€57

THE ANATOMY. 0.253133 AU TO N0 M1 6
NERVOUS SYSTEMOF. THE
FOX SQUiRRELg
SClURUS N'iGER RUFIVENTER

mwmmmm ”WEE H“?

,{GEOFFROYI

.Thesin f0! the Degree of M. i.
MICHIGAN STAT! COL£E6E

Nicholas lamb; Mizares

 

 

 

   
  
  
 
   
 
 
 
  
     

.. -A-.......... u“... -2 J. ‘ 1 ‘ h: .‘A-_ l'
I ' .
I
This is to certify that the u. I
thesis entitled {T T
| rho baton of the Antone-1c ilervous Systen
of the l‘ox Squirrel, Sciml mgr .'
Ruflventer (Geoffrey). ' ii
'\
presented by . i
‘ licholu J. inure: ;‘ 6‘ J
l ' P. ' II
t l. ,
r
has been accepted towards fulfillment r _
of the requirements for _ L I
K. 8. degree in “010a f . l]
— ., i
P

——-'p—-
'-

 

Date September 7: 1252-.

e . -' )1)‘ '3‘"

 

THE ANATOMY OF THE AUTONOMIC NERVOUS SYSTEM OF THE FOX
SQUIRREL, SCIURUS NIGER RUFIVENTER (GEOFFROY)

By
NICHOLAS JAMES MIZERES

A THESIS

Submitted to the School of Graduate Studies of Michigan
State College of Agriculture and Applied Science
in partial fulfillment of the requirements

for the degree of

MASTER OF SCIENCE

Department of Zoology

1950

ACKNOWLEDGMENTS ‘\

The author wishes to acknowledge with gratitude the
help received from the following persons of the Zoology
Department: Dr. R. A. Fennel, under ;hose guidance this
work was possible; Dr. H. R. Hunt, Dr. K. A. Stiles,

Dr. R. A. Manville, T. W. Jenkins, and A. D. Brower for
valuable suggestions and encouragement; Dr. D. W. Hayne
and w. L. Poff for valuable assistance in obtaining
specimens of the fox squirrel; Miss B. McCarthy for her
encouragement and help in obtaining materials; Mr. P. G.
Coleman for his excellent photographic work; and Professor
L. R. Schoenman of the Michigan Conservation Institute for

permission to obtain the specimens.

244564

I.
II.
III.

IV.

VIII.

IX.

XI.

XII.

XIII.

XIV.

CONTENTS

IntrOduCtioneooeooeeeooone.0.0000000000000000
Materials and MethOdSeooe00.00.000.000...coco

The Autonomic Ganglia of the Cephalic

RegiOHCOOOOOOOOOOOIOCOOOOOOC0.0.0.0....0.0...

The Ganglionated Cord and the vagus Nerve
of the Cervical Region.......................

The Autonomic Plexuses of the Cervical

Region.OOOOOOOOOOOOOOOOOOOOOOOOCOOOOOOOOOOOOO

The Ganglionated Cord of the Thoracic

RegionOCOOOOOOOOCOOOOOOOOOOOOOOOOOOOOOOOOOOOO

The Course of the Vagus Nerves in the
ThoraCic caVityOOOO..0.0000000000000000000000

The Autonomic Plexuses of the Thoracic

RegionCIOOOCOOOOOOI.OOOOCOOOCOOOOOCOOOOOO0.0.

The Collateral Ganglia of the Abdominal

RegionOOOOOOOOOOCOOOOOOOIOIOOOOOOOOOOOOOOO...

The Ganglionated Cord of the Abdominal

RegionOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO0..O...

The Autonomic Plexuses of the Abdominal

RegionOOOOOOIOCOOOOOOOOOOOOOOOOOOOOOOOOOO0.0.

The Hypogastric Plexus and the Pelvic
Visceral NerveSOOOOOOOOOOOOOOOOOOOOOOOO00....

