fleshy slips from the lower edges and external surfaces of the eight inferior ribs, at a little distance from their catrilages; the five superior slips meet on the ribs an equal number of the digitations of the serratus major anticus, and the three inferior are connected with the attachments which the latissimus dor- si has to the ribs. Often there are only seven portions. To gain a complete view of this muscle, the neighbouring portions of the pectoralis major, serratus anticus, and la- tissimus dorsi should be dissected with it. The muscular fibres proceed obliquely downwards and fonvards, and about the middle of the side of the belly terminate abruptly in a thin broad tendon, which is con- tinued in the same direction over all the fore part of the A 2 6 belly. Here it covers the anterior surface of the rectus abdominis; it is very thin at the upper part, where the rectus lies on the cartilages of the ribs, and is often remo- ved by the beginner, unless he is very cautious. Insertion: Tendinous and fleshy, into two anterior thirds of she outer edge of the crista of the os ilium, from the anterior superior spine of which, for it extends to the os pubis, forming Poupart's ligament into the ensiform carwiuge, and into the whole length of the linea alba. Situation: It is qui:e superficial, and covers the whole of the anterior part of the abdomen. The muscular part is closely covered by a thin expansion of cellular sub- stance, which might be mistaken for tendinous fibres, bir it is only the cellular membrane condensed, and ought to be removed along with the integuments. Use: To draw down the ribs in expiration, to bend the trunk forwards when both muscles act, or to bend it obliquely 10 one side when one of them acts singly ; to raise the pelvis obliquely when the ribs are fixed; to compress (he abdominal viscera, to thrust the diaphragm upwards, to assist in the expulsion of the urine and fe- ces, and of the foetus. Synonyma: Obliquus externus abdominis;—obliquus descendens;—obliquus major;—ilio-pubi-costo-abdomi- nal. In the course of the dissection of this single muscle, the following points must be attended to. The Linea Alba, a white line running along the mid- dle of the abdomen, from the cartilago ensiformis to the os pubis; formed by the tendinous fibres of the two obli- qui and the transversalis muscles, interlaced with those of the same muscles on the opposite side; it is half an inch broad at the navel; and decreases gradually both above and below that part; but particularly in the latter situation, where it is reduced at last to a mere line. Linea Semilunaris, a semicircular white line, run- ning from the os pubis obliquely upwards over the side of the abdomen, at the distance of about four inches from 7 the linea alba; formed by the tendons of the two oblique and transverse muscles uniting at the edge of the rectus, before they separate to form the sheath for that muscle. LiNEiE Transversa, three or four white lines, cross- ing from the linea semilunaris to the linea alba; formed by the tendinous intersections of the recti shining through the strong sheath which covers them:—These are not evi- dent in all subjects in this slage of the dissection. Umbilicus, or Navel. This which, before the integu- ments were removed, was a depression, appears now a prominence; it consists of condensed cellular membrane: In the foetus, it was a foramen which gave passage to the two umbilical arteries, the umbilical vein, and the urachus. Annulus Abdominalis, or Ring, an oblique slit or opening just above the angle of the pubis; formed by the tendon of the external oblique, divided into two portions called the pillars or columns of the ring, of which (the superior or internal) is attached to the symphisis, and the other (the inferior or external) to the angle of the pubis; and allowing a passage to the spermatic cord in the male, and the ligamentum teres of the uterus in the female. This slit is very improperly named a ring, since its fi- gure is triangular; the pubis is the base, the two columns are the two sides of the triangle. The apex has indeed a rounded figure in consequence of some transverse fibres, which connect the two columns where they first separate; and it points obliquely upwards and outwards. It belongs to the external oblique alone, there being no such opening, either in the internal oblique, or the transversalis; it is much smaller in the female than in the male. Ligamentum inguinale, seu Poupartii, seu Fallopii, a strong ligament, stretching from the anterior superior spinous process of the os ilium, to be fixed to the spine of the os pubis. This in truth is merely the lower edge of the tendon of the obliquus externus abdominis, extended from the anterior superior spinous process of the ilium to the angle of the pubis, although in compliance with received 8 notions, I have described it as a separate ligament. It covers ihe femoral vessels and nerves, and certain mus- cles, and has lately been often described under the name of the Crural Arch. It is also the same part as the posterior column of the abdominal ring. The student will be much confused by this multitude of names, un- less he remembers thai they denote only one object; that the crural arch, the inferior or outer column of the ab- dominal ring, PouparVs or the inguinal ligament, are so many names applied to the inferior border of the tendon ofihe external oblique muscle of the abdomen. I would advise the student, before he proceeds to the dissection of the other abdominal muscles, to dissect the parts in the groin, and to examine the situation of the great inguinal vessels. In taking off the skin from the groin, you will not find a strong regular fascia, as on the outer part of the thigh, , but a confused and irregular aponeurosis coming off from the abdomen, and going down upon the thigh, strengthened by the intermixture of condensed cellular substance, and very loose abovtTthe great vessels. Immediately under the skin, and above this aponeu- rosis, you perceive the congeries of lymphatic glands, and sometimes the lymphatic vessels themselves can be distinguished by their semi-transparent coats, and knot- ted appearance. Also, immediately under the skin you • will find the Vena Saphena running from below up- wards, at first'lying on the fascia, and then gradually sinking through it to join the femoral vein, about an inch below Poupart's ligament. .On removing this irregular fascia, we come down up- on the great vessels, which lie deeply imbedded in cellu- lar substance, and are closely invested and supported by a firm sheath, or fascia, consisting chiefly of cellu- lar substance, very much condensed. This should all be cautiously removed with the scissars, along with some lymphatic glands which lie amongst, the fat. Observe the order in which the parts are situated under the cru- 9 ral arch:—that the great external iliac vein lies next to the pubis; that the external iliac artery is on the outside of this, in close contact with it;—that the anterior crural nerve is half an inch exterior to the artery, and lies on the iliacus internus; and that the outer half of the space left under the crural arch is filled by the psoas magnus and iliacus internus muscles. Observe how the crural arch is stretched over the parts just enumerated;—how it forms a thin, but firm, sharp and crescent-shaped edge towards the pubis (constituting the seat of stricture in the femoral hernia, and sometimes called Gimbernafs liga- ment);—how the artery is placed in relation to the angle of the pubis and spine of the ilium;—how it passes under the middle of the arch, and, before it has fairly emerged into the thigh, sends off two considerable branches. (1.) A. Circumflexa Ilii is sent off from the outside, passes upwards and outwards, runs along the inside of Poupart's ligament, till it arrives at the anterior superior spinous process of the os ilium; thence it is continued along the inside of the spine of the ilium, lying close upon the bone between the transversalis abdominis and the up- per edge of the iliacus internus, to both of which it gives twigs, and ends in inosculating with the ileo-lumbar ar- tery. That distribution, however, cannot be seen in this stage of the dissection. (2.) A. Epigastrica comes off from the inside of the artery, crosses the external iliac vein, passes obliquely up- wards and inwards, under Poupart's ligament, to which it is but loosely connected, and runs behind the upper ex- tremity of the abdominal ring and spermatic cord, to reach the rectus abdominis. At first it is situated be- tween the posterior surface of that muscle and the perito- neum, but higher up between the muscular fibres and the sheath. It terminates in ramifications, which supply the rectus, and which inosculate with the ramifications of the mammaria interna, sent down from the thorax on each side of the sternum. The dissection of the other abdominal muscles may now be continued. 10 Dissect off the serrated origin of the external oblique from the ribs, and from the spine of the os ilium, and de- tach it from the obliquus internus, which lies below it, and which is connected to it by loose cellular substance, and by small vessels. Continue to separate the two muscles, till you find their tendons firmly attached, i. e. a little way beyond the linea semilunaris. Separate the tendon from the crural arch to within half an inch of the abdomi- nal ring. 2. Obliquus Ascendens Internus.—Arises by short tendinous fibres, which soon become fleshy, from the whole length of the spine of the os ilium, and from the fascia lumborum;* also fleshy from the upper part of Poupart's ligament at the part next to the os ilium. The fibres run in a radiated direction; those which ori- ginate from the back part of the os ilium, run oblique- ly upwards; those from the fore part of the ilium pass more transversely across the belly; and from Poupart's ligament the, fibres descend. The fleshy belly is continu- ed rather more forward than that of the external oblique, before it terminates in aflat tendon. Inserted into the cartilages of the six or seven lower ribs,—fleshy into three inferior, and, by a tendinous ex- pansion, which is extremely thin, resembling cellular membrane, into the four superior, and also into the ensi- form cartilage. The sheet of tendon in which the fleshy belly ends, is continued, single and undivided, into the linea semilunaris, where, adhering pretiy firmly to the tendons of the obliquus externus and transversalis, it divides into two layers. The anterior and more considerable layer joins the tendon of the external oblique, and runs over the rectus to be inserted into the whole length of the linea al- ba: the posterior and thinner layer, adhering to the ante- * Some describe it as arising from the sacrum and three inferior lumbar vertebra:; but this is not accurate. It arises from a tendi- nous fascia common to it and to certain muscles of the back, as the serra'us posticus inferior; this may with propriety be named Fas. cia Lumborum. 11 rior surface of the transversalis, passes into the linea alba behind the rectus, as low as halfway between the umbili- cus and os pubis; but below this place the whole tendon of the internal oblique passes along with that of the exter- nal oblique before the rectus, and is inserted into the lower part of the linea alba. The inferior edge of the -muscle extends in a nearly straight direction over the spermatic chord to be fixed by a tendinous attachment to the angle of the pubis. Situation: It is covered by the obliquus descendens externus and latissimus dorsi. Use: To assist the obliquus externus: but it bends the trunk in the reverse direction, so that the muscle on each side co-operates with the obliquus externus of the opposite side. Synonyma: Obliquus internus abdominis;—obliquus ascendens;—obliquus minor;—ilio-Jumbo-costi-abdomi- nal. About the middle of Poupart's ligament, a delicate fas- ciculus of fibres is sent off from this muscle over the sper- matic cord, where it passes under its edge in its way to the ring. This is named the Cremaster, and is continued down to the cord, till it is insensibly lost on the tunica vaginalis testis; it will be seen in the dissection of the scrotum: Its use is to suspend, draw up, and compress the testicle. We must now dissect the attachments of the internal oblique from the cartilages of the ribs, from the fascia lumborum, and from the spine of the os ilium, and, by continuing our dissection from behind forwards, separate it from the transversalis abdominis, which lies under it. This separation may be continued as far as where the tendons of the two muscles are inseparable, t. e. rather more forward than the linea semilunaris. As this mus- cle lies very close upon the transversalis, caution is requi- red to avoid detaching both muscles together. Let the student begin his separation at the crista of the ilium, where the course of the circumflexa ilii artery and vein 12 will shew him when he has arrived at the surface of the transversalis. 3. Transversalis Abdominis.:—Arises, tendinous, from the fascia lumborum, and back part of the spine of the os ilium; il-.zhy from all the remaining part of the spine of the ilium, a;.d from the inner surface of Poupart's liga- ment; and fleshy from the inner or back part of the carti- lages of the seven lower ribs, where its fibres meet those of the diaphragm. The fleshy fibres proceed transversely, and end in a flat sheet of tendon, which after being connected to the other tendons at the linea semilunaris, passes with the posterior layer of the internal oblique behind the rectus, and is inserted into the ensiform cartilage, and into the whole length of the linea alba, excepting its lowermost part; for, at the middle distance between the umbilicus and os pu- bis, a'slit or fissure is formed in this tendon, through which the rectus abdominis passes; and the remainder of the tendon passes before the rectus, to be inserted into the lower part of the linea alba. Its inferior edge is con- nected with that of the preceding muscle in its insertion into the pubis. Situation: It is covered by the obliquus descendens in- ternus, and is lined by the peritoneum. Use: To support and compress the viscera of the ab ■ domen. Synonyma: Transversus abdominis;—lumbo-ili-ab- dominal. Where the transversalis is detached from its origins, and turned back towards the linea semilunaris, the peri- toneum is laid bare, except in the neighbourhood of the crural arch, where it is covered by a thin fascia arising from Poupart's ligament, and continued upwards be- tween the peritoneum and transversalis muscle, until it is gradually lost. This is named by Mr. Aslley Cooper, its discoverer, the fascia transversalis, and prevents the bowels from being protruded under the inferior margins of the obliquus internus and transversalis muscles. It is 13 perforated about the middle between the ilium and pu- bes, by an opening for the passage of the spermatic chord, which then goes obliquely downwards, inwards and forwards to the ring of the external oblique. Thus the abdominal ring is a canal, having an upper or in- ternal opening, formed in the fascia transversalis, and a lower or external one in the tendon of the obliquus ex- ternus.* The sheath of the rectus is now to be attended to; it is formed by the tendons of the three other muscles, viz. the two obliqui, and the transversalis: 'These, when they reach the edge of the rectus, form the appearance named Linea Semilunaris; they then split and inclose the rec- tus in their duplicature: the whole tendon of the external oblique, with the anterior layer of the internal oblique, passes before the rectus; and the whole posterior layer of the internal oblique, together with the whole tendon of the transversalis muscles, passes behind the rectus, ex- cepting at the lower part; but, for two or three inches above the pubis, all the tendons go in front of the muscle, and the posterior part of the sheath is consequently de- ficient, the rectus lying naked on the peritoneum. The two oblique muscles are now to be replaced; then, making an incision by the side of the linea alba, and thus opening the sheath of the rectus through its whole length, you dissect it back towards the linea semi- lunaris, and thus lay bare the fibres of the muscle next to be described. 4. Rectus Abdominis.—Arises, by a flat tendon, from the fore part of the os pubis; as it ascends, its fleshy belly becomes broader and thinner. Inserted, by a thin fleshy expansion, into the ensiform cartilage, and into the cartilages of the three inferior true ribs. * For more complete descriptions of these very important parts, see Mr. Cooper's Works on Hernia, or Mr. lawrence's Treating on the same subject. B 14 Situation: This pair of muscles is situated on each side of the linea alba, under the tendons of the oblique Huscles. The muscle is generally divided by three ten- dinous intersections; the first is at the umbilicus, the se- cond where it runs over the cartilage of the seventh rib, and the third in the middle between these; and there is commonly a half intersection below the umbilicus. By these intersections, the muscle is connected firmly to the interior part of its sheath, forming the line^e trans- versa; while it adheres very slightly by loose cellular substance to the posterior layer. Use: To compress the fore part of the abdomen, to bend the trunk forwards, or to raise the pelvis. Synonyma: Pubio-sternal. On each side of the linea alba, and inclosed in the lower part of the sheath of the rectus, is sometimes found a small muscle, named 5. Pyramidalis.—Origin: Tendinous and fleshy, of the breadth of an inch from the os pubis, anterior to the origin of the rectus. Insertion: By an acute termination, near half-way be- tween the os pubis and umbilicus, into the linea alba and inner edge of the rectus muscle. Situation: It lies betwixt the lower portion of the two recti muscles. Use: To assist the lower part of the rectus. Synonyma: Pyramidalis, vel succenturiatus, pubio- umbilical. SECT. II. dissection of the cavity of the abdomen. The abdomen is divided into three regions, each of which is again subdivided. 15 1. The Epigastric, or upper region, includes the part covered at the side by the ribs; its lateral portions are named the right and left Hypochondria, and the de- pression in its middle the scrobiculus cordis. 2. The Umbilical, or middle region, is the space immediately under the former; and it extends below to the anterior superior spines of the ilia. Its sides are called the lumbar or iliac regions. 3. The Hypogastric, or lowest region, is subdivided into three parts, one middle, termed Regio Pubis, and two lateral, named Inguinal regions. Make a longitudinal incision from the scrobiculus cor- dis to the umbilicus, and from that point an oblique in- cision on each side towards the anterior spinous process of the os ilium, forming thus three triangular flaps. In doing this, avoid cutting the intestines, by raising the muscles from them after the first puncture. Before you disturb the viscera, observe the general situation of those parts which appear on the first opening of the abdomen. 1. The internal surface of the Peritoneum, smooth, shining, and colourless, covering the parietes of the ab- domen, and the surface of all the viscera. 2. In the triangular portion of integument folded down over the pubes, three ligamentous cords project through the peritoneum, two running laterally, and the other in the middle, towards the navel. These are the remains of the two umbilical arteries and the urachus. 3. The epigastric artery, accompanied by two veins, may be seen through the peritoneum, ascending oblique- ly upwards and inwards from under Poupart's ligament. 4 The upper edge of the liver is seen extending from the right hypochondriac region, across the epigastric, into the left hypochondriac region; in it a fissure is seen, into which enters, inclosed in a duplicature of peritoneum, the ligamentum teres, which was, in the foetus, the um- bilical vein. The fundus of the gall-bladder, if distend- 16 ed, is sometimes seen projecting from under the edge of the liver. 5. The Stomach will be found lying in the left hypo- chondriac region, and upper part of the epigastric; but, if distended, it protrudes into the umbilical region. 6. The Great Omentum proceeds from the great cur- vature of the stomach, and stretches down like a flap over the intestines. 7. The Great Transverse Arch of the Colon will be seen projecting through the omentum; it mounts up from the os ilium of the right side, crosses the belly under the edge of the liver, and under the greater curva- ture of the stomach, and descending again upon the left side, sinks under the small intestines, and rests upon the wing of the left or ilium. 8. The Small Intestines lie convoluted in the lower part of the belly, surrounded by the arch of the colon. Such is the general appearance on first opening the ab- domen; but this will vary somewhat, as one intestine may happen to be more inflated than another, or as the position of the body may have been after death. It will now be proper to consider the parts more minutely. 1. The Peritoneum.—Observe how it is reflected from the parietes of the abdomen over all the viscera, so that they may be said to be situated behind it; trace its reflections from side to side, and from above downwards; you will see that the external coat of every viscus, and all the connecting ligaments, are reflections or continuations of this membrane. (1.) The four Ligaments of the Liver are formed by the peritoneum, continued from the diaphragm and parietes of the abdomen. a, The Middle or Suspensory Ligament, inclosing in its duplicate the Ligamentum Teres. 6, The Coronary Ligament, connecting the upper surface of the Liver to the diaphragm. c, The Broad Ligament of the right side. 17 d, The Broad Ligament of the left side. (2.) The Lesser Omentum, or Epiploon, or the Mesogastrion, is formed by two laminae of peritoneum, passing from the under surface of the liver to the lesser curvature of the stomach, and containing in its duplicate the vessels of the liver. (3.) The Great Epiploon or Omentum.—Observe that the peritoneum, coming from both surfaces of the stomach, and from the spleen, proceeds downwards into the abdomen, and is then reflected back upon itself, till it reaches the transverse arch of the colon, where its la- minas separate to invest that intestine. This reflection is named the Great Omentum; it is a pouch or bag, com- posed of four laminae of peritoneum, and the opening into it is by the Foramen of Winslow: Observe the situation of this semilunar opening; it is on the right side of the abdomen, at the root ol* the lesser lobe, or lobulus spigelii of the liver; it leads under the little epi- ploon, under the posterior surface of the stomach, but above the pancreas and colon, into the sac of the omen- tum;—the omentum sometimes reaches to the lower part of the hypogastric region, sometimes not beyond the na- vel; it contains in its dupiicature more or less of adipose substance. (4.) The Mesentery.—Observe, that the peritoneum, reflected from each side of the vertebras, proceeds for- ward, to conneet the intestines loosely to the spine; that it begins opposite to the first lumbar vertebra, crosses ob- liquely from left to right, and ends half way between the last lumbar vertebra and the groin. At its commence- ment, it binds down the extremity of the duodenum, and it terminates where the head of the colon begins. The great circumference which is in contact with the intes- tines, is very much plaited or folded, and is several yards in length. Between the laminae of mesentery, observe the Conglobate Glands, less numerous in old age: the branches of the superior mesenteric artery ramifying and forming arches; the mesenteric veins accompanying tbft lb arteries; the trunk of the lacteals, situated contiguous to the mesenteric artery on its left side. It may sometimes be inflated by the blow-pipe. Nerves also run in the mesentery, but are not easily demonstrated. (5.) The Mesocolon is similar to the mesentery, and connects, in like manner, the colon to the spine. 2. Hepar, the Liver.—Situation: Partly in the right hypochondrium, which it fills up, reaching as low as the kidney of that side, partly in the epigastrium, and running also some way into the left hypochondrium. Connected by its four ligaments to the inferior surface of the diaphragm, and by the lesser epiploon to the small curvature of the stomach:—The little epiploon should now be removed, to discover the different parts of the liver. Observe the superior or convex surface adapted to the arch of the diaphragm; the inferior or concave surface resting on the stomach;—the posterior or thick edge lying against the vertebrae, and the anterior thin margin corresponding to the lower edge of the chest:—Observe the three lobes of the liver;—the great or right lobe;— the small or left lobe;—the lobulus spigelii;—the great fissure, separating the right and left lobe, and receiving the suspensory ligament, and the ligamentum teres;—the cavity of the portae between the great lobe and lobulus spigelii;—the fissure on the right side of the lobulus for the vena cava inferior, which fissure is almost a complete foramen;—the notch in the back part for the vertebra};— the depression in the right lobe for the gall-bladder. Observe the vessels in the cavity of the portae, the hepa- tic artery on the left side, the ductus communis choledo- chus on the right side, and betwixt, but at the same time behind them, the vena portae; they are all surrounded by a plexus of nerves. These vessels and nerves pass along the edge of the mesogaster, or little omentum, surround- ed and connected by adipose and cellular substance; the part is called Capsula Glissoni. Observe that the ligamentum teres was the umbilical vein of the foetus, 19 entering the vena portae, and that the ductus venosus in the foetus, (obliterated in the adult,) leaving the vena portae, passed into one of the venae cavae hepaticae. 3. Vesicula Fellis, the Gall-Bladder.—Situa- tion: In the right hypochondrium, in a superficial depres- sion on the under surface of the right lobe of the liver; it sends off the Ductus Cysticus, which, uniting with the Ductus Hepaticus, forms the Ductus Communis Choledochus ; this perforates the first curvature of the duodenum. 4. Ventriculus, the Stomach.—Situation: In the left hypochondriac and epigastric regions: Connected to part of the interior surface of the diaphragm, to the con- cave surface of the liver by the little epiploon, to the spleen by a reflection of peritoneum, and to the arch of the colon by the great omentum. Observe its greater curvature looking downwards, its lesser curvature looking upwards; and its two lateral surfaces. In the living body, the greater curvatur-e is turned forward, and a little downward, the lesser arch backward, i. e. towards the spine, while one of the lateral convex sides is turned upwards, and the other downwards. Observe the bulg- ing extremity on the left side, the cardia or upper ori- fice, where the oesophagus enters half-way between this great extremity and the lesser arch: the pylorus, or lower orifice, at the end of the small extremity, situated under the liver, and rather to the right side of the spine, feeling hard when touched. 5. The Intestines.—These form one continuous tube, but are divided into two portions, differing in their figure, structure, and functions, a.-,d distinguished by the names of small and large. The small intestine is divided into duodenum, jejunum, and ileum; the large into caecum, colon, and rectum. (1.) Small Intestine;—about four times the length of the body. a, The Duodenum is broader than any other part of the small intestine, but is short; it takes a turn from the 20 pylorus upwards, and to the right side, passing under the liver and gall-bladder; then, turning upon itself, it descends, passing as low as the right kidney; it is in this space that it receives the pancreatic and gall ducts; thence it crosses before the renal vessels, before the aorta, and upon the last vertebra of the back, firmly bound down by the peritoneum, which covers only its anterior surface; it then ascends from right to left, till it is lost under the root of the mesocolon. Turning back the colon and omentum, fixing them over the brim of the thorax, and pushing down the small intestines towards the pelvis, you find the duodenum coming out from under the mesocolon, but still tied close to the spine; it terminates in the jejunum, exactly where the mesentery begins. The intestine in this course forms nearly a circle, the root of the mesocolon being the only part lying between its two extremities. You have now to trace the rest of the small intestine, which lies convoluted in the umbilical and hypogastric regions. b, Jejunum constitutes the first or upper half of the remaining small intestine, and is situated more in the upper part of the abdomen; it is redder, and its coats feel thicker to the touch, from the greater number of the valvulae eonniventes on its inner surface; its diameter exceeds that of the ilium. c, The lower half is named Ileum; it is situated more in the lower part of the abdomen, and terminates in the great intestine, by entering the caput coli, or beginning of the colon. As a general observation it may be said, that the con- volutions of the small intestine occupy the middle of the umbilical and hypogastric regions; but their situation varies much, particularly according to the state of the bladder and rectum The course of the tube, indepen- dently of its convolutions, is from the left lumbar region, where the duodenum emerges from under the mesocolon to the right inguinal region, where the ileum terminates in the caput coli. 21 (2.) Great intestine. d, The Caecum, or blind gut, is tied down by the peritoneum to the loins on the right side, lying in the space under the right kidney, hid by the convolutions of the ileum. On its posterior part there is a little appen- dage, of the shape of an earth-worm, named Appendix Cmci Vermiformis. e, The Colon.—Its commencement at the caecum is termed Caput Coli, or head of the colon; it mounts upwards from the caecum over the anterior surface of the right kidney, to which it is connected by cellular sub- stance, passes under the gall-bladder, which, after death, tinges it with bile; and then, going across the upper part of the belly, forms its Great Transverse Arch. In its whole course it is contracted into cells by its muscu- lar fibres, which are united together, forming longitudi- nal bands; and it has some fatly projections attached to its surface, named Appendices Epiploicae. Both these circumstances distinguish the large from the small in- testine; which the difference of size does not always. When the large intestine is empty, it contracts, and may be even smaller than the small; but if it were in- flated, it could be distended to a much greater degree. The colon then goes backwards under the stomach and spleen into the left hypochondrium; and then, descend- ing over the left kidney, it is again tied down; it after- wards turns over the brim of the pelvis, being at this part unconfined, and forming a loose and remarkable curvature, which is named the Sigmoid or Iliac Flex- ure. After this convolution, the intestine assumes the name of The Rectum.—Drawing aside the intestines, you find the gut continued over the anterior surface of the sacrum and os coccygis to the anus. On pulling the stomach towards the right side, you will perceive, 6. The Lien, or Spleen. Situation: In the left hypo- chondriac region, between the great extremity of the 22 stomach, and the neighbouring false ribs, under the edge of the diaphragm, and above the left kidney; to all of which it is connected by the peritoneum: It is of an oval figure; its external surface is gently convex; its in- ternal surface irregularly concave, and divided by a longitudinal fissure, into which its vessels enter. 7. The Pancreas.—Situation: This gland was in part seen on removing the little epiploon; it is more fully exposed, by tearing through the great epiploon be- tween the great curvature of the stomach, and the trans- verse arch of the colon. It lies in the cavity into which the foramen of Winslow leads: it extends from the fis- sure of the spleen across the spine, under the posterior surface of the stomach, and terminates within the circle formed by the duodenum; it is only covered on its ante- rior surface by the peritoneum. The Pancreatic Duct pierces the coat of the duo- denum, and enters the cavity of that intestine, by an orifice common to it, and to the ductus communis chole- dochus. The duct runs along the very centre of the gland, where the whiteness of its coats will readily enable the student to distinguish it. All the abdominal viscera may now be removed, ex- cept the rectum, where it descends into the pelvis, which, being tied, should be allowed to remain, for it belongs to the demonstration of those parts: Or the liver and its vessels, with the pancreas, may be left, and the vessels entering the portae of the liver traced. The peritoneum should now be carefully dissected from the diaphragm, and from the sides and back part of the abdomen; thus the parts which lie more immedi- ately behind that membrane may be examined. 8 Renes, the Kidneys.—Two glandular bodies, situated in the posterior part of the cavity of the abdo- men, on each side of the lumbar vertebrae, between the last false rib and the spine of the ileum, and imbedded in a quantity of adipose membrane. In each kidney you may observe a lesser arch or con- 23 cavity turned obliquely forwards and inwards; a greater arch or convexity turned obliquely backwards and out- wards;—two lateral surfaces;—two extremities, the superior of which is nearer to that of the opposite kid- ney than the inferior. Observe the renal or emulgent artery entering the lesser arch, the vein and ureter pass- ing out. Observe the course of the ureter; it passes behind the peritoneum over the psoas muscle into the pelvis, and runs between the rectum and bladder, which last it enters. 9 The Capsule Renales.—Two glandular bodies, situated on the upper extremity of each kidney, of an irregular figure, crescent-like, or somewhat triangular. By the removal of the peritoneum, several muscles are exposed, situated at the superior and posterior parts of the abdomen. One single muscle is situated in the superior part of the abdomen. Diaphragma, the Diaphragm, or Midriff.—This is a broad, thin, muscular septum between the thorax and abdomen, situated obliquely; it is concave below, and convex above, the middle of it on each side reach- ing as high within the thorax as the fourth rib. It is divided into two portions : 1. The superior or greater musole of the diaphragm, forms the transverse partition between the chest and abdomen, Arising, by distinct fleshy fibres, 1. from the posterior surface of the ensiform cartilage; 2. From the cartilages of the seventh, and all the false ribs; 3. From the liga- mentum arcuatum, which is a ligament extended, some- what indistinctly, from the top of the twelfth rib to the lumbar vertebrae, forming an arch over the psoas and quadratus lumborum muscles. From these origins the fibres run, in different directions, like radii from the circumference to the centre of a circle, and are Inserted into a broad tendon, (tendinous centre, or cor- diform tendon,) which is situated in the middle of the ZA diaphragm, and in which, therefore, the fibres from the opposite sides are interlaced. 2. The inferior or lesser muscle, or appendix of the diaphragm, lies on the bodies of the vertebrae, and Arises, by four small tendinous feet, on each side, from the second, third, and fourth lumbar vertebrae; these tendons soon join, to form a strong pillar on each side, named the Crus of the Diaphragm. The crura run ob- liquely upwards and forwards, from two fleshy bellies, a fasciculus of each of which crossing over to the other, decussates with the opposite one, and thus forms the in- terval of the two crura into a superior and inferior open- ing. Inserted into the posterior part of the middle cordiform tendon. Situation: The diaphragm is covered on its superior surface by the pleura, and on its inferior by the perito- neum; it separates the thoracic from the abdominal vis- cera: It is perforated in its fleshy and tendinous parts by several blood-vessels, and other important organs. (1.) The aorta passes between the tendinous part of the crura, lying close upon the spine; and the thoracic duct passes betwixt the aorta and the right crus. (2.) A little above, and to the left side of the aorta, the oesophagus, with the eight pair of nerves attached to it, passes through an oval fissure formed in the fleshy co- lumns of the inferior muscle. These two parts are se- parated by the decussating fasciculi just described. (3.) The vena cava perforates the tendon towards the right side by a triangular hole. (4.) The posterior intercostal nerve, and branches of the vena azygos, perforate some of the posterior fibres of the crura:—The splanchnic, or anterior intercostal nerve, also passes through an opening in the substance of the crura. (5.) On each side of the sternum there is a small fissure, where the peritoneum and pleura are only sepa- rated by adipose membrane. 25 Use: The diaphragm is one of the chief agents in res- .ation; in contraction it enlarges the cavity of the tho- •iv, and produces inspiration; in expiration it is relaxed, '.'..! pushed up by the pressure of the viscera, from the ■ ion of the muscles of the abdomen, so as to diminish cavity of the chest: it also acts in coughing, laughing, 1 speaking, and in the expulsion of the urine and :es. Synonyma: Septum transversum;—septum muscu- 1 e;—Thoraco abdominal. Winslow calls the middle jneurosis the aponeurotic plane of the diaphragm; others it is called the centrum tendinosum. Four pair of muscles are situated within the posterior , rt of the cavity of the abdomen. 1. The Psoas Parvus.—It arises, fleshy, from the Jes of the last dorsal, and first lumbar vertebrae; it sends f a small long tendon, which, running on the inside of u.e psoas magnus, is Inserted, thin and flat, into the brim of the pelvis, at the junction of the os ilium and pubis. Situation: This muscle lies on the anterior part of the loins, betwixt the psoas magnus and the vertebras; some- times, however, it is wanting. Use: To assist the psoas magnus in bending the loins forward: in some positions, it will bend the pelvis on the loins. Synonyma: Pre-lumbo p'ubien. 2. The Psoas Magnus.—It arises, fleshy, from the side of the body, and transverse process of the last ver- tebra of the back, and in the same manner from all those of the loins, by as many distinct slips. It runs down over the brim of the pelvis, and is Inserted, tendinous, into the trochanter minor of the os femoris, and fleshy, into that bone immediately below the trochanter. Situation: It is situated betwixt the psoas parvus and iliacus internus, close to the fore part and sides of »he lumbar vertebras: at its origin it has some connection with the diaphragm, and with the quadralus lumbo- r rum. j Use: To bend the thigh forwards, and roll it outwards; I or, when the inferior extremity is fixed, to assist in bend- ing the body. St/nom/ma :Lumbaris internus—Pre-lumbo-trochantin. 3. The Iliacus Internus.—It arises, fleshy, from the transverse process of the last vertebra of the loins, from all the inner margin of the spine of the os ileum, from the edge of that bone between its anterior su- perior spinous process and the acetabulum, and from all its hollow part between the spine and the linea innominata. Its fibres descend under the outer half of Poupart's ligament, and join the tendon of the psoas magnus, Inserted with the psoas magnus. Situation: It fills up the internal concave surface of the os ileum, and is situated on the outside of the psoas magnils. It is covered by a pretty strong fascia, which is inserted into the crista of the ileum, and into the crural arch: Fascia Iliaca. The latter insertion pre- vents the bowels from descending under Poupart's liga- ment, except at the inner edge of the iliac vein, which is accordingly the situation of the crural hernia, and which the student should examine most carefully. A part of this fascia is also continued behind the femoral ves- sels over the pubis, to form a part of the sheath which encloses those vessels.* Use: To assist in bending the thigh, and in bringing it directly forwards. Synonyma: Iliacho-trochantin. JST. B. The insertion of the two last described mus- cles cannot be seen till the thigh is dissected, when it will be'found to lie between the vastus internus and the pectimeus. 4. The Quadratus Lumborum.—This muscle arises, * See the second part of Mr. Cooper's work on Hernia, and Mr. Lawrence's treatise quoted before. 27 tendinous and fleshy, from rather more than the posterioi third part of the spine of the os ileum. Inserted into the transverse process of all the vertebrae of the loins, into the posterior half of the last rib, and, by a small tendon, into the side of the last vertebra of the back. Situation: It is situated laterally at the lower part of the spine, more outwardly than the psoas magnus, between the origin of the psoas and the transversalis abdominis. Use: To move the loins to one side, pull down the last rib, and, when both muscles act, to bend the loins forwards. Synonyma: Lumbaris externus;—Ilio-Iumbi-costal. OF THE VESSELS AND NERVES SITUATED BEHIND THE PERITONEUM. 1. the arteries, viz. the aorta abdominalis, and its branches.* ffe The Aorta passes from the thorax into the abdo- men, between the crura of the diaphragm, close upon the spine. It then descends on the fore part of the ver- tebrae, lying not exactly in the middle, but rather inclin- ed to the left side. On the fourth lumbar vertebra, it bi- furcates into the two primitive or common iliac arteries. Branches of the Abdominal Aorta. 1. The two Phrenic Arteries arise from the Aorta,^ before it has fairly entered into the abdomen, and ramify * In the description of the blood-vessels, the ramifications of the principal trunks are enumerated ; but the student must remember that these can be seen only when injected, and when the subject is dissected for the express purpose of tracing the arteries. In an ordinary dissection, the trunks only can be demonstrated. 28 over the diaphragm; sometimes they come off in one trunk, which bifurcates; sometimes one of them arises from the cceliac. 2. The Cceliac Artery comes off at the point where the aorta has fairly extricated itself from the diaphragm; it is a single, large, but short trunk situated between the inferior surface of the liver, and the small curvature of the stomach, and surrounded by the meshes of the semi- lunar ganglion. It divides at once into three branches; and as they depart in different directions from one point, as from a centre, the trunk is called the Axis Arteria Cceliace. (1.) A. Coronaria Ventriculi, the middle branch, is the smallest of the three; it passes from the axis to- wards the left side, and arriving at the cardiac orifice of the stomach, where it attaches itself to that organ, sends a branch round the cardia, named Ramus Corona- rim Dexter. The trunk itself is then continued along the lesser curvature from left to right, to inosculate with the pyloricaor coranaria dextra: it sends off branches to the little epiploon, &c. It sometimes terminates in the liver, entering at the portae, and then it is the largest of the branches of the cceliac. In this case, the trunk, after ascending towards the left to reach the cardia, is reflect- ed to the right, in its way to the liver; and, at the point of reflection, gives off the coron. venlric. (2.) Arteria Splenica leaving the trunk of the cceliac, goes directly to the side, passes under the sto- mach, and along the upper border of the pancreas, run- ning in a tortuous and serpentine course: it enters the left concave surface of the spleen in several branches, but, before doing so, it gives off the following branches: a, Pancreatice Parv^e to the pancreas, where it runs along the border of that visctts. b, Vasa Brevia to the bulging extremity of the sto- mach. c, A. Gastro-epiploica Sinistra, which runs along 29 the greater curvature of the stomach, inosculating with the gastro-epiploica dextra. (3.) Aktekia Hepatica runs in a direction opposite to the splenic, towards the right side; but not more than half of its blood goes to the liver: It sends off" the fol- lowing branches: a, Pvlorica, or Coronaria Dextra, sometimes comes off from the trunk of the hepatic, sometimes from one of its branches;—reaching the pyloric end of the stomach, it sends its ramifications along the lesser curvature, to inosculate with the proper coronary artery. 