THE LUMBAR, THE SACRAL, AND THE COCCYGEAL 
NERVES IN THE DOMESTIC CAT. 
With Plate XXIII. 
T. B. Stowell, A.M., Pu.D., ( 
Principal of the State Normal and Training School at Potsdam, N. Y. 
Extracted from 
THE JOURNAL OF COMPARATIVE NEUROLOGY. 
C. E. HERRICK, Editor. 
CINCINNATI, OHIO, U. S. A. THE LUMBAR, THE SACRAL, AND THE COCCY- 
GEAL NERVES IN THE DOMESTIC CAT. 
With Plate XXIII. 
T. B. Stowell, A.M., Ph.D., 
Principal of the State Normal and Training School at Potsdam, N. Y. 
The present contribution to comparative neurology is 
offered in the hope that it may serve as a factor to strengthen 
the argument in favor of the substitution of comparative 
anatomy for anthropotomy in the first year's work of our 
medicdl courses, and also to justify the practice of calli- 
section or painless physiological experimentation. The con- 
stancy of character, i.e., the slight variation in nerve ramuli 
and their distribution, seems to favor making neurology the 
basis of comparative anatomy, rather than osteology or my- 
ology. Believing such to be the case, it is hoped that this 
study may prove helpful in establishing doubtful homologies. 
If the educational or cultural in contradistinction to the 
utilitarian view of the subject be considered, there seems 
abundant demand for the work undertaken by the paper as a 
guide to laboratory students with whom the end is general 
and not specific. For it is quite generally conceded that 
comparative anatomy furnishes one of the most available 
means for training the perceptive activities as well as those 
of comparison and induction. Furthermore, physiology is 
almost wholly a comparative science; while some of the facts 
known to physiology have followed direct experiment, the 
great majority are the results of partial experimentation upon 
other mammals. It needs no proof beyond mention to show 
287 288 
Journal of Comparative Neurology. 
that the present plan of study in the medical college is not 
as extensive as it should be to furnish the technical skill and 
exact knowledge which the profession demands. That human 
physiology is largely comparative will be readily admitted, 
but unless the student knows that the structures in the animal 
experimented upon are strictly homologous with the struc- 
tures in man the physiological experiment becomes merely 
an illustrative exercise, interesting and instructive, but not a 
demonstration of function in man. 
When it is shown that the nerve-supply is identical with 
the nerve-supply in man, then these experiments in which 
the nervous system is a controlling factor are conclusive 
evidence in human physiology also; e.g., at this moment my 
mind selects the elaborate experiments of Dr. H. P. Bow- 
ditch upon the vaso-motor nerves, the results of which were 
presented before Section F, A. A. A. S., Buffalo meeting, 
1886. 
Among reasons for the selection of a small mamrrfel may 
be named the cost and convenience of suitable preparation, 
preservation and manipulation. In regard to cost, it should 
be remembered that for exact work each individual should 
dissect an entire body-the reserve half serving for corrobo- 
ration, verification, correction of errors from accident or over- 
sight, study of variations in the same individual, etc. The 
writer found it a matter of no small expense and labor to 
prepare and to preserve in alcohol the adult cadavers which 
formed the basis of his studies in anthropotomy ;• the conve- 
nience of manipulation will be appreciated by those who 
have had the experience of transferring a large adult cadaver 
from tank to table. 
The adaptation of the domestic cat to the ends sought 
(comparative neurology) may be briefly stated as follows: 
1. The readiness with which structures may be homolo- 
gized with corresponding structures in man (certain nerves 
in the dog are quite unlike those in man, eg., vagi). That 
there are marked differences between the human brain and Stowell, Nerves in the Domestic Cat. 
289 
other mammalian brains is generally known, and possibly 
some other animal is preferable to the cat as a type for this 
portion of the neur-axis. 
2. The abundance of material for study. 
3. The inexpensiveness of (a) the bodv; ($) of suitable 
preparation of the same, injection, etc.; (c) of preservation 
of the same. 
4. The ease of manipulation; the tissues are much firmer 
than they are in a small human subject, foetus or infant. 
To these more apparent considerations may be added the 
fact that already elaborate works on felitomy are accessible, 
e.g., Straus-Durckheim's monogram on the " Skeleton Liga- 
ments and Muscles of the Cat" (" Anatomie du Chat," two 
vols.), or the less expensive reduced copies with " Explana- 
tions" by Prof. H. S. Williams; St. George Mivart's "The 
Cat," although this work does not seem to be a reliable guide 
to the study of American cats; the more scientific and exact 
work of Wilder and Gage, entitled " Anatomical Technol- 
ogy," and the numerous papers and addresses of the same 
authors, a partial list of which is found in the work cited; 
and the papers embodying some of the writer's studies in 
comparative neurology^1) 
PREPARATION. 
The cats were killed with chloroform and both arteries 
and veins were injected with the starch injection mass. 
When not in use the body was wrapped in a napkin saturated 
with alcohol and then placed in a tight vessel; the tissues are 
by this means preserved in excellent condition. 
GENERAL DESCRIPTION. 
The myel may be regarded anatomically as an elongated 
mass of alba and cinerea, and functionally as an aggregation 
i "The Vagus Nerves in the Domestic Cat:" The Trigeminus, The Facial, The 
Glosso-pharyngeal, The Accessory, The Hypoglossal, The Soft Palate. The literature of 
the subject was cited in a paper read before the American Philosophical Society, May 
21, 1886. 290 
Journal of Comparative Neurology. 
of sensory and motor centres especially characterized by 
reflex action. Corresponding to its relations with the ver- 
tebrae, it is usually divided into the five regions, cervical, 
thoracic, lumbar, sacral, and coccygeal; and the myelic nerves 
are named from the vertebrae cephalad of which they have 
their respective ectal origins. The lumbar and the sacral 
nerves form open plexuses (Pl. lumbalis and Pl. sacralis), 
from which nerves are distributed to the integument and the 
subjacent muscles. 
POSTURE. 
Ventri-cumbent, head toward dissector's left, or lateri- 
cumbent, with the venter toward the dissector. 
EXPOSURE. 
It is not imperative that the dissection begin at any par- 
ticular point, but most of the nerves send branches caudad 
rather than cephalad (v. diagram), hence it is recommended 
to begin at the thirteenth thoracic nerve and dissect caudad, 
removing the neural arch and exposing the myel as the dis- 
section progresses. Make a long incision through the integ- 
ument about 2 cm. sinistrad of the dorsi-meson, from the 
tenth thoracic vertebra to the base of the tail. From the 
cephalic end of this incision make a second incision ventrad 
4-6 cm., and reflect the flap of integument over the twelfth 
and thirteenth ribs. With the arthrotome remove the dorsal 
muscle from the sinistral side of the meson to the level of the 
vertebral laminae of the twelfth and the thirteenth thoracic 
vertebrae. With the tracer find the thirteenth thoracic and 
the first lumbar nerves just peripherad of the vertebrae, trace 
them centrad to the foramina intervertebrales, separate the 
connecting tissues from the foramina, then with the side- 
cutting nippers remove the neural arch of the thirteenth 
thoracic vertebra, taking the precaution to make the first 
incision near the neurapophysis, to insure protection to the 
myel. The dextral lamina can be removed without injury to Stowell. Nerves in the Domestic Cat. 