6, Gastro-epiploica Dextra, or Gastro-duodena- lis, passes under the pylorus, to reach the great curva- ture of the stomach, along which it runs, inosculating with the gastro-epiploica sinistra, and sending branches upwards to the stomach, and downwards, to the omen- tum; it also supplies the upper part of the duode- num, and sends off a considerable branch to the right extremity of the pancreas. The hepatic artery then divides into the right and left hepatic. The Right is distributed to the right lobe of he liver, and to the gall-bladder. The Left sup- plies the whole of the left lobe, the lobulus Spigelii, and part of the right lobe of the liver. 3. The Superior Mesenteric Artery is a single trunk: it leaves the aorta about half an inch lower than the cceliac artery,—it comes out from under the mesoco- lon, and stretches over the duodenum: it enters the fold of peritoneum forming the mesentery, and runs down in this, gradually incurvating from the left to the right side. From the right side or concavity of this arch, three branches are given to the colon. (1.) A. Ileo-Colica runs down to the caput coli and last turns of the ileum; its branches upon the small in- testines inosculate with those branches of the superior mesenteric distributed to the small intestines in general; and on the great intestine, it inosculates with the next branch. C 2 30 (2.) A. Colica Dextra.—This artery runs from the root of the superior mesenteric artery, across towards the right side of the colon, where that intestine begins to rise over the kidney. 3. A. Colica Media.—This branch goes directly up- wards from the trunk of the superior mesenteric, as it comes out from under the mesocolon. After running a little way upon the mesocolon, it divides; and the divi- sion going towards the right side, makes a large inoscu- lation with the colica dextra, while the left branch makes an opposite sweep, and joins the colica sinistra, which is a branch of the inferior mesenteric. Often there are only two branches instead of these three; viz. ileo-colica and colica dextra; then the c. media is a branch of the latter. Frequently too there is only one branch, called colica dextra, and dividing after its origin into the three above named. The left side or convexity of the arch of the superior mesenteric sends off from sixteen or twenty branches, which, after forming frequent anastomoses and arches, proceed to the small intestines. 4. The Renal or Emulgent Arteries are two in number. Each artery arising, below the superior me- senteric, from the side of the aorta, passes to the kidney, and after having given twigs to the renal capsule and adipose membrane, enters the lesser arch of the kidney. The right artery is longer than the left, and passes be- hind the vena cava ascendens. 5. The Spermatic Arteries are also two; they come off about an inch below the emulgent from the fore part of the aorta. Each artery descends behind the perito- neum, giving twigs to the parts in its course, and ac- companied by the spermatic vein and nerves. Itnhen passes through the abdominal ring, and enters the upper part of the testicle in five or six branches. In the fe- male it supplies the ovaria and fundus uteri. 6. The Inferior Mesenteric is a single trunk, which comes off rather from the left side of the aorta,. 31 below the spermatic arteries; it passes in the mesentery to the left side of the abdomen, where it divides as fol- lows. (1.) The Colica Sinistra, an artery which ascends along the left side of the colon, to inosculate with the A. Colica Media. (2.) Branches which pass to the sigmoid flexure. (3.) The great trunk of the artery runs down behind the rectum, on which it ramifies largely, and is termed Art. Hemorrhoidals Interna. 7. The Lumbar Arteries are five or six small arte- ries on each side, which arise from the back part of the aorta, and are distributed to the spinal canal, perito- neum, muscles of the spine, and of the sides of the ab- domen and pelvis. They inosculate with the A. Epi- gastrica, Circumflexa ilii, &c. 8. A. Sacra Media is a single artery, arises from the back part of the aorta at its bifurcation, and descends along the anterior surface of the sacrum, giving twigs to all the neighbouring parts. At the fourth lumbar vertebra, the aorta bifurcates into the two primitive or common iliacs. The Iliaca Communis runs along the edge of the psoas muscle, and at an inch or two from its origin divides into, (1.) The Internal Iliac, which passes down into the pelvis. (2.) The External Iliac, which, following the direc- tion of the psoas muscle, passes under Poupart's liga- ment, and becomes the inguinal artery. 2. VEINS. The Vena Cava Abdominalis, vel Inferior, is form- ed by the junction of the two common iliac veins; it passes up through the abdomen on the lumbar vertebrae, and on the right side of the aorta. In this course it receives the following veins, which resemble their corresponding arteries: 32 1. The Lumbar Veins. 2. The Emuigent or Renal Veins;—the left is the longest, as it crosses over the fore part of the aorta. 3. The Right Spermatic Vein;—the left enters the left renal vein. The vena cava then passes through the fissure of the liver, being nearly surrounded by that viscus, and re- ceiving three branches from it, called the Venje Hepa- tice. It then perforates the diaphragm, and enters the thorax. The common iliac vein of each side is formed by the union of two branches, the External and Internal Iliac Veins, which accompany the arteries of the same name:—The common Iliac vein of each side lies on the inside of its artery; hence both veins cross behind the right iliac artery, to unite and form the vena cava, on the fore part of the lumbar vertebrae.* " do not join the cava, but are united behind the pancreas, to form the Vena Portae. This vein ramifies anew through the liver, and its blood is re- turned into the vena cava by the venae cavae hepa- ticae. Although the trunks just enumerated are the chief veins that contribute to form the vena portae, yet the re- turning veins of all the viscera enclosed in the perito- neum, except the liver, are included in the same system, and join one or other of the large trunks. This is the case with the stomach, pancreas, gall-bladder, and omentum. The blood which goes to the spleen, large The Superior Mesen- teric Vein, the Inferior Mesenteric Vein, and the Splenic Vein, * It may be here proper to observe, that generally a great vein accompanies every great artery ; but when the ramifications be- come small, each artery is attended by two veins. 33 and small intestines, is all returned by the three great trunks. 3. NERVES. 1. The eighth pair, or Par Vagum, descending on each side of the oesophagus through the diaphragm, forms the two Stomachic Plexuses on the anterior and posterior surfaces of the stomach. These plexuses send some branches to the cceliac, to the hepatic, and to the splenic plexus. 2. The Splanchnic Nerve, or Anterior Intercostal, a branch sent off by the intercostal nerve in the thorax, enters the abdomen betwixt the crura of the diaphragm; here each nerve forms a Semilunar Ganglion by the side of the cceliac artery. From the ganglion, on each side, branches are sent across, which communicate intimately together, and form round the root of the cceliac artery, a very intimate plexus containing several ganglia of various sizes, for- merly called the Solar, but now more correctly the Cceliac Plexus. Nerves pass from this plexus, with the branches of the aorta, to the various viscera of the abdomen: in a common dissection these nerves cannot be clearly demonstrated, as they lie very close on the respective arteries, and are surrounded by much con- densed cellular substance; they form the hepatic, splenic, superior, and inferior mesenteric, renal, and spermatic plexuses. 3. The trunk of the intercostal nerve, the posterior intercostal, perforates the small muscle of the diaphragm close to the spine, runs down on the sides of the lumbar vertebrae, and along the upper edge of the psoas magnus. It terminates on the extremity of the os coccygis, by union with the nerve of the opposite side, in a ganglion named Ganglion Impar. In this course, it communi- cates with the lumbar nerves, and the various abdominal plexuses. 34 The Thoracic Duct may be seen passing from the abdomen into the thorax, between the aorta and the right crus of the diaphragm. It is larger here than in its subsequent course, and the dilated portion is called receptaculum chyli, as the lacteals pour in the chyle in this situation. J M CHAP. II. DISSECTION OF THE PERINEUM, AND OF THE MALE ORGANS OF GENERATION.* THE muscles and vessels to be demonstrated, lie deep amongst much loose cellular substance; and unless great caution is used, important parts will be removed, while the student supposes he is only clearing away cellular substance:—The rectum having been cleansed, a little baked hair may be introduced into its extremity, which will keep the anus gently protruding during the dissec- tion; or a cork, with a loop attached to it, may be intro- duced, and the mouth of the gut tied upon it;—this last method is preferable, as the intestine can then be turned in every direction:—The dissection will also be facili- tated by introducing a staff into the bladder, in order to mark out the situation of the urethra; the subject should be placed in the same position as for the lateral opera- tion of lithotomy. The muscles of the perineum consist of five pair, and a single muscle: Erector Penis, ^ Accelerator Urinje, | Qn eacn f Sphincter Transversus Perinei, } gi(je < Ani, single Levator Ani, ' { muscle. • Coccygeus, J • This dissection will be more complete, if the pelvis and lower extremities are injected; for thus the important branches of the pudic arte»y will be more easily traced. "J 3 b' ■ „ *v,;0 imnortant dissection, recollect • In commencing this »™P0™\h cru8 0f the penis, that the ^^Knds on the i J* of S.^™ f ^"on^that. the transversus pnnei %**&£&£&% SuTce" wEerf t^psit »».cles Let. The appear- te oHhese muscl will vary in different su^ects ^n those who have died weak and emac.a ed, the nores wS be pale and not very evident, while in strong mus- cu Ir men who have expired suddenly, they wi be very distinct This dissection is to be continued till all the narts between the tuberosities of the isch.a on each side, and between the tubis before, and the Up of the os coc- cygis behind, are fairly brought into view. Observe, The Erector Penis covering the crus of the penis. The Accelerator Urin* embracing the bulb and lower part of the Corpus Spongiosum of the Urethra. The Sphincter Ani, encircling the anus. The Transversus Perinei, crossing the perineum transversely. . ,. , a , 1 The Erector Penis—Arises, tendinous and ttesny, from the tuberosity of the os ischium; its fleshy fibres proceed upwards over the crus of the penis, adhering to the outer and inner edges of the ascending ramus of the os ischium, and of the descending ramus of the os pubis; —but before the two crura meet to form the body ot the penis it ends in a flat tendon, which is lost in the strong tendinous membrane that covers the corpus cavernosum. Situation: This muscle covers all the surface of the crus penis that is not in contact with bone; it arises on each side of the attachment of the crus to the bone. . 37 Use: It was formerly supposed to compress the crus penis, and thereby to propel the blood into the fore part of the corpus caveinosum; and to press the penis up- wards against the pubis. But its obvious effect must be that of drawing the crus downwards to the tuber ischii; which cannot have any influence in contributing to the erect state of the organ. Synonyma: Ischio-cavernosus;—Ischio-caverneux. 2. The Accelerator Urin.e—Arises, by a thin ten- dinous expansion, from the descending ramus of the pubis, and from the ascending ramus of the ischium, nearly as far down as the tuber;—this origin lies under the crus of the penis, and the fleshy fibres are seen com- ing out from the angle between the crus and the corpus spongiosum urethra; they proceed obliquely downwards and backwards, embrace the bulb and lower part of the corpus spongiosum, and are Inserted into a white tendinous line in the middle of the bulb of the urethra, joining there with the muscle of the opposite side. The lowermost fibres run nearly transversely, while the superior fibres are very oblique. Use: To drive the urine and semen forwards, by com- pressing the lower part of the urethra, and to propel the blood towards the corpus spongiosum and the glans penis. Synonyma: Ejaculator seminis;—Bulbo-cavernosus; —Bulbo-syndehmo-cavemeux. 3. The Transversus Perinei—Arises from the tough fatty membrane that covers the tuber ischii, immediately behind the attachment of the erector penis; thence its iibies run transversely inwards. Inserted into the central point of union where the sphincter ani touches the accelerator urinae, and where a kind of tendinous projection is formed, common to the five muscles. Use: To dilate the bulb of the urethra, to prevent the anus from being too much protruded, and to retract it when protruded. D 38 Synonyma: Transversalis penis;—Transversalis ure- thras;—Levator parvus seu externus;—Ischio-pubi-pros- tatique. There is sometimes another slip of fibres, the Trans- versus Perinei Alter, which has the same course, and is inserted into the posterior part of the bulb of the urethra. 4. The Sphincter Ani consists of two semicircular planes, which run round the extremity of the rectum, passing nearly as far out as the tuber ischii; the fibres of each side decussate where they meet, and are Inserted into the extremity of the os coccygis behind;* and before, into a tendinous point common to this mus- cle, and to the acceleratores urinae and transversi perinei. This tendinous point is worthy of remark; it seems to consist in part of an elastic ligamentous substance. Use: To close the anus, or extremity of the rectum, and to pull down the bulb of the urethra. It is in a stale of constant contraction, independently of the will, in order to prevent the contents of the rectum from escaping except at those times when we make an effort to evacuate them. Synonyma: Sphincter externus;—Sphincter cutaneus; —Coccygi-cutane'-spincter. More deeply seated than the muscles now described, we see some of the fibres of The Levator Ani.—This muscle arises from the inside of the os pubis, at the upper edge of the foramen thyroideum, from the inside of the os ischium, from the tendinous membrane covering the obturator internus and coccygeus muscles;—from the semicircular origin its fibres run down like radii towards a centre, and are Inserted in the two last bones of the os coccygis, and into the extremity of the rectum, passing within the * The sphincter ani often arises by an elastic tendon approach- ing to the mture of a ligament, from the apex of the. os coccygis. This tendon is of some length; it gives off muscular fibres, which surround the extremity of the rectum. 39 fibres of the sphincter ani, but on the outside of the longitudinal fibres of the gut itself. Situation: This muscle, with its fellow, very much resembles a funnel, st/rrounding the extremity of the rectum, the neck of the bladder, (which passes through a slit in his fibres,) the prostate gland, and part of the vesiculae seminales. Use: To draw the rectum upwards after the evacua- tion of the fasces, to assist in shutting it, and to com- press the vesiculaa seminales and other viscera of the pelvis. Synonyma: Musculus ani latus;—Levator magnus, seu internus;—Pubio-coccigi-annulaire. 6. The Coccygeus arises, tendinous and fleshy, from the spinous process of the os ischium, and covers the inside of the posterior sacro-sciatic ligament; it forms a thin fleshy belly. Inserted into the extremity of the os sacrum, and into the lateral surface of the coccygis, immediately before the gluteus maximus. Situation: It is placed betwixt the levator ani, and edge of the gluteus maximus. Use: To support and move the os coccygis forwards, and connect ft more firmly with the sacrum. Synon. Ischio-coccigien. The accelerators urinae and transversi perinei must now be removed from their insertions. They may be left suspended by their attachments to the bone. The rectum must be separated from the bladder, and pulled downwards. This dissection will expose a great part of the levator ani:—the neck and body of the bladder; —the prostate gland;—the vesiculae seminales;—the glandular anteprostatae;—part of the vas.a deferentia:— part of the ureters;—the urethra, its membranous part, its bulb, and corpus spongiosum;—the crura penis, and their origin from the ischium;—Observe, 1. The connection of the bladder and rectum, and the cellular substance interposed between them. 40 2. The prostate gland: Situated between the bladdei and rectum, surrounding the beginning of the urethra in such a manner, that one third of its thickness is situated above the urethra, and two thirds below it; its shape is somewhat pyriform, and. its consistence between carti- lage and ligament. 3. The Urethra.—The curve should be carefully observed. The urethra begins at the neck of the blad- der; it is a continuation of that part of the bladder which in the erect posture is lowest. (I.) Its beginning is embedded in the prostate gland. (2.) Its membranous part is very short,—situated between the prostate gland and bulb of the urethra:—in dissecting, remark, that there is a firm fasciculus of fibres surrounding it, and connecting it and the prostate gland to the arch of the pubis;—this fasciculus gives support to the urethra, and is termed the ligamentum triangulare urethrae. It is sometimes described as a compressor milscle of the prostate gland. (3.) The urethra then enters the corpus spongiosum. 4. The Corpus Spongiosum Urethra consists of a plexus of minute veins covered externally by a thin but u jiform tendinous sheet; it surrounds the urethra from a short distance from the bladder to its extremity: at its beginning, it forms a considerable body of a pyriform shape, termed the Bulb of the Urethra; that part of the bulb which is below the urethra, is named the pendu- lous part of the bulb. The corpus spongiosum is ex- panded at its anterior extremity, to form the glans penis. 5. The Glandule Anteprostat.e, or Cowper's Glands, are two small glands of the size of peas, situa- ted immediately before the prostate, and between the membranous part and bulb of the urethra. 6. The Vesiculae Seminales are two soft, whitish, knotted bodies, about three or four fingers-breadth in length, and one in breadth, and about three times as broad as thick; Situated between the rectum and lower part of the bladder obliquely, so that their inferior ex- 41 (remities are contiguous, and are affixed to the base oi the prostate gland, while their superior extremities are at a distance from each other, extending outwards and upwards, and terminating just on the inside of the inser- « lion of the ureters in the bladder. 7. The two Vasa Deferentia are seen running be- twixt the vesiculae seminales, and united to them and to the base of the prostate. Observe that part of the blad- der, left between these tubes, and connected by cellular substance to the rectum, which is pierced when the bladder is punctured from the latter part. 8. The Corpora Cavernosa Penis arise, on each side, by a process named the Crus, from the ramus and from the tuber ischii, ascend along the ischium and pubis, and are united immediately before the cartilaginous arch of the pubis:—they are covered by a strong, white, shining, fibrous, IigamenUD-tendinous substance, which is very elastic. Internally they are cavernous, and are separated from each other by a septum, which, from being perforated, is named Septum pecliniforme. By the union of the two corpora cavernosa, two grooves are formed:—(1.) A smaller one above, in which two arteries pass, a large vein or two betwixt them, and some large twigs of nerves. (2.) A larger groove below, whicli receives the urethra. 9. The Vesica Urinaria, or Urinary Bladder, is situated within the pelvis, immediately behind the ossa pubis, and before the rectum. It is covered on its upper and back part by a reflection of peritoneum; in front and below (where it is contiguous to the rectum), it is connected by cellular membrane to the surrounding parts. Shape, oval, but flattened before and behind, and, while in the pelvis, somewhat triangular. Divided, into the fundus or bottom, corpus or body, and cervix or neck. In the contracted state, the fundus is the broadest and roundest part, but, when distended, the cervix is broad- er than any other part. At the lop of the bladder, above the symphysis pubis, may be observed, the superior ligament of the bladder, consisting of the UracJius, a ligamentous cord, which runs up between the peritoneum and linea alba, as far as the navel,* and two of the ligamentous # cords, which are the remains of the umbilical arteries, and run up from the sides of the bladder.—The liga- mentum inferius vesicae connects the bladder to the upper and inner side of the ossa pubis- Observe the parts of the bladder not covered by peri- toneum; as they are the situations of surgical operations. These are the whole anterior surface, lying against the pubis, and rising above it, when the bladder is distended, so that it may be punctured above the pubis;—the sides, at the very lowest part of which the cut is made in the lateral operation of lithotomy, and where the viscus may be punctured from the perineum;—and the inferior sur- face, resting on the rectum, and ajlowing us to puncture from it. Observe also the direction of the axis of the bladder, in conformity with which all instruments should be introduced: this is in a line drawn from the navel to the os coccygis. 10. The entrance of the ureters into the bladder on the outside of the vesiculae seminales. 11. The rectum, following the curve of the os sacrum; and os coccygis. 12. The prepuce is a fold of skin forming a sheath or / covering for the glans penis. It makes a duplicature extending along the flat part of the glans from its basis to the orifice of the urethra, termed Fr^enum Pr.epltu. To have a more connected view of the relative situa- tion of these important parts, one side of the pelvis should now be removed, by dividing the symphysis pubis, and by sawing through the os ileum, or separat- ing it at its junction with the sacrum. By carefully re- moving all the cellular membrane, the student will be enabled more accurately to examine the situation of the parts above described. * In the foetus, it is a prolongation or production of tbe coats of the bladder. 13 OF THE VESSELS AND NERVES CONTAINED WITHIN THE PELVIS. 1. arteries. The A. Iliaca Interna, having left the trunk of the iliaca communis, passes immediately into the pelvis, where it gives off several large arteries. 1. A. Ileo-Lumbalis supplies the psoas and iliacus internus muscles. 2. A. Sacr^e Laterales, two or three small vessels which supply the sacrum, Cauda equina, and neighbour- ing parts. 3. A. Glutea, (or iliaca posterior) a very large branch, passes out of the pelvis thtfough the upper part of the sciatic notch to supply the haunch, but, in its pass- age, it gives some branches to the os sacrum, os coc- cygis, the rectum, and the muscles situated within the pelvis. 4. A. Sciatica passes out of the pelvis by the sciatic notch, and below the pyriformis muscle to supply the hip: in its passage it gives branches to the neighbouring parts. 5. A. Pudica (pudenda communis or interna) is the branch of the internal iliac, which is more immediately destined to supply the parts of generation, perineum, and lower part of the rectum: it goes out of the pelvis above the superior sacro-sciatic ligament, twists round it, and re-enters the pelvis above and before the inferior sacro- sciatic ligament: it then descends on the inside of the tuber ischii, ascends on the inner surface of the rami of the ischium and pubis; and, reaching the root of the penis, divides into two branches. (1.) A. Perinei, a branch, which, after giving twigs to the bulb of the urethra and neighbouring muscles, enters the crus of the penis, and subdivides into branches which pass to both extremities of the crus. u (2.) A. Dorsalis Penis, passes under the arch of the pubis, runs along the dorsum penis, and is distributed to the integuments. In its course the pudic artery gives off many branches. (1.) While in the pelvis, it gives twigs to the bladder, prostate and rectum. (2.) A. H^emorrhoidales Externa come from the pudic while passing by the anus. (3.) A. Transversa Perinei, following the course of the transversus perinei muscle. 6. A. Obturatrix descends on the inside of the psoas muscle, passes through the foramen in the obtura- tor ligament to the muscles on the inside of the thigh. 7. A Hypogastrica, which in the foetus sends off the umbilical artery, is in the adult continued only to the side of the bladder, to which it gives branches; in the female, it enters the neck of the uterus, and gives branches to the vagina. You must not expect to meet with uniformity in the distribution of these vessels in all subjects; sometimes the gluteal and pudic arteries come off by one trunk, some- times the pudic and sciatic, &c. &c. 2. VEINS. The veins attend the arteries and their ramifications; they unite to form the internal iliac vein, except the veins from the rectum, named Hcemorrhoidales, which ascend along its back part to join the inferior mesen- teric vein. 3. NERVES. The nerves met with in this dissection consist of numerous twigs sent off from the lumbar and sacra] nerves to supply the parts about the pelvis. But, in this dissection, we meet with three pair of 45 large nerves, which have their course through the pelvis, and pass to the thigh. 1. Course of the Anterior Crural Nerve while in the pelvis. The anterior crural nerve is formed by branches of the first, second, third, and fourth lumbar nerves; at its origin, it lies under the psoas magnus, and, as it descends, passes betwixt the psoas magnus and iliacus internus, till, having passed under Poupart's liga- ment, it emerges from betwixt those muscles, and ap- pears on the outer side of the inguinal artery. 2. Course of th<* Obturator Nerve within the pelvis. This nerve is formed by branches of the second, third, and fourth lumbar nerves: it lies under the internal bol- der of the psoas magnus, descends into the pelvis, and goes obliquely downwards, to accompany the obturator artery through the thyroid hole. 3. Course of the Great Sciatic Nerve within the pelvis. This nerve arises by branches from the fourth and fifth lumbar, and three'first sacral nerves, which unite together to form the largest nervous trunk in the body. The nerve passes betwixt the pyriformis and gemini, and thus escapes from the back part of the pelvis by the sciatic notch. Sometimes one of the branches goes through the pyriformis, and joins the sciatic trunk at the back of the pelvis. OF THE SCROTUM. Tuc scrotum consists externally of a loose, rugose skin, and internally of condensed cellular membrane, which have been described as a muscle, under the name of Dartos. On dividing the anterior part of the scrotum, on either side of the raphe, we expose, 1. The Testicle, a gland of an oval flattened form, covered by the tunica vaginalis, having on its upper edge an appendase termed Epididymis. 46 2. The Spermatic Chord, connecting the testicle to the abdominal ring. It consists of, a, The spermatic artery, a branch of the aorta; this divides into several branches, which enter the upper edge of the testicle. b, The spermatic veins, which form a plexus, that terminates in the abdomen, in a single vein. c, The spermatic nerves, which come from the inter- costal and lumbar nerves. d, The vas deferens, or excretory duct of the testicle; ■—-this is situated in the back part of the chord, and is distinguished by its firm cartilaginous feel. . e, The spermatic absorbents. /, These parts are all connected by cellular membrane, and by the tunica vaginalis, which is covered by a thin muscle * g, The cremaster;—this arises from the obliquus de- scendens internus, and is lost on the tunica vaginalis. CHAP. III. DISSECTION OF THE ORGANS OF GENERA- TION IN THE FEMALE. Previous to the dissection, it will be proper to exa- mine the external parts. The Mons Veneris is a rounded prominence, cover- ed with htirs after puberty, situated at the lower part of the belly, and arising on each side gradually from the groins; it consists of the common integuments, with an additional quantity of cellular and adipose sub- stance, and lies upon the fore part of the ossa pubis. From the inferior part of the mons'veneris arise The Labia Externa, called also the labia or alae pudendi: they are continued downwards.and forwards in the direction of the symphysis pubis, and terminate in the perineum anterius: they consist of integuments, cellular substance, and fat,—are thicker above than be- low,—and are red and vascular on their inner side. The places where the labia are joined to each other above and below, are termed Commissures. The longitudinal cavity or fissure, situated betwixt the labia, and extending from the mons veneris to the perineum anterius, is sometimes called the Sinus Pudo- ris; it is broader above than below, and contains seve- ral other parts. On separating the labia, we see, immediately below the superior commissure, The Clitoris, a red projecting body, situated below the arch of the pubis, and partly covered by its Pre- 48 puce: The prepuce is a fold of skin, continued from the inm.r surface of the labia so as to cover the superior and lateral part of the clitoris.—The clitoris resembles th< penis of the male, and consists of two cavernous bodies; these, however, cannot be traced in this stage of the dissection. That part of the body which forms an obtuse projection externally, is called the Glans. The Perineum Anterius is that portion of the soft parts which extend from the inferior commissure of the labia to the anus. The Perineum Posterius is the space betwixt the anus and point of the os coccygis. The Nymphs are two prominent doublings of the in- teguments, extending from the glans of the clitoris to the sides of the vagina. Their external side is continued from the inner surface of the labia, and frojfn the pre- pure of the clitoris, while their internal surface seems immediately continued from the fine, thin, vascular in- teguments covering roe clitoris itself; they are spongy, and consist internally of cellular and adipoge substance. A li'tle lower, we^see the orifice of the urethra; it is situated below the clitoris and arch of the pubis, betwixt the nymphae, and above the orifice of the vagina; it con- sists of a small rising prominence like a pea, in the centre of which is a small opening or hole. On each side of the orifice of the urethra, we meet generally wi'h the orifices of two mucous glands, which by some are named Cowper's Glands of the female. On separating the lower part of the labia pudendi, we see the Vestibulum, a space which leads to the vagina; it is bounded behind, by the canuncnlae mvrliformes, or by the hymen in virgins; on th% sides, by the labia; before, by the perineum anterius, which projects forwards, forming a kind of valve, so that a little pit is formed behind it, which is termed Fossa Navjcularis, or Scaphoides. The Hymen, or Circulus Membranosus, is a thin and extensile membrane, formed by a doubling of the inner 49 surface of the veslibulum and lower part of the vagina, the entrance of which is by its means much contracted in virgins. It generally has an opening in its upper part, but it is completely ruptured in the first coitus: its form is various, frequently semilunar, and then its base is attached to the vestibulum, while its cornua extend upwards as far as the sides of the urethra. After the destruction of the hymen, in married women, we see some irregular projections marking the orifice of the vagina, and termed Caruncul*: Myrtiformes: they are generally supposed to be the remains of the hymen, but are not exactly in the same situation. Behind these is the Vagina, or canal leading to the uterus; at the extremity of which may be felt projecting the Os Internum Uteri, or Os Tince, but it cannot be seen without dissection. The skin should be now divided on the side of the right labium, and the dissection should be carried from the groin to the side of the anus; the cellular membrane must be carefully removed, in order to expose the follow- ing parts. We find the Clitoris consisting of two spongy bodies/ termed Crura, which unite and form the body. The erus of each side is a cavernous body, arising from the ramus and upper part of the tuberosity of the ischium. continued along the ramus of the os pubis, and uniting with its fellow opposite to the symphysis pubis. The body formed by the crura does not extend upwards, but forms a curve downwards towards the urethra; it is divi- ded internally by the Sectum Pectiniforme, and is at- tached to the symphysis pubis by a suspensory ligament; it is invested by a ligamentous membrane. The muscles which are met with in this dissection consist of four pair, and two single muscles. The Erector Clitoridis, Transversus Perinei, Levator Ani, Coccygeus, E on each side. 50 The Sphincter Ani, ) . , . Spincter Vagina, \ two s,nSle musc,es- 1. The Erector Clitorides, arises, fleshy and ten- dinous, from the tuber ischii, from the inside of the ramus of the os ischium, and from the ramus of the os pubis: It passes over the crus of the clitoris, and, becoming tendinous, is lost upon it. Use: To draw the clitoris downwards and forwards, and, by compressing it, to propel the blood. Synonyma: First muscle of the clitoris;—Ischio- cavernosus;—Ischio-clitoridien. Arising from the same point, and surrounded by much cellular membrane, we find, 2. The Transversus Perinei.—Its origin is the same as in the male. It is inserted into a ligamentous substance in the peri- neum anterius, at the point where the sphincter ani and sphincter vaginae meet. This ligamentous or tendinous substance deserves at- tention. Here, as in the male, it is the point of union into which muscles are inserted. Use: To sustain the perineum. 3. Surrounding the extremity of the vagina, and a small part of the vestibulum, we find the Sphincter Va- ginje; it arises, anteriorly, from the crura of the cli- toris on each side; it surrounds the orifice of the vagi- na, and is Inserted into the ligamentous point of the perineum, where the fibres of each side meet, and are connected with those of the transversi perinei, and with the sphinc- ter ani. Use: To contract the mouth of the vagina, and com- press the plexos retiformis. Synonyma: Constrictor cunni;—Second muscle of the clitoris;—Anulo-syndesmo-clitoridien. 4. The Sphincter Ani exactly resembles the same muscle in the male. 5. The Levator Ani resembles the same muscle of .31 the male; it surrounds the sides of the vagina in part, and consequently assists in constricting and supporting it. 6. The Coccygeus is longer than in the male, from the greater transverse diameter of the inferior aperture of the pelvis. Under the fibres of the sphincter vaginae, you will find the Plexus Retifor.mis, or Corpus Cavernosum Vagina, a spongy body, consisting of cellular substance, interwoven with a number of convoluted blood-vessels; it arises from the sides of the clitoris, passes on each side of the extremity of the vagina, is not continued completely around it, but is lost on its posterior part. The Vagina is the canal leading from the vestibulum to the uterus. It lies betwixt the rectum and inferior surface of the urethra and bladder, and is connected to them by cellular membrane. It is composed of fibrous substance, partly ligamentous, and perhaps in part mus- cular; its inner surface is rugose, vascular, and occu- pied by mucous glands. On slitting it up, we see, at its posterior extremity, the Os Uteri, a rounded projec- tion, with a transverse fissure. The Uterus, or Womb.—This organ is best seen from the cavity of the abdomen. It is situated betwixt the bladder and rectum, to both of which it is connect- ed by reflections of peritoneum; it is of the shape of a pear, somewhat flattened, inwardly hollow, outwardly of a whitish colour, and of a firm consistence. The broad upper part of the womb is called the Fundus Uteri, the narrower part is ramed the neck, or Cervix Uteri, and the intermediate part its Body. The uterus has four ligaments, two on each side: 1. The Ligamentum Teres, or Round Ligament. It is a round long cord, extending from the side of the fundus uteri, and passing through the abdominal ring, to be lost in the groin. The Ligamentum Latum, or Broad Ligament, is a broad fold of peritoneum, reflected from the body of the uterus, and connecting it on the sides of the pelvis. The 52 uterus, together with its two broad ligaments, divide; the pelvis into an anterior and posterior half; in the former of which is the bladder, and in the 'atter the rectum. The duplicature of the broad ligament en- closes the Fallopian tube, ovary, and round ligament. The Fallopian Tubes are two. Each tube is con- tained in the upper part of the doubling of the broad ligament; it goes out from the fundus of the womb, and is a slender hollow tube: its outer end is curved down- wards and backwards, and terminates by a broad fring- ed extremity, termed Morsus Diaboli, or the Fimbriae. —This broad extremity is connected to the next pair of organs. The Ovaria are two small oval bodies, while and flat, situated by the sides of the uterus, and inclosed in the posterior fold of the broad ligament behind the Fallopian tube; each ovarium is connected to the fun- dus uteri by a short round ligament. The Bladder is situated before the uterus, and is described in the preceding chapter. The Urethra is short in females, and near the blad- der is surrounded by a spongy fleshy substance,—is con- nected to the cartilaginous arch of the pubis by the liga- mentum inferius vesicas. The Ureter descends from the kidneys over the psoas muscle; it runs for some space betwixt the bladder and vagina, and at last perforates the bladder near the neck. The Rectum lies behind the uterus.—See the preced- ing chapter. To obtain a more satisfactory knowledge of the rela- tive situation of the parts, the left side of the pelvis should be removed as in the male, and the parts examined in that situation. 53 CHAP. IV. DISSECTION OF THE THIGH. SECT. I. OF THE ANTERIOR PART OF THE THIGH. § 1. OF THE FASCIA, CUTANEOUS VESSELS, AND NERVES. Beneath the integuments common to every part of the body, you will find a strong fascia, or aponeuro- tic expansion, investing the whole thigh. This expan- sion is named the Fascia Lata Femoris; it consists partly of tendinous, partly of ligamentous fibres; it sur- rounds and covers all the muscles, and sends septa or partitions between them:—It is very strong, smooth, and tendinous on the outer part of the thigh; but, on the anterior and inner part, it is very thin, and of a cellu- lar texture. Therefore if you wish to demonstrate the whole extent of this facia, it should be first exposed on the outside of the thigh, and the dissection should be continued very carefully inwards on the fore part, where it is with difficulty distinguished from the common cel- lular membrane. But, in removing the common integuments from the fore part of the thigh, it will be proper to attend to some parts which are situated above the fascia. 1. The Vena Saphena Major is seen running up in the inside of the knee and thigh. At first it lies very superficial, betwixt the skin and fascia, and involved in the intermediate cellular membrane. As it aseends, it E 2 54 is gradually enveloped by the fibres of the fascia, and then sinks beneath it to join the femoral vein about an inch below Poupart's ligament:—In its course, it is join- ed by several cutaneous veins. 2. Immediately under the true skin, and more super- ficial than the veins or nerves, you may occasionally per- ceive the Lymphatic Vessels running, likes lines of a whitish colour, to enter the inguinal glands: they are more numerous on the fore part, than on the outside of the thigh. 3. Several Cutaneous Nerves are seen ramifying above the fascia. They all come from the lumbar or anterior crural nerve, pierce the fascia about the lower part of the abdomen and groin, and are distributed to the groin, and integuments on the fore part of the thigh. The fascia may now be exposed distinctly. Observe how extensively it arises from the bones, tendons, and ligaments. On the anterior and superior part of the thigh, it arises from Poupart's ligament,* from the os pubis, from the descending ramus of that bone, and from the ascending ramus and tuberosity of the ischium;—behind, and on the outside, from the whole spine of the ileum, and from the sacro-sciatic ligaments. It receives a num- ber of fibres from a muscle belonging to it, viz. the ten- sor vaginae femoris, and from the tendon of the gluteus maximus;:—it passes down over the whole thigh, is firmly fixed to the linea aspera, to the condyles of the femur, and to the patella,—and is continued over the knee, to be attached to the heads of the tibia and fibula, after which it forms the fascia of the leg. * At this part the fascia of the thigh is covered by a more su- perficial expansion, which lies over the lower part of the aponeu- rosis of the external oblique muscle, completely covers the crur:il arch, and descends some little way beyond the bend of the thigh. It has been called the superficial fascia. It covers the absorbent glands, &c. at the groin, and often consists of several layers sepa* rated by three glands and adipose substance. It has rather the appearance of condensed cellular membrane, than of a tendinous fascia. 53 On the upper and anterior part of the thigh, there is a slight hollow, where the great vessels descend under the crural arch. The fascia lata forms just on the out- side and upper part of this, a crescent-shaped fold, call- ed its semilunar edge, which is strongly connected to the crural arch, and sometimes contributes to the strangula- tion in femoral hernia. The fascia should now be dissected back; and in lift- ing up the thicker part of it, which covers the outside of the thigh, you may observe that it is composed of two laminae of fibres: The fibres of the outer lamina run in circles round the thigh, while those on the inside, which are stronger, and more firmly connected, run longitudi- nally. § 2. MUSCLES SITUATED ON THE FORE PART AND INSIDE OF THE THIGH. These are nine in number. 1. The Tensor Vagina Femoris—Arises, by a nar- row, tendinous, and fleshy origin, from the external part of the anterior superior spinous process of the os ileum: it forms a considerable fleshy belly. Inserted into the inner side of the great, fascia, where it covers the outside of the thigh, and a little below the trochanter major. Situation: Its origin lies between the origin of the sartorius, and the anterior fibres of the gluteus medius, betwixt which muscle it descends; it does not lie exter- nal to the fascia of the thigh, but is inclosed in a dupli- cature of it; its insertion lies anterior to that part of this membrane which arises from the tendon of the gluteus maximus. Use: To stretch the great fascia of the thigh, to assist in the abduction of the thigh, and in its rotation in- wards. Synonyma: Musculusfasciae latae;—Fascialis;—Mem- branous;—Ilio-aponeuri-femoral. 