291 
the dorsal muscles or integument, making it possible to use 
the dextral side to corroborate and to correct results obtained 
by dissecting the sinistral. The exposure of the myel in the 
arch of the caudal thoracic vertebra (thirteenth) exposes the 
ectal origin of the first lumbar nerve. The arch can be re- 
moved in a similar manner caudad and dextrad as the dissec- 
tion requires, using the precaution to trace the dorsal division 
of each nerve before removal of the dorsal muscle. The 
nerves should be traced from the ectal origin peripherad. 
LUMBAR NERVES. NERVI LUMBALES. 
Common Characters.-The lumbar nerves are seven pairs, 
and have characters in common. They are related with the 
sympathic system by anastomotic filaments to the adjacent 
ganglia (Fig. Pl. S. and S.), which filaments leave the ental 
surface of the nerve as it traverses the groove from the neural 
arch to the inter-vertebral foramen (foramen of exit); these 
anastomotic filaments are apposed to an arteriole-the dorsal 
branch of the A. lumbalis. At the ectal border of the fora- 
men of exit, each nerve divides into a dorsal and ventral 
portion; the dorsal nerve divides into two or more branches, 
which innerve the muscles of the back (MM. quadratus lum- 
borum, erector spinae, intervertebrales) (Fig. M. dor,), which 
are especially large in the cat. A branch from each dorsal 
nerve can be traced to the integument (Fig. Int.), where it 
joins in an open plexus with the adjacent nerves. 
The nerve trunk or ventral division dips ventrad close to 
the border of the centrum and mesad of the diapophysis; the 
origin is thus concealed by fascia, aponeuroses and super- 
posed muscles. At the ventral border of the centrum the 
nerve usually passes laterad (except the branch to form the 
lumbar plexus) apposed to the abdominal branch of the lum- 
bar artery. From the ental surface of the trunk adjacent to 
the centrum a branch is given off which separates into three 
to five ramuli to the proximal or aponeurotic portions of the 
M. psoas (Fig. Pso.), and two anastomotic rami to the sym- 292 
Journal of Comparative Neurology. 
pathic ganglia (Fig. S.) cephalad and caudad; in the cephalic 
three lumbar nerves, these rami join the great solar plexus 
(Fig. Pl. S.). 
The lumbar nerves are conveniently grouped into two 
groups, those which do not enter into the lumbar plexus, 
viz.,/7ze cephalic four pairs, comparable with the first lumbar 
(anthropotomy), and those which are so related, viz., the 
caudal three fairs, comparable with the lower four lumbar 
nerves (anthropotomy). 
Special Characters.- The first and second lumbar nerves 
give the first branch to the diaphragm (Fig. Dia.) instead of 
the M. psoas; they join the solar plexus (Pl. S.), they follow 
the abdominal lumbar artery through the aponeurotic origin 
fibres of the diaphragm, and lie upon its cephalic surface 25 
mm. peripherad of the foramen of exit. Five mm. still 
peripherad, in the aponeurotic interdigitations of the ectal 
oblique muscle (M. abdominis obliquus ectalis),the trunk 
separates into cephalic (Fig. ce.) and caudal (Fig. ca.) divi- 
sions. The cephalic division follows the abdominal artery, 
penetrates the overlying (ectal) muscle, innerves the ental, 
the transverse and the rectus muscles of the abdomen, anasto- 
moses with the cephalic divisions of the adjacent nerves (Fig. 
anas.), and sends terminal filaments to the adjacent integu- 
ment (umbilical and hypogastric). The caudal division has 
its course caudad and slightly ventrad; it lies upon the ectal 
surface of the ental muscle, to which it gives filaments in the 
umbilical and the hypogastric regions. This division lies 
entad of the cephalic division of the lumbar nerve next 
caudad. 
The third and fourth lumbar nerves (first lumbar of 
anthropotomy). These nerves have the ectal origins and 
proximal rami similar to the first and second. The third 
nerve joins the solar plexus cephalad, but the sympathic 
ganglion caudad. The fourth does not anastomose with the 
plexus. The cephalic divisions are distributed farther caudad, 
reaching the gluteal (Fig. Th.) and inguinal regions (Fig. Stowell, Nerves in the Domestic Cat. 
293 
Pub.), and giving numerous filaments in plexiform relations 
over the hypogastric integument. The caudal division of 
the third lies entad of the cephalic division of the fourth, 
and ectad of the cephalic ramus of the ilio lumbar artery; 20 
mm. from its origin it crosses a ramulus of the caudal ramus 
of the same artery as the arteriole perforates the lateral 
border of the M. abdominis rectus. The nerve gives filaments 
to the transverse (Fig. trans.) and to the ental oblique (Fig. 
M. ent.) muscles. The caudal division of the fourth lies 
apposed to the caudal ramus of the ilio-lumbar artery for 15- 
20 mm.; it passes between the cephalic and the caudal divi- 
sions of the genito-crural nerve. It innerves the transverse 
and ental muscles 10-15 mm- dorsad of the region supplied 
by the caudal division of the third, and terminates in the 
rectus abdominis muscle. 
The fifth, sixth and seventh lumbar nerves are distin- 
guished from the other lumbar nerves by the plexus (Pl. lum- 
balis) formed by the dorsal or caudal divisions of the ventral 
nerve trunks. These nerves rapidly increase in size, the 
seventh being considerably the largest. The union of the 
divisions or branches just ventrad of the vertebral diapophy- 
ses forms not only an important part of the lumbar plexus, 
but constitutes the lumbo-sacral cord of anthropotomy, from 
which nerves take their ectal origins, v. below. 
N. GENITO-CRURALIS, N. LUMBO-INGUINALIS; N. PUDENDUS 
EXTERNUS. 
The genito-crural nerve (second lumbar of anthropotomy) 
has its ectal origin by two roots; the cephalic root seems to 
be the lateral continuation of the fifth lumbar nerve, the 
caudal root is a large branch of the sixth lumbar nerve, given 
off at the foramen of exit centrad of the plexus. The root 
nerves are inter-related by anastomotic filaments. The trunk 
formed by the union of the roots penetrates the aponeurosis 
of the M. psoas, lies upon its ectal surface about 2 mm. 
laterad of the mesal border of the muscle, and separates into 294 
Journal of Comparative Neurology. 
two divisions, cephalic and caudal. The cephalic division, 
the crural branch (crur.), bends around the lateral border of 
the M. psoas, and 20 mm. peripherad of its origin it accom- 
panies the ilio-lumbar artery into the transverse muscle. Its 
course is caudad in the transverse and ectal muscles, and 
leaves the pelvis by the ectal abdominal ring entad of Pou- 
part's ligament; its course outside the pelvis is along the 
ectal fascia over the caudal thigh to the knee, and terminates 
in the integument of the proximal crus, where it joins fila- 
ments of the external cutaneous nerve. The caudal or dorsal 
division, the genital branch (gen.) lies upon the meso-ental 
surface or border of the M. psoas, entad of the ilio-lumbar 
artery, at which point it gives a large anastomotic branch to 
the open plexus of nerves and vessels of that region, and 
thence continues caudad in the ental muscle, to which it 
gives several filaments. At the Poupart's ligament (Fig. P.) 
it is reflected ventro-cephalad, and terminates in the integu- 
ment of the hypogastric region; filaments from the point of 
reflection extend to the integument over the pubes. (I have 
not traced this nerve in the male.) 
N. CUTANEUS ECTALIS. 
The external cutaneous nerve (Ext. Cut.) has its ectal 
origin by two roots; the cephalic root is a branch of the loop 
(Fig. Loop) between the fifth and the sixth lumbar nerves; 
the caudal root is a branch of the sixth nerve in common 
with the caudal root of the genito-crural. The origin and 
the distribution of the genito-crural and the external cutane- 
ous nerves indicate an intimate inter-relation. 
The course of the nerve lies ectad of the anastomotic 
branch from the G. sympathicus to the sixth lumbar nerve; 
it runs obliquely through the origin fibres of the M. psoas 
and comes to superficial view at the mesal border of that 
muscle at the point where the iliac artery lies apposed to the 
aponeurosis of the M. psoas, about 20-30 mm. cephalad 
of the ramus of the pubis. Exposure is readily made by Stowell, Nerves in the Domestic Cat. 
295 
tracing the mesal border of the M. psoas caudad from this 
point. 
The nerve lies ectad (ventrad) of the external iliac artery 
and vein, and entad of the common iliac vein which is ven- 
trad of and apposed to the artery; it bends around the artery 
and lies upon its ental surface, ectad (ventrad) of the hypo- 
gastric artery just cephalad of the ramus pubis. 
It leaves the pelvis through the abdominal ring, 20 mm. 
peripherad of which it separates into two divisions, one of 
which (Fig. ce.) is distributed to the integument of the hip 
(Fig. H.) and the proximal half of the caudal thigh (Fig. 
Th); the other division (Fig. ca.) is distributed to the in- 
tegument over the biceps muscle as far as the knee. The 
nerve was wanting on the sinistral side of one specimen 
(female). 
N. CRURJEUS ANTERIOR. 
The anterior crural (Ant. Crur.), the seventh lumbar 
nerve, is the largest of the spinal nerves whose origin is not 
referable to the union of two or more nerve trunks. It sup- 
plies muscular branches to the psoas, the iliacus, the sar- 
torius, the pectineus muscles and the muscles of the cephalic 
(inner) thigh except the tensor vaginae femoris, which is 
innerved by a slender ramus of the superior gluteal nerve 
(q. w); and cutaneous branches to the integument of the 
thigh, the leg, the cephalic part of the foot and the plantar 
surface of the toes. 
The seventh lumbar nerve at the foramen of exit sends 
anastomotic branches to the adjacent sympathic ganglia; its 
dorsal division innerves the muscles of the back (Fig. M. 
dor.) and the adjacent integument (Fig. Int.); the large 
ventral division (2 mm. in section) lies close to the lateral 
surface of the centrum and at its ventral border receives the 
large trunk (Fig. L. S. C.) of the sixth lumbar nerve, and 
sends an equally large trunk caudad (Fig. L. S. C., lumbo- 
sacral cord of anthropotomy) to the first sacral nerve. 296 
Journal of Comparative Neurology. 
Origin.-The anterior crural nerve is the ventral division 
of the seventh lumbar, of which it is strictly the continuation 
with a large accession from the sixth-or its origin may be 
referred to the lumbar plexus. 
Principal Rami.-The ectal origin of the nerve lies entad 
of the M. psoas, to which several filaments are given (Fig. 
Pso.) 2 mm. peripherad of its origin; 5 mm. peripherad a 
large branch is given caudad to the M. iliacus (Fig. M. il.). 
The general course of the nerve trunk is embraced by the 
M. psoas, the nerve reaching the ectal surface or lateral 
border of the muscle in the region of the iliac notch, or 20 
mm. ventro-caudad of its origin. Entad of Poupart's liga 
ment (Fig. P.) it gives from its lateral border a large ramus 
which innerves the sartorius muscle (Fig. Sar.), which ramus 
lies entad of a ramus of the profund artery 10 mm. from its 
origin. As the nerve crosses the artery a slender branch 
passes ectad of the artery to the mesal border of the sartorius 
muscle. The larger portion of this branch lies upon the 
ental surface of the muscle, and can be traced to its distal 
extremity or insertion, thus innerving its distal three-fourths; 
the smaller portion of the nerve is reflected proximad at the 
profund artery, and innerves the proximal (origin) one-fourth 
of the sartorius muscle, lying upon its ental surface. 
Entad of Poupart's ligament and 2 mm. peripherad of the 
sartorial branch, from the mesal border of the nerve is the 
ectal origin of the long saphenous nerve (N. cutaneus in 
ternus longus, Fig. Saph. 1.). 
THE LONG SAPHENOUS NERVE. 
This nerve lies ectad of the femoral artery and apposed to 
it and the long saphenous vein, the vein being mesad, the 
artery in the middle, and the nerve laterad upon the surface 
of the thigh. 
Principal Rami.-The first branch is given to the artery 
(Fig. A. fem.). At the knee (Fig. K.) two ramuli are given 
off; the lateral ramulus (Fig. 1. r.) is cutaneous; it accom- Stowell, Nerves in the Domestic Cat. 
297 
parties an arteriole and is distributed to the integument over 
the cephalic surface of the proximal third of the crus; the 
mesal ramulus (Fig. m. r.) lies ectad of the artery and vein 
and is distributed to the integument mesad of the vein, its 
terminal filaments anastomosing with other filaments of the 
nerve trunk. Below the knee (Fig. K.) (upon the crus) the 
nerve continues as two divisions corresponding with the two 
arteries, with whose courses they are nearly parallel; the 
lateral division is distributed to the integument over the 
cephalic surface of the distal half of the crus and the pes; 
the mesal division lies in the fascia ectad of the tibia; its 
course is just mesad of (behind) the cephalic malleolus, ectad 
of the tendon of the M. tibialis anticus; it forms a dense 
plexus upon the cephalic metatarsale (2) and joins the 
plantar plexus (Fig. Pl. Plan.), its terminal filaments being 
traceable to the distal extremities of the toes and to the 
plantar pads. 
The muscular division (deep layer of anthropotomy) of 
the anterior crural nerve, near its origin at Poupart's liga- 
ment, follows the profund artery, dips entad in Scarpa's 
triangle, and gives a branch to the M. sartorius (Fig. Sar.), 
which branch, 5 mm. peripherad (at the border of the M. 
rectus femoris), lies entad of the artery and separates into a 
peripheral and a central portion; the peripheral branch may 
be traced in pinniform arrangement throughout the distal 
three-fourths of the muscle to the knee; the central branch is 
reflected at the artery and is distributed to the proximal 
fourth of the muscle. 