56 2. The Sartorius—Arises, by short tendinous fibres, from the anterior superior spinous process of the os ileum, soon becomes fleshy, extends obliquely across the thigh, and passes behind the inner condyle. Inserted, by a broad and thin tendon, into the inner side of the tibia, immediately below its anterior tubercle. Situation: Its origin lies between that of the tensor vaginae femoris, and the outer attachment of Poupart's ligament, and above the anterior fibres of the iliacus in- ternus. It lies before the muscles of the thigh, crossing them like a strap about two inches in breadth: it runs down for some space upon the rectus femoris, passes over the vastus internus, and then over the triceps adductor longus. At the lower part of the thigh, it runs between the tendon of the triceps adductor magnus, and that of the gracilis.—In all this course, it is firmly bound down by the common fascia of the thigh. It is inserted above tendons of the gracilis and semitendinosus, over which it sends an aponeurotic expansion. Use: To bend the leg obliquely inwards on the thigh, and to bend the thigh forwards. Synonyma: Longissimus femoris;—Ilio-creti-tibial. 3. The Rectus Femoris—Arises, by a strong ten- don, from the inferior anterior spinous process of the os ileum; and, by another strong tendon, from the dorsum of that bone a little above the acetabulum, and from the capsular ligament of the hip joint. The two tendons soon unite, and send off a large belly, which runs down over the anterior part of the thigh, forming a complete penniform muscle, and terminates in a flat but strong tendon, which is Inserted into the upper extremity of the patella; where a thin aponeurosis is sent from it over the fore part of that bone, to terminate on the strong ligament which connects the lower part of the patella to the tibia, and is called Ligamentum Patellae. Situation: To expose the tendinous origins of this muscle, the origins of the sartorius and tensor vaginae fe- 57 moiis must be raised; and then that tendon, which pro- ceeds from the inferior spinous process, may be seen partly covered with the outer edge of the iliacus inter- nus, while the other tendon is exposed by raising the an- terior and inferior fibres of the gluteus minimus. The fleshy belly, at its uppermost part, is covered by the sar- torius, and, to allow that muscle to slide over it, is tendinous; below this, it is situated superficially, imme- diately under the fasciae, runs down over the vasti and crtmeus; and on its posterior surface, where it is in contact with those muscles, it is tendinous. Its insertion lies betwixt the two vasti. Use: To extend the leg on the thigh, and to bend the thigh on the pelvis; to bring the pelvis and thigh for- wards to the leg. Synonyma: Rectus cruris;—Rectus anterior;—Gra- cilis anterior;—Uio-rotulien. Under the rectus, and partly covered by it, there is a large mass of flesh, which, at first sight, appears to form but one muscle. It may, however, be divided into three; the separation on the external surface is not generally very evident, but, by following the course of the vessels which enter this mass, and by cutting through, perhaps, a few fibres externally, you will discover the line of se- paration; and this separation, as you proceed deeper with your dissection, will become very distinct. The three muscles are named vastus externus, vastus internus, and crurjeus: at the upper and middle parts of the thigh, they may be separated very distinctly; but for two or three inches above the condyles, they are connected inseparably. 4. The Vastus Externus—Arises, tendinous and fleshy, from the anterior surface of the root of the tro- chanter major, from the outer edge of the linea aspera, its whole length,—from the oblique line running to the external condyle,—and from the whole external flat surface of the thigh bone. The fleshy fibres run oblique- ly forwards. Inserted into the external suiface of the tendon of the 58 rectus cruris, and into the side of the patella:—Part of it ends likewise in an aponeurosis which passes over the side of the knee to the leg, and is firmly fixed to the head of the tibia, closely adhering to the capsule of the knee-joint. Situation: This muscle forms the large mass of flesh on the outside of the thigh ; it is in part concealed by the rectus: on its outer surface, it appears tendinous at its upper part, and fleshy lower down; on its internal surface, it is fleshy above, and tendinous below;—it laps over the outside of the cruraeus, where it arises from the linea aspera; it is situated anterior to the tendinous in- sertion of the gluteus maximus, and to the origin of the short head of the biceps flexor cruris. Use: To extend the leg, or to bring the thigh forwards upon the leg. 5. The Vastus Internus—Arises, tendinous and fleshy, from the fore part of the root of the trochanter minor, from all the upper edge of the linea aspera, from the oblique line running to the inner condyle, and from the whole internal surface of the thigh bone. Its fibres ■descend obliquely downwards and forwards. Inserted into the lateral surface of the tendon of the rectus cruris, and into the side of the patella; it also sends off aponeurosis, which is continued down to the leg, and covers the inner part of the capsule of the knee. Situation: This muscle embraces the inside of the fe- mur in the same manner as the last described muscle does the outside, but it is much smaller;—it is also in part covered by the rectus. At its upper part the sartorius passes over it obliquely; it laps over the cruraeus, and is separated from it with greater difficulty than the vastus externus is. Where it arises from the root of the tro- chanter, it lies anterior to the common tendon of the ilia- cus internus and psoas magnus; and where it arises from the linea aspera and oblique line, it is situated anterior to, and in contact with the insertions of the pectineus and triceps adductor femoris. Like the vastus externus, its 59 outer surface is tendinous above, while below its inner surface is tendinous, and the fleshy fibres pass obliquely from the one tendinous expansion to the other. Use: Same as the last. 6. The Crur.eus, or Cruralis—Arises, fleshy, from between the two trochanters of the os femoris, from all the fore part of the bone, and from the outside as far back as the linea aspera; but from the inside of the bone it does not arise, for between" the fore part of the femur and the inner edge of the linea aspera, there is a smooth plain surface, of the breadth of an inch, extending nearly the whole length of the bone, from which no muscular fibres arise. Inserted into the posterior surface of the tendon of the rectus, and upper edge of the patella. Situation: The principal part of this muscle is lap- ped over, and concealed, by the bellies of the two vasti; and the small part, which is seen projecting between the anterior edges of those muscles, lies behind the belly of the rectus cruris. Use: Same as the last. Synonyma: These three muscles are described by Du- mas as a triceps, which he names Tri-femoro rotulien. 7. The Gracilis arises, by a broad thin tendon, from the lower half of that part of the os pubis which forms the symphysis, and from the inner edge of the descend- ing ramus:—It soon grows fleshy, and forms a belly, which, becoming narrower as it descends, terminates in a tendon, which passes behind the inner condyle of the thigh bone, and is reflected forwards, to be Inserted in the inside of the tibia. Situation: It arises from the os pubis on the inside of the origins of the triceps adductor femoris, lying betwixt it and the cros penis; from the pubis to the knee it runs immediately under the integuments on the inside of the thigh; it is inserted below the tendon of the sartorius, and above that of the semitendinosus. 60 Use: To bring the thigh inwards and forwards, and to assist in bending the leg. Synonyma: Gracilis interior;—Rectus interior;—Sous- pubi-creti-tibial. S. The Pectinalis. Arises, fleshy, from that ridge Of the os pubis which forms the brim of the pelvis, and from the concave surface below the ridge: It forms a thick flat belly. Inserted, by a flat tendon, into the linea aspera, imme- diately below the lesser trochanter. Situation: Its origin lies on the inside of the belly of the psoas magnus, where that muscle slides over the brim of the pelvis, and on the outside of the origin of the ad- ductor longus:—It descends between the lower edge of the psoas, and the upper edge of the adductor longus: and it is inserted between these two muscles, and pos- terior to the origin of the vastus internus. Use: To bend the thigh forwards, to move it inwards, and to perform rotation, by turning the toes outwards. Sxjnonyma: Pectinaeus—Pubio-femoral. 9. The Triceps Adductor Femoris consists of three distinct muscles, which, passing from the pelvis to the thigh, lie in different layers upon one another, and have nearly the same action. (1.) The Adductor Longus. Arises, by a short strong tendon, from the upper and inner part of the os pubis, near its symphysis;—forms a large triangular belly, which, as it descends, becomes broader, but less thick. Inserted, tendinous, into the middle parts of the linea aspera, occupying rather more than one third of its length. Situation: It arises betwixt the pectinalis and gracilis and above the adductor brevis:—The upper edge of its belly ranges with the lower edge of the pectinalis; and its insertion lies posterior to the origin of the vastus internus, and anterior to the insertion of the adductor magnus. til Synonyma: Adductor primus;—Triceps primus;—long head of the triceps;—Spino-bubio-femoral. (2.) The Adductor Brevis—Arises, fleshy and ten- dinous, from the os pubis, between the lower part of the symphysis pubis, and the foramen thyroideum:—it forms a fleshy belly. Inserted, tendinous, into the upper third of the linea aspera. Situation: Its origin lies under the origins of the pec- tinalis and adductor longus, and on the outside of the ten- don of the gracilis:—Its belly descends behind the belly of the pectinalis, and behind the superior fibres of the adductor longus; and its largest part is therefore con- cealed, but a small part appears between the lower edge of the pectinalis, and upper edge of the adductor longus: —It is inserted behind those muscles, but before the ad- ductor magnus. Synonyma: Triceps secundus;—Adductor secundus; —Short head of the triceps;—Sous-pubio-femoral. (3.) The Adductor Magnus—Arises, principally fleshy, from the lower part of the body, and from the descending ramus of the os pubis, and from ihe ascending ramus of the ischium, as far as the tuberosity of that bone. The fibres run outwards and downwards, having various degrees of obliquity. Inserted, fleshy, into the whole length of the linea as- pera, into the oblique ridge above the internal condyle of the os femoris, and, by a roundish long tendon, into the upper part of that condyle. Situation: This large muscle arises behind and below the two other adductors; it forms a flat partition betwixt the muscles on the fore and back parts of the thigh; its insertion lies behind the insertions of the long and short adductors, and on the inside of the tendinous insertion of the gluteus maximus, and of the origin of the short head of the biceps flexor cruris: the superior fibres which cross the thigh transversely run along the lower edge of the nuadratus femoris. F 62 Use: To approximate the thighs to each other;—to roll them outwards. The two anterior heads will bend the thigh; the posterior will extend it, if it be bent forwards. Synonyma: Adductor tertius et Adductor quartus;— Triceps tertius; Great head of the triceps; Ischio-pubio- femoral. § 3. arteries, veins, and nerves on the fore pari and inside of the thigh. 1. arteries. The Femoral Atrery may be said to pass along the inside of the thigh, where it emerges from under Poupart's ligament; it lies cushioned on the fibres of the psoas mag- nus, is called the inguinal artery, and is very nearly in the mid space between the angle of the pubis, and the an- terior superior spine of the ileum, nearer however by a finger's breadth to the former; having left the groin, it assumes the name of Femoral, and in its course down the thigh, runs over the following muscles:—The pectinalis, part of the adductor brevis, where that muscle projects betwixt the pectinalis and adductor longus; the whole of the adductor longus, and about an inch of the adductor magnus: It then slips betwixt the tendon of the adductor magnus and the bone, and, entering the ham, becomes the Popliteal artery. To find the artery in any part of its course from the crural arch to the tendinous opening, turn out the foot, ascertain the place of that vessel at the crural arch according to the above description, and then draw a straight line downwards.—In this course, it has the belly of the vastus internus situated on its outside; it lies between the origin of that muscle, and the tendinous insertion of the muscles over which it crosses; and there is a strong interlacing of the tendinous fibres, forming a deep groove for the artery; it is also invested by a firm sheath, which consists of condensed cellular membrane, 63 intermixed with some tendinous fibres:—For some inches below Poupart's ligament, this artery is on its fore part only covered by cellular substance, absorbent glands, and the general fascia of the thigh; but, meeting with the in- clined line of the sartorius, it is, during the rest of its course, covered by that muscle. It perforates the tendon of the adductor magnus, at the distance of rather more than one third of the length of the bone from its lower extremity. Observe, that in popliteal aneurism the artery maybe taken up either at the upper or inner, the lower or outer, margin of the Sartorius, or immediately behind that _ muscle: of which situations the first is the best, the ^ second next best, and the third by far the leasj^eli- gible. branches of the femoral artery.* The A. Profunda comes off from the femoral artery at the distance of three or four inches from Poupart's ligament; it is nearly as large as the femoral itself, runs down for some little way behind it, and terminates in three or four branches, which, perforating the triceps adductor, are named Arteria Perforantes. These, ramifying in every direction, supply all the great mass of muscles situated on the back part of the thigh, and inosculate largely with the sciatic, gluteal, and obturator arteries. Th in other words, to bend the ankle joint. 79 Synonyma: Tibio-sus-metatarsien. 2. Extensor Longus Digitorum Pedis—Arises^ tendinous and fleshy, from> the outer part of the head of the tibia; from the head of the fibula; from the an- terior angle of the fibula almost its whole length; and from part ofthe smooth surface be.ween the anterior and internal angles; from a small part of the interosseous ligament;'from the fascia and intermuscular ligaments. Below the middle of the leg, it splits into four round tendons, which pass under the annular ligament, become flattened, and are Inserted into the root of the first phalanx of each of the four small toes, and expanded oyer the upper side of the toes as far as the root of the last phalanx. Situation: This muscle also runs entirely superficial; it lies between the tibialis anticus and peroneus longus, being firmly connected to them by intermuscular liga- ments; but, at the lower part ofthe leg, it is separated from the tibialis anticus by the extensor pollicis lon- gus, and from the peroneus longus by the peroneus brevis. Use: To extend all the joints of the four small toes: —to bend the ankle joint. Synonyma: Peroneo-tibi-sus-phalangettien commun. Peroneus Tertius—Arises, fleshy, from the ante- rior angle of the fibula, and from part of the smooth surface between the anterior and internal angles, extend- ing from below the middle of the bone downwards to near its inferior extremity; sends its fleshy fibres for- wards to a tendon, which passes under the annular liga- ment, in the same sheath as the extensor digitorum lon- gus, and is Inserted into the base of the metatarsal bone that sup- ports the little toe. Situation: The belly is inseparably connected with the extensor longus digitorum, and is properly the outer part of it; it lies between that muscle and the peroneus bre- vis. The tendon runs down on the outside of that ten- 80 don of the extensor longus digitorum which goes to the little toe. The whole of the muscle is superficial. Use: To assist in bending the foot. Synonyma: Nonus Vesalii;—Petit-peroneosus-meta- tarsien. 4. Extensor Proprius Pollicis Pedis—Arises, ten- dinous and fleshy, from part ofthe smooth surface between the anterior and internal angles of the fibula, and from the neighbouring part of the interosseous ligament, ex- tending from some distance below the head ofthe bone to near i's inferior extremity; a few fibres also arise from the lower part of the tibia;—the fibres pass obliquely downwards and forwards into a tendon, which, inclining inwards, passes over the fore part of the astragalus and os naviculare, and over the junction of the os cunei- forme internum and os cuneiforme medium, to be Inserted into the base of the first and of the second phalanges of the great toe.* Situation: The belly is concealed between the tibialis anticus and extensor fligitorum longus, and cannot be seen till those muscles are separated from one another; —the tendon is superficial, running between the tendons of those two muscles. Use: To extend the great loe and to bend the ankle. Synonyma: Extensor longus pollicis;—Peroneosit6- phalanginien du pouce. 5. The Peroneus Longus—Arises, tendinous and fleshy, from the fore part and outside of the head of the fibula, and from the adjacent part of the tibia, from the external angle of the fibula, and from the smooth surface between the anterior and external angles as far down as owe third of the length of the bone from its lower extre- mity; also from the fascia of the leg and intermuscular ligaments. The fibres run obliquely outwards into a tendon, which.passes behind the outer ankle, through a * N. B. It is to be understood, that the great toe has only two phalanges. 81 groove in the lower extremity of the fibula: is then re- flected forwards through a superficial fossa in the outside of the os calcis, passes over a projection, runs in a groove in the os cuboides, passes over the muscles in the sole of the foot, and is Inserted, tendinous, into the outside of the base ofthe metatarsal bone that sustains the great toe, and into the os cuneiforme internum. Situation: The belly is< quite superficial; it lies be- tween the outer edge of the extensor longus digitorum and the anterior edge of the soleus, connected to both by intermuscular ligaments. The tendon is superficial where it crosses the outside of the os calcis, but, in the sole of the foot, is concealed by the muscles situated there, and will be seen in the dissection of that part. Use: To extend the ankle joint, turning the sole of the foot outwards. Synonyma: Peroneus maximus, vulgo, Peroneus pos- terior;—Peroneus primus, seu posticus;—Tibi-peroneo- tarsien. 6. The Peroneus Brevis—Arises, fleshy, from the outer edge of the anterior angle of the fibula, and from part of the smooth surface behind that angle; beginning about one third down the bone, and continuing its adhe- sion to near the ankle; from the fascia of the leg, and from the intermuscular ligaments:—The fibres run ob- liquely towards a tendon, which passes through the groove of the fibula behind the outer ankle, being there inclosed in the same ligament with the tendon of the peroneus lor.gus, then through a separate groove on the outside of the os calcis, and is Inserted into the external part of the base of the me- tatarsal bone that sustains the little toe. Situation: This muscle arises between the extensor longus digilorum and peroneus longus; its belly is over- lapped, and concealed by the belly of the peroneus lon- gus; but, as it continues fleshy lower down, it is seen» above the ankle, projecting on each side of the tendon of 82 that muscle: Below, it is separated from the peroneus tertius by that projection of the fibula which forms the outer ankle, and which is only covered by the common integuments. The tendon, where it passes through the groove of the fibula, lies under that ofthe peroneus lon- gus, i. e. nearer the bone; but it is soon seen before it, and, on the side of the os calcis, runs above it. Use: Same as that of the peroneus longus. Synonyma: Peroneus medius vel anticus;—Peroneus secundus;—Peroneus brevis;—Grand peroneosus-meta- tarsien. MUSCLES ON THE UPPER PART OF THE FOOT. Only one muscle is found in this situation. Extensor Brevis Digitorum Pedis—Arises, fleshy and tendinous, from the anterior and upper part of the os calcis, from the os cuboides, and from the astraga- lus; forms a fleshy belly, divisible into four portions; these send off four slender tendons, which are Inserted, the first tendon, into the first phalanx of the great toe; and the other three into all the small toes ex- cept the little one, uniting with the tendons of the ex- tensor digitorum longus, and being attached to the upper convex surface of all the phalanges. Situation: The belly of this muscle lies under the tendons of the extensor digitorum longus and peroneus brevis; it is not, however, concealed, but is seen pro- jecting behind and betwixt these tendons; it assists in forming the tendinous membrane which invests tke upper surface of all the phalanges of the toes. Use: To extend the toes. Synonyma: It is sometimes described as two muscles, the extensor brevis pollicis pedis, and ex»ensor brevis digitorum pedis:—Ca'caneo-sus-phalangettien commun. S3 OF THE VESSELS AND NERVES IN THE FORE PART OF THE LEG AND FOOT. 1. ARTERIES. Arteria Tibialis Antica.—The anterior tibial ar- tery passes from the ham betwixt the inferior edge of the popliteus, and the superior fibres of the soleus, and then through a large perforation in the interosseous liga- ment, to reach the fore part of the leg; this perforation is much larger than the size of the artery, and is filled up by the fibres of the musculous tibialis posticus, which may be thus said to arise from the fore part of the tibia. —The artery then runs down close upon the middle of the interosseous ligament, between the tibialis anticus and extensor proprius pollicis; below the middle of the leg, it leaves the interosseous ligament, and passes gra- dually more forwards; it crosses under the tendon of the extensor proprius pollicis,* and is then situated be- tween that tendon, and the first tendon of the extensor longus digitorum: at the ankle it runs over (he fore part ofthe tibia, being now situated more superficially: then over the astragalus and os naviculare, and over the junc- tion of the os cuneiforme internum and medium; cross- ing under that tendon of the extensor brevis digitorum which goes to the great toe.—Arriving at the space be- tween the bases of the two first metatarsal bones, it plunges into the sole of the foot, and immediately joins the plantar arch. BRANCHES. 1. A Recurrens, which ramifies over the forepart of the knee, inosculating with the articular arteries. 2. Numerous twigs to the tibialis antiVus, extensor pol- licis, and other muscles on the fore part of the leg. * It is crossed by that tendon just above the lower head of the tibia, while under the annular ligament. 84 3. A. Malleolaris Interna ramifies over the innei ankle, and inosculates with the perineal and posterior tibial arteries. 4. The External Malleolar ramifies over the outer ankle. 5. The Tarsal and Metatarsal Arteries are two small branches which cross the tarsal and meta- tarsal bones, and pass obliquely to the outer edge of the foot. From the tarsal or metatarsal artery come off the In- terosseal Arteries, which supply the interosseal spaces, and the back part of the toes. 6. A large branch comes off from the anterior tibial, where it is about to plunge into the sole of the foot; it runs along the space betwixt the two first metatarsal bones, and that the anterior extremity of those bones, bifurcates into, (1.) A. Dorsalis Hallucis, a considerable branch which runs on the back part of the great toe. (2.) A branch which runs on the inner edge of the toe next to the great one. 2. VEINS. The Anterior Tibial Vein consists of two branches, which accompany the artery and its ramifications. 3. NERVES. The Anterior Tibial Nerve, is a branch of the peroneal nerve; it is seen in the ham arising from the peroneal, and crossing under the muscles on the outside of the fibula:—It emerges from under the extensor lon- gus digitorum, comes in contact with the anterior tibial artery, and accompanies it down the leg ; it is distribut- ed on the back of the foot and toes. •16 SECT. II. DISSECTION OF THE POSTERIOR PART OF THE LEG. The fascia which invests the posterior part of the leg is much thinner and less strong than in the fore part; it must be removed, to expose the parts now to be de- scribed. MUSCLES ON THE POSTERIOR PART OF THE LEG. These are seven in number. 1. The Gastrocnemius Externus, or Gemellus— Arises, by two distinct heads:—The first, or Internal Head, arises, tendinous, from the upper and back part of the internal condyle of the os femoris, and fleshy from the oblique ridge over that condyle.—The second, or External Head, arises in the same manner, from the external condyle. Each of the heads forms a fleshy belly, the fibres of which are oblique, passing from a tendinous expansion which covers the posterior surface of the muscle to another tendinous expansion which co- vers the anterior surface, or that surface which lies near- est the bones. The two bellies, of which the internal is by much the largest, are separated by a considerable tri- angular interval, in which the popliteal blood-vessels and nerves pass to the leg, but descending, unite a little be- low the knee joint in a middle tendinous line, and be- low the middle of the tibia send off a broad flat tendon, which unites a little above the ankle with the tendon of the soleus. Reflect the two heads of the gastrocnemius from the femoral condyles, and you will then expose 2. The Soleus, or Gastrocnemius Internus— which arises, by two origins or heads. The first, or External Origin, which is by much the largest, arises, principally fleshy, from the posterior surface of the head H i 86 of the fibula, and from the external angle of that bone, for two thirds of its length, immediately behind the pe- roneus longus. The second, or internal head, arises, fleshy, from an oblique ridge on the posterior surface of the tibia, just below the popliteus, and from the inner angle of that bone, during the middle third of its length. The two heads which are separated at first by the pos- terior tibial artery and nerve, unite immediately, form a large belly, which, covered by the tendon of the gastroc- nemius, is continued, fleshy, to within a short distance of the ankle joint; a little above which the tendons of the gastrocnemius and soleus unite, and form a strong, round tendon, named the Tendon Achillis which slides over the upper and posterior part of the os calcis, where it is furnished with a small bursa mucosa, to be Inserted into a rough surface on the back part of that bone. Situation: The gastrocnemius arises between the hamstring tendons: Its belly is superficial, and forms the upper or greater calf of the leg: on lifting it up, the ten- don is seen continued some way on its inner surface. The soleus has its largest part concealed by the gas- trocnemius, but part of it appears on each side of the belly of that muscle; and, at the lower part of the leg, the belly is seen projecting through the tendon ofthe gastrocnemius, and forming the lower calf. Its fleshy belly is tendinous on its posterior surface, where the ten- don of the gastrocnemius slides over it; and there is a bursa mucosa betwixt the upper part of the os calcis, and the tendo Achillis. Use: To elevate the os calcis, and thereby, to lift up the whole body, as a preparatory measure to its being carried forward in progression;—to carry the leg back- wards on the foot when that is fixed;—the gastrocnemius, from its origin in the thigh, also bends the leg on the thigh. Synonyma: Gastrocnemius:—Bi-femoro-calcanien. Soleus: Tibio-peronei-calcanien, 87 Both muscles are sometimes called Extensor Tarsi Suralis, vel Extensor Magnus. The heads of the gastrocnemius should now be lifted up, which will expose 3. The Plantaris.—This muscle arises, fleshy, from the upper part of the external condyle, and from the ob- lique ridge above that condyle, forms a pyramidal belly about three inches in length, which adheres to the cap- sule of the knee joint, runs over the popliteus, and ter- minates in a lonj, slender, thin tendon. This tendon passes obliquely inwards over the inner head of the soleus, and under the gastrocnemius; emerges from be- tween those two muscles, where their tendons unite, and then runs down by the inside ofthe tendo Achillis, to be Inserted into the posterior part ofthe os calcis, on the inside of the insertion of the tendo Achillis, and some- what before it. Situation: The origin and belly of this muscle are con- cealed by the external head of the gastrocnemius; the lower part of the tendon is the only part that is super- ficial. Use: To extend the foot, and roll it inwards, and to assist in bending the leg. Synonyma: Tibialis gracilis; Extensor tarsi minor:— Petit femoro-calcanien. 4. The Popliteus—Arises, within the capsular liga- ment of the knee, by a round tendon, from a deep pit or hollow on the outer side of the external condyle; adheres to the posterior and outer surface of the external semi- lunar cartilage; passes, within the cavity of the joint, over the side ofthe condyle to its back part; perforates the.capsular ligament, and forms a fleshy belly, which runs obliquely inwards, being covered by a thin tendinous fascia, to be Inserted, broad, thin, and fleshy, "into an oblique ridge on the posterior surface of the tibia, a little below its head, and into the triangular space above that ridge. Situation: This muscle is concealed entirely by the i 88 gastrocnemius; it lies above the inner head of the soleus, it is more deeply situated than the plantaris, which crosses over it. Use: To bend the leg, and, when bent, to roll it, so as to turn the toes inwards. Synonyma: Femoro-popliti-tibial. The belly of the soleus should now be lifted, in order to expose the deeply-seated muscles. A strong membra- nous fascia is seen connecting and investing them, which is to be removed. This fascia also covers the posterior tibial vessels and nerve, but the description ofthe course of these vessels, though seen in this stage of the dissec- tion, must be deferred. The deep-seated muscles are, The Flexor Longus Digitorum Pedis; situated behind the tibia. The Flexor Longus Pollicis Pedis, situated behind the fibula. The Tibialis Posticus, which is almost concealed by the two other muscles, and by the fascia, which connects them, and binds them down. 5. The Flexor Longus Digitorum Pedis Perfo- rans—Arises, fleshy, from the posterior flattened surface of the tibia, between its internal and external angles, below the attachment of the soleus, and continues to arise from the bone to within two or three inches ofthe ankle; the fibres pass ouliquely into a tendon which is situated on the posterior edge of the muscle. This tendon runs behind the inner ankle in a groove of the tibia, passes under a strong ligament which goes from the inner ankle to the os calcis, and having received a strong tendinous slip from the flexor pollicis longus, divides about the. middle of the sole of the foot into four tendons, which pass through the slits in the tendon of the flexor digitorum brevis, and are Inserted into the extremity ofthe last joint ofthe four lesser toes. Situation: The belly of this muscle is concealed by 89 the, soleus, and lies on the inside ofthe flexor longus pol- licis. The situation of the tendon is described with the muscle situated in the sole ofthe foot. Use: To bend the last joint of the toes, and to assist in extending the foot. Synonyma: Flexor tertii internodii digitorum pedis;— Tibio-phalangeitien-commun. 6. Flexor Longus Pollicis Pedis—Arises, fleshy, from the posterior flat surface of The'fibula, continuing its origin from some distance below the head of the bone (o within an inch ofthe ankle. The fleshy fibres terminate in a tendon, which passes behind the inner ankle through a groove in the tibia; next through a groove in the astraga- lus, crosses in the sole of the foot Uie tendon of the flexor longus digitorum, to which it gives a slip of tendon; passes between the two sesamoid bones, and is Inserted into the last joint ofthe great toe. Situation: The belly of this muscle is covered by the soleus; it lies on the outside.of the flexor longus digitorum, between that muscle and the peroneus longus; the tendon, where it passes behind the inner ankle, is situated more backward than the tendon of the flexor digitorum longus, that is, nearer the os calcis, and will be seen in the foot. Use: To bend the last joint of the great toe, and, being connected by a cross slip to the flexor digitorum commu- nis, to assist in bending the other toes. Synonyma: Peroneo-phalanginien du gros orteil. 7. The Tibialis Posticus—Arises, fleshy, from the posterior surface of both the tibia and fibula, immediately below the upper articulation of these bones with each other; from the whole ofthe interosseous ligament; from the angles of the bones to which that ligament is attached; and from the flat surface ofthe fibula behind its internal angle for more than two thirds of its length. The fibres run obliquely towards a middle tendon, which, becoming round, passes behind the inner ankle through a groove in the tibia. H2 90 Inserted into the upper and inner part of the os navicu- lar, being further continued through a groove in that bone to the internal and external cuneiforme bones; it also sends some tendinous filaments to the os calcis, the os cuboides, and the bases of the metatarsal bones supporting the second and middle toe. Situation: This muscle may be said to arise from the tibia and fibula before the interosseous ligament, as its fibres fill up a perforation in the upper extremity of that ligament. The belly is concealed at its lower part by the flexor longus digitorum and flexor pollicis, and cannot be seen till those muscles are separated; but a part of it is discovered above the upper extremity of these muscles, and immediately below the fibres of the popliteus; and this part must lie under the anterior surface of the soleus. The tendon crosses under that ofthe flexor longus digitorum above the ankle, and, where it passes through the groove in the tibia, is situated more forward than the tendon of that muscle. It is thickened where it runs through the groove of the os naviculare; and its insertion lies close in contact with the bones, and is concealed by the muscles in the sole of the foot. Use: To extend the foot, and turn it inwards. Synonyma: Tibio-tarsien. VESSELS AND NERVES OF THE POSTERIOR PART OF THE LEG. 1. ARTERIES. Arteria Tibialis Postica.—The posterior tibial ar- tery, which is the continued trunk ofthe popliteal, sinks under the origins of the soleus, and runs down the leg be- tween that muscle and the more deeply scattered flexors 91 ofthe toes: It does not lie in immediate contact with the fibres of the flexors, but, like the femoral artery, is in- vested by a s.rong sheath of condensed cellular membrane. It is, together with its veins and accompanying nerve, also supported by the fascia which binds down the deep-seated muscles. As it descends, it gradually advances more forwards, following the course of the flexor tendons: it passes behind the inner ankle, in the sinuosity of the os calcis, lying posterior to the tendon of the flexor longus digitorum, and anterior to that of the flexor longus pol- licis. Here it is close upon the bone, and its pulsation may be felt. It sinks under the abductor pollicis, arising from the os calcis, and immediately divides into two branches: (1.) The Internal Plantar Artery is the smallest, and ramifies among the mass of muscles situated on the inne;' edge ofthe sole of the foot. (2.) The External Plantar Artery directs its course outwards, and having reached the metatarsal bone of the little toe, forms the Plantar Arch, which crosses the three middle metatarsal bones obliquely, about their mid- dle, and terminates at the space betwixt the two first metatarsal bones, where the trunk of the anterior tibial artery joins the arch. The convexity of this arch is to- wards the toes, and sends off the following branches. a, A small branch to the outside of the little toe. 6, Ramus digitalis primus, or the first digital artery, which runs along the space between the two last meta- tarsal bones, and bifurcates into two branches, one to the inner side of the little toe, and the ether to the outer side of the next toe. c, The second digital artery, which runs along the next interosseous space, and bifurcates in a similar manner. d, The third digital artery. e, The fourth, or great digital artery, which supplies the great toe, and the inner side of the toe next to it. The concavity of the arch sends off the interosseal ar- teries, three or four small twigs, which go to the deep- 92 seated parts in the sole of the foot, and perforating be- tween the metatarsal bones, inosculate with the supe- rior interosseal arteries on the upper side ofthe foot. The branches of the Posterior Tibial Artery in the leg are, 1. The Peroneal Artery, which comes off from the tibial a little after it has sent off the anterior tibial, of which this artery is sometimes a branch; it is generally of a considerable size, sometimes nearly as large as the tibial itself; it runs upon the inside of the fibula, giving numerous branches to the peroneal muscles and flexor of the great toe; but its course is irregular and inconstant* At the lower part ofthe leg, it splits into, a, A. Peronea Anterior, which passes betwixt the lower heads of the tibia and fibula, to the'fore part of the ankle, where it is lost. 6, A. Peronea Posterior is properly the termina- tion of the artery: it descends along the sinuosity of the os calcis, inosculating with the branches of the tibialis postica, and terminates in the posterior part of the sole of the foot. 2. Muscular branches arise from the artery as it de- scends; twigs also are sent over the heel and ankle. 2. VEINS. Ven.e Tibiales Posticje.—The posterior tibial veins are generally two in number; they accompany the arte- ry, and terminate in the popliteal vein; they are formed of branches, which correspond to those of the artery. 3. NERVES. The Posterior Tibial Nerve, which is the conti- nuation of the great sciatic nerve, sinks below the soleus, and accompanies the posterior tibial artery; it gives off numerous filaments to the muscles in its neighbourhood. At first it continues, as in the ham, immediately behind 93 the artery, but it gradually gets on the outside of it as it descends: so that where they pass along the sinuosity of the os calcis, the nerve is situated close in contact with the side of the artery, but nearer to the projection of the heel than that vessel is. With the artery, it divides into, 1. The internal plantar nerve, and, 2. The external plantar nerve.—These nerves supply the muscles and integuments in the sole of the foot. SECT. III. DISSECTION OF THE SOLE OF THE FOOT. The cuticle is very much thickened on the sole of the foot from constant pressure; betwixt the integuments and plantar aponeurosis, we find a tough granulated fat, which adheres firmly to the aponeurosis, and is dissected off with difficulty Aponeurosis, seu Fascia Plantaris, is a very strong, tendinous expansion, which arises from the projecting extremity of the os calcis, and passes to the root of the toes, covering and supporting the muscles of the sole of the foot. Where it arises from the heel, it is thick, but narrow; as it runs over the foot, it becomes broader and thinner; and it is fixed to the head of each of the meta- tarsal bones by a bifurcated extremity, which, by its splitting, leaves room for the tendons, &c. to pass. It seems divided into three portions, which are connected by strong fasciculi of tendinous fibres; and fibres are sent down, forming perpendicular partitions among the muscles, and separating them into three classes. 1. The middle portion, which is the largest, and un- der which are contained the flexor brevis digitorum, and the ten-Ions of the flexor longus and lumbricales. 2. The external lateral portion, which covers the muscles of the little toe,.. 94 3. The internal lateral portion, concealing the musdies of the great toe. On removing the plantar aponeurosis, the first order of muscles in the sole of the foot is exposed: it consists of three muscles: Abductor Pollicis, situated on the side of the great toe. Abductor Minimi Digiti,on the side ofthe little toe. Flexor Brevis Digitorum Pedis, the mass in the mid- dle situated between the two abductors. 1. Abductor Pollicis Pedis—Arises, tendinous and fleshy, from the lower and inner part of the os calcis; from a ligament which extends from the os calcis to the os naviculare; from the inside of the os naviculare and cuneiforme internum; and from the fascia plantaris. Inserted, tendinous, into the internal sesamoid bone, and base of the first phalanx of the great toe. Use: To move the great toe from the rest. Synonyma: Thenar-calcaneo-phalangien du pouce. 2. Abductor Minimi Digiti Pedis—Arises, tendi- nous and fleshy, from the outer side of the os calcis; and from a strong ligament, which passes from the os calcis to the metatarsal bone of the little toe; also from the fascia plantaris. Inserted, tendinous, into the base ofthe metatarsal bone ofthe little toe, and into the outside of the base of the first phalanx. This muscle can frequently be divided distinctly into two portions. Use: To move the little toes from the other toes. Synonyma: Parathenar major, and metatarseus;—Cal- caneo-phalangien du petit doigt. 3. Flexor Brevis Digitorum Pedis Perforatus —Arises, fleshy, from the anterior and inferior part ofthe protuberance of the os calcis, and from the inner surface of the fascia plantaris; also from the tendinous parti'ions betwixt it and the abductors of the great and little toe;— it forms a thick fleshy belly, and sends off four tendons. 95 which split for the passage of the tendons ofthe flexor longus digitorum, and are Inserted into the second phalanx of the four lesser toes. The tendon of the little toe is often wanting. Use: To bend the second joint of the toes. Synonyma: Calcaneo phalanginien commun. Situation: The muscles of this order are quite super- ficial, being only covered by the fascia plantaris. The first order of the muscles being removed, or be- ing lifted from their origins, and left hanging by their tendon, the second order is exposed. 1. The tendon of the Flexor longus digitorum pedis is seen coming from the inside of the os calcis : and having reached the middle of the foot, dividing into its four tendons, which pass through the slits of the tendons of the flexor digitorum brevis, and are inserted into the base of the last phalanx of the four lesser toes. 2. The tendon of the Flexor longus pollicis is seen crossing under* the tendon of the flexor longus digito- rum, and, having given to it a short slip of tendon, pro- ceeding between the two sesamoid bones to the base of the last phalanx of the great toe. 3. Flexor Digitorum Accessorius, or Massa Car- nea Jacobi Sylvii—Arises, fleshy, from the sinuosity at the inside of the os calcis, and, tamdinous, from that bone more outwardly:—it forms a belly of a square form. Inserted into the outside of the tendon of the flexor digitorum longus, just at its division. Use: To assist the flexor longus. 4. Lumbricales Pedis—Arise, by four tendinous and fleshy beginnings, from the tendons of the flexor longus digitorum, immediately after their division. Inserted, by four slender tendons, into the inside of * In the erect posture, it crosses above, lying nearer to the metatarsal bones than that tendon ; but in the description, the sole of the foot is supposed to be placed uppermost. 