At the origin of the last branch the nerve penetrates the 
M. rectus femoris (Fig. M. r. fem.), to which three rami are 
given. The proximal ramus innerves the proximal third of 
the muscle, the second lies upon the ental surface of the 
muscle and innerves its distal two-thirds, to the insertion at 
the patella; the third ramus enters the caudal border of the 
muscle near its middle. These three rami are motor. Five 
mm. peripherad of the branch to the M. sartorius a ramus is 298 
Journal of Comparative Neurology. 
given to the M. vastus internus (V. int.) and to the M. crureus. 
At the caudal border of the M. vastus internus filaments are 
given to the muscle; the nerve lies entad of the M. rectus 
femoris and the adjacent M. vastus externus, whose ental 
surface it penetrates, accompanied by an artery, and distri- 
butes filaments from three ramuli to the M. vastus externus. 
The nerve can be traced around the lateral border of the 
femur with the internal circumflex (?) artery into the M. 
pectineus. 
N. OBTURATOR. 
Origin.-The obturator nerve (N. Obt.) has its ectal 
origin from the lumbo-sacral cord between the seventh 
lumbar and first sacral nerves, 16 mm. caudad of the anterior 
crural nerve; in one specimen the origin was by the union of 
a lumbar (seventh) and a sacral (first) root at the ventral 
border of the ilium. Its course is caudad, ectad of the ental 
iliac artery and ventro-mesad of the ventral border of the 
ilium; it pierces the obturator muscle 30 mm. caudad of the 
origin of the nerve; it leaves the pelvis through the Fm. 
obturator, peripherad of which it divides into several rami. 
Principal Rami.-The first ramus (N. obturator acces- 
sorius (?)) is directed ectad to the superposed M. pectineus 
(Fig. M. Pec.). A long ramus bends over the cephalic 
surface of the origin of the adductor muscle, lies upon the 
ental surface of the M. gracilis apposed to an arteriole, and 
innerves the gracilis (Fig. M. grac.), in which muscle it may 
be traced to its aponeurotic insertion at the knee, centrad of 
which anastomotic filaments relate it with the long saphenous 
nerve. 
Four rami lie upon the ectal surface of the proximal end 
of the adductor muscles (MM. magnus and brevis), just peri- 
pherad of the foramen, in which muscles they terminate. 
Entad of the M. adductor longus, between it and the M. 
adductor brevis, two ramuli cross the M. adductor brevis and 
are distributed to the M. adductor magnus, attended by rami Stowell, Nerves in the Domestic Cat. 
299 
of the internal iliac artery. Terminal ramuli like a leash 
supply the M. adductor longus and the M. obturator externus. 
SACRAL NERVES. 
General Description.-The sacral vertebrae are three, and 
the nerves are corresponding three pairs. These nerves are 
characterized by the length of the ectal roots and by the dis- 
tance through which they are traced in the neural arch and 
in the groove from the arch to the intervertebral foramina. 
At their respective foramina of exit they separate into two 
unequal divisions, the dorsal and the ventral; the dorsal 
division passes directly dorsad and divides into cephalic and 
caudal rami, each of which anastomoses with the terminal 
filaments of the adjacent nerves, and each sends a considerable 
branch to the open plexus of cutaneous nerves; the ventral 
division passes directly ventrad and laterad to join in the 
formation of the sacral plexus, from which nerves are distri- 
buted to the caudal extremity. Each ventral nerve receives 
an anastomotic nerve from the adjacent sympathic ganglia 
(Fig- S.). 
THE FIRST SACRAL NERVE. 
Special Description.-The first sacral nerve is the largest 
of the spinal nerves, and has its ectal origin in the neural 
arch of the sixth lumbar vertebra, at the caudal border of 
which may be found its dorsal root ganglion; it traverses the 
long groove (io mm.) in the seventh lumbar vertebra, and 
finds its exit through the foramen mesad of the crista ilii and 
ventro-mesad of the broad diapophysis of the first sacral 
vertebra. Immediately peripherad of the foramen of exit it 
is joined by the lumbo-sacral cord (Fig. L.-S. C.)-which in 
a medium-sized cat is 2 mm. in section-and has its course 
mesad and ventrad of the diapophysis and the crista ilii, by 
which it is concealed, and which renders its exposure some- 
what difficult. The nerve trunk at this point (its central 
io mm.) is about 4 mm. in section. 300 
Journal of Comparative Neurology. 
Principal Rami.-The first nerve from the sacral plexus, 
N. Gemellus (Fig. Gem.), is given from the ectal surface of 
the first sacral nerve where it is joined by the lumbo-sacral 
cord (Fig. L.-S. C.) at the caudal border of the first sacral 
vertebra, and is directed dorsad; it lies close to the vertebra 
for its central 5 mm., and then passes laterad into the gemellus 
muscle, and is distributed by three branches. This muscle 
has its origin along the sacral vertebras, but its relation with 
the M. gluteus maximus and its insertion with the M. obtu- 
rator internus, as well as the innervation, lead to its identifi- 
cation as the M. gemellus superior. 
From the cephalic border of the first sacral nerve a branch 
is sent laterad and around the ramus of the ilium cephalad of 
the acetabulum to the M. pyriformis (Fig. Pyr.). The nerve 
trunk lies ectad of the sacral artery and vein, and leaves the 
pelvis through the great sciatic foramen upon the ectal sur- 
face of the M. quadratus femoris, the M. obturator and the 
M. pyriformis, and entad of the MM. glutei. 
About 10 mm. caudad of the foramen of exit a branch 
from the ental surface is given to the M. gluteus maximus 
(Fig. M. gl. max.), and 5 mm. still peripherad a branch 
caudad and entad of the M. obturator internus (M. obt. in.), 
which branch divides into two rami, the shorter being dis- 
tributed to the overlying obturator and the longer terminat- 
ing in the quadratus muscles. The nerve to the M. gluteus 
is sometimes a branch from the second sacral nerve (see 
Fig. F). 
THE SECOND SACRAL NERVE. 
The ventral division of this nerve is much smaller than 
the first sacral nerve; it takes a ventro-laterad course, and 
joins the first sacral just mesad of the trochanter. The union 
of these two trunks constitutes the great sciatic nerve JJq- v.". 
Principal Rami.- The dorsal division is already described 
in common with the other sacral nerves, v. " General De- 
scription." Its caudal branch joins the plexus which innerves Stowell, Nerves in the Domestic Cat. 
301 
the dorsal muscles and the integument of the tail.. A large 
anastomotic loop joins the ventral division of the third sacral 
nerve just peripherad of the foramen of exit. A slender 
branch is sometimes given as a distinct nerve to the overlying 
M. gluteus maximus (Fig. M. gl. max.). 
THE THIRD SACRAL NERVE. 
The ventral division is the smallest of the sacral nerves; 
it divides into ental and ectal branches. The ental or deep 
branch lies upon the ectal surface of the long levator ani 
muscle (Fig. L. A.), to which it is distributed. The ectal 
branch joins the second sacral nerve in a large anastomotic 
branch or loop, and peripherad of this a smaller loop joins 
the first coccygeal nerve (Fig. N. Coc.) and at the same 
point gives off the second root of the N. coccygeus (Fig. N. 
Coc.). 
Principal Rami.-The nerve trunk divides into three 
branches, which lie entad of the rami to the M. gluteus maxi- 
mus and the M. obturator internus, already described. The 
cephalic branch joins the N. ischiadicus at the origin of the 
sciatic root of the pudic nerve; the middle branch is the 
sacral root of the pudic nerve; the caudal branch separates 
into two rami, one of which is the sacral root of the N. glu- 
teus (N. glut.), and the other forms, with a branch from the 
first coccygeal nerve (q. v.) and a branch from the pudic, a 
slender nerve to a ribband muscle (Fig. M?) described below 
v. N. Coccygeus. 
N. GLUTEUS SUPERIOR. 
At the union of the lumbo-sacral cord with the first 
sacral nerve to form the main trunk of the great sciatic, a 
large branch, the superior gluteal nerve (N. gl. S.), is sent 
laterad and bends over the dorsal border of the ilium just 
cephalad of the acetabulum and entad of the MM. glutei. It 
leaves the pelvis by the great sciatic foramen, and io mm. 
peripherad of its origin divides into three branches; the Journal of Comparative Neurology. 
302 
cephalic branch is distributed .to the M. gluteus medius (M. 
gl. med.), which lies ectad of the nerve and whose ental 
surface it penetrates; the caudal branch is distributed to the 
M. gluteus minimus (M. gl. min.), which lies entad and 
caudad-these two rami are the homologue of the superior 
branch of anthropotomy; the middle branch - inferior of 
anthropotomy-the largest branch, perforates the M. gluteus 
minimus and innerves the M. tensor vagime femoris (T.V.F.), 
in which it can be traced to the distal fourth. A few fila- 
ments are given to the M. gluteus minimis. 
N. ISCHIADICUS. 
The great sciatic nerve (Fig. Ischiad.) is the largest of 
the spinal nerves; its ectal origin is the sacral plexus, or the 
union of the first and second sacral nerves. Within the 
pelvis, its course is caudad to the sciatic foramen; peripherad 
of the pelvis it lies upon the ectal border of the M. obturator 
internus and the MM. gemelli, mesad of the great trochanter, 
laterad of the ischiac tuberosity, and entad of the MM. pyri- 
formis, biceps and glutei. Its exposure is effected in the 
meros by the removal of the M. gluteus maximus and the M. 
biceps. The great sciatic nerve is cutaneous and muscular in 
its distribution; it supplies the integument of nearly all the 
caudal limb, and the muscles of the meros, the crus, and the 
pes as given below. 
Principal Rami.- The first branch is given off at the 
union of the second sacral nerve, and innerves the M. quad- 
ratus femoris (Fig. Quad.). The second branch is the sciatic 
root of the pudic nerve (q. v.), in common with the root of a 
gluteal nerve (b. v.). The third branch is a considerable 
nerve entad of the M. pyriformis, and which is divided into 
three smaller rami: («) the first of which enters the ental 
surface of the M. biceps, c;-8 mm. peripherad of its origin 
(Fig. M. bi.); (Z>) the second is covered by the M. biceps, 
to which it gives it ramulus at its mesal (lower) border, and 
continues entad of the M. semi-tendinosus and a plexus of Stowell, Nerves in the Domestic Cat. 
303 
vessels (ramuli of the profund artery and veins (?)); it lies 
upon the ental surface of the muscle 20-30 mm., then pene- 
trates its substance as two terminal ramuli (Fig. M. semi- 
ten.); (c) the third ramus crosses the ectal surface of the 
vessels named, peripherad of which, or 20 mm. from its 
origin, it enters the M. semi-membranosus as two terminal 
ramuli (Fig. M. semi-mem.). The fourth branch is a slender 
filament, about the middle of the thigh, which is given to the 
distal half of a ribband muscle (Fig. M?) 2 mm. in width, 
which lies in the fascia upon the ental surface of the M. 
biceps, which muscle it crosses obliquely-this muscle has 
its origin just cephalad of the M. pyriformis upon the dia- 
pophysis of the first caudal vertebra, lies entad of the M. 
pyriformis and the M. biceps, and is inserted in the aponeu- 
rotic fascia of the mesal border of the biceps about midway 
between knee and ankle; it is readily separable from the 
biceps; the total length in a cat of medium size is about 90 
mm.; the proximal end of the muscle is innerved by a ramu- 
lus whose roots are traceable to the third sacral, the first 
coccygeal and the pudic nerves. The fifth branch innerves 
the distal third of the M. biceps (M. bi.); it is given off 40 
mm. peripherad of the trochanter, just centrad of the short 
saphenous nerve. 
N. CUTANEUS INTERNUS. 
The short saphenous nerve (Saph. br.) has its ectal origin 
just centrad of the division of the sciatic trunk into the pop- 
liteal and the peroneal nerves. It crosses the popliteal space 
embedded in the adipose which occupies this region, is ectad 
of the artery and entad of the M. biceps; it lies apposed to 
the artery upon the dorsal surface of the biceps and entad of 
the ectal fascia. Its filaments terminate in the integument 
over the caudal side of the foot and the fifth toe. 
The great sciatic trunk divides into two unequal nerves, 
the caudal and smaller, N. peroneus, and the cephalic, larger 
nerve, N. popliteus. 304 
Journal of Comparative Neurology. 
N. PERONEUS. 
This nerve lies entad of the insertion third of the M. 
biceps and ectad of the M. gastrocnemius, which muscle it 
crossesa bout io mm. peripherad of the caudal condyle. As 
the nerve dips between the M. peroneus longus and the 
M. peroneus tertius, the 
N. MUSCULO-CUTANEUS 
(Fig. mus.-cut.) takes its origin and has its course entad of 
the M. peroneus, apposed to the anterior tibial artery; it 
becomes ectal (superficial) with the artery about midway 
between the knee and the ankle, or near the tendinous part 
of the M. peroneus longus; following the artery its ramuli 
may be traced to the integument upon the dorsum of the foot 
and the second, third and fourth toes. Its caudal filaments 
anastomose with the short saphenous nerve. Ten mm. peri- 
pherad of its origin it gives a branch to the M. peroneus 
tertius, and io mm. still peripherad a large ramus passes 
entad and lies upon the ectal surface of the M. peroneus 
brevis, apposed to an arteriole (a branch of the anterior tibial 
arteiy), which muscle it innerves. The trunk crosses the 
ectal surface of the muscle (peroneus brevis) obliquely and 
bends around the caudal border of the large tendon as it 
passes through the sheath caudad of the malleolus; it then 
lies entad of the tendon and upon the ectal surface of the 
short extensors of the toes, which muscles it penetrates, 
lying between the fourth and the fifth metatarsalia, and entad 
of the tendon to the fifth toe, bnt ectad of the one to the 
fourth toe at the distal end of the metatarsale, at which point 
it joins a ramus of the ( ?) nerve, thence it is distributed to 
the integument of the fourth toe. 