96 the Qrst phalanx of the four lesser toes, and into the tendinous expansion that is sent from the extensors to cover the upper part of the toes. Use: To promote the flexion of the toes, and to draw them inwards. Situation: The muscles of the second order are co- vered and concealed by those of the first order; but the insertion of their tendinous extremities may be seen on removing the integuments. The second order of muscles being removed, we ex- pose the third order. 1. Flexor Brevis Pollicis Pedis.—It arises, ten- dinous, from the under and fore part of the os calcis, where it joins with the os cuboides; also from the os cuneiforme externum; it forms a fleshy belly, which is connected inseparably to the abductor and adductor pol- licis. Inserted, by two tendons, into the external and inter- nal sesamoid bones; and it is continued on into the base of the first phalanx of the great toe. Use: To bend the first joint of the great toe. Synonyma: Tarso-phalangien du pouce. 2. Adductor Pollicis Pedis—Arises, tendinous and fleshy, from a strong ligament which extends from the os calcis to os cuboides, and from the roots of the second, third, and fourth metatarsal bones: it forms a fleshy belly, which seems at its beginning, divided into two portions. Inserted, tendinous, into the external sesamoid bone, and root of the metatarsal bone of the great toe. Use: To bring this toe nearer the rest. Synonyma: Antithenar-tarso-metatarso-phalangien du pouce. 3. Flexor Brevis Minimi Digiti Pedis—Arises, tendinous and fleshy, from the os cuboides, and from the root of the metatarsal bone of the little toe. Inserted, tendinous, into the base of the first phalanx of the little toe, and into the anterior extremity of the metatarsal bone. 9; Use: To bend this toe. Synonyma: Parathenar minor;—Flexor primi intei- uodii minimi digiti;—Metatarso-phalangien dupetit doigt. 4. Transversalis Pedis—Arises, tendinous, from the anterior extremity of the metatarsal bone supporting the little toe; becoming fleshy, it crosses over the ante- rior extremities of the other metatarsal bones. Inserted, tendinous, into the anterior extremity of the metatarsal bone of the great toe, and into the internal sesamoid bone, adhering to the adductor pollicis. \ Use: To contract the foot, by bringing the toes nearer each other. Synonyma: Metatarso-phalangien du pouce. Ranging with this order of muscles, we may also ob- serve, A broad strong ligament, passing from the anterior sinuosity of the os calcis over the surface of the os cu- boides. The tendon of the tibialis posticus, dividing into nu- merous tendinous slips, to be inserted into the bones of the tarsus. Situation: The muscles of the third order lie under those of the second order, but are only partially conceal- ed:—The flexor brevis pollicis lies under the tendon of the flexor longus pollicis; the adductor pollicis lies on the outer side of the flexor brevis, and is in part concealed by the tendons of the flexor digitorum longus.—The flexor brevis minimi digiti is a small fleshy mass, lying on the metatarsal bone of the little toe, and not concealed by any muscle of the second order. The transversalis pedis runs across under the tendons of the flexor digitorum longus and lumbricales, and is seen projecting betwixt those tendons. Having removed the muscles last described, we expose the fourth and last order. The tendon ofthe peroneus longus is seen passing along a groove in the os cuboides, and crossing the tarsal bones, to be inserted into the base of the metatarsal bone of the I 98 great toe, and into the internal cuneiforme and second metatarsal bones. Interossei Pedis Interni, are three in number, situ- ated in the sole of the foot.—They arise, tendinous and fleshy, from between the metatarsal bones of the four lesser toes, and are Inserted, tendinous, into the inside of the base of the first phalanx of each ofthe three lesser toes. Use: To move the three lesser toes inwards towards the^reat toe. Synonyma: Interossei inferiores;—Abductor medii di- giti, abductor tertii, and minimi digiti pedis;—Sous me- tatarso-lateri-phalangiens. Irterossei Pedis Externi, are four in number, larger than the internal interrossei, and situated on the back of the foot; they are bicipites, or arise by two slips. Arise, tendinous and fleshy, between the metatarsal bones of all the toes. Inserted, the first, abductor indicis pedis, into the inside ofthe base ofthe first phalanx ofthe fore toe;—the second, adductor indicis pedis, into the outside of the same toe;— the third, adductor medii digiti pedis, into the outside ofthe middle toe;—the fourth, adductor tertii digiti pedis, into the outside of the third toe. Use: To separate the toes. Synonyma: Sus-metatarso-lateri-phalangicns. l'J9 CHAP. VI. DISSECTION OF THE HEAD. SECT. I OF THE EXTERNAL PARTS OF THE HEAD. The integuments of the head are thick, and covered with hair; under the cutis there is a cellular substance, which is much condensed, and closely connected with the epicranium, or expanded tendon ofthe occipito-frontalis. This connection renders the dissection of that muscle difficult. The Occipito-frontalis is the only muscle which properly belongs to the hairy scalp; it is a single broad digastric muscle, Arising, on each side of the head, fleshy and tendinous, from the transverse ridge of the occipital bone, as far for- wards as the mastoid process;—it forms a broad thin tendon, which covers the whole upper part of the cra- nium. Inserted, fleshy, on each side, into the orbicularis pal- pebrarum, skin of the eye-brows, and the internal angular process of the os frontis and os nasi. Situation: The tendon adheres firmly by cellular mem- brane to the skin, but very loosely to the pericranium, or periosteum ofthe cranium. At its insertion it inter- mixes with the muscles of the upper part of the face. Use: To pull the skin of the head backwards, raise the eye-brows, and corrugate the skin ofthe forehead 100 Synonyma: Epicranius;—Frontalis et occipitalis. The muscles of Hie ear are of three classes. 1. The common muscles move the external ear; they are not always so distinct as to admit of a clear demon- stration. (1.) Attollens Aurem—Arises from the tendon of the occipito-frontalis, and from the aponeurosis of the temporal muscle. Inserted into the upper part of the root of the cartilage ofthe ear, opposite to the antihelix. Use: To draw the ear upwards. Synonyma: Attollens auricolae;—superior auris;— Temporo-conchinien. (2.) Anterior Auris—Arises, thin and membranous, from the posterior part of the zygomatic process of the temporal bone. > Inserted into a small eminence on the back of the helix, opposite to the concha. Use: To draw the eminence a little forwards and up- wards. Synonyma: Anterior auriculas;—Zygomato-conchi- nien. (3.) The Retrahentes Auris—Arise, by two or three distinct slips, from the external and posterior part ofthe mastoid process, immediately above the insertion of the sterno-cleido mastoideus. Inserted into that back part of the ear which is opposite to the septum, dividing the scapha and concha. Use: To draw the ear back, and stretch the concha. Synonyma: Deprimens auriculas;—Posterior auris;— Mastoido-conchinien. 2. The proper muscles of the ear must be here de- scribed, but the student must not expect to meet with them distinctly marked in every subject; in general they are very confused and indistinct. (1.) Helicis Major—Arises from the upper and acute part of the helix, anteriorly. Inserted into its cartilage, a little above the tragus. 101 Use: To depress the part from which it arises. Synonyma: Helix. (2.) Helicis Minor—Arises from the inferior and anterior part of the helix. Inserted into the crus of the helix, near the fissure on the cartilage opposite to the concha. Use: To contract the fissure. Synonyma: Concho-helix, (3.) Tragicus—Arises from the middle and outer part ofthe concha, afthe root ofthe tragus, along which it runs. Inserted into the point of the tragus. Use: To pull the point of the tragus a little forwards. Synonyma: Concho-tragique. (4.) Antitragicus—Arises from the internal part of the cartilage that supports the antitragus; and, running upwards, is Inserted into the tip of the antitragus as far as the in- ferior part of the antihelix. Use: To turn the tip of the antitragus a little outwards, and depress the extremity ofthe antihelix towards it. Synonyma: Antheli-tragique. (5.) Transversus Auris—Arises from the prominent part of the concha on the dorsum ofthe ear. Inserted opposite to the outer side ofthe antihelix. Use: It draws the parts to which it is connected towards each other, and stretches the scapha and concha. Synonyma: Concho anthelix. 3. The muscles of the internal ear are situated within the temporal bone itself; they are very small, and can only be seen when the internal parts of the organ of hearing are prepared; but, in order to render the history of the muscles complete, I shall insert a description of them. (1.) Laxator Tympani—Arises, by a small begin- ning, from the spinous process of the sphenoid bone, and side of the Eustachian tube. It runs backwards, and a little upwards, along with the nerve called Chorda Tym- I 2 102 pani, in a fissure of the glenoid or articular cavity of the os temporis. Inserted into the long process of the malleus. Use: To draw-the malleus obliquely forwards towards its origin, and consequently the membrana tympani by which that membrane is made less concave, or is re- laxed. Synonyma: Externus mallei;—Obliquus auris;—An- terior mallei;—Spheni-salpingo-malleen. (2.) Tensor Tympani—Arises, by a small fleshy beginning, from the cartilaginous extremity of the Eu- stachian tube, just where it begins to be covered by the pars petrosa and spinous process of the sphenoid bone, and runs along the bony half-canal of the tympanum, where it is invested by a membranous vagina. Inserted into the neck of the malleus, above the small process, advancing likewise as far as the handle. Use: To pull the malleus and membrana tympani to- wards the pars petrosa, by which that membrane is made more concave and tense. Synonyma: Internus auris;—Internus mallei;—Sal- pingo-malleen. A third muscle has by some been described, under the name of External or Superior Muscle of the mal- leus; but this is much less distinct. It is described as Arising from the external, superior, and posterior part of the meatus externus, to be fixed by a small tendon, to the neck of the malleus. Synonyma: Acoustico-malleen. (3.) Stapedius is a short and thick muscle.—It arises . from, and lies concealed within, the small bony pyramid at the bottom of the tympanum; the cavity it fills is near the bony canal of the portio dura of the auditory nerve. It terminates in a small tendon, which goes out of the cavity through the small hole in the apex of the pyra- mid, runs forward, and is Inserted into the neck of the stapes, on the sides of the longest and most crooked leg of that bone. 103 Use: To draw the stapes obliquely upwards towards the pyramid, by which the posterior part of its base is moved inwards, and the interior part outwards. Synonyma: Musculis stapedis;—Pyramidal stapedien. SECT. II. OF THE CONTENTS OF THE CRANIUM, OR THE BRAIN AND ITS MEMBRANES. A transverse incision, extending from ear to ear over the crown of the head, being made through the tendon of the occipito-frontalis, the two flaps may, with facility, be inverted on the face and neck. Remove the superior part of the cranium by a saw directed anteri- orly through the frontal bone above the orbitar process, and posteriorly as low as the transverse ridge ofthe oc- cipital bone. Thus the subsequent demonstration of the brain will be conducted with greater facility. When the superior part of the cranium, commonly called the Calvarium, or skull-cap, is torn off, which re- quires considerable force, you expose the Dura Mater, a firm, compact, and whitish membrane, somewhat shin- ing, rough on its outer surface, from the rupture of vessels which connected it to the cranium, and covered with bloody spots in consequence of the blood effused from these ruptured orifices. It is described as being separa- ble into many laminae, into two with facility; and it is said that these two laminae, by separating and re-uniting, form the triangular cavities, named Sinuses, which are in fact large veins. This division of layers can hardly be admitted as correct in the recent state of the mem- brane. The Superior Longitudinal Sinus lies in a groove formed by the two parietal bones; it extends along the 104 sagittal suture from the crista galli of the ethmoid bone to the middle of the os occipitis, where it bifurcates into the two lateral sinuses; in its passage backwards, its size is increased. When slit open, its triangular form is evi- dent; it is lined by a smooth membrane, and in it may be remarked the numerous openings of the veins of the pia mater, the frena, or slips of fibres crossing from side • to side, glandulae Pacchioni internae, et externa), little bodies like millet-seed seen on the outer and inner sur- face of the sinus. The arteries of the dura mater are divided into the anterior, middle, and posterior. 1. Arteria Meningea Media, (called also the Spi- nalis or Spheno-spinalis,) the great middle artery, is a branch of the internal maxillary; it passes through the spinous hole of the sphenoid bone, and is seen arising from the anterior inferior angle of the parietal bone, (in a groove of which it lies,) and spreading its numerous branches over the dura mater. The anterior and posterior arteries are small. 2. A. Meningea Anterior is sent off from the ex- ternal carotid, and enters the cranium by the foramen lacerum orbitale superius. 3. A. Meningea Posterior is given off by the ver- tebral artery; the dura mater also receives small twigs from the occipital, pharyngeal arteries, &c. The nerves of the dura mater are said to come from the fifth pair; if they exist at all, they are small, and seldom demonstrated. OF THE SEPTA OF THE BRAIN, OR PROCESSES OF THE DURA MATER. 1. The Falx, (septum sagittale, verticale, medias- tinum cerebri, or falciform process) is a long and broad fold, or duplicature of the inner lamina of the dura ma- ter, dividing the cerebrum into two hemispheres, extend- ing from the crista galli of the ethmoid bone, along the 105 middle of the os frontis and point of junction ofthe two parietal bones, to the crucial ridge of the occipital bone, where it terminates in the middle of the next septum. 2. The Tentorium Cerebelli, or transverse septum. This separates the cerebrum from the cerebellum, and is formed by the inner lamina of the dura mater, reflected off from the os occipilis along the groove of the lateral sinuses, and the edge or angle of the temporal bones. It is frequently called Tentorium Cerebello Super Ex- tensum. Its position is horizontal. There are some other folds ofthe dura mater not visi- ble in this stage of the dissection. 3. The falx of the cerebellum, or small occipital sep- tum, will be seen when the cerebrum is removed. It extends from the middle of the tentorium along the mid- dle spine of the os occipitis to the foramen magnum, dividing the cerebellum into two parts. 4. The sphenoidal folds, two small folds of the dura mater, one on each side of the sella turcica, stretching from the posterior to the anterior clinoid processes. The dura mater also, in many parts of the brain, se- parates its laminae to form sinuses; the principle of these will be noticed in the course of the dissection. This membrane should now be divided in the line of the di- vision of the cranium; its internal surface is smooth, glistening, and free from adhesion, except in the course of the longitudinal sinus; into which veins pass from the pia mater. Detach the falx from the crista galli, and turn it backwards, observe in its lower edge the Interior Lon- gitudinal Sinus, which enters a sinus in the tentorium, termed Torcular Herophili, or straight sinus. This will fully expose the convolutions of the brain, which are closely invested by the pia mater. The Pia Mater consists of two membranes. 1. The Tunica Arachnoides is a fine membrane, covering uniformly the surface of the pia mater, with- out passing into the interstices of its duplicatures. It js 106 attached to it, is extremely thin, transparent, without ves- sels, demonstrated with difficulty on the upper surface of the brain by the blow pipe, (which raises it into cells,) but on the base of the brain it can be distinctly seen. 2. The proper Pia mater, or tunica vasculosa, is a very vascular membrane, transparent in the interstices of its vessels, investing the substance of the brain, descending betwixt all its convolutions, and lining its different cavi- ties; but, where it lines the ventricles, it is fine, deli- cate, and less vascular, than on the surface, and betwixt the convolutions of the brain: It is connected to the dura mater by its veins passing into the longitudinal sinus. The brain is divided into three parts: 1. The cere- brum; 2. The cerebellum; 3. The medulla oblongata. The Cerebrum consists of two distinct substances: 1. The cineritious or cortical substance forming the outer part. 2. The white or medullary substance forming the inner part. The brain is divided by the falx into two hemispheres, and by the pia mater into numerous convolutions. Each hemisphere is divided into three lobes, 1. The Anterior Lobes rest on that part of the cranium which forms the two orbits, and is called the anterior fossse of the basis of the cranium. 2. The Middle Lobes are situated before and above the medulla oblongata, and rest on the middle fossse of the basis cranii, which are formed by the sphenoid and temporal bones. 3. The Posterior Lobes are supported by the ten- torium. The anterior and middle lobes are parted by a deep narrow sulcus, which ascends obliquely backwards from the temporal ala of the os sphenoides to near the mid- dle of the os parietale; it is termed Fissura Cerlbri, or fissura Magna Silvii. By gently separating with the fingers the two hemi- 101 spheres of the brain * we see passing betwixt them a longitudinal white convex body, the Corpus Callosum: it lies under the falx, incurvates downwards at both its extremities, and is continued anteriorly into the medul- lary substance betwixt the corpora striata, posteriorly into the fornix and inferior cornu of the lateral ventri- cle on each side. On the surface of the corpus callosum is seen the Raphe, formed by two longitudinal medullary lines united by transverse fibres. When the brain is cut horizontally on the level of the corpus callosum, an appearance is produced, termed The Medullary arch, or Centrum Ovale. Under this arch are the two lateral ventricles.f If one of these be cautiously perforated on the side ofthe corpus callosum, and gently inflated by a blow-pipe, its extent may be seen; but, if much force be used, the ai* will pass into the other ventricle. The two ventricles are separated by a medullary par- tition, which descends from the inferior surface of the corpus callosum to the fornix, the Septum Lucidum; it consists of two laminae, with a narrow cavity between. To see this septum, one of the ventricles must be laid open, and the septum pulled gently to the other side. The Lateral Ventricles are two, right and left, lined with a fine membrane, narrow, consisting of a bo- dy, and three prolongations or cornua. 1. The body is formed betwixt the corpus callosum, the medulla of the brain, the convexity of the corpus striatum, and the thalamus nervi optici. 2. The anterior cornu or horn is formed betwixt the more acute convexity ofthe corpus striatum, and the an- terior part of the corpus callosum. • Between the hemispheres and on the surface of the corpus • callosum, we observe the arterise collosae, which are the continua- tion of the trunks of the anterior cerebri. f To show the lateral ventricles, the corpus callosum should be cut away close to the septum lucidum, and then the ventricle of that body, and the thickness and breadth of the septum itself, will be more clearly seen. 108 3. The posterior cornu (called also the digital cavityj may be traced stretching backwards and downwards into the posterior lobe of the brain. 4. The inferior or descending cornu cannot be traced in this stage of the dissection; it seems like the continued cavity of the ventricle, takes a curve backwards and out- wards, and then, turning forwards, descends into the middle lobe of the brain. The lateral ventricles communicate with each other, and with the third ventricle, by an opening under the fore part of the arch of the fornix.* In the lateral ventricles we meet with, The Fornix, a medullary body, flat, and of a trian- gular shape, which divides the two lateral and the third ventricles. It is exposed on tearing away the septum lucidum; its lower surface is towards the third ventricle; its lateral margins are in the lateral ventricles; on its upper surface it supports the septum lucidum, and under its most anterior part is the foramen Monroianum:—One of the angles of this body is forward, and the other two towards the back part: it rests chiefly on the thalami nervorum opticorum, but is separated from them by a vas- cular membrane called the velum. The extremities of the bodies of the fornix are named its Crura. 1. The crus anterius is double, bends downwards be- fore the anterior commissure of the brain, with which it is connected, and may be traced into the corpora caudi- cautia. * It has been doubted whether or not this be an opening; the choroid plexus passes through it, and seems to unite the surfaces ; it is absurdly named the Foramen Monroianum, from a mistaken notion that Dr. Munro discovered it, and may be seen by gently turning the anterior crus of the fornix to one side ; it is a space betwixt the most anterior part of the convexity of the thalami nervorum opticorum, and the anterior crus of the fornix This foramen may always be easily found by following the course of the plexus choroides, as it passes forwards in the ventricle. It is a slit, rather than a round hole, in the natural state. 109 2. The two crura posteriora, coalescing with the back part of the corpus callosum, pass, on each side, into the inferior cornu of the lateral ventricle, and terminate in a pointed form on the hippocampus major. Divide the body of the fornix, invert it, by turning the anterior crus forwards, and the posterior crura backwards; on the under surface of the latter is an appearance of transverse lines, named Corpus Psalloides, psalterium, or lyra. The inversion of the fornix exposes The Plexus Choroides.—This is a continuation of the pia mater, a spongy mass, consisting of folds of tor- tuous vessels, partly covering the thalami nervorum opti- corum, and continued into trTe inferior cornu ofthe lateral ventricles. The plexus of each side is connected to its fellow by the velum interpositum, a membrane which passes under the fornix, and lies on the third ventricle and corpora quadrigemina. From this plexus the blood is received by the Vena Galeni situated in the middle of the velum which con- sists of two parallel branches; these run backwards, unite, and enter the fourth sinus of the dura mater, call- ed TORCULAR HEROPHILI. This plexus should now be detached at its fore part, and turned back; it will remain as a guide to the knife in tracing the inferior cornu of the lateral ventricle. We now see, The Corpora Striata, two smooth cineritious con- vexities, in the fore part of the lateral ventricle, broad, and rounded anteriorly, becoming narrow, and diverging as they pass backwards, consisting of medullary and cor- tical substance disposed in striee. The Thalami Nervorum Opticorum, two large oval whitish eminences, placed by the side of each other be- tween the diverging extremities or crura of the corpora striata; towards their fore part is a peculiar eminence or convexity, called the Anterior Tubercle; they are elon- gated downwards, to form the optic nerves. K no Taenia Semicircularis, a white medullary line, run- ning in the angle betwixt the corpus striatum and thala- mus nervi optici of each side. Commissura anterior Cerebri, a short cylindrical medullary cord, stretched transversely between the fore and lower part ofthe corpora striata, immediately under the anterior crura of the fornix. Just above the commissura anterior, and before the thalami, is the Vulva, or foramen commune anterius, a small slit or indentation, formed by the anterior crus of of the fornix, bifurcating, and inserting itself, on each side, between the corpus striatum and thalamus nervi optici. This slit is the space by which the three ven- tricles communicate. Commissura Mollis is an exceedingly soft, broad, cineritious junction betwixt the convex surfaces of the thalami nervorum opticorum. On separating the optic thalami, we discover the Third Ventricle.—This is a longitudinal sulcus, or slit, situ- ated betwixt the thalami nervorum opticorum, and be- twixt the crura cerebri. Above, it is covered by the fornix and velum interpositum; at its upper and fore part, it communicates with the two lateral ventricles; below the commissura anterior, it opens into the infundibulum. This opening is termed iter ad infundibulum. Back- wards, it is continued by a canal which passes under the tubercula quadrigemina into the fourth ventricle. This passage is named iter ad quartum ventriculum, aquae- ductus Sylvii, or canalis medius. Anus, or foramen commune posterius, is situated be- hind the commissure of the optic thalami, and before the corpora quadrigemina. It is closed up by the velum in- terpositum, and, when that is removed, leads into the back part of the third ventricle. The Pineal Gland, a small, soft, greyish and conical body, of the size of a pea, is seated above the tubercula quadrigemina, and behind the thalami, to which it is connected by two white pedunculi, or foot-stalks; its Ill base is turned forwards, and the apex backwards; it is covered by the plexus choroides and posterior crura of the fornix. It contains an earthy matter, either in its own substance, or that of the pedunculi; resembling sand, and where viewed by a magnifier assuming a gra- nulated and clear light yellow appearance. It was named by Soemmerring, who first discovered that it be- longs to the healthy structure of the brain, the acervu- LLS GLANDUL/E PINEAL1S. Commissura Posterior, a transverse cord at the back part of the third ventricle, before the tubercula quadrigemina, and above the iter ad quartum venlricu- lum. Tuberci. la Quadrigemina, four small white bodies, adhering together, lying under the pineal gland, behind the third ventricle, and above the fourth. The upper- most two are named Nates, and the other two Testes. From the under part of the testes, there projects back- wards, connecting itself with the crura ccrebelli, a thin medullary lamina, which is the valvula Vieussenii, pro- cessus a cerebello ad testes, velum interjectum, valvula major. The inferior cornu of the lateral ventricle, which de- scends into the middle lobe of the brain, may now be traced, by following the tract of the choroid plexus;* in it is seen, The Hippocampus Major, or Cornu Ammonis: At its commencement it is narrow, but it becomes a broad medullary projection ofthe floor of the ventricle, and its extremity, which is called Pes Hippocampi, is curved inwards. The thin edge on its inside, which follows the whole of its circuit, is named the Corpus Fimbriatum, or Taenia Hippocampi. The posterior crus of the fornix runs along its inner and anterior part, in the form of a thin floating edge. * Or it may be exhibited by cutting away successive slices of the side of the b;;.in, until the ventricle is exposed. 112 In the posterior cornu of the lateral ventricle, which passes into the posterior lobe of the brain, there is a si- milar medullary projection, but smaller, the Hippocam- pus Minor. In the anterior part of the third ventricle, below the iter ad infundibulum, are seen the Corpora Albicantia Willisii, (corpora mamillaria or subrolunda) two medul- lary eminences of the size of peas; the remainder of these bodies is seen on the outer surface of the base of the brain. This completes the demonstration of the cerebrum. The whole of the posterior lobes, and the lateral part of the middle lobes, may be removed. This exposes to your view, The Tentorium, and the Falx Cerebelli. At this point you should trace the bifurcation ofthe longitudinal sinus into the two lateral sinuses. The lateral sinuses are formed by the splitting of the laminae of the tento- rium; hence they follow the course of that membrane, run along their grooves in the occipital bone, and dip downwards and forwards through the foramen lacerum in basi cranii, to terminate in the internal jugular veins. The Torcular Heropiiili, or fourth sinus, runs along the middle ofthe tentorium, and joins the extremity of the longitudinal sinus at the point where it bifurcates. The great notch of the tentorium is a circular open- ing left on the anterior part of the tentorium, allowing a junction between the cerebrum and cerebellum. Now proceed to the examination of the cerebellum; and, in order to accomplish this demonstration, it will be convenient to remove the posterior part of the os occi- pitis. Cerebellum.—This part of the brain, divided info two lobes by the falx cerebelli, or septem occipitale, 'h covered by a vascular membrane; consists of medullary and cineritious substance; but, instead of convolutions, has numerous deep sulci, into which the pia mater dips: and forms thin flat strata, 113 Remark the following processes. 1. Appendix, vel processus vermiformis superior, situ- ated under the pia mater, on the anterior and superior part of the cerebellum. 2. Appendix, or processus vermiformis posterior, will be found situated between the two lobes on the under surface of the cerebellum, and immediately behind the medulla oblongata. On separating the two lobes behind, and making a deep incision, we discover, The Fourth Ventricle.—The sides of this ventricle are formed by the cerebellum, the anterior part by the medulla oblongata, the upper and back part by the valvula cerebri; it is lined by a thin vascular membrane, and has on its fore part a groove or fissure, which, terminating in a sharp point, is named Calami's Scriptorius. On each side of this groove are seen several m< dullary lines, which are the origin ofthe portio mollis of the seventh pair of nerves. The iter a tertio ad quartum ventriculum enters the upper part of the fourth ventricle. The valvula cerebri hangs orer it. On cutting the cerebellum perpendicularly, there is formed, from the intermixture of cineritious and medul- lary matter, a tree-like appearance, named Arbor ViTiE, of which the trunk is termed the peduncle ofthe cere- bellum, and is continued to the back part ofthe medulla oblongata. This concludes the demonstration of the cerebellum. To demonstrate the- medulla oblongata and nerves, either the brain must be removed from the cranium, or it may be gradually inverted in the progress of the demon- stration;—and this is the better method. The inversion must be begun at the fore part by raising the anterior lobes ofthe cerebrum. Thus you will see, 1. The First Pair of Nerves, The Olfactory, called also Processus. Mamillares. They arise from the outside of the corpora striata, between the anterior and middle lobe of the brain; run under the anterior K 2 114 lobes, being lodged in two superficial grooves, and lying between the pia and dura mater; expand into a small oval ganglion, from which several small filaments descend through the cribriform plate ofthe ethmoid bone, to ramify on the membrane lining the nose. 2. The Second Pair, the Optic, arise from the pos- terior part of the optic thalami, and also from the tubercula quadrigemina; they make a circle round the crura cerebri called the Tractus Opticus. The two nerves approach gradually, and unite, just before the pituitary gland, on the fore part of the sella Turcica. They then diverge, and each nerve passes out at the foramen opticum of the sphenoid bone, to form the retina of the eye. On each side of these nerves are seen the Carotid Arteries. Each artery emerges from the cavernous sinus by the side of the anterior clinoid process: sends a branch forwards, which, uniting with a similar branch ofthe other carotid, forms the anterior part of the Cir- culus Arteriosus Willisii; while other branches, pass- ing backwards, and uniting with branches ofthe basilar artery, complete the posterior part of the arterial circle. A fold of dura mater passes from the anterior to the posterior clinoid process of each side. This fold is double, and forms by its duplicature the Cavernous SINUS. On dividing the optic nerves, and inverting them, we seethe infundibulum, a funnel of cineritious substance, leading from the inferior and anterior extremity of the third ventricle to the pituitary gland; it is generally im- perforate before it reaches the gland. The Pituitary Gland, a reddish body somewhat globular, consisting of two lobes, is situated in the sella Turcica of the sphenoid bone, partly covered by a fold of dura mater, and attached to the infundibulum. The circular sinus is situated at this point. On detaching the cerebrum from the back part of the sella Turcica, the tunica arachnoides is very evident. 3. The Third Pair of Nerves, Motores Oculorum, 115 arise from the crura cerebri,* pass outwards and forwards on the outer side ofthe posterior clinoid process into the cavernous sinus, and run through the foramen lacerum orbitale suprrius to the muscles ofthe eye. Between these two nerves are seen the two vertebral arteries, ascending and uniting, to form the basilary artery. 4. The Fourth Pair, Trochleares or Pathf.tici, are very slender, and situated immediately under the edge of the tentorium. This nerve arises from the valvula cerebri, comes out from betwixt the cerebrum and cere- bellum, passes by the side of the pons Varolii, and, passing through the cavernous sinus, continues its course through the foramen lacerum orbitale superius, to supply the ob- liquus superior muscle ofthe eye. 5. The Fifth Pair, Trigemini, are much larger than the fourth, and are situated more out wards and backwards. Each of these nerves arises by a number of filaments, from the anterior and lowest part of the crus cerebelli, where the crus unites with the pons Varolii;—it passes forwards, enters the cavernous sinus, where it untwists itself, and forms a flat irregular ganglion, the Ganglion Gasserianum, and then divides into three great branches. (1.) Ramus Occularus.—The ophthalmic nerve of Willis passes through the foramen lacerum orbitale supe- rius to the appendages of the eye. (2.) Ramus Maxillaris Superior passes through the foramen rotundum to the upper jaw and face. (3.) Ramus Maxillaris Inferior passes through the foramen ovale to the lower jaw and tongue. 6. The Sixth Pair, Motores Oculorum Externi, or abductores.—This nerve is small, but not so small as the fourth pair; it is seen arising betwixt the pons Varolii and corpora pyramidalia: it enters the cavernous sinus,— • The two crura pass obliquely backwards and inwards, so as to converge and meet in front of the tuber annulare ; it is from the hollow formed by their convergence, and named by Vicq d'Azyr, /•m the eighth pair, deep under (he angle, of the jaw. I; passes behind the carotids towards the muscles arising from .'he styloid process; une principal '"acch of it passes betwen the stylo-pharyngeus and styiu-gtossus to the a.iigu^ 134 while other twigs run behind the stylo-pharyngeus, to supply the pharynx. (3.) Nervus Laryngeus Superior, vel Internus.— The superior or internal laryngeal nerve passes behind the internal carotid artery, obliquely, downwards and forwards; then, under the hyo-thyroideus muscle, it plunges betwixt the os hyoides and thyroid cartilage, ac- companying the laryngeal artery, and supplying the in- ternal parts of the larynx. (4.) In the neck, also, the par vagum gives off fila- ments to the cervical ganglions ofthe intercostal nerve, and to communicate with the other nerves of the neck. Filaments also unite with twigs ofthe intercostal, and run down over the carotid artery to the great vessels of the heart, where they form the superior cardiac plexus. The par vagum enters the thorax by passing betwixt the subclavian artery and vein. 2. The Intercostal, or Great Sympathetic Nerve. —This nerve lies behind the carotid, in the cellular mem- brane, betwixt that vessel and the muscles covering the vertebrae of the neck. It is distinguished from the par vagum by being smaller, lying nearer the trachea, and adhering to the muscles ofthe spine; also by its forming several ganglions. It arises from the sixth pair in the cranium, and comes out by the same foramen as the carotid artery. Immediately after its exit from the skull, it forms the Superior Cerivcal Ganglion, which is very long, and of a reddish colour. The nerve afterwards becomes smaller, and descends; and opposite the fifth or sixth cervical vertebra, it forms another swelling, the Inferior Cervical Ganglion. Sometimes it has another ganr glion about the fourth or fifth vertebra of the neck, the Middle Cervical Ganglion: but this is not a constant appearance. The nerve then passes behind the subcla- vian artery into the thorax. The branches of the intercostal nerve are numerous, and they generally pass off from the ganglions. Imme- 135 dialely below the base of the cranium, twigs go to the eighth and ninth pairs, and to the upper cervical nerves. In the middle of the neck, some 'wigs pass over the carotid; others go to the parts covering the trachea, and uniting with filaments of the par vagum, form the ex- ternal laryngeal nerves; others unite with the descendens noni, or descending branch of the ninth pair, and some filaments assist the twigs of the par vagum to form the superior cardiac nerve. In the lower part of the neck, twigs are sent to communicate with the cervical nerves, &c. 3. The Ninth Pair, Nervus Ilypo-glossus, or Lin- gual nerve, having left the skull by the anterior condy- loid foramen, is connected with the eighth pair and in- tercostal nerve. Like them, it lies deep, and comes out from under the angle of the jaw. It is seen passing from behind the internal jugular vein, and then over the caro- tid artery, running betwixt these two vessels. It next passes under the mylo-hyoideus, running over the stylo- glossus, hyo-glossus, and genio-hyo-glossus, which last muscle its numerous branches perforate. Branches.—While the ncive is passing betwixt the jugular vein and the carotid artery, it sends off the De- scendens Noni.—This small and delicate nerve descends on the fore part of the vein and artery, and is distribut- ed to the muscles on the anterior part of the trachea. It is joined by filaments of the cervical nerves. 1. The Lingual Branch sent off by the third branch of the 'fifth pair of nerves, is also seen in the dissection of the neck. It is found under the mylo-hyoideus; it lies close upon the lower edge of the jaw-bone, betwixt the inferior edge of the pterygoideus internus and the upper part of the mylo-hyoideus. It gives numerous twigs to the sublingual giand and submaxillary duct, which are situated near it, and is lost in the substance of the tongue. o. Nervus Accessorius ad par Vagum.—The ac- cessory nerve, having passed out of the cranium with the 136 par vaginum, separates from it, passes behind the inter- nal jugular vein obliquely downwards and backward; it perforates the mastoid muscle, and is distributed to the trapezius and muscles about the shoulder; it is much connected with the third and fourth cervical nerves. 6. The Seven Cervical Nerves come out from the foramina betwixt the vertebrae of the neck. They send numerous branches to the muscles, &c. on the side of the neck, and communicate by filaments with all the other nerves in the neck. In this stage ofthe dissection, we may also see, 7. The Phrenic Nerve, formed by branches of the third and fourth cervical nerves.—This small nerve lies upon the belly of the anterior scalenus muscle, and dives into the thorax, betwixt the subclavian artery and vein. 8. The Recurrent Nerve, a branch sent off from the par vagum in the thorax, is also seen in the neck. Dissect between the under surface of the trachea and oesophagus at the lower part of the neck, and you will find the recurrent nerve situated there. 9. The upper part of the Great Brachial Plexus may be seen, arising on the side of the neck, from the lower cervical nerves, and passing behind the anterior scalenus, to reach the arm. 137 CHAP. VIII. DISSECTION OF THE THORAX. SECT. I. OF THE MUSCLES WHICH LIE UPON THE OUTSIDE OF THE THORAX. In removing the integuments from the fore part ofthe thorax, the pectoralis major and interior edge ofthe del- toid muscle should be dissected in the course of their fibres; and to do this, it will be necessary to remember that the fibres run obliquely from the sternum and cla- vicle to the upper part ofthe os humeri.* They are not covered by any fascia, but by a condensed cellular mem- brane, which is similar to a thin aponeurosis, and is with difliculty dissected away, unless it be done very regularly. Three pairs of muscles are described in this dis- section. 1. The Pectoralis Major—Arises, tendinous, from the anterior surface of the sternum, its whole length; fleshy, from the cartilages of the fifth, sixth, and some- times the seventh ribs, and from two anterior thirds ofthe clavicle. The fleshy fibres run obliquely across the breast, and, converging, form a strong flat tendon, which is Inserted into the ridge of the os brachii on the outside * Called also Os Brachii. M2 138 of the groove for the long tendon of the biceps flexor cubiti. Situation: The belly of this muscle is superficial. It is separated from the deltoid muscle by cellular mem- brane and fat, by the cephalic vein, and a small artery named A. Thoracica Humeraria. Its tendinous fibres, arising from the sternum, are interlaced with those of the opposite, so as to form a kind of fascia covering the bone, and the origins from the ribs are intermixed with the obliquus externus abdominis. The clavicular and tho- racic portions of the muscle are separated by a line of cellular membrane. The tendon is covered by the anterior edge of the deltoid; it forms the anterior fold of the arm-pit, arid appears twisted, for the fibres which proceed from the thoracic portion of the muscle, seem to pass behind those proceeding from the clavicle, and to be inserted into the os humeri somewhat higher up. Use: To move the arm forwards, and obliquely up- wards, towards the sternum. Synonyma: Pectoralis;—Sterno-costo-clavio-humeral. The pectoralis major should be lifted up from its ori- gin, and suspended by its tendon.—This will expose the next two muscles. 2. The Pectoralis Minor—Arises, by three tendi- nous and fleshy digitations, from the upper edges of the third, fourth, and fifth ribs, near their cartilages; it forms a fleshy triangular belly, which becomes thicker and nar- rower as it ascends, and is Inserted, by a short flat tendon, into the anterior part of the coracoid process of the scapula. Situation: The belly of this muscle is covered by the pectoralis major: the tendon passes under the anterior edge of the deltoid, and is connected at its insertion with the origins of the coraco-brachialis, and of the short head of the biceps flexor cubiti, and also with the liga- mentum propriutn scapulae anticum, a strong ligament, which passes from the external edge of the coracoid pro- 139 cess, to be affixed to the posterior margin ofthe acro- mion of the scapula. Use: To draw the scapula forwards and downwards, and, when that bone is fixed, to-elevate the ribs. Synonyma: Serratus anticus;—Serratus minor anti- cus;—Costo-coracoidien. 