The nerve trunk at the origin of the musculo-cutaneous 
branch gives a ramus to the overlying M. peroneus longus, 
which nerve accompanies an arteriole from the anterior tibial 
artery. Entad of the M. peroneus longus with the last Stowell, Nerves in the Domestic Cat. 
305 
described nerve, an equally large branch lies just entad and 
dips between the M. extensor digitorum longus and the M. 
peroneus tertius. Ten mm. peripherad of its origin the nerve 
bifurcates, the anterior tibial artery (Fig. A.) occupying the 
angle between the branches. The cephalic branch (Fig. ce.) 
innerves the M. extensor longus digitorum; the caudal branch 
(Fig. ca.) lies entad of the anterior tibial artery and accom- 
panies the artery to the dorsum of the foot. Entad of the 
groove a ramus is given to the tarsal ligament and the origin 
fibres of the M. extensor brevis. The terminal filaments join 
in the plexus to the integument of the dorsum of the foot 
and toes. 
N. TIBIALIS ANTICUS. 
This branch (Fig. Tib. a., and m.) of the peroneal is 
given off between the origin of the musculo-cutaneous 
nerve and the bifurcation of the peroneal; it can be traced 
30-40 mm. in the substance of the M. tibialis anticus, 
and sends a ramus peripherad to the M. extensor longus 
digitorum. 
N. POPLITEUS. 
The cephalic division of the great sciatic nerve crosses 
the popliteal space and continues peripherad between the 
heads of the M. gastrocnemius. At the proximal end of the 
crus it gives its first branch to the ectal surface of the caudal 
head of the M. gastrocnemius (Fig. M. gas.), and immedi- 
ately peripherad a large ramus penetrates the same muscle 
and is distributed to the muscle from its ental surface; a con- 
siderable portion of this ramus perforates the gastrocnemius 
and innerves the M. Soleus (Sol.), which is entad; from this 
penetrating ramus ramuli are given to both heads of the 
muscle. Twenty mm. peripherad a second large branch to 
the body of the same muscle (Fig. M. gas.), peripherad of 
which the nerve trunk bifurcates, forming ental (Fig. dv. 
ent.) and ectal (Fig. dv. ect.) divisions. 306 
Journal -of Comparative Neurology. 
N. POST-TIBI ALIS. 
The cntal division of the popliteal nerve is muscular in 
distribution. Ten mm. peripherad of its origin a large ramus 
innerves the M. popliteus (Fig. Pop.), which lies just entad. 
The trunk crosses the ectal surface of the post-tibial artery, 
and io mm. peripherad it innerves the M. flexor longus digi- 
torum (M. fl. long, dig.) by several pinniform ramuli. As 
the nerve penetrates the flexor muscle a ramus is given to 
the M. tibialis posticus, and still peripherad three or four 
filaments are given to the M. flexor longus pollicis?-a 
muscle whose tendon unites in the plantar surface with 
the broad tendon of the long flexors (pollex is wanting in 
the cat). 
The ectal division lies apposed to the post-tibial artery 
and gives no rami centrad of the groove of the long flexor 
muscle, in which groove are the tendon, the nerve and the 
post-tibial artery. Peripherad of the groove the nerve bifur- 
cates and lies upon the ental surface of the M. flexor brevis 
digitorum. The cephalic ramus, 
N. INTER-PLANTARIS, 
innerves the short flexor muscles, lies along its cephalic 
border, and terminates in cutaneous ramuli to the pads of 
the second and third toes; a few filaments are directed 
entad to the underlying muscle, the M. flexor accessorius 
(fl. ac.). 
N. PLANTARIS, 
The caudal ramus of the ectal division, lies upon the broad 
tendon of the long flexor muscle and the second layer of 
muscles. A slender ramus is given caudad to a small muscle 
upon the distal end of the calcaneum-the fibres of this 
muscle run transverse and the aponeurosis joins the broad 
tendon of the long flexor. Near the proximal end of the 
meta tarsalia a branch is given entad, Stowell, Nerves in the Domestic Cat. 
307 
THE ENTAL PLANTAR NERVE, 
which lies ectad of the proximal end of the interosseus 
muscles and within their substance, and crosses the foot 
obliquely from the head of the metatarsale of the fifth toe 
toward the distal end of the metatarsale of the second. The 
nerve trunk lies entad of the caudal border of the short flexor 
and at the distal end of the second metatarsale (pollex want- 
ing); it divides into a leash of four nerves, each of which 
dichotomoses and innerves the interosseous muscles (M. int.); 
slender filaments are given to the third layer of muscles. 
The ental branch innerves the third and fourth lumbricales, 
the three plantar interossei muscles, and the four muscles 
which occupy the plantar arch of the metatarsalia-these 
muscles have their origins at the proximal end of the meta- 
tarsalia and insertion in the aponeurosis of the common ex- 
tensor tendon and by a short tendon into the proximal end 
of the proximal phalange. A portion of the muscle seems 
to be equivalent to the dorsal interossei (anthropotomy ), and 
a portion is not satisfactorily homologized. The deep plantar 
also innerves a muscle, which has its origin from the os 
cuboides and crosses the plantar metatarsus obliquely and 
inserts by a tendon upon the caudal surface of the proximal 
phalange of the second toe, probably an adductor muscle. 
THE ECTAL PLANTAR NERVE 
bends around the tendon of the muscle, and, crossing its 
ectal surface, lies entad of the tendon of the long flexor of 
the second toe. At the distal end of the proximal segment 
of the fifth toe it bifurcates, and can be traced to the pad of 
the fourth and fifth toes. A slender filament is given to the 
M. abductor minimus (Fig. M. ab. min.). 
N. PUDICUS (N. PUDENDUS). 
The pudic nerve (Pud.) has its ectal origin by two roots. 
The sacral root is the largest of the terminal branches of the 308 
Journal of Comparative Neurology. 
third sacral nerve, and lies entad of the pudic artery; the 
sciatic root is given off from the sciatic nerve abont 15 mm. 
peripherad of the union of the first and second sacral nerves, 
in common with the sciatic root of the N. gluteus to the 
M. glutei (Fig. N. glu.). It leaves the pelvis through the 
sacro-sciatic foramen, and is apposed to the pudic artery; its 
general course is meso-caudad, entad of the pudic artery and 
vein, upon the ectal surface of the internal obturator muscle. 
Twenty mm. peripherad of the union of the two root nerves, 
the pudic separates into dorsal and ventral divisions, which 
are muscular and cutaneous respectively in distribution. 
N. PERINEUS DORSALIS, 
The dorsal division (Fig. dor.), lies upon the ectal surface of 
the rectal muscle; its branches innerve the broad M. levator 
ani (Fig. L. A.), the M. sphincter ani (Fig. sph. A.), and 
20 mm. of the longitudinal rectal muscles (Fig. rec.), which 
muscles are supplied by the hemorrhoidal artery and vein. 