2. The Subclavius—Arises, by a flat tendon, from the cartilage of the first rib, and forms a broad fleshy belly, which is Inserted, into the inferior surface of the clavicle, be- ginning about one inch from the sternum, and continuing as far as the ligamentous connection of the clavicle to the coracoid process. Situation: This muscle is situated between the clavi- cle and sternum, concealed by the pectoralis major, and alienor part of the deltoides. Use: To draw the clavicle downwards and forwards, and perhaps to elevate the first rib. Synonyma: Costo-claviculaire. Having lifted up the pectoralis minor from its origin, the situation of the subclavian vessels which pass under the clavicle, and over the first rib, may be seen. (See the dissection of the Axilla.) SECT. II. OF THE PARTS CONTAINED WITHIN THE CAVITY OF THE THORAX. The cavity ofthe thorax may now be opened, by cut- ting through the cartilages of the ribs on each side, and separating the lower part of the sternum from the dia- phragm. That bone must then be lifted upwards, and the first and second parts of which it is composed divided by an incision along the inner surface of their junction; 140 or the whole sternum may be removed, by separating it at its articulations with the clavicle. The latter method is preferable, as it allows us to examine more readily the great vessels passing out of the thorax. On looking under the sternum, while it is lifted up, we see the Mediastinum, separating, as it is gradually torn from the posterior surface of the sternum, into two layers, and thus forming a triangular cavity. This cavi- ty is artificially produced, and is entirely owing to the method of raising the sternum. When the sternum is laid back or removed, the fol- lowing parts are to be observed: The Mediastinum, now collapsed, dividing the tho- rax into two distinct cavities, of which the right is the largest. The lungs of each side lying distinct in these cavities. The pericardium, containing the heart, situated in the middle of the thorax, between the two laminae of the mediastinum, and protruding into the left side. The internal surface of the pleura, smooth, colourless, and glistening, lining the ribs, and reflected over the lungs. 1. The Pleura.—Each side of the thorax has its particular pleura:—The pleurae are like two bladders, situated laterally with respect to each other; by adhering together in the middle of the thorax, and passing oblique- ly* from the posterior surface of the sternum to the dor- sal vertebrae, they form the mediastinum.—The pleura lines the ribs, and the upper surface of the diaphragm, and is reflected over the lung, which is in fact behind it; it forms the ligamentum latum pulmonis, a reflection of this membrane, which connects the inferior edge of the lungs to the spine and diaphragm. * They run obliquely, not being in general attached to the mid- dle of the sternum, but towards its left side, especially at the lower part of the bone, near the diaphragm. Besides the peri- cardium, the mediastinum contains betwixt its laminse some adi- pose membrane and absorbent glands. 141 2. The Lungs.— Colour, reddish in children, greyish in adults, and bluish in old age.—Shape, corresponding to that of the thorax, somewhat pyramidal, convex to- wards the ribs, concave towards the diaphragm, and irre- gularly flatted next the mediastinum. Division (1.) The Right Lung is the largest, and is divided into three lobes, two greater ones, and an inter- mediate lesser lobe. (2.) The Left Lung has two lobes, and also a square notch opposite the apex of the heart. Into the sulci or grooves which form the divisions of the lungs into lobes, the pleura enters; that part of the lung which is affixed to the spine, is called its root; it is the part by which the great vessels enter. 3. The Pericardium is a strong, white, and compact membrane, smooth, and lubricated upon the inside, forming a bag for containing the heart, and having its inner lamina reflected over the substance of the heart itself. 4. When you slit open the fore part of the pericardi- um, you expose the Heart. The right ventricle pro- trudes; the right auricle is also towards you; while the left auricle is retired, and its tip is seen lapping round upon the left ventricle. From under the tip of the left auricle, a branch of the coronary vein, and one of the coronary artery, ramify towards the apex of the heart, marking the situation of the septum cordis. The left ventricle will be found firm, fleshy, and resisting, whilst the right ventricle is more loose, and seems partly wrapt round the other. The heart is situated obliquely in the middle of the breast; its posterior surface is flat, and lies upon the diaphragm; its apex is turned forwards, and towards the left side, so that, in the living body, it is felt striking be- tween the fifth and sixth ribs, at the point where the car- tilages and bony extremities are united. The Vena Cava Superior is seen coming down from the upper angle of the pericardium. The Inferior Cava is seen 142 coming up through the diaphragm; but only a very small part of this vein is covered by the pericardium; the two veins enter the right auricle. The Right Auricle is turned forwards, and might be called the anterior; it ge- nerally appears black, by the blood shining through its thin coats. The Right Ventricle is situated almost directly opposite. The Pulmonary Artery arises from the right ventricle; its root is concealed by the right au- ricle; it ascends on the left side of the aorta; it divides into, 1. the right pulmonary artery, which passes under the arch of the aorta, crosses behind it and the vena ca- va superior to the right lung, and is the longest; and, 2. the left pulmonary artery, which passes to the left lung, crossing the descending aorta anteriorly. The Pulmo- nary Veins enter the left auricle, two veins come from each lung; the right veins are longest as they pass be- hind the vena cava superior. The left auricle is situat- ed on the left side of the right auricle, and somewhat behind it; its tip is seen lapping round upon the Left Ventricle; this is situated behind and on the left side ofthe right ventricle; its substance is stronger and more firm to the touch. The Aorta arises from the back part and right side of the left ventricle; its root is covered by the pulmonary artery; it then ascends betwixt that arte- ry and the vena cava superior. Immediately from the root of the aorta, within the pericardium, the two coro- nary arteries are sent off to supply the heart itself. SECT. III. DISSECTION OF THE GREAT VESSELS OF THE HEART. The Vena Cava Superior will be seen descending before the root of the lungs, and on the right side of the aorta. Immediately before perforating the pericardium. 143 it is joined upon its posterior part by the vena azygos, which comes forwards from the spine, returning the blood from the intercostal spaces. Behind the sternum, and just above the arch of the aorta, the superior cava is seen receiving two great branches. 1. A branch coming from the right side, formed by the right subclavian vein, and the right internal jugular. 2. A larger branch coming from the left side; it is formed by the left subclavian and left internal jugular, which unite to form a trunk. This trunk crosses before the arteries arising from the arch of the aorta, and then enters the superior vena cava. Into the posterior part of the angle formed by the union of the left subclavian and the left jugular, the thoracic duct empties itself. On each side, the internal jugular vein descends along the neck by the side of the carotid, while the subclavian vein comes from the arm. The Vena Cava Inferior, immediately after passing through the diaphragm from the abdomen, enters the pericardium. The Aorta leaves the heart opposite the fourth dorsal vertebra; it crosses over the pulmonary artery, ascends obliquely upwards, backwards, and to the right side, as high as the second dorsal vertebra. Here it forms an Arch or incurvation, which passes from the right to the left side, and at the same time obliquely from before backwards; it then comes in contact with the upper part of the third dorsal vertebra, and descends along the spine in the posterior mediastinum. This arch ofthe aorta is situated behind the first bone of the sternum, behind and somewhat below the left branch of the vena cava supe- rior. From the upper part of the arch come off three large arteries. 1. The Arteria Innominata, or common trunk of the right carotid and subclavian, ascends above an inch, and bifurcates into, 144 a, The right carotid, which ascends in the neck by the side of the trachea. ' b, The right subclavian, which passes outwards to the arm. 2. The left carotid. 3. The left subclavian conies off from the extremity of the arch. The arch of the aorta also gives off some small twigs which pass to the pleura, the mediastinum, and thymus. The Thymus is a soft glandular body, lying before the lower part of the trachea and great vessels of the heart, a little higher than the tops of the two pleurae. It is very large in the foetus, smaller in adults, and nearly disappears in the aged. Where the aorta begins to descend, it is connected to the pulmonary artery by a ligament, which, in the foetus, was a large canal, the Ductus Arteriosus. COURSE OF THE SUBCLAVIAN ARTERY ON EACH SIDE. The subclavian artery passes upwards and outwards, runs under the clavicle, and over the middle of the first rib; it passesbetween the bellies ofthe anterior and middle scaleni muscles, then runs under the arch ofthe pectoralis minor, and enters the axilla, where it assumes the name of Axillary Artery. The order in which the following arteries are sent off from the subclavian varies much; sometimes they come off singly, at other times in large trunks, which subdivide. Backwards the subclavian sends off, 1. The Vertebral Artery.—This artery arises from the back part of the subclavian, passes outwards and enters the foramen in the transverse process of the last cervical vertebra, and ascends 'hrough the transverse pro- cesses of the vertebrae, to enter the foramen magnum of the occipital bone. 145 2. The Inferior Thyroid Artery ascends obliquely inwards, passes behind the internal jugular vein to ramify on the thyroid gland, where it inosculates largely with the superior thyroid arteries. Branches from this artery pass to the trachea and oesophagus, to the muscles of the neck, and of the scapula: one of these is the supra sca- pulary artery, (see the account of the branches of the ax- illary artery.) 3. A. Cervicalis Anterior, vel Profunda, passes deep to the muscles situated on the fore part of the cervical vertebrae, and ascends as high as the base of the skull. 4. A. Cervicalis Posterior, vel Superficialis, is larger than the last; it ascends obliquely outwards, gene- rally passes betwixt the transverse processes of the last cervical and first dorsal vertebrae, and ascends on the back part of the neck, deeply seated; some of its branches pass down the back superficially. Anteriorly, the subclavian artery gives off, 5. A. Mammaria Interna. The internal mammary arises from the fore part of the subclavian opposite the cartilage ofthe first rib; it runs down on the inside of the cartilages of the ribs, and terminates in the abdominal muscles, where it inosculates with the epigastric. It is a large artery, and its branches are very numerous. They pass to the external muscles of the chest, to the intercostal muscles, pleura, &c. It also sends off the Arteria Phrenica Superior, vel comes nervi phrenici which, with two veins, accompanies the phrenic nerve' to the diaphragm. 6. The subclavian artery gives twigs to the root of the neck, and to the muscles about the scapula. 7. A. Intercostalis Superior. Frequently a trunk comes off from the subclavian, especially on the right side, which passes downwards and backwards, and lodges itself by the spine, to supply the two or three superior intercostal spaces. N 146 COURSE OF THE SUBCLAVIAN VEIN. The subclavian vein is situated anteriorly to the sub- clavian artery; it passes inwards behind and under the subclavius muscle, and before and over the belly of the anterior scalenus, (so that this last muscle lies betwixt the vein and artery.) It runs over the first rib, from under the arch of the pectoralis minor, where it is found in con- tact with the axillary artery, and is called the Axillary Vein. The branches of this vein accompany and correspond to the ramifications of the subclavian artery, returning the blood from the thyroid gland, neck, chest, intercostal spaces, &c. The subclavian vein also receives the in- ternal jugular, which passes down behind the clavicle. THE COURSE OF THE BRACHIAL PLEXUS OF NERVES May also be examined. This plexus is formed by branches of the four lower cervical and first dorsal nerves, which pass between the anterior and middle scaleni muscles into the axilla. In this passage they are situated higher up than the artery. A considerable part of the scaleni muscles may now be seen; the upper insertion of these muscles must be dissected with the muscles of the back part of the neck. 1. The Scalenus Anticus—Arises, by three tendons, from the transverse processes of the fourth, fifth, and sixth vertebrae of the neck. Inserted, tendinous and fleshy, into the upper edge of the first rib, near its cartilage. Synonyma: Scalenus prior;—First scalenus;—Anterior portion ofthe first scalenus;—Trachelo-costal. 2. The Scalenus Medius—Arises, tendinous, from the ^transverse processes of all the vertebrae of the neck. Inserted into the upper and outer part of the first rib, 147 from its root to within the distance of half an inch from the scalenus anticus. Synonyma: Second Scalenus;—posterior portion of the first scalenus;—Trachelo-costal. 3. The Scalenus Posticus—Arises, tendinous, fi^m Lie transverse processes ofthe fifth and sixth vertebrae of (he neck. Inserted into the upper edge ofthe first rib, near the spine. Synonyma: Third scalenus;—Scalenus secundus;— Trachelo-to.s'al. Situation: These muscles are covered before by the sterno-mastoideus and trapezius, behind by the trapezius and levator scapulae; but the scaleni are so connected with the muscles of the spine, that the whole of them cannot be demonstrated till the muscles of the back and neck are dissected. Use of these three muscles: To bend the neck to one side, and, when the muscles of both sides act, to bend it forwards; or, when the neck is fixed, to elevate the ribs, and dilate the chest. SECT. IV. IHSSUCTIOX OF THE AXILLA, OI£ Aim PIT. ' There is a considerable resemblance in the dissection of the axilla to that of the ham or groin; in each of these situations we meet with important blood-vessels and nerves, closely connected together, embedded in adi- pose membrane, and sealed in the flexure of a joint. The axilla is formed by two muscular folds which bound a miiidle cavity. The anterior fold is formed by the pectoralis major passing from the thorax to the arm, the posterior by the latissimus dorsi coming from the back- 148 In the intermediate cavity there is a quantity of cel- lular membrane and absorbent glands, covering and con- necting the great vessels and nerves. This cellular and adipose membrane is continued from the interstice above the clavicle betwixt the edges of the trapezius and mas- toid muscles. All the space before the root of the neck above the first rib, and under the clavicle and coracoid procegsof the scapula, and the interstices of the muscles passing through that space, are filled up by a quantity of adipose membrane; and this is not exactly similar to the fat in other parts of the body; it is more granulated, wa- tery, and of a reddish colour; it surrounds the great ves- sels and nerve, rendering the dissection both tedious and difficult. The Axillary Vein will be found lying anterior to the artery, that is, nearer the integuments. It seems to be a continuation of the basilic vein, which runs along the inside of the arm quite superficial, and of the two or three venae satellites, or veins which accompany the bra- chial artery. The axillary vein receives branches corres- ponding to the ramifications of the artery. Passing under the clavicle, it becomes the subclavian vein, and runs over the first rib, and before the anterior scalenus muscle into the thorax. Deeper seated, and immediately behind the axillary vein, lies the Axillary Artery. It is seen coming from under the clavicle; from under the arch formed by the pectoralis minor, it comes over the middle of the first rib, and between the anterior and middle scaleni mus- cles. In the axilla it is surrounded by the meshes ofthe nerves, and runs along the inferior edge of the coraco- brachialis muscle; when it has passed the anterior edge of the pectoralis major, it assumes the name of the Bra- chial Artery. The branches of the axillary artery are, ' 1. A. Mammaria Externa, called also, A. Thoraci- cae Externae—The external mammary artery consists of three or four branches which run downwards and for 149 wards obliquely over the chest. These branches some- times come off separately from the axillary artery, at other times by one or two common trunks, which "sub- divide. They supply the pectoral muscles and mamma. Some of their branches pass to the muscles of the shoul- der, to the side of the chest, and to the muscles on the inside of the scapula. 2. A. Scapularis Interna, Supra-scapularis or Dorsalis Scapulae, is sent off from the back part of the axillary artery. It runs across the bottom of the neck towards the root of the coracoid process, and passes through the semilunar notch in the superior costa ofthe scapula; it supplies the supra-jspinatus muscle, and then passes under the acromion, to ramify on the muscles be- low the spine of the scapula. It is generally a branch of the A. Thyroidea Inferior, and is then named A. Trans- versalis Humeri. 3. A. Scapularis Externa, Infrascapularis, or Thoracica Posterior, arises from the under and back part nf the axillary artery, attaches itself to the inferior costa of the scapula, where it splits into two great branches. 1. A large branch, which passes to the outer surface of the scapula below the spine, and has its principal ramifi- cations close upon the bone. 2. The other branch (which is larger) passes to the inner surface ofthe sca- pula, supplies the subscapulars, and sends branches downwards to the muscles of the back and loins. 4. Arteria Circumflexa Humeri Posterior, Hu- meralis, or Reflexa-articularis, arises from the lower and fore part of the axillary artery, and runs backwards close to the bone, surrounds its neck, and is lost on the inner surface ofthe deltoid: it gives also tuigsto the joint and neighbouring muscles. o. A. Circumflexa Anterior is a much smaller artery, often a branch of the circumflexa posterior; it encircles the neck of the bone on its fee part, and is lost on the inner surface ofthe deltoider. where it inosculates with the posterior circumflex arte . N 2 150 The Great Brachial Nerves accompany the sub- clavian artery over the first rib. In the axilla they are united by numerous cross branches, forming the Axillary or Brachial Plexus, which is continued from the clavicle as low as the edge of the tendon ofthe latissimus dorsi, and which surrounds the axillary artery with its meshes. From the axillary plexus seven nerves pass off. 1. Nervus Supra-scapularis, Scapularis Externus, Scapularis.—This nerve comes off from the upper edge of the plexus: it crosses the axilla at the highest part, runs towards the superior costa of the scapula, accompa- nies the external scapular artery through the semilunar notch, and supplies the mUscles on the posterior surface of the scapula. 2. N. Circumflexus, Articularis, Axillaris, or Hu- meralis, lies deep: it passes from the back part of the plexus, goes backwards round the neck of the bone, ac- companying the posterior circumflex artery, and is dis- tributed to the miisculus deltoides, and the muscles on the outside of the arm. Small nerves also pass from the ax- illary plexus to the subscapular muscle, the teres major, latissimus dorsi, and pectoral muscles. 3. The External Cutaneous Nerve, or Nervus-Mus- culo-cutaneus. 4. The Radial Nerve. 5. The Ulnar Nerve. 6. The Muscular or Spiral Nerve. 7. The Internal Cutaneous Nerve. These five nerves will be described in the dissection of the arm and fore-arm. Ifrl SECT. V. DISSECTION OP THE POSTERIOR MEDIASTINUM,* AND OF THE NERVES AND VESSELS WHICH HAVE THEIR COURSE THROUGH THE THORAX. Course of the Phrenic Nerve through the thorax. On each side this nerve is seen entering the thorax betwixt the subclavian artery and subclavian vein; it then proceeds downwards and forwards before the root of the lungs, and on the outside of the pericardium, be- twixt that bag and the pleura: it is lost on the diaphragm. The left phrenic nerve has a somewhat longer course than the nerve of the right side, as it passes over the pe- ricardium, where that bag covers the apex of the heart. This nerve is accompanied by one artery and two veins; some twigs pass from the phrenic nerve into the abdo- men, to the liver, &c. Behind the arch of the aorta and great vessels pass- ing from the heart, is seen the Trachea. It enters the thorax between the two pleurae, and, opposite the third or fourth dorsal vertebra, bifurcates into two parts: one of which passes toward the right, the other toward the left, to enter the lung of each side. By folding back the lungs towards the left side ofthe chest, we expose the pleura reflected from the under sur- face of the root of the lungs to the spine and ribs. A triangular space is formed betwixt the two pleura and the bodies of the dorsal vertebrae; this space or cavity is named the cavity of the posterior mediastinum. It contains many important parts, and must therefore be carefully dissected. But first let us attend to the course of the intercostal, or great sympathetic nerve, which is seen running by the side of the spine. The Intercostal Nerve, where it enters the thorax, * By Posterior Mediastinum is designed that part of the medi- astinum situated behind the root of the lungs. 152 is situated behind the great vessels; close upon the ar- ticulation of the first rib with the body of the first dor- sal vertebra, it forms a ganglion, a twig of which fairly encircles the subclavian artery, while other filaments are entwisted round the root of the vertebral artery. The intercostal nerve then descends along the thorax; it lies upon the heads of the ribs, where they are articulated with the vertebrae; it receives additional branches from all the dorsal nerves, and in each intercostal space it forms a ganglion. This nerve may be dissected with greater facility when the lungs are removed, and the ribs sawed off near the spine, which will enable the dissec- tor to trace its branches more fully. It lies behind the pleura, but is seen through it; it passes into the abdo- men by the side of the spine, running through the fibres of the small muscle of the diaphragm. i BRANCHES OF THE INTERCOSTAL IN THE THORAX. The Anterior Intercostal, or Splanchnic Nerve, should be attended to. It is formed by three or four twigs, which come off from the intercostal betwixt the fourth and eighth dorsal vertebrae; these twigs, passing forwards on the bodies of the vertebrae unite to form the splanchnic nerve, which may be traced entering the ab- domen, betwixt the crura of the small muscle of the dia- phragm. From the intercostal, also, twigs are given off, which assist the branches of the par vagum, and of the dorsal nerves, in forming several plexuses to supply the vis- cera of the thorax. The right intercostal nerve lies under the pleura by the right side of the spine. Still nearer the middle of the spine, you see the Vena Azygos. In dissecting, it is found situated betwixt the right intercostal nerve and the aorta; it begins below from ramifications of the lum- ber arteries, which pierce the small muscle of the dia- phragm. This vein ascends along the spine, receiving 153 veins from each of the intercostal spaces of the right side, and, about the middle of the back, it receives a considerable trunk, which-comes from under the aorta, and returns the blood from the left side of the thorax. At the fourth dorsal vertebra, the vena azygos leaves the spine; it makes a curve forward, and empties its blood into the back part of the vena cava superior, im- mediately before that vein enters the pericardium. Descending through the posterior mediastinum, will be also found the Aorta. This great artery, having formed its arch, comes in contact with the third dorsal vertebra, and is now called the Descending Aorta, or Thoracic Aorta. It descends along the bodies of the dorsal vertebrae, rather on their left side; it lies behind the oesophagus, and passes betwixt the crura of the dia- phragm into the abdomen. BRANCHES OF THE AORTA IN THE THORAX. 1. A. Intercostales Inferiores.—The arteries which supply the three or four superior intercostal spaces, generally come off in one common trunk, which after- wards subdivides. The Intercostalis Superior, on the right side, is mostly sent off by the subclavian; on the left side by the aorta. The Inferior Intercostals are eight or nine in number on each side of the thorax; they come off separately from the side or back part of the aorta, and seem to tie that great artery to the spine. Each intercostal artery passes immediately into the interval betwixt two ribs, and there subdivides into, (1.) A branch which perforates between the heads of the" ribs to the muscles of the back; this branch also gives twigs which enter the spinal canal. (2.) The continued trunk of the artery runs forwards, in the interval of the two ribs, giving many branches to the intercostal muscles. When it reaches the ante- rior part of the thorax, it is lost in the muscles. 154 Each intercostal artery is accompanied by one or two veins, branches of the vena azygos, and by an intercos- tal or dorsal nerve. 2. A. Bronchiales, are two, sometimes three, small twigs of the aorta, one of which passes to the lungs on each side; they sometimes arise from the subclavian and superior intercostal. 3. Small arteries pass forwards from the aorta on the oesophagus, named A. CEsophageae; others run to the pericardium and pleura. The dissector also finds in the posterior mediastinum the Thoracic Duct. He must look for it behind the oesophagus, betwixt the vena azygos and aorta: it is col- lapsed, and appears like cellular membrane condensed, and can only be distinguished when inflated or injected; it was seen in the abdomen close to the aorta, and pass- ing into the thorax between the crura of the diaphragm. It ascends along the posterior mediastinum, and, about the fourth dorsal vertebra, passes obliquely to the left side, behind the aorta descendens, and behind the great arch of the aorta, until it reaches the left carotid artery. It runs behind this artery, and behind the left internal jugular vein; and, after forming a circular turn or arch, (the convexity of which is turned upwards,) it descends and enters the left subclavian vein at the point where that vein is joined by the left internal jugular. In its course along the spine, the thoracic duct frequently splits into two branches, which re-unite. The absorbents of the right superior extremity, and ofthe right side of the head and thorax, usually form a trunk, which enters the right subclavian vein. The (Esophagus is also situated betwixt the layers of the posterior mediastinum. It lies immediately befoYe the aorta, but rather towards its left side; it is seen de- scending from the neck behind the trachea; it passes through an opening in the lesser muscle of the diaphragm, and immediately expands into the stomach. Behind the trachea and vessels going to the lungs. 155 and on the fore part of the oesophagus, we meet with a congeries of lymphatic glands. COURSE OF THE PAR VAGUM, OR EIGHTH FAIR OF NERVES, IN THE THORAX. From the neck, the par vagum passes betwixt the subclavian vein and artery into the thorax; it immedi- ately sends off a large branch, the Recurrent Nerve, back into the neck. On the right side, this branch twists round under the arteria innominata; on the leftside, un- der the arch of the aorta, it ascends behind the carotid, and lodges itself betwixt the trachea and oesophagus, to both of which it gives branches. The par vagum, having given off the recurrent, de- scends by the side of the trachea, and behind the root of the lungs. It here sends off numerous filaments to the lungs, which, uniting with twigs from the great sympa- thetic, form the Anterior and Posterior Pulmonary Plexuses; these plexuses lie on the anterior and poste- rior surfaces of the root ofthe lungs. Qther twigs of the par vagum pass, to form the inferior Cardiac Plexus about the pericardium. The trunk of the eighth pair soon reaches the oeso- phagus; the left par vagum runs on the fore part of the oesophagus, the right nerve on its back part. Here they split into several branches, which unite again, and form a Plexus. This plexus is called the (Esophageal. The two nerves continue their course along the oesopha- gus, and pass with it through the diaphragm, to ramify on the stomach, and form the stomachic plexus. The twelve dorsal or intercostal nerves are also seen in this dissection, emerging from the spinal canal, be- tween the,bodies of the vertebrae, and supplying the in- tercostal muscles, &c. 156 SECT. VI. DISSECTION OP THE HEART, WHEN REMOVED FROM THE BODY. The heart consists of three tunics or coats. 1. An external smooth one, which is a reflection of the internal lamina of the pericardium. 2. A middle muscular coat. 3. A smooth internal coat, which is a continuation of the internal coat of the great veins and arteries. In the right side of the heart we always meet with a con- siderable quantity of coagulated blood. In the left side, there is much less. Slit open, with the scissors, the two venae cavae on their fore part, the inner • surface of these veins, and of the right auricle, will be seen lined by a smooth membrane; and in the auricle, the musculi pectinati, or bundles of muscular fibres, will be seen projecting. At the point of union between the two cavae, there is a projection form- ed by the thickening of the muscular coat, the Tubercu- lum Loweri. The Septum Auricularum is seen sepa- rating the right from the left auricle;—observe that it is thin, that in it there is an oval depression, named Fossa Ovalis. Round this fossa the fibres are thicker, forming the annulus ovalis; this is the remains ofthe Foramen Ovale of the foetus; and in many adult subjects a probe may be passed through the superior part of the fossa ob- liquely into the left auricle. The Valvula Nobilis, or Eustachian Valve, is a membrane-like duplicature ofthe inner coat of the auricle, observed where the vena cava inferior is continued into the auricle, and stretching from that vein towards the opening into the right ventricle. This valve is sometimes found reticulated. Behind this valve is the orifice of the Coronary Vein, with its small valve. The Foramina Thebesii are minute orifices of veins, which open into all the cavities of the heart; they are most numerous, however, in the right auricle. 157 The Ostium Venosum, or opening of the right auricle into the right ventricle, is somewhat oval; it has a valve which projects into the right ventricle. The Right Ventricle may now be opened by an in- cision, carried from the root of the pulmonary artery down to the apex ofthe heart. This incision should be made with care, lest the parts on the inside ofthe ven- tricle be destroyed by it; it should pass along the right side of the septum ventriculorum, the situation of which is marked out by large branches ofthe coronary artery and vein. A small opening should first be made, into which one blade of the scissors can be introduced: the incision may be continued through the apex of the heart, or a flap may be made by another cut, passing from the beginning of the first along the margin of the right auricle. —In this ventricle, observe the projecting bundles of muscular fibres, the Tricuspid Valves arising from the margin.of the ostium venosum, and projecting into the right ventricle. This valve forms a complete circle at its base, but has its edge divided into three parts, which are attached by tendinous filaments, named Chords Tendine^e, to the Carney Columns, or muscular bun- dles ofthe ventricle. The Septum Ventriculorum, or partition ofthe two ventricles, is marked out externally by two veins running from the apex to the basis of the heart. Slit up the pulmonary artery; observe how it arises from the back part ofthe right ventricle, how smooth the inside ofthe ventricle becomes as it approaches the en- trance of the artery, or ostium arteriosum. Observe the three Semilunar or Sigmoid Valves. Their bases arise from the artery, their loose edges project into its cavity, and in the middle of the loose edge of each valve is seen a small white body, termed Corpus Sesamoideum Arantii. The artery is seen bifurcating into the right and left pulmonary arteries, and, just before its bifurcation, sending off to the aorta the ductus arteriosus, which in the adult is a ligament. 0 158 The Left Auricle has four pulmonary veins opening into its cavity, which may be exposed by slitting up two of those veins. Observe that its coats are thicker than those of the right auricle. The septum auricularum, with the fossa ovalis, is here seen less distinctly than on the right side. Observe also the ostium venosum, opening into the left ventricle, and giving attachment to the Val- vula Mitralis. The Left Ventricle may be opened in the same manner as the right, by an incision carefully made in the left side of the septum or partition of the ventricles, and continued round the upper part of the ventricle, under the auricle. Observe the great thickness of the muscular coat; the Valvula Mitralis, forming two projections, which are attached by the chordae tendineae to the fleshy columns of this ventricle. Slit up the aorta; it has three semilunar valves, which resemble those of the pulmonary artery;—behind these valves the artery bulges out, forming the Sinuses of the aorta. Above two of the valves lie the orifices of the two coronary arteries, of which the left is the largest. 159 CHAP. IX. DISSECTION OF THE FACE. SECT. L OF THE MUSCLES. Under the integuments of the face, there is always a considerable quantity of adipose membrane; many of the muscles are very slender, and lying embedded in this fat, require careful dissection. The whole side of the face is also supplied with numerous ramifications of the facial nerve, or portio dura of the seventh pair. These nervous twigs are generally removed with the integuments. Twelve pair of muscles, and one single muscle, arc described in this dissection. 1. The Orbicularis Palpebrarum—Arises, from the internal angular process of the frontal bone, and from a tendon at the inner angle of the eye, by a number of fleshy fibres which pass round the orbit, covering first the superior and then the inferior eye-lid, and also the bony edges ofthe orbit. Inserted, by a short round tendon, into the nasal process of the superior maxillary bone. Situation: This muscle is intermixed, at its upper part, with the occipito-frontalis; it covers the upper part of the lacrymal sac. Use: To shut the eye, by bringing down the upper lid, and pulling up the lower; the fibres contracting to- wards the inner angle, as to a fixed point, compress the 160 eye-ball and lacrymal gland, and convey the tears towards the puncta lacrymalia. Synonyma: Orbicularis palpebrarum et ciliaris;—The ciliaris is only a part of the muscle covering the cartilages ofthe eye-lids, which are called the Cilia or Tarsi;— Maxillo-palpebral. 2. The Corrugator Supercilii—Arises, fleshy, from the internal angular process of the os frontis; it runs out- wards and a little upwards, to be Inserted into the inferior fleshy part ofthe occipito- frontalis muscle, extending outwards as far as the middle of the superciliary ridge. Situation: This muscle is concealed by the occipito- frontalis. It lies close to the upper and inner part of the orbicularis palpebrarum, with which it is connected. Use: To smooth the skin ofthe forehead, by pulling it down after the action ofthe occipito-frontalis. When it acts more forcibly, it pulls down the eye-brow and skin of the forehead, and produces vertical wrinkles. Synonyma: Musculus supercilii;—Musculus frontalis verus, seu corrugator;—Cutaneo-sourcillier. 3. The Compressor Naris—Arises, narrow from the outer part of the ala nasi, and neighbouring part of the os maxillare superius. From this origin a number of thin separate fibres run up obliquely along the cartilage of the nose towards the dorsum nasi, where the muscle joins its fellow, and is Inserted, slightly, into the lower part of the os nasi and nasal process of the superior maxillary bone. Situation: It is superficial; its origin is connected with the levator labii superioris alaeque nasi; and its up- per part with some ofthe descending fibres of the occi- pito-frontalis. Use: To compress the ala towards the septum nasi; but, if the fibres of the occipito-frontalis, which adhere to it, act, the upper part of this muscle assists in pulling the ala outwards: It also corrugates the skin of the nose. 161 Synonyma: Transversalis seu myrtiformis;—Dilatores alarum nasi;—Constrictor nasi;—Maxillo-narinal. 4. Levator Labii Superioris Aljeque Nasi— Arises by two distinct origins; the first from the nasal process of the superior maxillary bone, where it joins the os frontis at the inner canthus of the eye; it descends along the nasal process, and is inserted into the outer part of the ala nasi, and into the upper lip. The second arises, broad and fleshy, from the external orbitar pro- cess of the superior maxillary bone, immediately above the foramen infra-orbitarium; it runs down, becoming narrower, and is inserted into the upper lip and orbicu- laris oris. Situation: The first portion is sometimes called Le- vator Labii Superioris Alaeque Nasi, and the second Levator Labii Superioris Proprius. Their origins are partly covered by the orbicularis palpebrarum. They descend more outwardly than the ala nasi. Use: To raise the upper lip towards the orbit, and a little outwards; the first portion will also draw the ala nasi upwards and outwards. Synonyma: Incisivus lateralis et pyramidalis;—Ele- vator labii superioris proprius;—Maxillo-labii-nasal. The infra-orbitary artery, vein, and nerve, are seen emerging from the infra-orbitary foramen under"this muscle. 5. Zygomaticus Minor—Arises, from the upper pro- minent part of the os malas, and, descending obliquely downwards and forwards, is Inserted into the upper lip near the corner ofthe mouth. Situation: Its origin is covered by the orbicularis pal- pebrarum; it has its course between the levator labii su- perioris alseque nasi and the zygomaticus major. Fre- quently the orbicularis palpebrarum sends down a slip of fibres to the upper lip, which slip runs between the zygomaticus minor and levator labii superioris alaeque nasi. 0 2 162 Use: To draw the corner of the mouth and upper lip obliquely upwards and outwards. Synonyma: Petit zygomato-labial. 6. Zygomaticus Major—Arises, fleshy, from the os malae, near the zygomatic suture. Inserted into the angle of the mouth, appearing to be lost in the depressor anguli oris, and orbicularis oris. Situation: Its origin is partially covered by the orbi- cularis palpebrarum; it lies more outwardly than the zygomaticus minor. Use: To draw the corner of the mouth and under lip upwards and outwards. Synonyma: Zygomaticus;—Grand zygomato-labial. 7. The Levator Anguli Oris—Arises, thin and fleshy, from a depression of the superior maxillary bone betwixt the root of the socket of the first dens moralis, and the foramen infra orbitarium. Inserted, narrower, into the angle of the mouth. Situation: It lies more outwardly than the levator la- bii superioris alaeque nasi; it is in part concealed by that muscle, by the zygomaticus minor, and part of the zygo- maticus major. At its insertion it is particularly con- nected with the depressor anguli oris. Use: To draw the corner of the mouth upwards. Synonyma: Levator labiorum communis;—Caninus; —Sus-maxillo-labial. 8. The Depressor Anguli Oris—Arises, broad and fleshy, from the lower edge of the inferior maxillary bone, at the side of the chin, and gradtally becoming narrower, is Inserted into the angle of the mouth. Situation: This muscle is firmly connected with the platysma myoides; at its insertion it is blended with the zygomaticus major and levator anguli oris. Use: To pull down the corner of the mouth. Synonyma: Depressor labiorum communis ^Trian- gularis: Sous maxillo-labial. 9. The Depressor Labii Inferioris—Arises, fleshy 163 and broad, from the side ofthe lower jaw, a little above its lower edge; it runs obliquely upwards and inwards, and is < Inserted into the edge of the under lip. Situation: This muscle, at its insertion, decussates with its fellow. It is in part covered by the depressor anguli oris. It forms the thick part of the chin, and has its fibres interwoven with fat. Use: To pull the under Lip downwards. Synonyma: Depressor labii inferioris proprius;—Qua- dratus;—Mentonier-labial. 10. The Buccinator—Arises, tendinous and fleshy, from the lower jaw, as far back as the root of the co- ronoid process; from the upper jaw, as far back as the pterygoid process of the sphenoid bone; it then conti- nues to arise from the alveolar processes of both jaws, as far forwards as the dentes cuspidati. The fibres run forward, and are Inserted into the angle of the mouth. Situation: This muscle lies deep, adheres to the mem- brane that lines the mouth; and a quantity of fat is al- ways found between its fibres and the other muscles and integuments. It is partly concealed by the masseter, and by the muscles which pass to the angle of the mouth, as the levator and depressor anguli oris, and zygomati- cus major. It is inserted behind these muscles. In the cheek it is connected with the platysma myoides. Use: To draw the angle of the mouth backwards and outwards, and to contract its cavity, by pressing tho cheek inwards. Synonyma: Retractor anguli oris;—Alveolo-maxil- laire. The single muscle is the Orbicularis Oris.—It consists of two planes of se- micircular fibres, which decussate at the angles of the mouth. These fibres are formed chiefly by the muscles which are inserted into the lips; they surround the 164 mouth. The superior portion runs along the upper lip, the inferior portion along the under lip. Situation: It is connected and intermixed with the insertions of all the preceding muscles of the face. Some of the fibres are connected to the septum nasi, and are by Albinus termed Nasalis Labii Superioris. Use: To shut the mouth by contracting and drawing both lips together. Synonyma: Sphincter labiorum;—Semi-orbicularis superior et inferior:—Constrictor labiorum;—Labial. 11. Depressor Labii Superioris AleqUjE Nasi— Arises, thin and fleshy, from the os maxillare superius, where it forms the alveoli ofthe dentes incisiva and dens caninus; thence it runs up under part of the levator la- bii superioris alaeque nasi. Inserted into the upper lip and root of the ala rcasi. Situation: It is concealed by the orbicularis oris and levator labii superioris alaeque nasi. It- may be disco- vered by inverting the upper lip, and dissecting on the side of the frenum which connects the lip to the gums. Use: To draw the upper lip and ala nasi downwards and backwards. Synonyma: Depressor alae nasi;—Incisivus medius;— Depressor labii superioris proprius;—Maxillo-alveoli nasal. 12. The Levator Labii Inferioris—Arises, from the lower jaw at the root of the alveolus of the lateral incisor. Inserted into the under lip and skin ofthe chin. Situation: Those two small muscles are found by the side of the frenum of the lower lip. They lie under the depressor labii inferioris. Use: To raise the under lip and skin of the chin. Synonyma: Levator menti;—Incisivus inferior;—Ele- vator labii inferioris proprius;—Sous-maxillo-cutane. On the side of the face we observe two strong mus- cles, and two other muscles are concealed by the angle rf the inferior maxilla. 