The last nerve is the 
N. H.EMORHHOIDES. 
A branch is given to the anal gland (Fig. gl.)-a large 
olive-colored gland just laterad of the anus, whose duct opens 
ectad of the sphincter muscles, or sometimes just entad. 
Another ramus, 
N. PERINEUS DORSALIS, 
Innerves the sphincter vagina* and the ectal labium( ?). 
N. PERINEUS VENTRALIS, 
77ze ventral division (Fig. ven.), is distributed to the vagina, 
the ectal labium, the perineum, the urethra, the M. accelera- 
tor unnae, and the transverse muscle just entad of the peri- 
neal integument. A considerable ramus is given to its plate- 
trope (Plat.) in the meson, and the nerve terminates as a 
large nerve in the glans clitoris (N. dorsalis penis sen clitoris, Stowell, Nerves in the Domestic Cat. 
309 
Fig. Cl.), the peripheral 5 mm. being parallel with its plate- 
trope. 
NN. COCCYGEI. 
The coccygeal nerves are seven or more pairs, and with 
the exception of the first (cephalic) one, innerve the caudal 
muscles and integument. They decrease in size caudad, until 
it may be questioned whether the extreme filaments are 
properly designated nerves. The ectal root fibres are 
attenuated and the dorsal ganglion is hardly distinguishable 
caudad of the seventh; hence I have mentioned the number 
as seven. Like the other spinal nerves, they divide into 
dorsal and ventral divisions; the dorsal innerve the dorsal 
muscles and integument and form the roots of a single nerve 
trunk, 
N. DORSALIS 
(Fig. dor.?), caudad of the seventh caudal vertebra, whose 
filaments innerve the adjacent structures. The ventral divi- 
sions join their fellows to form a ventral nerve trunk, 
N. VENTRALIS 
(Fig. vent.?). The rami of the ventral trunk have a two-fold 
distribution; the first ramulus innerves the ental or the 
inter-vertebral muscle (Fig. M. ent.), and midway between 
the several pairs a ramulus innerves the ectal muscle of 
the tail (Fig. M. ect.). The plan of formation of the 
dorsal and the ventral caudal nerves is seen in the diagram 
(Fig- B). 
N. COCCYGEUS CEPHALICUS. 
The first coccygeal nerve has a distinctive distribution, 
and requires a separate description. The ventral division 
separates into a ventral and a dorsal or caudal branch. The 
ventral branch becomes the anastomotic loop to the third 
sacral nerve, the coccygeal or principal root of the 310 
Journal of Comparative Neurology. 
N. COCCYGEUS 
(Fig. N. coc.) to the muscle by the same name, one root of a 
nerve to the urocyst (Fig. Uro.), and one root of the nerve to 
the ribband muscle ? (Fig. M.?). 
RECAPITULATION. 
The cat is a good type for the study of comparative 
anatomy. The nervous system offers special advantages, as 
a basis of comparison, for establishing homologies, for iden- 
tification, etc. 
Zootomy should precede anthropotomy in the collegiate 
and the medical curricula. 
Preparation.-Injection of arteries and veins with starch 
injection mass. 
Posture.-Ventri-cumbent, head sinistrad. 
Exposure. - By reflection of integument over caudal 
thorax, sinistral side, beginning with removal of neural arch 
of caudal thoracic vertebra; dissection caudad. 
LUMBAR NERVES. 
Characters in common: Paired; dorsal and ventral divi- 
sions at ectal origin; related with sympathic system; muscu- 
lar and cutaneous in distribution; two groups, cephalic four 
not involved in lumbar plexus, caudal three so involved; the 
cephalic group innerve muscles and integument of back, 
MM. psoas, phrenicus, abdominis entalis, ectalis, transver- 
salis and rectus, and the abdominal integument. 
N. Genito-cruralis.- Origin: Fifth and sixth lumbar 
nerves, two roots. Distribution: Crural division, integu- 
ment of caudal meros, and proximal crus; anastomoses with 
N. N. cutaneus ectalis; genital division, plexus at ilio lumbar 
artery, hypogastric and ventro-perineal integument. 
N. Cutaneus Ectalis.- Origin: Loop and sixth lumbar 
nerve, t'wo roots. Distribution: Integument of hip and thigh, 
joins last described nerve. Stowell, Nerves in the Domestic Cat. 
311 
N. Crilrceus Anterior.- Origin: Seventh lumbar. Dis- 
tribution: MM. psoas, iliacus, sartorius, vastus externus, 
V. internus, rectus femoris, cruraeus, pectineus, and gives 
origin to 
N. Cutaneus Internus Longus. - Distribution: To in- 
tegument of cephalic crus, dorsum of foot and plantar 
plexus. 
N. Obturator.- Origin: Loop between seventh lumbar 
and first sacral nerves, lumbo-sacral cord (anthropotomy). 
Distribution: MM. pectineus, obturator, adductor magnus 
and longus, gracilis. 
SACRAL NERVES. 
Characters in common: Paired, three pairs; dorsal and 
ventral divisions; related with sympathic system; muscular 
and cutaneous; unequal size; formation of sacral plexus, 
which is the origin of several nerves. 
Special Characters: First sacral nerve, largest of spinal 
nerves; joined with the lumbar cord in the lumbo-sacral cord. 
N. Gemellus.- Origin: Ramus of first sacral at foramen 
of exit. Distribution: M. gemellus superior. 
Second Sacral Nerve.-Much smaller than the first nerve; 
union with first nerve forms N. ischiadicus; joins the third 
nerve in the anastomotic loop. 
Third Sacral Nerve.-Smallest sacral nerve; joins sacral 
and coccygeal plexuses; innerves the M. levator ani; the 
urocyst; by its rami becomes the sacral root of NN. coccy- 
geus, gluteus, pudicus, and a nerve not homologized. 
N. Gluteus Superior.- Origin: Sacral plexus at first 
sacral nerve. Distribution: Cephalic branch to M. gluteus 
medius, caudal branch to M. gluteus minimus, middle branch 
to M. tensor vaginae femoris. 
N. Ischiadicus.- Origin: Union of first and second sacral 
nerves. Distribution: MM. quadratus femoris, glutei, pyri- 
formis, biceps, semi-tendinosus, semi-membranosus, obtura- 
tor internus, ribband muscle?. 312 
Journal oe Comparative Neurology. 
Rami Known as Nerve Trunks.-NN. pudicus, cutaneus 
interims brevis, popliteus, peroneus,.gluteus, q. v. 
N. Peroneus.- Origin: Division of N. ischiadicus cen- 
trad of knee. Distribution: Rami: N. musculo-cutaneus, in- 
tegument of dorsum of foot, and second, third and fourth 
toes, M. peroneus brevis, M. peroneus tertius; N. tibialis 
anticus, MM. tibialis anticus, extensor longus digitorum, 
extensor brevis digitorum; ligamentum tarsale; plexus dor- 
salis pedis. 
N. Popliteus.- Origin: Division of N. ischiadicus, cen- 
trad of knee. Distribution: MM. gastrocnemius, soleus, 
popliteus, flexor longus digitorum, tibialis posticus, flexor 
longus pollicis( ?), flexor brevis digitorum, transversus, ab- 
ductor minimi, interossei; integument of foot and pads. 
N. Pudicus. -Origin: Two roots, sciatic and sacral. 
Distribution: Dorsal division, to MM. levator ani, sphincter 
ani; rectum, vagina, anal gland; ventral division, to M. 
accelerator urinae, perineum, vagina, ectal labium, urethra, 
glans clitoris, platetrope. 
COCCYGEAL NERVES. 
Characters in common: Paired, seven or more pairs; 
great length of ectal roots; rapid decrease in size, caudad; 
dorsal and ventral divisions; dorsal divisions unite to form a 
dorsal trunk, N. dorsalis, and the ventral divisions form 
ventral trunk, N. ventralis. 
Distribution: Muscles and integument of tail. 
N. Coccygeus cephalicus.- Origin: First coccygeal nerve. 
Distribution: MM. levator ani, sphincter ani; gives anasto- 
motic loop to third sacral nerve in the sacral plexus; by its 
rami forms the coccygeal roots of several nerves-N. coccy- 
geus, nerve to the urocyst, nerve to ribband muscle. 
DESCRIPTION OF DIAGRAM. 
A. fem., arteria femoralis; Acc., musculus accelerator urinae; anas., 
N. anastomoticus; Ca., divisio caudalis: Ce., divisio cephalica; Cl., 
glans clitoris; crtir., crural division of the genito-crural nerve; dac., StoweliT, Nerves in the Domestic Cat. 
313 
dactylus; Dia., diaphragm, M. phrenicus; Du. dor., divisio dorsalis; 
Dv. ven., divisio ventralis; Fm., foramen exitus; gen., genital division 
of the genito-crural nerve; Gl., glandula ani; H., hip, integument over 
the gluteal region; int., integument, cutaneous nerve; isch., ischium; 
k., knee; Lab.', labium ectale; loop, anastomotic nerve joining nerve 
trunks in plexiform relation; L.-S. C., lumbo-sacral cord; l.r., ramus 
lateralis; M.?, muscle not identified, v. text; M. ad. long., M. adductor 
longus; M. ad. mag., M. adductor magnus; M. bi., M. biceps; M.crur. 
M. crurseus; M. dor., musculi dorsales, quadratus lumborum, erector 
spinae, inter-vertebrales, etc.; M. eel., M. obliquus abdominis ectalis; 
Af. ent., M. obi. abd. entalis; M. flex. long, dig., M. flexor longus digi- 
torum; M. flex. br. dig., M. flexor brevis; M. flex. long, pol., M. flexor 
longus pollicis; M. gas., M. gastrocnemius; M. gl. max., M. gluteus 
maximus; M. gl. med., M. medius; M. gl. min,, M. minimus; M.gl.S., 
M. superior; M.grac., M. gracilis; M. Hi., M. iliacus; M. I. A., M. 
levator ani; M. obt., M. obturator; M. obt. int., M. internus; M. pec., 
M. pectineus; M. pso., M. psoas; M. pyr., M. pyriformis; A/. quad., 
M. quadratus femoris; m.r.., ramus mesalis; M. red.. M. abdominis 
rectus; M. fem., M. rectus femoris; M. sar.,lA. sartorius; M. semi- 
mem., M. semi-membranosus; M. semi-ten., M. semi-tendinosus; M. 
sph. a., M. sphincter ani; M. tib. p., M. tibialis posticus; M. trans. M. 
abdominis transversalis; M. T. V. F., M. tensor vaginae femoris; M. v. 
ext., M. vastus externus; M. v. int., M. vastus internus; N. coc., N. 
coccygeus; TV. crur.. N. ramus cruraeus; N.gem., N. gemellus; N.gen., 
N. ramus genitalis; N. glut., N. gluteus; N. gl. s., N. gluteus superior; 
N. mus,-cut., N. musculo-cutaneus; N. obt.. N. obturator; N. per., N. 
peroneus; N. pop., N. popliteus; N. saph. br., N. cutaneus internus 
brevis, short saphenous; N. saph. I., N. cutaneus internus longus, long 
saphenous; P. Poupart's ligament; peri., perineum; plat., platetrope; 
Pl. plan.. Plexus plantaris; Pl. S., plexus Solaris; pub., pubes; .S',, gan- 
glium sympathicum; Th., integument over the meros, thigh; ure., 
urethra; uro., urocystis; vag., vagina. 
WEIGERT'S METHOD OF STAINING THE 
MEDULLARY SHEATH OF NERVES.(') 
In the paper quoted, Dr. Weigert gives a full account of 
the famous method bearing his name, together with a his- 
torical review of the stages in its differentiation. 
The method, as now revised, consists of four stages, as 
follows: (1) Hardening in chromic salts; (2) introduction 
i Weigert, " Zur Markscheidenf arbung " Deutsche medicinische Wochenschrift. 
Festnummer zur Ehren Rudolf Virchows, October 13, 1891. 314 
Journal of Comparative Neurology. 
of copper in the chromium compound within the sheaths; 
(3) staining with haematoxylin; (4) differentiation by means 
of borax-ferricyanid of potassium. The precipitate which 
tends to appear during the staining is prevented by the addi- 
tion of the carbonate of lithium. 
The modified method, as here published for the first time, 
is as follows: Fragments suitable for microscopic sections are 
thoroughly hardened in bichromate of potassium, and, after 
treatment with alcohol, are imbedded in celloidin. After 
coagulation in 80 per cent, alcohol they were, according to 
the old method, brought into a solution of neutral cupric 
acetate in an equal volume of water and kept in the brood- 
oven twenty-four hours. The modification consists in the 
substitution of equal volumes of neutral cupric acetate and 
tartrate of soda (C4H4O6KNa-|-4H2O). Large fragments 
may remain for forty-eight hours without injury, provided 
the temperature is not permitted to rise too high. The frag- 
ment then is passed into an aqueous solution of cupric ace- 
tate and remains twenty-four hours longer in the warm 
chamber. After rinsing, the specimens go into 80 per cent, 
alcohol, where they become available for sectioning any time 
after an hour or so. 
For staining, two stock solutions are required: (A) c.cm. 
saturated aqueous solution of carbonate of lithium -|- 93 c.cm. 
distilled water; (B) 1 gm. hsemotoxylin 10 c.cm. alcohol. 
These are to be combined just before using in the proportion 
of 9 volumes of A to 1 volume of B. Sections stain in three 
or four hours, though the staining is not injured by leaving 
them twenty-four hours in the fluid. This process is, unfor- 
tunately, only available for free sections, which then require 
no development, but, after rinsing, are brought into 90 per 
cent, alcohol and are cleared in a mixture of 2 volumes of 
analin oil -j- 1 volume of xylol, followed by pure xylol and 
balsam. Journal of Comparative Neurology, Vol. I. 
PLATE XXIII