165 1. The Masseter is divided into two portions, which decussate one another. The Anterior Portion arises, tendinous and fleshy, from the superior maxillary bone, where it joins the os malae; from the lower edge of the os malae, and from its zygo- matic process. The strong fibres run obliquely down- wards and backwards, and are inserted into the outer surface of the side of the lower jaw, extending as far back as at its single. The Posterior Portion arises, principally fleshy, from the inferior surface of the os malae, and of the whole of the zygomatic process, as far back as the tubercle before the socket for the condyle of the lower jaw. The fibres slant forwards, and are inserted, tendinous, into the outer surface of the coronoid process of the lower jaw. Situation: The anterior portion conceals almost the whole ofthe posterior portion. The greater part of this muscle is superficial. Below, it is covered by the pla- tysma myoides; and above, a small portion of it is con- cealed by the origin of the zygomaticus major. Use: To pull the lower to the upper jaw, and to move it forwards and backwards. Synonyma: Zygomato-maxillaire. 2. Temporalis—Arises, fleshy, from a semicircular ridge in the lower and lateral part ofthe parietal bone, from all the squamous portion of the temporal bone, from the external angular process of the os frontis, from the temporal process of the sphenoid bone, and from an aponeurosis which covers the muscle. From these dif- ferent origins the fibres converge, descend under the bony jugum formed by the zygomatic processes of the temporal and cheek bones. Inserted, by a strong tendon, into the upper part ofthe coronoid process of the lower jaw, to which it adheres on every side, but more particularly its fore part, where the insertion is continued down to near the last dens molaris. Situation: This muscle is of a semicircular shane. It 166 is covered by a fascia or aponeurosis. This fascia ad- heres to the bones which give origin to the upper part of the muscle, and, descending over it, is inserted into the ju- gum, and adjoining part ofthe os malae and os frontis. The temporalis, at its origin, lies under the expanded tendon of the occipito-frontalis, and under the small tendons which move the external ear. Its insertion is concealed by the jugum and by the masseter; so that, to expose it, the masseter must be cut away. Use: To pull the lower jaw upwards, and press it-, against the upper. Synonyma: Crotaphites;—Arcadi-temporo-maxillaire. In order to expose the following muscles, we must re- move the muscles of the cheek and jaw, the masseter and insertion of the temporalis must be taken away, and the coronoid process of the inferior maxilla removed by a saw. 3. The Pterygoideus Externus—Arises, from the outer side of the external plate of the pterygoid process of the sphenoid bone, from part of the tuberosity of the os maxillare adjoining to it, and from the root of the temporal process of the sphenoid bone. It passes back- wards and outwards, to be Inserted into a depression in the neck of the condyloid process ofthe lower jaw, and into the anterior and inner part of the ligament of the articulation of that bone. Situation: This muscle passes almost transversely from the skull to its insertion. It is concealed by the muscles of the face and neck, and by the ascending processes of the lower jaw. Use: When this pair of muscles act together, they bring the jaw horizontally forwards. When they act singly, the jaw is moved forwards, and to the opposite side. Synonyma: Pterygoideus minor;—Pterigo-colli-max- illaire. 4. The Pterygoideus Internus—Arises, tendinous and fleshy, from the inner and upper part of the internal 167 plate of the pterygoid process of the sphenoid bone, filling all the space between the two plates; and from the ptery- goid process of the os palati between these plates. Inserted, by tendinous and fleshy fibres, into the inside ofthe angle ofthe lower jaw. Situation: To expose this muscle, the jaw must be removed from its articulating cavity, and then pulled for- wards, and toward the opposite side; or it may be sawn across at its symphysis, and the other half removed. It is larger than the pterygoideus externus; and betwixt the two muscles there is a considerable quantity of cellular membrane, and the trunk of the inferior maxillary and gustatory nerves. Like that muscle, it is concealed by the lower jaw and facial muscles. Along its posterior edge we observe the Ligamentum Laterale Maxilla? Inferioris, a ligamentous band, which extends from the back part of the styloid process to the angle of the lower jaw. Use: To draw the jaw upwards, and obliquely towards the opposite side. Synonyma:Pterygoideus major;—Pterigo-anguli-max- illaire. On the side of the face is situated a considerable sali- vary gland, the Parotid Gland, a large white mass, irregularly oblong and protuberant, filling up all the space betwixt the angle and ascending processes of the jaw, the mastoid processes, root of the cartilage of the ear, and zygomatic process of the temporal bone. From its an- terior and upper part a white canal or duct passes for- wards over the masseter, and perforates the buccinator from without inwards, opening into the mouth opposite the first dens molaris. The coats of this duct are very thick and firm, consisting of a ligamentous substance. 168 SECT. II. OF THE VESSELS AND NERVES OF THE FACE. arteries. The A. Maxillaris Externa, the third branch of the carotid, comes from the neck over the lower jaw at the anterior edge of the masseter. It then runs under the depressor anguli oris, passes towards the angle of the mouth, and is often much contorted. Here it is named the A. Facialis or Angularis. It ascends, by the side of the nose, and reaching the inner angle ofthe eye, is lost on the muscles situated there, inosculating freely with the temporal, internal maxillary, and ophthalmic arteries. In this course it gives off many branches; 1. Twigs to the masseter, depressor anguli oris, and chin; 2. A. Coro- Naria Labiorum. This artery is very much contorted. —At the angular commissure ofthe lips, it divides itself into two branches, which run along the superior and in- ferior portions of the orbicularis oris, and join the same branches of the other side. 3. While the facial artery ascends by the side ofthe nose, it gives off the external nasal arteries to the outside of the nose, and the A. Buccales to the cheek. The External Carotid is found ascending behind the parotid gland. It perforates the gland at its upper part, ascends over the zygomatic process immediately before the ear, and divides into the anterior, middle, and pos- terior temporal arteries, which ramify over the side of the head, giving also branches to the forehead and oc- ciput. But the carotid, while it lies imbedded under the pa- rotid, sends several twigs to the substance of that gland, and a considerable artery which passes forwards, and ramifying on the side of the face, is named A. Trans- versalis Faciei. At this point also, the carotid sends 169 off a large artery, the A. Maxillaris Interna. As inany branches of this artery are met with in the dis- section of the face, it is proper to give a view of its dis- tribution. The internal Maxillary passes behind the condyloid process of the lower jaw; it directs its course towards the bottom ofthe orbit of the eye; and it is at this point that it sends off its numerous branches. (1.) Arteria Media Durje Matris (or Meningea spheno-spinalis or spinosa), passes through the spinal hole of the sphenoid bone into the cranium, and is distributed to the dura mater. (2.) A. Maxillaris Inferior, vel Dentalis Inferior, runs downwards, enters the foramen at the root of the ascend- ing processes of the lower jaw, then passes through the canal of the lower jaw; supplying the teeth and sockets, and emerges by the foramen mentale, to be distributed to the chin. It is accompanied by a nerve and one or two veins. (3.) A. Pterygoideae and A. Temporales Profundas, are small branches of the internal maxillary which pass to the pterygoid muscles, and to the inner part of the temporal muscle. (4.) A. Pharyngeae, branches to the pharynx, palate, and base of the skull. (5.) A. Alveolaris, which gives branches to the teeth of the upper jaw, and to the jaw bone itself. (6.) A Branch through the foramen spheno-patytinum to the nose; and, (7.) An Artery through the palato-maxillary canal to the palate. The continued trunk of the internal maxillary enters the orbit by the spheno-maxillary slit. It sends off a branch which runs along the inner side of the orbit, and passes out at the inner canthus of the eye on the forehead. The artery itself runs along the bottom ofthe orbit in a canal on the upper part of the great tuberosity of the os maxillare superius, and emerges by the foramen infra- orbiiariurn on the face; hence it is termed A. Infra-Or- bitaria, and is distributed to the cheek and side of the nose. The Frontal Artery is also seen in the dissection of P 170 the face, passing from the orbit through the foramen supra-orbitarium to be distributed to the forehead. This artery is sent off' from the ophthalmic artery, which is a branch of the internal carotid. If the face be injected, a remarkable anastomosis of arteries will be observed at the inner angle of the eye. veins. The veins of the face are numerous, and pass into the external and internal jugular veins. NERVES. 1. The Portio Dura of the seventh pair, Nervus Communicans Faciei, or Facial nerve, after its course through the temporal bone in the aqueduct of Fallopius, come? out by the foramen stylo-mastoideum. It imme- diately gives off branches to the neighbouring parts, as behind the ear. It then passes through the substance of the parotid gland, and emerges on the face in three great branches, which have frequent mutual communications: this division of the nerve is called Pes Anserinus. (1.) The ascending branch ramifies on the temple and forehead. (2.) The middle branch sends its ramifications over the side of the face, the proper Facial Nerves. (3.) The descending branch sends its twigs along the chin, down upon the neck, and backwards upon the occiput. 2. The Superior Cervical Nerves send off seve- ral branches, which ramify on the side of the face and head, and communicate freely with the branches of the poxtio dura. As in the course of this dissection, we meet with manv twigs of the second and third branches of the fifth* pair of nerves, it will be advisable here to de- scribe these nerves. 171 3. Nervus Maxillaris Superior, or Second Branch of the Fifth Pair. The superior maxillary nerve, hav- ing left the cranium by the foramen rotundum of the sphenoid bone, emerges behind the antrum maxillare, at the lower back part of the orbit, and at the root cf the pterygoid process of the sphenoid bone. It imme- diately sends out branches; 1. A small branch which passes through the spheno-maxillary slit to the perioste- um and fat of the orbit. 2. The largest branch is the Infra-Orbitary Nerve. It enters the channel in the top of the antrum maxillare, accompanying the infra- orbitary 3rtery, comes out at the foramen infra-orbitari- um, and is widely distributed to the cheek, under lip, and outside of the nose, communicating with ramifica- tions of the portio dura. 3. Branches to the temporal muscle, os malae, &c. 4. Other branches form a small ganglion at the root of the orbit, which sends twigs, named the superior Nasal Nerves, through the foramen spheno-palatinum to the nose. 5. The Vidian Nerve, which enters the foramen pterygoideum, and passes again into the cranium, to connect itself with the portio dura. 6. The Palatine Nerve, which runs through the palato- maxillary canal to the palate. 7. Twigs which supply the gums and alveoli of the upper jaw. 4. Nervus Maxillaris Inferior, or Third Branch of the Fifth Pair. The inferior maxillary nerve leaves the cranium by the foramen ovale of the sphenoid bone. It has its course downwards and outwards; and, having given twigs to the parts near which it passes, as the mas- seter, pterygoid, and temporal muscles, it divides at the angle of the lower jaw into two branches. 1. The NcrvBs Dentalis Inferior enters the foramen at the angle of the lower jaw; accompanies the inferior dental artery along the canal in that bone, giving nerves to the teeth; emerges by the foramen mentale, and is distributed to the chin. 2. The Nervus Gustatorius, vel Linguales, passes to the tongue. It was seen in the dissection of the neck lying close upon the lower jaw-bone, below 172 the inferior edge of the pterygoideus-internus, and above the superior fibres of the mylo-hyoideus. It supplies the substance of the tongue, and the salivary glands situated at the root of the tongue. This nerve receives the chorda tympani, a small twig which comes from the seventh pair through the slit in the articulating cavity of the temporal bone. 5. In the dissection of the face, we also meet with the Frontal Nerve, which comes from the first branch of the fifth pair, and which is seen accompanying the frontal artery through the foramen supra-orbitarium. It is distributed to the forehead. 173 CHAP. X. DISSECTION OF THE THROAT. On looking into the mouth, we observe a soft curtain hanging from the palate bones, named the Velum Pen- dulum Palati, or soft Palate. The apex of (he velum forms a small projecting glandular body, termed the Uvula,- or pap of the throat. From each side of the uvula, two muscular half-arches or columns are sent down, the anterior to the root of the tongue, the poste- rior to the side of the pharynx. Between these half- arches on each side, are situated the glands termed Amyg- dale, or Tonsils. The common opening behind the an- terior arch is named the Fauces, or top of the Throat, from which there are six passages, two upwards, being one to each nostril, called the Posterior Nostrils; two at the sides, called Eustachian Tubes, passing on each side to the ear;* two downwards, of which the anterior is the passage through the glottis and larynx into the trachea; the posterior, which is the largest, is the pha- rynx, or top of the oesophagus, and leads to the stomach. * A probe may be introduced through the anterior nostrils into the Eustachian mbe; the tube opens into the pharynx in a direc- tion opposite to the space between the roots of th> middle and inferior turbinated bones. P2 174 SECT. I. MUSCLES SITUATED ABOUT THE ENTRY OF THE FAUCES. These consist of four pairs, and a single muscle in the middle. 1. Constrictor Isthmi Faucium—Arises, by a slen- der beginning, from the side of the tongue, near its root; thence running upwards within the anterior arch, before the amygdala, it is Inserted into the middle of the velum pendulum pa- lati, as far as the root of the uvula. It is here connect- ed with its fellow, and with the beginning ofthe palato- pharyngeus. Situation: It forms the anterior half-arch. Use: To draw the velum towards the root of the tongue, which at the same lime it raises, and, with its fellow, to contract the opening into the fauces. Synonyma: Glosso-staphylinus. 2. The Palato-Pharyngeus—Arises, by a broad be- ginning, from the root of the uvula in the middle of the velum pendulum palati, and from the tendinous expan- sion of the circumflexus palati. The fibres pass along the posterior arch behind the amygdalae, and run back- wards to the superior and lateral part of the pharynx, where they are scattered, and mixed with those of the stylo-pharyngeus. Inserted into the edge of the upper and back part of the thyroid cartilage, and into the back part of the pha- rynx. Situation: It forms the posterior half-arch or column. Use: To draw the uvula and velum downwards and backwards, and pull the thyroid cartilage and pharynx upwards: to shut the passage into the nostrils, and in swallowing, to thrust the food from the fauces into the pharynx. 175 Synonyma: Thyro-staphylinus;—Thyreo-pharyngo- staphylinus;—Palato-pharyngien. The Salpingo-Pharyngeus of Albinus is composed of a few fibres of this muscle, which arise from the an- terior and lower part of the cartilaginous extremity of the Eustachian tube, and are inserted into the inner part of the last-mentioned muscle. 3. The Circumflexus, or Tensor Palati— Arises, from the spinous process of the sphenoid bone, behind the foramen ovale, and from the Eustachian tube near its osseous part; runs down along the pterygoideus inter- nus, and forms a round tendon, which passes over the hook of the internal plate of the pterygoid process of the sphenoid bone, and soon spreads into a broad tendinous expansion. Inserted into the velum pendulum palati, and semilu- nar edge of the os palati. Situation: Its insertion extends as far as the suture which joins the two ossa palati. Some of its posterior fibres generally join with the constrictor pharingis su- perior and palato-pharyngeus. Use: To stretch the velum, to draw it downwards, and to one side. Synonyma: Spheno-salpingo-staphylinus, seu Staphy- linus externus;—Musculus tubas novus, vel Palato-salpin- geus;—Pterygo-staphylinus;—Spheno-salpingo-staphi- lin. 4. The Levator Palati—Arises, tendinous and fleshy, from the extremity of the petrous portion of the temporal bone, and from the Eustachian tube. Inserted into the whole length of the velum pendulum palati, as far as the root of the uvula, uniting with its fellow. Use: To draw the velum upwards and backwards, so as to shut the passage from the fauces into the mouth and nose. Synonyma: Levator palati mollis;—Petro-salpingo- stapbylinus, vel Salpingo-staphylinus internus;—Salpin- 176 go-staphylinus Valsalvae, vel Pterygo-staphylinus exter- nus ;_Spheno-staphylinus:—Petro-salpingo-staphilin. The single muscle is the Azygos Uvulae.—It arises, fleshy, from the extremi- ty ofthe suture which unites the ossa palati; runs down the whole length of the velum, like a small earth-worm, adhering to the tendons of the circumflexi palati; Inserted into the tip of the uvula. Use: To raise the uvula upwards and forwards, and shorten it. Synonyma: Staphylinus, or Epistaphyhnus;—Palato- stapbylinus. SECT. II. MUSCLES SITUATED ON THE POSTERIOR FART OF THE PHARYNX. Of these there are three pair. 1. The Constrictor Pharyngis Inferior.—This muscle arises, from the outside of the ala of the thyroid cartilage, near the attachment of the tbyreo-hyoideus mttscle, and from the side of the cricoid cartilage, near the crico-thyroideus. Inserted into the white line on the back part of the pharynx, where it is united to its fellow. Situation: This muscle covers the under part of the middle constrictor; the superior fibres run obliquely up- wards, while the inferior fibres have a transverse direc- Use: To compress that part of the pharynx which it covers, and to raise it with the larynx a little upwards. Synonyma: Thyro-pharyngeus and crico-pharyngeus; —Crico-thyro-pharyngien. 2. The Constrictor Pharyngis Medius—Arises 177 trom the superior edge of the cornu of the os hyoides, extending as far forwards as the graniform process, or appendix; and from the ligament which connects it to the thyroid cartilage. The superior fibres ascend ob- liquely, the others run more transversely. Inserted into the cuneiform process of the os occipitis, before the foramen magnum, and into a white line in the middle of the posterior surface of the pharynx, where it is joined to its fellow. Situation: The lower part of this muscle is covered by the muscle last described, while the upper part co- vers the inferior fibres of the constrictor superior. Use: To compress that part of the pharynx which it invests, and to draw it and the os hyoides upwards. Synonyma: Hyo-pharyngeus, and Chondro-pharyn- geus;—Hyo-glosso-basi-pharyngien. 3. Constrictor Pharyngis Superior—Arises, above, from the cuneiform process of the os occipitis, before the foramen magnum; lower down from the pterygoid pro- cess of the sphenoid bone; from the upper and under jaw, near the alveolar processes of the last dentes mo- lares; and from the back part of the buccinator muscle. Some fibres also come from the root of the tongue, and from the palate. Inserted into a white line in the middle of the posterior surface of the pharynx. Situation: The larger part of this muscle is covered by the constrictor medius. Use: To compress the upper part of the pharynx, and draw it forwards and upwards. Synonyma: Cephalo-pharyngeus, Pterygo-pharyngeus, mylo-pharyngeus, and glosso-pharyngeus;—Pterigo-syn- desmo-staphili-pharyngien. 178 SECT. III. MUSCLES OF THE LARYNX. The Larynx is composed of five Cartilages: 1. The Thyroid Cartilage, situated immediately below the os hyoides in the middle of the throat. 2. The Cricoid Cartilage, situated immediately below the thyroid carti- lage, betwixt it and the superior rings of the trachea. 3. The Epiglottis, a broad triangular cartilage, very elas- tic, situated behind the root ofthe tongue, and covering the entrance into the upper part of the larynx. 4. and 5. The arytenoid cartilages, two small bodies, like peas, situated behind the thyroid cartilage, on the upper edge of the back part of the cricoid cartilage, and between the two alae or wings of the thyroid cartilage. These two small cartilages form betwixt themselves and the thyroid a longitudinal fissure, extending frdm before back- wards, which is called the Glottis, or Rima Gldttidis, and leads to the trachea. The muscles situated about the glottis, consist of four pair of small muscles, and a single one. 1. The Crico-Aryt^enoideus Posticus—Arises, fleshy, from the posterior part of the cricoid cartilage, and is Inserted, narrow, into the back part of the arytenoid cartilage of the same side. Use: To open the rima glottidis a little, and, by pull- ing back the arytenoid cartilage, to render the ligament of the glottis tense. Synonyma: Crico-creti-arithenoidien. 2. The Crico-ArytjENoideus Lateralis—Arises, * fleshy, from the side of the cricoid cartilage, where it is covered by the ala of the thyroid cartilage. Inserted into the outer side of the arytenoid carti- lage. Situation: It lies more forward than the last described muscle. 179 Use: To open the rima glottidis, by pulling the liga- ments from each other. Synonyma: Crico lateri-arithenoidien. 3. The Thyreo-Aryt^noideus—Arises, from the middle and inferior part of the posterior surface of the thyroid cartilage; runs backwards, and a little upwards and is ' ' Inserted into the fore part of the arytenoid cartilage. Situation: It is situated more forwards than the mus- cle last described. Use: To pull the arytenoid cartilage forwards, and thus shorten the ligament of the larynx or glottis. Arytaenoideus Obliquus—Arises from the base of one arytenoid cartilage; and, crossing its fellow is Inserted into the tip ofthe other arvtenoid cartilage. Use: When both act, they pull the arytenoid carti- lages towards each other. Synonyma: Arytaenoideus minor. The single muscle is the ARYTiENoiD*:us Transversus, which arises from the whole length of one arytenoid cartilage, and passes across to be Inserted into the whole length of the other arytenoid cartilage. Situation: It is situated anterior to the arytaenoidei ob- liqui. Use: To shut the rima glottidis, by bringing the ary- tenoid cartilages together. On each side of the larynx, there are also a few mus- cular fibres, which are named as follows. 1. Thyreo-Epiglottideus—Arising, by a few pale separated fibres, from the thyroid cartilage, and Inserted into the epiglottis laterally. Use:To draw the epiglottis obliquely downwards, or, when both muscles act, directly downwards; and at the' same time to expand it. 2. The Aryt^eno-Epiglottideus—Ames, by a few 180 slender fibres, from the lateral and upper part of the ary tenoid cartilage, and is Inserted into the epiglottis, along with the former muscle. Use: When both muscles act, to pull the epiglottis close upon the glottis. 181 CHAP. XL DISSECTION OF THE ORBIT OF THE EYE. The globe or ball ofthe eye is situated about the mid- dle of the orbit. It is connected to the bone of its mus- cles, and by the optic nerve; and all these parts are im- bedded posteriorly in a soft, fatly substance, which fills up the bottom of the orbit.—The tunica, or membrana conjunctiva, is seen lining the inner surface of the eye- lids, and reflected from them over the anterior part of the globe of the eye, so that the back part of the eye- ball, and all the muscles and nerves, are situated behind it. This membrane must therefore be dissected away, the upper part of the orbit, which is formed by the os frontis, removed with a saw, and the fat surrounding the muscles, vessels, and nerves, cautiously dissected away with the scissors. SECT. I. MUSCLES SITUATED WITHIN THE ORBIT. Seven muscles are contained within the orbit, of which one belongs to the upper eye-lid, and six to the globe of the eye. 1. The Levator Palpebr^: Superioris—Arises, by a small tendon, from the upper part of the foramen opti- cum of the sphenoid bone; the tendon forms a broad flat bellv. Q 182 Inserted, by a broad thin tendon, into the upper eye- lid, adhering to the tarsal cartilage, which gives form to the eye-lid. Use: To open the eye, by drawing the superior eye- lid upwards. Synonyma: Aperiens palpebram rectus;—Orbito-sus- palpebral. There are four straight muscles, or recti, belonging to the globe ofthe eye. These four muscles resemble each other, all arising by narrow tendons from the margin of the foramen opticum, where they surround the optic nerve; all forming strong fleshy bellies, and inserted, by broad, thin tendons, at the fore part of the globe of the eye, into the tunica sclerotica, or outer tunic of the eye, and under the tunica conjunctiva. 2. The Levator Oculi—Arises,by a narrow tendon, from the upper part of the foramen opticum ofthe sphe- noid bone; it forms a fleshy belly, and is Inserted into the superior and anterior part of the tuni- ca sclerotica, by a broad thin tendon. Sitiiation: It lies below the levator palpebrae supe- rioris. Use: To raise the globe of the eye. Synonyma: Elevator;—Rectus attollens oculi;—Sus- optico spheni scleroticien. 3, The Depressor Oculi—Arises from the inferior margin of the foramen opticum, and is Inserted into the inferior and anterior part of the tu- nica sclerotica. Use: To move the globe ofthe eye downwards. Synonyma: Rectus deprimens oculi;—Sous-opti-sphe- no-scleroticicn. 4 The Adductor Oculi—Arises, from the inner part ofthe foramen opticum, and is Inserted into the inner and anterior part of the tunica sclerotica. It is 'he shortest of the four recti muscles. Use: To draw the eye towards the nose. 183 Synonyma: Rectus adducens oculi;—Orbito-intus- scleroticien. 5. The Abductor Oculi—Arises from the outer part ofthe foramen opticum. Inserted into the outer part of the tunica sclerotica. It is the longest of the recti. Use: To move the globe outwards. Synonyma: Rectus abducens aculi;—Orbito-extus* scleroticien. The two next are oblique muscles. 6. The Obliquus Superior, or Trochlears—Arises, by a small tendon, from the margin of the foramen op- ticum, between the levator and abductor oculi. Its long slender belly runs along the inner side ofthe orbit to the internal angular process ofthe os frontis, where a car- tilaginous pully is fixed. The muscle then forms a ten- don, which passes through the pully, runs obliquely down- wards and outwards, inclosed in a membranous sheath; and becoming broader and thinner, is Inserted into the tunica sclerotica, about half way be- tween the insertion of the levator oculi, and the entrance of the optic nerve. Use: To roll the globe ofthe eye, and turn the pupi! downwards and outwards. Synonyma: Obliquus major;—Optico-trochlei-sclero- ticien. The Obliquus Inferior—Arises, narrow, and prin- cipally tendinous, from the outer edge ofthe orbitar pro- s cess of the superior maxillary bone, near its junction with the os unguis. It runs obliquely outwards and back- wards, under the depressor oculi, and is Inserted, by a broad thin tendon, into the sclerotica, between the entrance of the optic nerve, and the insertion ofthe abductor oculi. Use: To draw the globe of the eye forwards, inwards and downwards, and to turn the pupil upwards. Synonyma: Obliquus major;—Maxillo-scleroticien. In the orbit, we also meet with the Lachrymal 184 Gland.—This gland is of a yellowish colour; it is situated in a depression of the os frontis near the temple. It ad- heres closely to the fat which surrounds the muscles and posterior convexity of the eye. It sends off several small ducts which pierce the tunica conjunctiva lining the upper eye-lid; these ducts cannot be seen, unless the part be macerated in water, when they are filled with the liquid. The Puncta Lachrymalia are two small holes near the internal angle ofthe palpebrae, situated one in each eye-lid. They lead into the Lachrymal Sac. This sac is an oblong membranous bag, situated at the inner angle ofthe eye, in a depression formed by the os unguis, and nasal process of the superior maxillary bone. It receives the tears by the puncta lachrymalia, and from the sac they are conveyed into the nose by a Duct, named the Lachrymal, or Nasal. The lower extremity of this duct opens into the nose on one side of the antrum maxillare, and under the os spongiosum inferius. A probe, with its extremity bent, may be introduced from the nose through this duct into the lachrymal sac. The Caruncula Lachrymalis is a small reddish granu- lated body, situated at the internal angle of the pal- pebrae. SECT. II. OF THE "VESSELS AND NERVES MET WITH IN THE ORBIT OF THE EYE. ARTERIES. The Ophthalmic, or Ocular Artery, is a branch of the internal carotid. It enters the orbit from the basis ofthe cranium by the foramen opticum. It gives branches to the lachrymal gland, fat, muscles, and globe of the eye. 185 One twig, named the A. Centralis Retinae, enters the substance of the optic nerve, and is continued on to the retina;—twigs also pass to the eye-lids, and to the inner angle of the eye. The arteria Frontalis is a branch of " this artery; it is seen running towards the supra-orbi- tary notch or foramen, and is distributed to the fore- head. The Infra-Orbitary Artery is found in the lower part of the orbit; it is the continued trunk of the internal maxillary, entering the orbit by the spheno-maxillary slit. It is seen passing along the canal in the upper part of the great tuberosity of the os maxillare superius, and emerges on the face by the infra-orbitary hole. VEINS. These correspond with the arteries; they discharge their blood partly into the branches ofthe external jugu-p lar vein near the forehead and temples, and partly into the internal jugular. NERVES. 1. The Optic Nerve is seen coming through the foramen opticum, and entering the back part ofthe globe ofthe eye, to form the retina. 2. The Nerve ofthe Third Pair, Motor Oculi, having entered the orbit through the superior orbitary fissure, or foramen lacerum, is divided jnto four branches. (1.) The first runs upwards, and subdivides into two nerves, of which one supplies the levator oculi, and the other the levator palpebrae superiors. (2.) The second branch goes to the depressor oculis, - and is short. (3.) The third branch supplies the obliquus inferior, and also gives off a twig, which assists in forming the lenticular ganglion. (i.) The fourth branch supplies the adductor oculi. Q2 ISO* 3. The Nerve of the Fourth Pair, N. Patheticus, or Trochlearis, enters the orbit by the superior orbitary fissure, and runs to the obliquus superior. 4. The first branch of the Nerve of the Fifth Pair, named Ophthalmic, or Orbitary, enters the orbit by the superior orbitary fissure, and divides into three branches. (1.) The Frontal, Supra-orbitary, or Superciliary Nerve, accompanies the frontal artery along the upper part of the orbit, close to the bone; and having passed through the supra-orbitary notch, is distributed to the forehead. (2.) The Nasal Nerve, or inner branch, runs towards the nose, and is distributed to the inner side of the orbit, and to the nose. (3.) The Temporal or Lachrymal Branch, supplies the lachrymal gland, and the parts at the outer side of the orbit. The Lenticular Ganglion is a small ganglion, situ- ated within the orbit, formed by short branches of the ophthalmic nerve, and by a twig of the third pair. It sends off delicate nerves, which run along the sides of the optic nerve, and pierce the coats of the eye. 5. The second branch of the Fifth Pair, called the Superior Maxillary Nerve, sends off a branch through the bony canal in the bottom ofthe orbit. This is the Infra-orbitary Nerve. It accompanies the artery of the same name, and emerges on the face by the infra- orbitary hole. 6. The trunk of the Sixth Pair of Nerves passes through the superior orbitary fissure to the abductor oculi. These delicate nerves are surrounded by the adipose substance found in the orbit, and require to be dissected with the utmost care. !8t CHAP. XII. DISSECTION OF THE MUSCLES SITUATED ON THE POSTERIOR PART OF THE TRUNK AND NECK. From the number and intimate connection of these muscles, their description necessarily is complicated, and their dissection difficult. The smaller muscles, indeed, cannot be separated, without dividing some of their fibres. We do not here, as in the limbs, find the muscles distinctly marked, loosely connected by cellular mem- brane, and separated with facility: but closely united, and in many places having their fibres so intermixed, as to render their divisions indistinct and uncertain. In this dissection we meet with twenty-two distinct pair of muscles, besides a number of small muscles situated between the processes of contiguous vertebrae. On removing the integuments of the posterior part of the neck and back, we expose, 1. The Trapezius—It arises, by a thick round ten- don, from the lower part ofthe protuberance in the mid- dle of the os occipitis behind, and, by a thin tendinous expansion, from the superior transverse ridge of that bone; from the five superior cervica spinous processes by the ligamentum nuchae; tendinous, from the two in- ferior cervicaf spinous processes, and from the spinous processes of all the vertebrae of the back. The fleshy fibres coming from the neck descend obliquely, while those from the back ascend. Inserted, fleshy, into the posterior third part of the cla- 188 vicle; tendinous and fleshy, into the acromion, and into the upper edge of all the spine of the scapula. The fi- bres slide over a triangular surface at the extremity of the spine of that bone. Situation: This muscle is quite superficial, and con- ceals all the muscles situated in the posterior part of the neck, and upper part ofthe back. It adheres to its fellow the whole length of its origin. Its anterior fibres lie pos- terior to those of the sterno-mastoideus, but are not in contact with them, a considerable quantity of adipose substance being interposed. The posterior cervical li- gaments, (ligamentum nuchas vel colli,) is a ligament which arises from the middle of the occipital bone, runs down on the back part of the neck, adhering to the spi- nous processes of the cervical vertebrae, and giving ori- gin to the fibres of the trapezius, and of other muscles. Use: To move the scapula in different directions. The superior fibres draw it obliquely upwards, the middle transverse ones draw it directly backwards, and the in- ferior fibres move it obliquely downwards and backwards. Also, to draw back the head, and contribute to its rotato- ry motion. Synonyma: Cucullaris ;—Occipiti-dorso-clavi-sus- acromien. It should be reflected from the spine and head. 2. The Latissimus Dorsi—Arises, by a broad thin tendon, from all the spinous processes of the os sacrum, and of the lumbar vertebrae; from the spinous processes of the seven inferior dorsal vertebrae; from the posterior part of the spine of the os ilium; also from the extre- mities of the four inferior false ribs, by four distinct fleshy digitations, which intermix with those of the obli- quus externus abdominis. The inferior fleshy fibres as- cend obliquely; the superior run transversely: they pass over the inferior angle of the scapula, (from which the muscle often receives a thin fasciculus of fibres,) to reach the axilla, where they are all collected and twisted. Inserted, by a strong flat tendon, into the inner edge of 180 the groove in the os humeri, which receives the long ten- don of the biceps fh xor cubiti. Situation: Where this muscle arises from the dorsal vertebrae, it is concealed by the origin of the trapezius. The remainder of it is placed immediately under the skin, and covers the deeper seated muscles of the loins and back. It is situated superior to the gluteus maximus, and posterior to the obliquus externus abdominis. Its inser- tion cannot be traced till the muscles of the arms are dissected; it forms the fold on the postorior part of the hollow of the armpit. The tendon of this muscle, with the subjacent tendon of the serratus .posticus inferior, assists in forming the fascia lumborum. Use: To pull the arm backwards and downwards, and to roll the os humeri. It should be reflected from the spine, pelvis, and ribs. Synonyma: Ani-scalptor;—Dorsi-lumbo-sacro-hume- ral. Remove the trapezius and latissimus dorsi, and two muscles will be seen passing from the neck to the scapula. 3. The Raomboideus. This muscle is divided into two portions. (1.) Rhomboideus major, (the inferior portion,) arises, tendinous, from the spinous process of the four or five superior dorsal vertebra?. Inserted into all the base of the scapula below its spine^ extending as far as its inferior angle. (2.) Rhomboideus Minor, (the superior portion,) arises, tendinous, from the spinous processes of the three inferior vertebrae of the neck, and from the ligamentum nuchae. Inserted into the base ofthe scapula, opposite to the triangular plain surface at the root ofthe spine. Situation: This muscle lies beneath the trapezius and latissimus dorsi; a small part«of the rhomboideus 190 major may be seen between these muscles, and the infe- rior part of the base of the scapula. Use: To draw the scapula obliquely upwards, and di- rectly backwards. Synonyma: Cervici-dorso-scapulaire. The rhomboidei should be reflected from the spine. 4. The Levator Scapula—Arises from the trans- verse processes of the five superior vertebrae ofthe neck, by five distinct tendinous and fleshy slips, which unite and form a considerable muscle. Inserted, tendinous and fleshy, into the base ofthe sca- pula, above the root ofthe spine, and under the superior angle, (not into the angle itself, as it is usually describ- ed.) Situation: This muscle is concealed by the trapezius and sterno-mastoideus; but a small part of its belly may be seen in the space between the edges of these muscles. The origin of the levator scapulae is partly concealed by the splenius capitis; and the digitations, where they arise from the transverse processes, lie betwixt similar attach- ments of the scaleni muscles before, and of the splenius colli behind. Use: To draw the scapula upwards, and a little for- wards. Synonyma: Elevator, seu Musculus Patientiae;—An- gularis, vel Levator proprius;—Trachelo-anguli-scapu- laire. Detaching the rhomboideus from its origin in the spine, you will see another muscle passing from the whole of the basis of the scapula. 5. The Serratus Magnus—Arises, by nine fleshy digitations, from the nine superior ribs. These digitations are seen on the anterior part of the thorax; they pass ob- liquely backwards, and form a strong fleshy muscle. Inserted, principally fleshy, into the whole of the base of the scapula. Situation: This muscle lies between the scapula and the ribs, so that, to see its course, the articulation of the 191 clavicle to the sternum should be divided, and the sca- pula lifted from the trunk It is concealed by the latis- simus dorsi, by the two pectoral muscles, and the scapula 1 he only part of it which can be seen before the removal of those muscles, projects betwixt and below them on the side of the trunk. The lower digitations, which pass more anteriorly than the edge ofthe latissimus dors, are intermixed with the superior digitations of the obliquus externus abdominis. The superior digitations arise be- hind the pectoralis minor. The insertion of the muscle is between the subscapularis, which arises from the in- ternal surface of the scapula, and the insertions of the rhomboideus and levator scapulae. Use: To move the scapula forwards, and, when the scapula is forcibly raised, to draw the ribs upwards Synonyma: Serratus major amicus;—Costo-basi'-sca- pulaire.* The removal of the rhomboideus also exposes, 6. The Serratus Superior Posticus. This muscle arises, by a thin broad tendon, from the spinous processes ot the three inferior cervical vertebrae, and of the two superior dorsal. ■ Inserted, by distinct fleshy slips, into the second, third fourth, and sometimes the fifth ribs, a little beyond their © " Situation: This muscle is concealed by the rhomboi- deus and scapula, except a few of its superior fibres which appear above the upper edge of the rhomboideus minor. It covers part of the origin of the splenius. Use: To elevate the ribs, and dilate the thorax. Synonyma: Cervici-dorso-costal. Reflect it from the spine. 7. The Splenius is divided into two portions: (l.)The Splenius Capitis—Arises, tendinous, from the spinous processes of the two superior dorsal, and five inferior cervical vertebrae. It forms a flat broad muscle I'he upper extremity may now be removed from the trunk. 192 which ascends obliquely, and is inserted, tendinous, iuto the posterior part of the mastoid process, and into a small part of the os occipitis, immediately below its su- perior transverse ridge. Situation: This muscle is covered by the trapezius, and by the insertion of the sterno-cleido-mastoideus, and a small part of it is seen on the side of the neck belvvixt those two muscles. The lower part of its origin is co- vered by the serratus superior posticus. Reflect it from the occiput. (2.) The Splenius Colli—Arises, tendinous, from the spinous processes of the third, fourth, fifth, and sometimes the sixth dorsal vertebrae. It forms a small fleshy belly, which ascends by the side of the vertebrae, and isinserted into the transverse processes of the four or five superior cervical vertebrae, by distinct tendons, which lie behind similar tendons of the levator scapulae. Situation: This muscle is concealed by the serratus superior posticus, and splenius capitis. Use: To bring the head and upper vertebrae of the neck obliquely backwards. When both muscles act, they pull the head directly backwards. Synonyma: Cervici-dorsi-mastoidien, et dorso-trache- lien. Reflect it from the dorsal vertebrae. 8. The Serratus Posticus Inferior—Arises, by a broad thin tendon, from the spinous processes of the two or three inferior dorsal vertebrae, and from the three sut perior lumbar spines by the fascia lumborum. Inserted, by distinct fleshy slips, into the lower edges of the four inferior ribs, at a little distance from their cartilages. Situation: This is a thin muscle, of considerable breadth, situated at the lower part of the back, under the middle ofthe latissimus dorsi. Its tendon lies under that of the latissimus dorsi, but, although firmly adhering to it, is distinct, and may be separated by cautious dissec- tion. Its insertion into the ribs is situated immediately * 193 behind the attachments connecting the latissimus dorsi to the ribs, which attachments must therefore lie behind the obliquus externus abdominis, and serratus posticus in- ferior. Use: To pull the ribs downwards and backwards. Synonyma: Dorso-lumbo-costal. Reflect it from the spine. The Fascia Lumborum is now seen. It is a tendinous fascia, arising from the lumbar vertebrae and os sacrum, giving origin to the lower part of the serratus posticus in- ferior, and to the posterior fibres of the obliquus internus and transversalis abdominis. It is also connected with the tendon of the latissimus dorsi. On detaching from the spine of this fascia, and the serratus posticus inferior, we expose a thick muscular muss, filling up all the space betwixt the spinous pro- cesses of the vertebrae, and the angles of the ribs. This mass consists of three muscles: (1.) Sacro-Lumbalis on the outside, (2.) Longissimus Dorsi in the middle, (3.) Spinalis Dorsi close to the spinous processes. These three muscles are closely connected together; so that, to effect their separation, it is necessary to divide some of the fibres. 9 and 10, The Sacro-Lumbalis and Longissimus Dorsi—Arises, by one common origin, tendinous ex- ternally, and fleshy internally, from the spinous processes and posterior surface of the os sacrum; from the posterior part of the spine ofthe os ilium, extending nearly as far forwards as the highest part of that bone when the body is erect; from the spinous processes, and from the roots ofthe transverse processes of all the lumbar vertebrae. The thick fleshy belly, formed by this extensive origin^ ascends, and, opposite to the last rib, divides into the two muscles. The sacro-lumbalis is inserted into all the ribs near their angles, by long and thin tendons. The tendons which pass to the superior ribs are longer, ascend nearly 194 straight, and are situated nearer to the spine than those ndous which pass to the lower ribs. On separating the inner edge of this muscle, (i. e. the edge next to the spine from the latissimus dorsi, and turning the belly towards the ribs, we see six or eight small tendinous and fleshy bundles, which pass from the inner side of this muscle, to be inserted into the upper edge of the six or eight inferior ribs These are called the Musculi Accessorn ad Sacro- UUse- To pull the ribs downwards, to assist in erecting the trunk of the body, and in turning it to one side. Synonyma: Lumbo-costotrachelien. The longissimus dorsi is inserted into all the ribs ex- cept the two inferior, betwixt their tubercles and angles by slips which are tendinous and fleshy, and into the transverse processes of all the dorsal vertebrae by small double tendons. The insertions in the ribs proceed from the outer side of the muscle, while the attachments to the transverse processes are seen on separating the longissimus dorsi of the spinalis dorsi. Use: To extend the vertebrae, and keep the body crcct« Synonyma: Lumbo-dorso-trachelien. 11 The Spinalis Dorsi is much smaller than the two last described muscles; below, it cannot be separated from the longissimus dorsi, without dividing some fibres; it lies betwixt that muscle and the spine. Arises, tendinous, from the superior processes of the two superior lumbar vertebrae, and of the three inferior dorsal. Inserted into the spinous processes of the nine upper verebrae of the back, except the first, ly as many distinct tendons. Use: to extend the vertebrae, and to assist in raising the spine. Synonyma: Lumbo-dorsal-spinal. The three last described muscles are covered below by the serratus posticus inferior and latissimus dorsi; 195 above, by the rhomboideus, serratus superior posticus. and trapezius. 12. The Cervicalis Descendens—Arises from the upper edge of the four or five superior ribs, by as many distinct tendons, which lie on the inside ofthe tendinous insertions of the sacro-lumbalis. It forms a small belly, which ascends upwards, and is Inserted, by three distinct tendons, into the fourth, fifth, and sixth cervical vertebrae. Situation: This muscle is small; it is frequently de- scribed as an appendage to the sacro-lumbalis. It arises between the sacro-lumbalis and longissimus dorsi, and is inserted into the transverse processes between the sple- nius colli and levator scapulae; of course it is concealed by the rhomboideus, &c. It often receives a fleshy slip from the upper part of the longissimus dorsi. Use: To turn the neck obliquely backwards. Synonyma: Transversalis collateralis colli. 13. The Transversalis Colli—Arises from the transverse processes of the five superior dorsal vertebrae, by five tendinous and fleshy slips, and is Inserted, tendinous, into the transverse processes of the five or six inferior cervical vertebrae. Situation: The origin of this muscle lies on the inside of the longissimus dorsi, and is sometimes considered as an appendage to it. The insertion is situated between the cervicalis descendens and trachelo-mastoideus. Use: To turn the neck obliquely backwards, and a little to one side. Synonyma: Transversalis cervicis;—Transversalis • colli major. ' 14. The Trachelo-Mastoideus lies nearer to the bone than the last described muscle. Arises from the transverse processes of the three up- permost vertebras of the back, and of the five inferior of the neck, by as many thin tendons, which unite and form a fleshy belly. 19b Inserted, tendinous, into the posterior surface of the mastoid process. Situation: This muscle lies on the outside ofthe corn- plexus, and on the inside of the transversalis colli; its insertion is concealed by the splenius capitis; it is co- vered also by the levator scapulae. Use: To keep the head and neck erect, and to draw the head backwards, and to one side. Synonyma: Trachelo-mastoideus, seu Capitis par ter- lium Fallopii;—Complexus minor, seu Mastoides late- ralis. 15. The Complexus—Arises, by tendinous and fleshy fibres, from the transverse processes of the seven superior dorsal, and of the four or five inferior cervical vertebrae. It forms a thick, tendinous, and fleshy belly. Inserted, tendinous and fleshy, into the hollow betwixt the two transverse ridges of the os occipitis, extending from the middle protuberance of that bone, nearly as far as the mastoid process. Situation: This is a large muscle. Its origin from the cervical vertebrae is nearer to the spine than the trachelo mastoideus, and it arises in the back nearer to the spine than the transversalis colli; it is covered by the sple- nius; but a large portion of it is seen between the sple- nius and spine, immediately on removing the trapezius. Use: To draw the head backwards, and to one side. Synonyma: Complexus, seu Biventer cervicis;—Com- plexus major;—Dorso-trachelo-occipital. On removing the complexus from the occiput, we find, close to the spine, 16. The Semi-Spinalis Colli.—It arises, by distinct tendons, from the transverse processes ofthe six superior dorsal vertebrae, ascends obliquely close to the spine, and is Inserted into the spinous processes of all the vertebrae of the neck, except the first and the last. Situation: This muscle is situated close to the verte- brae at the posterior part ofthe neck and back. It arises 197 on the outside of the semi-spinalis dorsi; its greater part is concealed by the complexus and longissimus dorsi; and the part which projects between these muscles, is concealed by the serratus superior posticus. Use: To extend (he neck obliquely backwards. Synonyma: Spinalis cervicis;—Transverso-spinalis colli. 17. Semi-Spinalis Dorso—Arises from the trans- verse processes of the seventh, eighth, and ninth verte- brae of the back, by distinct tendons which soon grow fleshy. Inserted, by distinct tendons, into the spinous pro- cesses of the five superior dorsal vertebrae, and of the two lower cervical. Situation: This muscle lies nearer the spine than the lower part of the semi-spinalis colli; its inferior origins' lie on the outside of the insertion of the spinalis dorsi. Use: To extend the spine obliquely backwards. Synonyma: Semi-spinalis externus, seu Transverso- spinalis dorsi. The removal ofthe complexus brings also in view se- veral small muscles situated at the superior part of the neck, immediately below the occiput. 18. The Rectus Capitis Posticus- Major—Arises, fleshy, from the side of the spinous process of she denta- ta, or second cervical vertebrae. It ascends obliquely outwards, becoming broader, and is Inserted, tendinous and fleshy, into the inferior trans- verse ridge of the os occipitis, and into part of the con- cavity above that ridge. Situation: This muscle is situated obliquely between the occiput and the second vertebrae of the neck li lies under the complexus; its outer fibres also pass under the insertion of the obliquus capitis superior. Use: To extend and pull the head backwards, and to assist in its rotation. Synonyma: Rectus major;—Spino-axoido-occiphal. 19. The Rectus Capitis Posticus Minor—Arises, R 2 198 tendinous and narrow, from an eminence in the middle ofthe back part of the atlas, or first cervical vertebra. It becomes broader, and is Inserted, fleshy, into the inferior transverse ridge of the os occipitis, and into the surface betwixt that ridge and the foramen magnum. Situation: It is partly covered by the rectus capitis posticus major; but a large portion of this pair of mus- cles is seen projecting between the recti majdres, and is situated beneath the complexus. Use: To draw the head backwards. Synonyma: Rectus minor;—Tuber-atloido-occipital. 20. Obliquus Capitis Superior—Arises, tendinous, from the upper and posterior part of the transverse pro- cess of the first cervical vertebra. ' Inserted, tendinous and fleshy, into the inferior trans- verse ridge of the os occipitis behind the mastoid pro- cess, and into a small part of the surface above and be- low that ridge. Situation: This muscle is situated laterally between the occiput and atlas. It is inserted under the complex- us and trachelo-mastoideus, and it covers some of the euter fibres of the insertion of the rectus capitis posticus major. . Use: To draw the head backwards, and to assist in rolling it. Synonyma: Obliquus superior, sive Minor;—Trache- lo-atloido-occipital. 21. Obliquus Capitis Inferior—Arises, tendinous and fleshy, from the side of the spinous process of the dentata or second cervical vertebra. It forms a thick belly, and is Inserted into the under and back part ofthe transverse process of the atlas. Situation: This muscle is obliquely situated between the two first vertebrae of the neck. It is covered by the •complexus and trachelo-mastoideus, except a small part which is seen between these two muscles, and is conceal- 199 ed by the splenius. Its origin lies between the origin of the rectus capitis posticus major, and the superior inser- tion of the semi-spinalis colli. Use: To rotate the head, by turning the first vertebra upon the second. Synonyma: Obliquus inferior, sive Major;—Spini- axoido-tracheli-atloidien. 22. The Multifidus Spin*:. On removing the muscles of the spine which have been described, we find situated beneath them the Mul- tifidus Spinae. It is that mass of muscular flesh which lies close to the spinous and transverse processes of the vertebrae, extending from the dentata to the os sacrum. The bundles of which it is composed seem to pass from the transverse, to be inserted into the spinous processes. Arises, tendinous and fleshy, from the spinous processes and back part of the os sacrum, and from the poste- rior adjoining part of the os ileum; from the oblique and transverse processes of all the lumbar vertebrae; from the transverse processes of all the dorsal vertebrae; and from those of the cervical vertebrae, excepting the three first. The fibres arising from this extensive origin pass obliquely, to be Inserted, by distinct tendons, into the spinous processes of all the vertebrae of the loins and back, and into those of the six inferior vertebrae ofthe neck. The fibres aris- ing from each vertebrae are inserted into the second one above it, and sometimes more. Use: To extend the back obliquely, or move it to one side. When both muscles act, they extend the vertebras backwards. Synonyma: Transversalis lumborum dorsi et colli;— Transverso-spinalis lumborum, dorsi et colli; vel Semi- spinalis. The small muscles situated between the processes of the vertebrae are, 1. Interspinales colli, dorsi, et lumborum.—These are small bundles of fibres, which fill up the spaces be- 200 tween the spinous processes of the vertebrae. Each of these little muscles arises from the surface of one spi- nous process, and is inserted into the next spinous pro- cess. In the neck they are large, and appear double, as the spinous processes of the cervical vertebrae are bifurcated. In the back and loins they are indistinct, and are rather small tendons than muscles. ■ Use: To draw the spinous processes nearer to each other. 2. The Intertransversalis colli, dorsi, et lumbo- rum, are small muscles which fill up, in a similar man- ner, the space between the transverse processes of the vertebrae. In the neck they are bifurcated and distinct, in the back, they are small and slender, and in the loins they are strong and fleshy. Use: To draw the transverse processes towards each other. 201 CHAP. XIII. DISSECTION OF THE MUSCLES SITUATED BETWEEN THE RIBS, AND ON THE INNER SURFACE OF THE STERNUM. The muscles which fill up the space between the ribs are named Intercostals: they are disposed on each side of the thorax in two layers, and each layer consists of eleven muscles. The Intercostales Externi—Arise from the infe- rior acute edge of each superior rib, extending from the spine to near the junction of the ribs with their carti- lages. The fibres run obliquely forwards and downwards, and are Inserted into the upper obtuse edge of each inferior rib, from the spine to near the cartilage of the rib. Situation: these muscles are seen, on removing the muscles which cover the thorax. Synonyma: Inter-laferi-costaux. The Levatores Costarum are twelve small muscles, situated on each side of the dorsal vertebras. They are portions of the external intercostals. Each of these small muscles arises from the transverse process of one of the dorsal vertebrae, and passes downwards, to be inserted into the upper side of the rib next below the vertebrae, near its tuberosity. The first of these muscles passes from the last cervical vertebrae, the eleven others from the eleven superior dorsal vertebrae. The three or four inferior Levatores are lon- ger, and run down to the second rib below the transverse 202 process from which they arise. Hence Albinus names them the Levatores Costarum Longiores et Breviores. Synonyma: Supra costales. 2. The Intercostales Interni—Arise from the in- ferior acute edge of each superior rib, beginning at the sternum, and extending as far as the angle of the rib. The fibres run obliquely downwards and backwards, and are Inserted into the superior obtuse edge of each inferior rib from the sternum to the angle. Portions of the in- ternal intercostals pass over one rib, and are inserted in- to the next below it. Synonyma: Inter-pleuri-coslaux. Thus the intercostal muscles decussate, and are double on the sides ofthe thorax; but, from the spine to the an- gles of the ribs, there are only the external intercostals, and, from the cartilages to the sternum, only the inter- nal, and some cellular membrane covering them. The whole ofthe internal intercostals, and the back part ofthe external, are lined by the pleura. Use: To elevate the ribs, so as to enlarge the cavity of the thorax. One pair of muscles is situated on the inner surface of the sternum. The Triangularis Sterni, or Sterno-Costalis—Arises, tendinous and fleshy, from the edge ofthe whole cartila- go ensiformis, and from the edge of the lower half of the middle bone of the sternum. The fibres ascend oblique- ly upwards and outwards, and form a flat muscle, which is Inserted, by three or four triangular fleshy and tendi- nous terminations, into the cartilages ofthe third, fourth, fifth, and sixth ribs. Situation: This muscle lies on the inside of the ribs and sternum, and is lined by the pleura. Use: To depress the cartilages and the bony extremi- ties of the ribs, and consequently to assist in lessening the cavity of the thorax. 203 CHAP. XIV. DISSECTION OF THE MUSCLES SITUATED ON THE ANTERIOR PART OF THE NECK CLOSE TO THE VERTEBRAE. Four pair of muscles are here situated. 1. The Longus Colli—Arises, tendinous and fleshy from the sides ofthe bodies ofthe three superior dorsal vertebrae, and from the anterior surface of the transverse processes of the four or five lower cervical vertebrae. Inserted, tendinous and fleshy, into the fore part ofthe bodies of all the. vertebrae of the neck. Situation: This muscle lies behind the oesophagus and behind the great vessels and nerves of the neck. ' Use: To bend the neck forwards, and to one side! Synonyma: Predorso-cervical. 2 The Rectus Capitis Internus Major—Arises tendinous and fleshy, from the anterior points ofthe trans- verse processes of the third, fourth, fifth, and sixth cervi- cal vertebrae. It forms a considerable fleshy belly. Inserted into the cuneiform process of the os occipitis a little before the condyloid process. Situation: This muscle lies before the scaleni and more outwardly than the longus colli, over the part of which it passes. Use: To bend the head forwards. Synonyma: Rectus anterior longus;—Grand trachelo- basilaire. 3. The Rectus Capitis Internus Minor—Arises fleshy, from the fore part of the body of the first vertebra 804 6f the neck, near its transverse process; and ascending obliquely, is Inserted near the root of the condyloid process of the occipital bone, under the last described muscle. Use: To bend the head forwards. Synonyma: Rectus anterior brevis;—Petit-trachelo- basilaire. 4. The Rectus Capitis Lateralis—Arises, fleshy, from the anterior and upper part of the transverse pro- cess pf the atlas. Inserted, tendinous and fleshy, into a scabrous ridge of the os occipitis, which extends from the condyloid pro- cess of that bone towards the mastoid process. Situation: It is situated immediately behind the inter- nal jugular vein, where it comes out from the cranium. Use: To pull the head a little to one side. Synonyma: Transversalis anticus primus;—Tracheli atloido-lateral. 205 CHAP. XV. DISSECTION OF THE SUPERIOR EXTRE- MITY. SECT. I. OF THE SHOULDER AND ARM. In the thigh we saw a strong fascia, arising from the neighbouring bones and ligaments, firmly investing the muscles, and giving origin to some of their fibres; but on removing the integuments of the shoulder and arm, we do not meet with any regular fascia. The muscles, like those on the outside of the thorax, are covered by con- densed cellular substance; and this substance might be taken for a thin aponeurosis, but it is widely different in its nature, and ought to be regularly dissected off with the integuments. In removing the integuments, we meet with several cutaneous veins and nerves. The cutaneous veins* of the upper extremity are the following. 1. The Basilic Vein is seen arising from a small vein on the outside ofthe little finger, named Salvatella. It then runs along the inside ofthe fore-arm near the ul- na, receiving the internal and external ulnar veins from the anterior and posterior surface ofthe fascia. It passes * The veins are described from their origin in the fore-arm for the sake of perspicuity; they ramify above the fascia ofthe fore- arm. S 20G over the fold of the arm near the inner condyle of the humerus; here it is superficial. It ascends along the arm, becoming more deeply seated, and included in the sheath which invests the brachial artery. As it approaches the neck of the humerus, it sinks deep between the folds of the arm-pit, and terminates in the axillary vein, which may be considered as a continuation of the basilic vein. It communicates with the deeper seated veins, and re- ceives numerous branches from the muscles. 2. The Cephalic Vein begins on the back of the hand, between the thumb and metacarpal bone of the fore-finger, by a small vein, named Cephalica Pollicis. It runs along the radius between the muscles and inte- guments, receiving the internal and external radial veins. It passes over the bend of the arm near the external con- dyle, and ascends along the outside of the arm near the outer edge of the biceps flexor cubiti. It then runs be- twixt the edge of the deltoid and pectoral muscles, dips down under the clavicle, and enters the subclavian vein. In all this course the cephalic vein receives branches. 3. The Median Vein. Several veins are seen run- ning along the middle of the anterior part of the fore- arm. The trunk formed by these veins is called the Mediana Major. It ascends on the flat part of the fore- arm, betwixt the basilic and cephalic veins, and bifur- cates at the fold of the arm into two branches: 1. The Mediana Basilica, passing off obliquely to join the ba- silic vein; 2, The Mediana Cephalica, which joins the cephalic. The cutaneous nerves of the arm are seen ramifying above the muscles; they consist of, 1. The Internal Cutaneous Nerve, a branch of the axillary plexus. It is seen accompanying the basilic vein, and twisting its fibres over it. It descends along the inside of the arm, crosses over the fore part of the elbow joint, and, in the dissection of the fore-arm, will be seen dividing itself into twigs, which ramify between 207 the fascia and integuments, and are distributed to the in- inside of the fore-arm and wrist. 2. The upper part of the arm receives cutaneous nerves from the branches of the dorsal nerves, which come out ofthe thorax between the ribs. 3. The shoulder and back part of the scapula receive twigs from the cervical nerves. 4. The external cutaneous, ulnar, and spiral nerves, also send twigs to the integuments of the arm and fore- arm. muscles situated on the shoulder and arm. These are ten in number. 1. The Deltoides—Arises, tendinous and fleshy, from the posterior third of the clavicle, from the whole of the acromion, and from the lower margin ofthe whole spine of the scapula. From these several origins the fibres run in different directions, and converge. Those arising from the clavicle run outwards and downwards: those from the spine of the scapula outwards, forwards, and downwards; and those from the acromion directly downwards. Inserted, tendinous, into a triangular rough surface on the outer side of the os humeri, near its middle. Situation: This muscle is entirely superficial, except where the thin fibres of the platysma myoides arise from its anterior surface. It arises from the same extent of bone as the trapezius is inserted into, and is therefore opposite to that muscle which passes upwards from its origin, while the deltoid runs downwards. It forms a strong coarse muscle, consisting of large fasciculi of fibres. It conceals the insertion of the pectoralis major, and the origins ofthe biceps flexor cubiti and coraco-brachialis, and covers the whole of the fore part, and outside ofthe shoulder joint. Its insertion is situated betwixt the bi- ceps flexor cubiti and the short head of the triceps ex- tensor, and immediately above the origin of the brachi- 208 alis internus. Its external surface is quite fleshy; but, on cutting it across, its internal surface is found tendi- nous: and where it slides over the great tuberosity of the humerus, there is a large bursa, or sacculus mucosus. From the insertion of the deltoid to the outer condyle of the os humeri, is extended an Intermuscular Ligament, which separates the muscles on the anterior part of the arm from those on the posterior part, and gives attach- ment to the fibres of both. It is named the External Intermuscular Ligament. Use: To draw the arm directly upwards, and to move it a little forwards and backwards, according to the dif- ferent directions of its fibres. Reflect it from the sca- pula and clavicle, that you may expose more completely the muscles on the dorsum of the former bone. Synonyma: Sous-acromio-clavi-humeral. The following two muscles, which fill up the posterior surface of the scapula, are covered by a fascia, which adheres to the spine and edges of that bone. On dis- secting off this fascia, the fleshy fibres of the muscles will be found arising from its inner surface. 2. The Supra Spinatus—Arises, fleshy, from all that part of the base of the scapula that is above its spine, from the superior costa as far forwards as the semilunar nitch, from the spine itself, and from the concave surface betwixt it and the superior costa. The fleshy fibres, as they approach the neck of the scapula, terminate in a tendon which passes under the acromion, slides over the neck of the scapula, (to which it is connected by loose cellular membrane,) adheres to the capsular ligament of the shoulder joint, and is Inserted into the anterior and superior part of the great tuberosity near the head of the os humeri. -}•**-*• Situation: This muscle fills up the fossa or ca^fyC , above the spine of the scapula, and is entirely concealed". ' ' Its belly is covered by the fibres of the trapezius passing into the spine of the scapula; and its tendon passes under the deltoid. 209 Use: To raise the arm. Synonyma: Super-scapularis:—Sus-sphini-scapulo- trochiterien. 3. The Infra-Spinatus—Arises, principally fleshy, from the lower part of the spine ofthe scapula as far back as the triangular flat surface; from the base of the bone below the spine to near the inferior angle; from the posterior ridge of the inferior costa; and from all the dorsum of the bone below the spine. The fibres ascend and descend towards a middle tendon, which runs for- wards over the neck of the bone, and adheres to the capsular ligament. Inserted, by a strong short tendon, into the middle part of the great tuberosity of the os humeri. Situation: This muscle is in part concealed. The anterior part of its belly, and its tendinous insertion, are covered by the deltoid, and the trapezius passes over its upper and back part, but a considerable portion of the belly of this muscle is seen betwixt these two muscles, and above the superior fibres of the latissimus dorsi. It is inserted below the tendon of the supra-spinatus. Use: To roll the humerus outwards, to assist in rais- ing the arm, and in moving it outwards when raised. Syndixyma: Sus-spini-scapulo-trochiterien. 4. The Teres Minor—Arises, fleshy,from the narrow depression between the two ridges in the inferior costa of the scapula, extending from the neck of the bone to within an inch or two of the inferior angle. It passes forwards along the inferior edge of the infra-spinatus, ad- heres to the capsular ligament of the shoulder joint, and is Inserted, tendinous and fleshy, into the lower and back part of the great tuberosity of the os humeri. Situation: It is inserted below the tendon of the infra- spinatus. Its origin lies between the infra-spinatus and teres major, and is partly concealed by them. The mid- dle of its belly is superficial, and not covered by any muscle; but its insertion is concealed by the deltoid. S 2 210 The fascia which covers the infra-spinatus, envelopes al- so the teres minor; and the two muscles are, in some subjects, so closely united, as to be with difficulty sepa- rated. Use: To draw the humerus downwards and back- wards, and to roll it outwards. Synonyma: Margini-sus-scapulo-trochiterien. 5. The Teres Major—Arises, from an oblong, rough, flatted surface, at the inferior angle of the scapula. It forms a thick belly, which passes forwards and upwards towards the inside of the arm. Inserted, by a broad thin tendon, into the ridge of the os humeri, at the inner side of the groove for lodging the tendon of the long head of the biceps flexor cubiti. Situation: The origin of this muscle is superficial, and adheres to the lower fibres of the infra-spinatus. Its belly passes before the long head of the triceps extensor cubiti. Its tendon is inserted along with the tendon of the latissimus dorsi. Observe the relative situation of these tendons; they both pass under the coraco-brachia- lis and short head of the biceps flexor, to reach the place of their insertion. They appear at first inseparably united, but on dividing them with some care, we find an intermediate cavity lubricated with synovia. The ten- don ofthe latissimus dorsi is anterior to the tendon ofthe teres major; but the lower edge of the latter extends farther down the arm. Use: To roll the humerus inwards, and to draw it backwards and downwards. Synonyma: Anguli-scapulo-humeral. 6. The Subscapulars—Arises, fleshy, from all the base ofthe scapula internally, from the superior and infe- rior costae, and from the whole internal surface of the bone. It consists of tendinous and fleshy bundles, which converge, slide over the inner surface ofthe neck ofthe scapula, pass In the hollow under the root of the coracoid process, and adhere to the inner part of the capsular li- gament of the shoulder joint. 211 Inserted, by a strong tendon, into the lesser tuberosity near the head of the os humeri. Situation: The whole of this muscle is concealed by the scapula and muscles of the shoulder. It lies betwixt that bone and the serratus magnus. The tendon passes under the coraco-brachialis and short head of the biceps flexor, to reach the lesser luberositv: The lower edge of this muscle is in contact with the upper edge ofthe teres major. Use: To roll the os humeri inwards, and to draw it to the side of the body. Synonyma: Sus-scapulo-trochinien. 7. The Biceps Flexor Cubiti—Arises by two heads. The first and outermost called the Long Head, arises by a strong tendon, from a smooth surface in the upper edge of the glenoid cavity of the scapula. It passes over the head ofthe os humeri, within the capsular ligament of the shoulder-joint, and enters a groove betwixt the two tuberosities of that bone. It forms a strong fleshy belly. The second and innermost, called the Short Head, arises, tendinous, from the lower part of the coracoid pro- cess of the scapula, in common with the coraco-brachia- lis, and sends off a fleshy belly. These two fleshy bellies are at first only connected by condensed cellular membrane. They form a thick mass; and, below the middle of the arm, become inseparably united. They send off a strong tendon, which is at first broad, but soon becomes rounder, and passes over the fore part of the elbow joint. It then slides over the car- tilaginous middle surface ofthe tubercle at the upper end of the radius, and is Inserted into the posterior and internal rough part of that tubercle. A bursa mucosa is placed between the tendon and front ofthe tubercle. Situation: The tendon of the long head cannot, be seen till the capsular ligament ofthe shoulder is opened: Where it runs in the groove of the os humeri, it lies be- twixt the pectoralis major and latissimus dorsi, and is 212 firmly bound down by tendinous fibres passing from the capsular ligament and adjacent tendons. The short head arises from the coracoid process, betwixt the origin of the coraco-brachialis and the strong ligament which passes from the coracoid process to the acromion. These two origins are concealed by the deltoides and pectoralis ma- jor. The belly of the muscle is immediately under the integuments, and so is the tendon where it passes over the elbow joint. It is seen sinking between the supina- tor radii longus and pronator teres, to arrive atTits point of insertion; and at the bend of the elbow, it sends off from its inside au aponeurosis, which assists in forming the fascia of the fore-arm. Use: to turn the hand supine, to bend the fore-arm on the arm, and the arm on the shoulder. Synonyma: Biceps brachii;—Biceps, sive Coraco-ra- dialis;—Biceps internus:—Scapulo-coraco-radial. 8. The Coraco Brachialis—Arises, tendinous and fleshy, from the middle part of the apex of the coracoid processes of the scapula. Its fibres, as it descends, also arise from the edge of the short tendon of the biceps flexor cubiti. It forms a flat fleshy belly which is always perforated by the nerve, named Musculo-Cuta- n> us; Inserted, tendinous and fleshy, about the middle of the internal part of the os humeri, into a rough ridge. Situation: This muscle'is much connected with the short head ofthe biceps flexor cubiti.* It arises betwixt that muscle and the origin of the pectoralis minor. In the arm, it lies behind, and on the inside of the biceps, and is concealed by the pectoralis major and deltoides, ex- cepting a small part of it which is seen projecting betwixt the biceps flexor and triceps extensor cubiti. It is in- serted immediately below the tendons of the latissimus dorsi and teres major, and before the brachialis externus. The lower part of its insertion passes betwixt the bra- chialis internus and brachialis externus. The internal intermuscular ligament is seen extending 213 from the lower part of this muscle along a ridge to the in- ternal condyle, and separating the brachialis internus from the brachialis externus, or third head of the triceps extensor cubiti. Use: To move the arm upwards and forwards. Synonyma: Coraco-humeral. 9. The Brachialis Internus—Arises, from the middle of the os humeri, by two fleshy slips, which pass on each side of the insertion of the deltoid muscle; fleshy from all the fore part of the bone below, nearly as far as the condyles. The fibres converge, pass over the elbow joint, and adhere to the capsular ligament. Inserted, by a strong short tendon, into the rough sur- face immediately below the coronoid process ofthe ulna. Situation. The most external ofthe fleshy slips of this muscle lies between the deltoid and short head of the triceps extensor, the internal between the deltoid and coraco- brachialis. The belly is almost entirely conceal- ed by the biceps flexor cubiti, excepting a small portion which projects beyond the outer edge of that muscle. The tendon dips down betwixt the supinator radii longus and pronator teres, crosses under the tendon ofthe biceps flexor, and is inserted on the inside of that tendon. Use: To bend the fore-arm. Synonyma: Brachiaeus;—Humero-cubital. 10. The Triceps Extensor Cubiti is the great muscle which covers all the back part of the arm.—It arises by three heads. The first, or long head, arises, by a broad tendon, from the inferior costa of the scapu- la near its cervix, and forms a large belly, which covers the back part of the os humeri The second, or short head, arises, on the outer and back part ofthe os humeri, by an acute tendinous and fleshy beginning, from a ridge which runs from the back part of the great tuberosity towards the outer condyle. The fibres begin to arise a little below the tuberosity, and are continued down to the condyle. They also arise from the surface of bone be- hind the ridge, and from the intermuscular ligament 214 which separates them from the muscles on the fore part of the arm. The third head, called Brachialis Ex- ternus, arises, by an acute beginning, from the inside of the os humeri above its middle, and from a ridge ex- tending to the inner condyle. It also arises from the sur- face behind this ridge, and from the internal intermuscu- lar ligament. The three heads unite above the middle of the os humeri, and invest the whole back part of the bone.— They form a thick strong tendon, which is Inserted into the rough back part of the process of the ulna, called Olecranon, and partly into the condyles of the os humeri, adhering firmly to the capsular ligament. Situation: The long head, where it arises from the scapula, is concealed by the deltoid; it arises betwixt the teres minor and teres major, and passes betwixt those muscles to the arm; and, in the remainder of its course, is superficially seated. The short head arises immedi- ately below the insertion of the teres minor, its upper part is therefore covered by the deltoides. Below the deltoid, it is superficial, and arises more outwardly than the brachialis internus, supinator radii longus, and ex- tensors of the carpus. The brachialis externus is situ- ated immediately underthe integuments; it begins to arise below the insertion of the teres major. It passes down the arm between the triceps longus, and coraco-brachi- alis at first, afterwards between the triceps longus and brachialis internus. The tendon ofthe triceps sends off a thin fascia, which covers the triangular surface of the ulna, on which we commonly lean. Numerous fibres are also sent off, to assist in forming the fascia of the fore-arm. Use: To extend the fore-arm. The long head will also assist in drawing the arm backwards. Synonyma: Anconeus major, Anconeus externus, and Anconeus internus;—Biceps externus, and Brachialis externus;—Triceps Brachii;—Tri-scapulo-humero-ole cranien. 215 SECT. II. dissection of the fascia and muscles situated on the cubit or fore-arm.* On removing the integuments of the fore-arm, we find, as in the leg, a strong fascia investing all the muscles! This fascia is continued from the intermuscular liga- ments which pass down to the condyles ofthe os humeri. It is attached to the condyles, and it adheres firmly to the olecranon of the ulna. It receives, on the posterior part, a great addition of fibres from the tendon of the triceps extensor; and on the fore part of (he arm, it ap- pears to be a continuation of the aponeurosis which is sent off from the biceps flexor cubiti. Above the fascia, we meet with several cutaneous veins and nerves. The veins have been already described; the nerves are twigs of the branches of the brachial plexus. The relative situation ofthe vessels at the bend of the arm should be well attended to. The cutaneous veins situated here vary much in size. The vena basilica is seen running over the fore part of the bend of the arm near the inner condyle, the vena cephalica situated near the outer condyle; and each of these veins receives a branch passing obliquely from the vena mediana major. These vessels lie above the fascia, while the brachial artery lies deep beneath the fascia, in a hollow resem- bling that of the axilla. It descends over the joint near the inner condyle, on the inside of the tendon of the biceps flexor cubiti, and under the aponeurosis sent off from that muscle to the common fascia of the fore-arm. It lies embedded in cellular substance, betwixt the pro- * In the following description, the palm of the hand is suppos- ed to be turned forwards, so that the railius and thumb are upon the outer side ofthe fore-arm, and the ulna and little finger upon its inner side. 21G nator teres sl1. flexor muscles of the wrist and fingers on uie side, and the supinator longus and extensor mus- cles on the other. In this hollow, it divides into the radial ulnar, and interosseal arteries. The artery is ac- companied by two veins; and on its inner side runs the radial nerve. The dissection of the fascia of the fore-arm is simi- lar to that of the fascia of the leg. It is found firmly attached to the fibres of the muscles, so that the exposed surface appears ragged. It sends down betwixt them partitions, named Intermuscular Ligaments or Tendons, which connect the muscles, and give origin to many of their fibres. muscles situated on the fore part of the cubit, and arising from the inner condyle of the os HUMERI. These are eight in number, and may be divided in- to two classes; the superficial, and the deep-seated. First, The superficial. All the muscles passing from the inner condyle, may be said to arise by one common tendinous bead from the condyle; and this head may be said to divide into the different muscles; but they will be here described as arising distinct from the condyle. It must, however, be recollected, that their origins are intimately connected by intermuscular ligaments, and that they cannot be sepa- rated without dividing some of their fibres. 1. The Pronator Radii Teres—Arises, tendinous and fleshy, from the anterior surface of the inner con- dyle of the os humeri, and from the coronoid process of the ulna. It also arises from the fascia of the fore- arm. The fibres pass outwards, run by the side of the tubercle of the radius, and pass over the outer edge of that bone, to be Inserted, tendinous and fleshy, into a rough surface on the back part of the radius about its middle. 2n r Situation: Of the muscles which pass from the inter- nal condyle, the pronator teres is situated nearest the outer edge of the arm. It lies immediately on the inside of the tendon of the brachialis internus. Its tendon, to arrive at its place of insertion, passes under the belly of the supinator longus, and, when that muscle is removed will be found inserted into the radius immediately below the supinator brevis. Use: To roll the radius, together with the hand, in- wards. Synonyma: Pronator teres, sive Obliquus;—Epitro- chlo-radial. 2. The Flexor Carpi Radialis—Arises, by a nar- row tendinous beginning from the lower and fore part of the internal condyle of the os humeri: fleshy from the fascia and intermuscular ligaments, and from the upper end ofthe ulna It forms a thick belly, which runs down the fore-arm, and terminates in a flat tendon. This tendon passes under the annular ligament* of the wrist, run? through a groove in the os trapezium, and is Inserted into the fore part of the base of the metacar- pal bone sustaining the fore finger. Situation: This muscle is situated immediately under the fascia, excepting its upper extremity, over which the pronator teres crosses. It arises between the pronator teres and palmaris longus, and descends betwixt those muscles. Below the insertion of the pronator, it is si- tuated betwixt the supinator radii longus and palmaris longus. Its insertion cannot be seen till the palm of the * The annular ligament of the wrist consists of two parts. 1. The ligamentum carpi trans,versale externum passes from the sty- loid process of the ulna and os pisiforme, transversely, over the back of the wrist, and spreads out broad, to be affixed to the sty- loid process-of the radius. Under it pass the tendons ofthe ex- tensor muscles. 2 The ligamentum carpi transversale internum is a strong ligament, which passes across the fore part ofthe wrist. It arises from the os pisiforme and os unciforme on the inner edge of the wrist, and is attached to the os scaphoides and os trapezius on the outer edge. Under it pass the tendons of the flexor mus- cles. T 218 hand is dissected, where it will be found concealed by the muscles of the ball of the thumb. Use: To bend the hand, and to assist in its pronation. Synonyma: Radialis internus;—Epitrochlo-metacar- pien. 3. The Palmaris Longus—Arises, by a slender ten- don, from the fore part of the inner condyle of the os hu- meri; and fleshy, from the intermuscular ligaments; it forms a short fleshy belly, which soon sends off a long slender tendon. This tendon descends along the fore- arm, and is Inserted, near the root ofthe thumb, into the ligamen- tum carpi transversale internum, and into a tendinous membrane that covers the palm of the hand named Fas- cia, or Aponeurosis Palmaris. Situation: It arises betwixt the flexor carpi radialis and flexor ulnaris. Its tendon descends betwixt these two muscles, and above the fibres of the flexor digitorum sublimis. This muscle is sometimes wanting. Use: To bend the hand, and to stretch the palmar aponeurosis. Synonyma: 4Ulnaris gracilis;—Epitrochlo-carpi-pal- maire. 4. The Flexor Carpi Ulnaris—Arises, tendinous, from the inferior part of the internal condyle of the os humeri; tendinous and fleshy, from the inner side ofthe olecranon, and by a tendinous expansion from the poste- rior ridge* of the ulna, to near the lower end of the bone. It also arises from the intermuscular ligaments and fascia of the fore-arm. The fibres pass obliquely forwards into a tendon which runs over the fore part of the ulna, and is Inserted into the os pisiforme, and sometimes sends its fibres over a small ligament which goes to the base ofthe metacarpal bone of the little finger. Situation: This muscle arises behind the other muscles * The ridge which leads to the styloid process. 219 which pass from the internal condyle. It runs along the inner edge of the fore-arm, between the flexor sublimis on the fore part, and the extensor-carpi-ulnaris on the back part of the ulna. The tendon is bound down by a thin aponeurotic slip, which passes from the inner part ofthe annular ligament ofthe wrist. Use: To bend the hand. Synonyma: Ulnaris internus;—Epitrochli-cubito-car- pien. 5. The Flexor Sublimis Perforatus—Arises, ten- dinous and fleshy, from the under part of the internal condyle of the os humeri; tendinous from the lower part of the coronoid process of the ulna; fleshy, from the tuber- cle of the radius, from the middle of the fore part, of that bone, and from the middle third of its outer edge. These origins form a strong fleshy mass, which sends off four tendons. The tendons are connected by cellular- membrane, and pass together under the annular ligament of the wrist; after which they separate, become thinner and flatter, pass along the metacarpal bone and first pha- lanx of each ofthe fingers, and are Inserted into the anterior and upper part of the second phalanx, each tendon being, near the extremity of the first phalanx, divided for the passage of a tendon ofthe flexor profundus. Situation: To expose the origin of this muscle, the bellies of the pronator teres, flexor carpi radiaiis, and palmaris longus, must be detached from the condyle. It arises behind these muscles, and is connected to them by intermuscular ligaments. It descends along the fore-arm under these muscles, but a part of it is seen projecting towards the inner edge of the arm, betwixt the tendons of the palmaris longus and flexor carpi ulnaris. It arises from the radius immediately below the insertion ofthe biceps flexor cubiti, and on the inside of the insertion of the pronator teres. Its tendons will be seen in the dis- section of the palm ofthe hand. 220 Use: To bend the second joint or phalanx ofthe fin- grers. Synonyma: Sublimis;—Perforatus;—Epitrochlo-coro- ni-phalanginien. By removing the belly of the flexor sublimis, we ex- pose the deep-seated muscles. 6. The Flexor Profundus Perforans—Arises, fleshy, from the smooth concavity on the inside of the ulna, betwixt the coronoid process and the olecranon; from the smooth flat surface of the ulna, betwixt its pos- terior and internal angles; from the under part of the eoronoid process; from the fore part of the ulna below that process, and betwixt the internal angle and that an- gle which gives attachment to the interosseous ligament. It also arises from the inner half of the interosseous liga- ment. This muscle forms a thick mass, which descends along the fore part of the ulna, adhering to that bone as low as one third of its length from its inferior extremity, and terminates in sending off four tendons. These ten- dons are flat, pass together under the annular ligament of the wrist, run through the slits in the tendons of the flex- or sublimis, and are Inserted into the fore and upper part of the third or last phalanx of all the fingers. Situation: This muscle is concealed by the flexor sub- limis and flexor carpi ulnaris. Its tendons will be seen in dissecting the hand. Use: To bend the last joint ofthe fingers. Synonyma: Profundus;—Perforans;—Cubito-phalan- gettien commun. 7. Flexor Longus Pollicis Manus—Arises, by an acute fleshy beginning, from the upper and fore part of the radius, immediately below its tubercle, fleshy from the outer edge and anterior surface of that bone as low as two inches above its inferior extremity, and from the outer part ofthe interosseous ligament. It has also gene- rally a tendinous origin from the internal condyle of the os humeri. This origin forms a distinct fleshy slip 4,4. 1 which is joined to the inner and upper part of the por- tion ofthe muscle arising from the radius. The fibres pass obliquely into a tendon on the anterior surface of the muscle. The tendon passes under the annular liga- ment of the wrist, runs between the two heads of the short flexor ofthe thumb, and between the two sesamoid bones, and is Inserted into the base of the extreme phalanx of the thumb. Situation: This muscle lies by the side of the flexor profundus; the portion which arises from the inner con- dyle passes over the belly of the flexor profundus, and under the flexor sublimis. The whole muscle is con- cealed by the flexor sublimis ; its tendon will be seen in dissecting the short muscles of the thumb. Use: To bend the last joint ofthe thumb. Synonyma: Flexor tertii internodii;—Radio-phalan- gettien du pouce. On separating the lower part of the two last described muscles, we expose a small square muscle, passing trans- versely just above the wrist. 8. The Pronator Quadratus—Arises, broad, ten- dinous, and fleshy, from the inner edge of the ulna, ex- tending from the lower extremity of the bone two inches up its edge. The fibres run transversely, adhere to the interosseous ligament, and are Inserted into the lower and anterior part cf the radius. Situation: This muscle lies close to the bones, co- vered by the flexor longus pollicis and flexor digitorum sublimis. Use: To turn the radius, together with the hand, in- wards. Siinouyma: Cubito-radial. T 2 222 MUSCLES SITUATED ON THE OUTER AND RACK PART OF THE FORE-ARM, AND ARISING FROM THE OUTER CON- DYLE OF THE OS HUMERI. These muscles are eleven in number, and may be divided into two classes: 1. The Superficial; and, 2. The deep-seated. THE SUPERFICIAL. The muscles which arise from the outer condyle are much more distinct in their origins than those which arise from the inner condyle. Several of them arise a considerable way up the os humeri; but there is here also a common tendinous origin, from which the extensor carpi radialis brevior, extensor digitorum communis, and extensor carpi radialis, proceed; so that these mus- cles are intimately connected. 1. Supinator Radii Longus—Arises, tendinous and fleshy, from the external ridge of the os humeri which leads to the outer condyle. It begins to arise nearly as far up as the middle of the bone, and ceases to adhere about two inches above the condyle. It forms a thick fleshy belly, which passes over the side of the elbow joint, becomes smaller, and terminates above the mid- dle of the fore-arm in a flat tendon. The tendon be- comes gradually rounder, and is Inserted into a rough surface on the outer side of the inferior extremity of the radius. Situation: This muscle is situated immediately under the integuments along the outer edge of the arm and fore-arm. It begins to arise from the os humeri imme- diately below the insertion of the del'oid. Its origin lies betwixt the brachialis internus and short head of the triceps extensor cubiti, from which it is separated by the external intermuscular ligament. It descends along the radius, placed at first between the extensor carpi radialis ZZo longior and pronator teres, lower down between the ten- dons of the flexor carpi radialis and extensor radialis lon- gior. Its insertion is crossed by the extensors of the thumb. . Use: To roll the radius outwards, and turn the palm of the hand upwards, also to bend the fore-arm on the humerus. Synonyma: Supinator longus, sive major;—Humero- sus-radial. 2. The Extensor Carpi Radialis Longior__Arises tendinous and fleshy, from the external ridge of the os humeri, beginning immediately below the origin of the supinator longus, and continuing to arise as far as the upper part of the outer condyle. It forms a thick short belly, which passes over the side of the elbow joint, and terminates above the middle of the radius in a flat tendon. The tendon runs along the radius, and, be- coming rounder, passes through a groove in the 'back part of the inferior extremity of that bone, to be Inserted into the posterior and upper part of the me- tacarpal bone of the fore finger. Situation: The belly lies under the supinator longus but part of it projects behind that muscle. The tendon descends behind that of the supinator, and passes under the extensors of the thumb, and annular ligament ofthe wrist, to arrive at the place of its insertion. Use: To extend the wrist, and move the hand back- wards, and to assist in bending the fore-arm. Synonyma: Radialis externus longior;—Radialis ex- ternus primus;—Humero-sus-metacarpien. 3. The Extensor C^rpi Radialis Brevior—Arises tendinous, from the under and back part of the external condyle of the os humeri, and from the external latemal ligament of the elbow joint. Its thick belly runs along the outside of the radius, and terminates in a tendon, which passes through the same groove in the radius as the extensor radialis longior, and under the annular li- gament. 001 Inserted, by a round tendon, into (he upper and back part of the metacarpal bone that supports the middle finger. Situation: This muscle lies partly under the extensor radialis longior; but it also projects behind it. The tendon is seen behind, or more inwardly than the tendon of the long extensor; it passes under the extensors of the thumb and the indicator. Use: To extend the hand. Synonyma: Radialis externus brevior;—Radialis se- cundus epicondylo-sus-metacarpien. 4. The Extensor Digitorum Communis—Arises, tendinous, from the under part of the external condyle of the os humeri; fleshy, from the intermuscular liga- ments which connect it to the extensor carpi radialis bre- vior before, and the extensor carpi ulnaris behind, and from the inner surface of the fascia. It descends along the back part of the fore-arm, and adheres to the ulna where it passes over it. The fleshy belly terminates in four flat tendons, which pass under the annular ligament in a depression on the back part of the radius, and are Inserted into the posterior part of all the bones of the fingers by a tendinous expansion. Situation: It arises betwixt the extensor radialis bre- vior and the extensor carpi ulnaris. It descends betwixt these muscles, and is situated immediately under the in- teguments. The tendons are connected on the back of the metacarpal bone, by cross slips.—The inner part of this muscle is sometimes described as a separate mus- cle, and is called Extensor Proprius Minimi Digiti, vel Auricularis. It passes through a separate depression of the radius, and a particular ring of the annular liga- ment. Use: To extend all the joints of the fingers. Synonyma: Epicondylo-sus-phalangettien commun. The posterior surface of each finger is covered with a tendinous expansion which is formed by the tendons of the common extensor, of the lumbricales, and interossei. 225 This tendinous expansion terminates in the third or ex- treme phalanx. 5. The Extensor Carpi Ulnaris—Arises, tendi- nous, from the upper part of the external condyle; fleshy, from the intermuscular ligaments and inside of the fascia. It crosses towards the ulna, and arises, fleshy, from the* back part of that bone. It terminates in a strong tendon, which passes through a groove in the back part of the lower end of the ulna, under the annular ligament, and is Inserted into the posterior and upper part of the meta- carpal bone of the little finger. Situation: This muscle is entirely superficial. It arises from the condyle betwixt the extensor digitorum com- munis and anconeus. It descends along the fore-arm betwixt the extensor digitorum communis and flexor car- pi ulnaris. Use: To extend the wrist, and bring the hand back- wards; but chiefly to bend the hand laterally towards the ulna, as it will appear by pulling its tendon in the dissected subject. Synonyma: Ulnaris externus;—Epicondilo-cubito-sus- metacarpien. 6. The Anconeus is a small triangular muscle, situ- ated at the outer side of the olecranon, immediately under the integuments. %;S It arises,' tendinous, from the posterior and lower part of jthe external condyle of the os humeri; forms a thick triangular fleshy mass, adhering to the capsular ligament of the elbow joint, and is Inserted into the concave surface on the outside of the olecranon, and into the posterior edge of the ulna. Situation: This muscle lies betwixt the upper part of the extensorlbarpi ulnaris and the olecranon. It is part- ly covered by the tendon of the triceps extensor cubiti, and is enveloped in a fascia sent off from that tendon. Use: To assist in extending the fore-arm. Synonyma: Anconeus minor;—Anconeus vel Cubita- lis;—Epicondylo-ctuSital. 226 By removing the superficial muscles, we expose THE DEEP-SEATED. 7. The Supinator Radii Brevis—Arises, tendinous, from the lower part of the external condyle ofthe os hu- meri; tendinous and fleshy, from the ridge running down from the coronoid process along the outer surface of the ulna. The fibres adhere firmly to the ligament that joins these two bones, pass outwards round the upper part of the radius, and are Inserted into the upper and outer edge of the tubercle of the radius, and into an oblique ridge extending from the tubercle downwards and outwards to the insertion of the pronator teres. Situation: This muscle nearly surrounds the upper and outer part of the radius. It is concealed at the outer edge of the arm by the supinator longus and extensores carpi radiales: behind, by the extensor digitorum com- munis, extensor carpi ulnaris, and anconeus; before, by the brachialis internus, and by the tendon of the biceps flexor cubiti, close to which tendon this muscle is inserted. Use: To roll the radius outwards, and bring the hand supine. Synonyma: Epicondylo-radial. On the back part of the fore-arm we meet with three muscles going to the thumb, and one to the fore finger. 8. The Extensor Ossis Metacarpi Pollicis— Arises, fleshy, from the middle and posterior part of the ulna, immediately below the termination of the ancone- us, from the interosseous ligament, and from the poste- rior surface ofthe radius below the insertion ofjhe supi- nator radii brevis. The fleshy fibres terminate in a5tfen- don which passes through a groove in the outer edge of the lower extremity ofthe radius. Inserted, generally by two tendons, into the os trape- zium, and into the upper and back part of the metacar- pal bone of the thumb. 827 Use: To extend the metacarpal bone of the thumb outwardly. Synonyma: Abductor longus pollicis manus;—Exten- sor primi internodii;—Extensor primus pollicis;—Cubito- radi-sus-meiacarpien du pouce. 9. The Extensor Primi Internodii Pollicis Manus —Arises, fleshy, from the back part ofthe ulna below its middle, from the interosseous ligament and radius. It runs along the lower edge of the extensor ossis metacarpi, and forms a tendon, which passes through the same groove as the tendon of that muscle, and is Inserted into the posterior part ofthe first bone of the thumb. Part of the tendon is also continued into the base ofthe second or extreme phalanx. Use: To extend the first phalanx of.the thumb oblique- ly outwards. Synonyma:-Extensor minor pollicis manus;—Exten- sor secundi internodii;—Extensor pollicis primus;— Cubilo-sus-phalangien du pouce. 10. The Extensor Secundi Internodii Pollicis Manus—Arises, tendinous and fleshy, from the posteri- or surface of the ulna above its middle, and from ihe in- terosseous ligament. Its belly partly covers the origins of.the two other extensors ofthe thumb, and terminates in a tendon, which runs through a distinct groove in the back part of the radius, and is Inserted into the posterior and upper part of the second or extreme phalanx of the thumb. Use: To extend the last joint of the thumb obliquely backwards. Synonyma: Extensor major poMicis manus;—Extensor pollicis secundus;—Extensor tertii internodii;—Cubito- sus-phalangettien du pouce. Situation of the extensors of the thumb —The origins of these muscles are concealed by the extensor digi orum communis and extensor carpi ulnaris.—Their bellies are seen coming from betwixt the extensor digitorum com- munis and extensor carpi radialis brevior, and, passing 228 under the annular ligament ofthe wrist, to arrive at the place of their insertion.—The tendon ofthe extensor se- cundi internodii is at a considerable distance from the tendons ofthe two other extensors; so that in the inter- mediate space, we see the terminations of the tendons of the extensores carpi radiales. They invest the back part of the thumb with a fascia. 11. The Indicator—Arises, by an acute fleshy be- ginning, from the middle of the back part of the ulna, and from the interosseous ligament. Its tendon passes through the same sheath of the annular ligament with the extensor digitorum communis, and is Inserted into the posterior part of the fore finger with the tendon of the common extensor. Situation: It arises nearer to the inner edge of the arm than the extensor secundi internodii pollicis. It is con- cealed by the extensor digitorum communis, and extensor carpi ulnaris. The tendon passes under that of the com- mon extensor. Use: To assist in extending the fore finger. Synonyma: Extensor secundi internodii indicis pro- prius;—Extensor indicis proprius;—Cubito-sus-phalan- gettien de l'index. General Observations.—In dissecting the fore-arm, yo.u will not expect to find each muscle separate from the contiguous ones, as far as its very origin from the bones. The partitions of fascia unite them most firmly to a con- siderable distance from their commencement: and these connections should not be disturbed, since they are as just- ly to be regarded in the light ofthe origins ofthe myscles, as the attachments which the fibres have to the bone. The muscles are divided into two masses; of which one lies over the radius and back ofthe fore-arm, and con- tains the supinators and extensors: the other, situated over the ulna, and inner side ofthe fore-arm, consists of the pronators and flexors. Although some muscles in each of these masses arise quite separately, others are joined into a common tendinous and fleshy origin, in the 229 way above described. First clear all the muscles as they lie; and after observing them in their relative position, reflect each muscle, beginning with the superficial ones, and reading its description at the same time. SECT. III. dissection of the palm of the hand. The tendons which pass over the bones of the carpus into the palm ofthe hand are firmly bound down by the annular ligament of the wrist. They are invested and connected by cellular membrane, which forms sheaths, and secretes synovia to facilitate their motions. - In the sole of the foot we saw a strong fascia, sup- porting and covering the muscles, and passing from the heel to the toes. On removing the integuments from the palm of the hand, we meet with a similar fascia. It arises from the tendon of the palmaris longus, and from the annular ligament of the wrist, expands over all the palm of the hand, and is fixed to the roots ofthe fingers, splitting to transmit their tendons. This is the Fascia or Aponeurosis Palmaris. It is triangular. Where it arises from the wrist, it is narrow, and does not cover the bases of the metacarpal bones of the little and fore finger.—As it runs over the hand, it becomes broader, and is fixed by a bifurcated extremity in the lower end of each of the metacarpal bones ofthe four fingers.—The palmar fascia is strong and thick, conceals and supports the muscles of the hand', and may be distinguished into four portions, which are connected by transverse fibres, while other fibres pass from them downwards, adhere strongly to the edges of the metacarpal bones, and sepa- rate the tendons of each finger. U 230 There is a small thin cutaneous muscle situated be- tween the wrist and the little finger. The Palmaris Brevis—Arises, from the annular li- gament of the wrist, and from the inner edge of the fas- cia palmaris. Inserted, by small scattered fibres, into the skin and fat which covers the short muscles of the little finger and inner edge of the hand. Use: To assist in contracting the palm ofthe hand. Synonyma: Palmaris cutaneus. The fascia palmaris may now be removed. Under it will be seen the four tendons of the flexor sublimis per- forata. They are seen coming from beneath the annu- lar ligament of the wrist, and diverging as they pass to- wards their respective fingers. Each tendon splits at the extremity of the first phalanx, for the passage of the tendon ofthe flexor profundis perforatus, and inserted in- to the base of the second phalanx. Under the flexor sublimis are the four tendons of the flexor profundus perforans, which pass through the slits in the tendons of the former, and are inserted into the bases of the third phalanges of the fingers. The Lumbricales are four small muscles, which arise, tendinous ami fleshy, from the outer side of the tendons of the flexor profundus perforans, soon after those ten- dons have passed the ligamentum carpi annulare. Each of these muscles has a small belly, which terminates in a tendon. The tendon runs along^ the outer edge of the finger, and is Inserted into the tendinous expansion which covers the back part of the phalanges of the fingers, about the mid- dle of the first joint. Use: To bend the first phalanges of the fingers, the flexor profundus being previously in action, to afford them a fixed point. Synonyma: Annuli-tendino-phalangiens. The short muscles of the thumb and fore finger ar? five in number. 231 1. The Abductor Pollicis Manus—Arises, by a broad tendinous and fleshy origin, from the anterior sur- face of the annular ligament of the wrist, and from the os naviculare and os trapezium. Inserted, tendinous, into the outer side of the root of the first phalanx of the thumb, and into the tendi- nous membrane which covers the back part of allthe phalanges. Situation: This muscle is situated immediately under the integuments, and is the outermost portion ofthe mus- cular mass forming the ball of the thumb. Use: To draw the thumb from the fingers. Synonyma: Abductor brevis pollicis manus, and ab- ductor brevis alter;—Abductor, Thenar;—Scapho-sus- phalanginien du pouce. 2. The Flexor Ossis Metacarpi Pollicis, or Op- ponens Pollicis—Arises, broad and fleshy, from the an- nular ligament of the wrist, and from the os naviculare and os trapezium. Inserted, tendinous and fleshy, into the anterior and lower part of the metacarpal bone of the thumb. Situation: It lies under the abductor pollicis, and is almost entirely concealed: but a few of its fibres are seen projecting beyond the edge of that muscle. Use: To bring the first bone of the thumb inwards. Synonyma: Flexor primi internodii;—Antithenar, sive Semi-interosseus pollicis;—Carpo-phalangien du pouce. 3. The Flexor Brevis Pollicis Manus arises by two distinct heads. (I.) The outer head arises from the inside ofthe an- nular ligament; from the anterior surface of the os tra- pezium and os trapezoides; and from the root of the metacarpal bone of the fore finger, Inserted into the outer sesamoid bone, which is con- nected by a ligament to the root of the first phalanx of the thumb. (2.) The inner head arises from the upper part of Iht 232 os magnum and os unciforme, and from the root of the metacarpal bone of the middle finger. Inserted into the inner sesamoid bone, which is con- nected by a ligament to the root *rjf the first phalanx of the thumb. Situation: This muscle is in great part concealed by the abductor pollicis. Its inner origin is under the first lumbricalis; its upper part is seen projecting: and be- tween its two portions we find the tendon of the flexor longus pollicis. Use: To bend the first joint of the thumb. Synonyma: Flexor secundi internodii; Thenar;—Car- po-phalanginien du pouce. * 4. The Adductor Pollicis Manus—Arises, fleshy, from almost the whole length of the matacarpal bone sustaining the middle finger. The fibres converge, and pass over the metacarpal bone of the fore finger, to be Inserted, tendinous, into the inner part of the root of the first phalanx of the thumb. Situation: The belly of this muscle is concealed, as it lies close to the bone under the tendons of the flexor r*™. fundus and lumbricales. The tendon is seen where it is inserted into the thumb, and runs along the inner edge of the flexor brevis pollicis. Use: To pull the thumb towards the fingers. Synonyma: Adductor ad minimum digitum;—Meso- thenar;—Metacarpo-phalanginien du pouce. 5. The Adductor Indicis Manus—Arises, tendinous and fleshy, from the os trapezium, and from the inner side of the metacarpal bone of the thumb. It forms a fleshy belly, runs over the side of the first joint of the fore finger, and is Inserted, by a short tendon, into the outer side ofthe root of the phalanx of the fore finger. Situation: This muscle is seen most distinctly on the back of the hand. It is there superficial, and is crossed by the tendon of the extensor secundi internodii polli- 233 cis. In the palm of the hand it is concealed by the muscles of the ball of the thumb. Use: To move the fore finger towards the thumb, or the thumb towards the fore finger. Synonyma: Semi-interosseus. The insertion ofthe flexor carpi radialis is exposed by removing the muscles of the thumb. The short muscles of the little finger are three in number. 1. The Abductor Minimi Digiti Manus—Arises, fleshy, from the os pisiforme, and adjacent part of the annular ligament of the wrist. Its fibres extend along the metacarpal bone of the little finger. Inserted, tendinous, into the inner side of the first phalanx, and into the tendinous expansion which covers the back; part of the little finger. Situation: The belly of this muscle is superficial. It is only covered by the straggling fibres of the palmaris brevis. Use: To draw the little finger from the rest. Synonyma: Hypothenar minor;—Extensor tertii in- ternodii minimi digiti;—Carpo-phalangien du petit doigt. 2. The Flexor Parvus Minimi Digiti—Arises, fleshy, from (he outer side of the os unciforme, and from the annular ligament of the wrist, where it is affixed to that bone. Inserted, by a roundish tendon, into the base ofthe first phalanx of the little finger. Situation: This muscle is also covered by the fibres of the palmaris brevis. It lies on the inner side ofthe abductor minimi digiti, and its tendon is firmly connect- ed to the tendon of that muscle. Use: To bend the little finger, and bring it towards the other fingers. Synonyma: Abductor minimi digiti ;-r-Carpo-phalan» gien second. 3. Adductor Metacarpi Minimi Digiti Manus— Arises, fleshv, from the os unciforme, and adjacent part U2 234 of the annular ligament of the wrist. It forms a thick mass, which is Inserted, tendinous, into the fore part of the metacar- pal bone of the little finger, nearly its whole length. Situation: It is concealed by the bellies of the abduc- tor and flexor brevis minimi digiti. Use: To bend and bring the metacarpal bone of the little finger towards the rest. Synonyma: Metacarpus;—Flexor primi internodii minimi digiti;—Carpo-metacarpien du petit doigt. The Interossei are small muscles situated between the metacarpal bones, and extending from the bones of the carpus to the fingers. They are exposed by remov- ing the other muscles of the thumb and fingers. The Interossei Interni are seen in the palm ofthe hand, and are four in number. They arise, tendinous and fleshy, from the base and sides of the metacarpal bones, and are inserted into the side of the first phalanx of the fingers, and into the tendinous expansion which covers the posterior surface of all the phalanges. 1. The First, named Prior Indices, arises from the outer part of the metacarpal bone ofthe fore finger; and is insert into the outer side of the first phalanx of that finger. Use: To draw the fore finger towards the thumb. 2. The Second, named Posterior Indicis, arises from the root and inner side of the metacarpal bone of the fore linger; and is inserted into the inner side ofthe first pha- lanx of the fore finger. Use: To draw that finger out- wards. 3. The Third, named Prior Annularis, arises from the root and outer side of the metacarpal bone of the ring- finger ; and is inserted into the outer side of the first phalanx of the same finger. Use: To pull the ring-finger towards the thumb. 4. The Fourth, named Interosseus Auricularis, arises from the root and outer side ofthe metacarpal bone of the little finger; and is inserted into the outer side of the 235 first phalanx of the little finger. Use: To draw the lit- tle finger outwards. The internal interossei also assist in extending the fin- gers obliquely. Synonyma: Sous-metacarpo lateri-phalangiens. The Interossei Externi, seu Bicipites, are three in number. They are larger than the internal, and are si- tuated betwixt the metacarpal bones on the back of the hand. Each of these muscles arises, by a double head, from two metacarpal bones, and is inserted into the side of one of the fingers, and into the tendinous expansion which covers the posterior part of the phalanges. 1. The First, named Prior Medii, arises from the roots of the metacarpal bones of the fore and middle fingers; and is inserted into the outer side of the middle finger. Use: To draw the middle finger towards the thumb. 2. The Second, named Posterior Medii, arises from the roots of the metacarpal bones of the middle and ring fingers, and is inserted into the inner side of the middle finger. Use: To draw the middle finger towards the ring-finger. 3. The Third, named Posterior Annularis, arises from the roots of the metacarpal bones of the ring and little fingers; and is inserted into the inner side of the ring- finger. Use: To draw the ring-finger inwards. The external interossei also extend the fingers. Synonyma: Sous-metacarpo-lateri-phalangiens. SECT. IV. OF THE VESSELS AND NERVES OF THE SUPERIOR EXTREMITY. arteries. The subclavian and axillary arteries have been de= scribed. 236 The Brachial Artery may be said to have its course along the inside of the arm. Having left the axilla, it runs along the inferior edge ofthe coraco-brachialis. Ra- ther higher up than the middle of the os humeri, it crosses over the tendinous insertion of that muscle, being here situated between the belly of the biceps flexor cubiti, and the superior fibres of the brachialis externus. The ar- tery then passes behind the inner edge of the biceps flexor cubiti, descending betwixt that muscle and the fibres of the brachialis internus. In dissecting this vessel, we find it invested by a fascia or sheath, formed by cellular mem- brane and some tendinous fibres. This fascia may be traced extending from the internal intermuscular liga- ment. It covers the brachial artery and radial nerve; and the great basilic vein, as it enters into the axilla, is found lying in the fore and inner part of this sheath. It supports and connects these vessels. On dissecting this fascia, we find, close to the margin of the coraco-brachi- alis and biceps flexor cubiti, the great radial nerve: un- der it the brachial artery; and, more superficially seated, the venae comites and the vena basilica. As the artery approaches the lower extremity of the os humeri, it in- clines forwards toward the fold of the arm, and dives be- neath the aponeurosis which arises from the inside of the tendon ofthe biceps flexor cubiti. Its situation at the fold of the arm has been described. BRANCHES OF THE BRACHIAL ARTERY. 1. A. Profunda Humeri Superior, or Muscularis Superior, is sent off from the inner side of the brachial artery, immediately where it has left the fold ofthe arm- pit. It passes downwards and backwards round the os humeri, and is accompanied by the muscular or spiral nerve. It passes betwixt the brachialis externus and short head of the triceps extensor cubiti. Here it lies deep among the muscles, and divides into two branches. One accompanying the nerve, spreads its ramification over 237 the outer condyle, and anastomoses with the arteries be- low the elbow. The other branch is distributed along the inside of the arm, and about the inner condyle. 2. A. Profunda Humeri Inferior, vel Minor, or Muscularis Inferior, is smaller than the last, and is sent off from the brachial artery about two inches lower down. It descends among the muscles on the inside of the arm, and is lost about the inner condyle. 3. The anastomising or collateral arteries are as fol- low: (1.) The Ramus Anastomoticus Major passes from the inside of the brachial artery, about two or three inches above the inner condyle. It is distributed about the con- dyle; and its principal branch accompanies the ulnar nerve in the groove betwixt the olecranon and inner con- dyle, to anastomose with the recurrent branches of the arteries of the fore-arm. (2.) There are two or three more anastomosing branches, which are sent off from the brachial artery, and ramify over the anterior and posterior surfaces of the two condyles. 4. Small branches to the muscles of the arm. The Brachial Artery, where it lies deep under the aponeurosis of the biceps, divides into three branches. 1. The radial; 2. The ulnar; and, 3. The interosseous artery. The two last generally come off by one trunk, which subdivides. 1. Arteria Radialis.—The radial artery is smaller than the ulnar, and in its course more superficial. It leaves the ulnar artery, and inclines towards the radial and outer edge of the fore-arm. At first it lies betwixt the pronator teres and supinator longus. It then descends close along the inner edge of the supinator longus, and about the middle of the fore-arm passes over the insertion of the pronator teres. It then holds its course betwixt the supinator longus and flexor carpi radialis, and is ac- companied by a branch of the muscular or spiral nerve. In this situation the artery continues its course along 238 the radius, till, reaching the lower extremity of that bdne, it divides into two branches. (1.) Ramus Volaris, A. Superficialis Vol.e, is by much the smallest of the two branches. It passes into the muscular mass which forms the ball of the thumb, and spreads its ramifications on the palmar fascia, annu- lar ligament of the wrist, and muscles of the thumb, an- astomosing with the ramifications ofthe superficial palmar arch. (2.) The trunk of the radial artery crosses over the lower extremity of the radius to the back of the hand. It passes under the extensors of the thumb, over the os scaphoides and the junction of the os trapezium and tra- pezoides, and, arriving at the space betwixt the bases of the metacarpal bones of the thumb and fore finger, plunges into the palm of the hand. The branches of the radial artery, in its course along the fore-arm, are the following. (1.) The recurrent artery is sent off from the radial immediately after it leaves the ulnar artery, and is dis- tributed over the anterior part of the outer condyle, where it anastomoses with branches of the brachial artery. (2.) Small arteries to the muscles of the fore-arm, and to the radius. (3.) A branch leaves the artery immediately after it has returned over the edge of the radius, and rami- fying on the back of the hand, is named Dorsalis Carpi. (4.) Small vessels are sent off to the back part of the thumb, named A. Dorsalis Carpi. Having reached the palm of the hand, the radial artery divides into two branches. (1.) A. Pollicis, which sends two or three arteries along the anterior part ofthe thumb, and also often gives off a twig, the A. Radialis Indicis, which passes along the outer edge of the fore-finger", and inosculates with a branch of the ulnar artery. (2.) The trunk of the radial artery forms the Deep- 23i) seated Palmar Arch. From the root of the thumb, it passes across the metacarpal bones near their bases' and terminates at the metacarpal bone of the little finger, inosculating with a branch of the ulnar artery. This arch lies deep, close to the bones. It supplies the interosseous muscles and deep-seated parts of the palm, and some of its branches pass betwixt the metacarpal bones to the back of the hand. 2. Arteria Ulnaris, or Cubitalis. The ulnar artery is the largest branch ofthe brachial, and generally gives off the interosseous artery. It takes its course deep among the muscles on the inside of the fore-arm. It is seen passing under the pronator teres, flexor carpi ra- dialis, palmaris longus, and flexor sublimis perforatus, but over the flexor profundus perforans. It descends in the connecting cellular membrane, between the flexor sublimis and profundus; but about the middle of the fore-arm, it emerges from these muscles, and appears at the ulnar edge of the arm, betwixt f>e flexor sub- limis and flexor carpi ulnaris. It passes over the an- nular ligament of the wrist, which binds down the flexor tendons of the fingers, but is covered by the fascia which ties down the tendon of the flexor carpi ulnaris. It passes under the palmar aponeurosis, on the inside ofthe os pisiforme, reaches the base ofthe meta- carpal bone of the little finger, and begins to form the Superficial Palmar Arch. This arch lies above the tendons of the flexor sublimis perforatus, immediately beneath the palmar aponeurosis. It crosses the meta- carpal bones betwixt their bases and the middle of their bodies. It begins at the root of the little fin- ger, and terminates at the root of the thumb, in in- osculations with the branches of the radial artery. The convex side of the arch is turned towards the fingers, and sends off five branches. (1.) A branch to the muscles and inner edge of the little finger. (2.) Ramus digitalis primus, or the first digital artery, 240 which runs along the space betwixt the two last meta carpal bones, and bifurcates into two branches, one to the outside of the little finger, and the other to the inner side of the ring finger. (3.) The second digital artery, which bifurcates in a similar manner, and supplies the outer edge ofthe ring- finger, and the inner side of the middle finger. (4.) The third digital artery, which is distributed to the outer edge of the middle finger, and to the inner side of the fore finger. (5.) The ramus Pollicis ulnaris is the last branch of the ulnar artery, and is sent to the muscles of the thumb. From the concavity of the arch are sent off the in- terosseous arteries of the palm, small twigs which sup- ply the deep-seated parts, and perforate betwixt the metacarpal bones to the back of the hand. The branches of the ulnar artery, in its course along the fore-arm and wrist, are the following. (1.) The Recurrent Arteries are two in number. They are sent off from the ulnar artery immediately be- low the elbow, sometimes in one common branch, which subdivides. The anterior recurrent runs over the fore part of the inner condyle; the posterior recurrent passes over the back part. These arteries inosculate with branches of the brachial. (2.) Twigs to the muscles ofthe fore-arm. (3.) A. Dorsalis Carpi is sent off from the ulnar artery a little above the wrist to the back of the hand. Twigs are also given off to the annular ligament and neighbour- ing parts. (4.) A. Palmaris Profunda is sent off from the ul- nar artery, where it descends on the inside of the os pisi- forme. It passes into the flesh at the root of the little finger, and inosculates with the termination of the deep- seated palmar arch of the radial artery. 3. Arteria Interossea, (or lnterrossea Communis). 241 This artery is generally sent off from the ulnar. It in> mediately divides into two branches: (1.) The external or posterior interosseous artery is the smallest branch. It passes through the upper part of the interosseous ligament, to supply the muscles on the posterior part ofthe fore-arm. It sends off the A. Recurrens Interossea, which ramifies on the middle of the back part of the elbow joint. (2.) The internal or anterior interosseous artery de- scends upon the middle of the interosseous ligament, be- twixt the flexor longus pollicis and flexor profundus per- forans, giving twigs to the adjacent muscles. Arriving at the upper edge of the pronator quadratus, it perforates betwixt the radius and ulna to the back part ofthe arm, and spreads its extreme branches on the wrist and back of the hand. VEINS. The cutaneous veins have been already described. The brachial artery is accompanied by two veins, named Venae Comiles, or Satellites. These receive branches corresponding to the ramifications of the artery. NERVES. In the dissection of the axilla, we demonstrated the great axillary plexus, and traced its two first branches, the external scapular and circumflex nerves. The dis- tribution ofthe five remaining branches ofthe plexus must now be described. (3.) The External Cutaneous Nerve, (Musculo- cutaneus, or Perforans Casserii,) is the third branch of the axillary plexus. It passes through the belly of the coraco-brachialis muscle. After its passage it continues its course obliquely across the arm, betwixt the Biceps flexor cubiti and the Brachialis internus. It gives twigs X 242 to these muscles, and appears as a superiicial nerve on the edge of the supinator longus. It runs over the outer condyle, and is distributed to the integuments on the out- side ofthe fore-arm, and back of the hand. (4.) The Radial (or Median) Nerve accompanies the brachial artery to the bend of the elbow, and is con- tained in the same sheath as the artery. In its passage down the arm, it lies before that vessel, but at the elbow is situated ,on its inside. It gives off no branches until it has sunk under the aponeurotic expansion of the biceps flexor. Here it distributes many nerves to the muscles of the fore-arm, to the pronator teres, flexor carpi radialis* the flexors of the thumb and fingers, and the pronator quadratus. The trunk of the nerve perforates the pronator teres, passes betwixt the flexor digitorum sublimis and flexor profundus, and continues its course betwixt these muscles down to the wrist. Near the wrist it becomes more superficial, lying amongst the tendons of the flexors, and before it descends under the annular ligament, sends a superficial branch to the integu- ments and short muscles of the thumb. The nerve it- self passes with the flexor tendons of the fingers under the annular ligament of the wrist, emerges from these tendons, and appears on their outside, near the root of the thumb. It ramifies superficially in the hand, setting off four branches. The first branch passes to the thumb; the second to the side of the fore finger next the thumb; the third divides into two nerves, of which one passes to the inner side of the fore finger; the fourth also subdivides into two, to the inside of the middle finger, and outer side of the ring-finger. These nerves pass before the flexor tendons, but behind the superficial palmer arterial arch, to reach the fingers. (5.) The Ulnar Nerve descends along the inside of the arm. It is at first situated immediately under the in- teguments, but below the middle of the arm is tied down by the intermuscular ligament which passes to the inner condyle of the humerus. The nerve becomes here more 243 deeply seated; it runs between the inner condyle in the hollow behind it and the olecranon, and in the flesh of the brachialis externus, or third head of the.triceps extensor. After passing the condyle, it continues its course betwixt the two heads of the flexor carpi ulnaris, till it reaches the ulnar artery. It then accompanies the ulnar artery, lying on its inside and running along the fore-arm betwixt the. flexor ulnaris and flexor digitorum sublimis; It sends twigs to the neighbouring muscles, and, when arrived near the wrist, divides into two branches. 1. The Smaller Branch, called Ramus posticus, passes under the tendon of the flexor carpi ulnaris, and over the lower end of ihe ulna, to be distributed to the back of the hand, and of the little and ring fingers. 2. The continued trunk of the nerve passes on the inside of the ulnar artery, over the annular ligament of the wrist. It passes under the palmar aponeurosis, and divides into three principal branches. The first supplies the integuments and muscles on the ulnar edge of the hand, and the inner side of the little finger. The second is distributed to the outer side of the little finger, and inner side ofthe riug-finger. The third branch passes deep under the long tendons, accom- panies the deep-seated palmar arch, and terminates in the short muscles ofthe thumb and fore finger, commu- nicating with the radial nerve. (6.) The Muscular or Spiral Nerve (Radial of some anatomists) passes from the axilla behind the os humeri, making a spiral turn round the bone to reach the outside of the arm. It first descends between the brachi- alis externus and short head of the biceps extensor cubiti, accompanying the arteria profunda humeri superior, and passing deep into the flesh of the arm. Before it makes this turn, it gives branches to the muscles, also a cutane- ous branch, which descends on the inside of the arm. From the back part of the arm the great trunk ofthe nerve is reflected spirally forwards. It is seen emerging betwixt the supinator longus and brachialis internus, seat- ed deep and close to the bone. It descends betwixt these 244 muscles, keeping close to the edge of the supinator longus. Immediately after passing the fold of the arm, it sends off a nerve, which descends, superficial, upon the radial jdge of the fore-arm, as far as the wrist; and, at this point, the trunk of the muscular nerve divides itself into two branches. The first, a large branch, perforates the supi- nator brevis, and supplies the extensor muscles ofthe hand and fingers. The second branch accompanies the supi- nator longus down the fore-arm, and near the wrist turns under the tendon of that muscle, over the edge ofthe ra- dius. It then divides into several branches which rami- fy on the bac'k'of the wrist, thumb, and fore finger. (7.) The Internal Cutaneous Nerve descends, superficial, along the inside of the arm and fore-arm. It was described among the cutaneous nerves of the arm. THE END. Mel • Hist \t\% f ^ J? ■% J> V 1/ , i ■ r*A... . ..