The Ganglionated Cord of the Pelvic

RegionOOOOOOOOO0.00...OOOOOCCOOOOOOOOOOOOIOOO

List of References...........................

curriculum VitanOOOOOOOOOOO...0.00.00...O...

Page
1
2

3

10

16

23

25

28

31

38

41

47

1L8
50
51

Plate
Plate

Plate

Plate

Plate

Plate
Plate

Plate

Plate

Plate

Plate

Plate

Plate

Plate

I.
II.

III.

IV.

V.

VI.
VII.

VIII.

IX.

XI.

XII.

XIII.

XIV.

LIST OF ILLUSTRATIONS

Lateral View of the Brain..............

Ciliary Ganglion of the Left Eye,
Ventral Aspect.........................

The Submaxillary Ganglion, Ventral

VieWOOOOOOOOOOOOOOOCOOOOOOOOOOOCCOOOOOO

Ventral View of the Right Auditory
Bulla and Adjacent Structures Pulled
Laterally...OOOOOOOOOOOOOOOOOOOOOOO0.0.

Internal Ventral View of the Left
Auditory BullaOOOOOOOOOOOOOOOOOOOOOOOOO

Ventral View of the Neck and Thorax....

Variations in the Middle Cervical
Ganglion...IOOOOOOOOOOOOOOOOOCOOOO0....

The Vagus Nerves and Ganglionated
Cord of the Thoracic Cavity with the
Heart Pushed toward the Left Side......

Collateral Ganglia and Plexuses of the
Abdominal Region, Right Ventral

ASpectOOOOOOOOOCOCOOOOOOOOO0000......O.

The Posterior Mesenteric Ganglion
and. Plexus, Female...-OOOOOOOOOOOOOOOOO

Variations in the Abdominal
COlla-teral GangliaOOOOOOOOOOOOO00......

The Ganglionated Cord of the
Abdominal Region, Ventral Aspect.......

Ventral View of the Male Hypogastric
Region Showing the Spermatic Plexuses..

The Ganglionated Cord of the
PelVic RegionOOOOOOOOOOOOOOIOOOOOOOOOOC

Page

7

8

9

19

2O
21

22
30

35

36
37
40
1+6

49

I. INTRODUCTION

Although there is abundant literature on the hist-
ological analysis of the mammalian autonomic nervous
system, very little detailed anatomical work has been
done on mammals, excluding man. In the rat and cat,
Greene (1935), Reighard and Jennings (1935) and others
present a generalized account of the autonomic nervous
system but little or no attempt has been made to study
in detail the various types of ganglia, their connections
with the various plexuses, or their variations. Also,
no attempt has been made to interpret anatomically the
autonomic ganglia of the head region.

The fox squirrel was chosen not only because of
its relative abundance and importance in game management
but also because it is a typical mammal that may be used
as a laboratory study when feasible. It is hoped that
this work will offer some help in the better understanding
of the mammalian autonomic nervous system and to provide

a small link in its evolution.

2.

II. MATERIALS AND METHODS

Six adult specimens, three males and three females,
of the fox squirrel were live-trapped in the Baker Wood
Lot on the campus of Michigan State College. After
chloroforming, they were immediately embalmed with a
formalin preservative injected through the femoral vein.
No color injection was used because it would have made
it difficult to separate vessels from the fine plexuses
and small ganglia. Most of the dissection was done with
the aid of a 3x magnifier. For the fine plexuses and
the ganglia of the head region the binocular dissecting
microscope was used extensively.

Fourteen pen and ink drawings accompany the descrip—
tion. At the bottom of each drawing a scale in milli-
meters will be found. The drawings were made during the
time of dissection and the photographs represent a reduc-
tion of about four-fifths the original drawings.

Since this work is anatomical in its scope the
terms, "sympathetic" and "parasympathetic," have not
been used in describing the various subdivisions of the
system. These terms are mainly physiological concepts
and do not necessarily conform to anatomical description.
The anatomical terms, "thoraco—lumbar" and "cranio-
sacral," also were not used because this work is based

upon regional dissection.

3.

III. THE AUTONOMIC GANGLIA OF THE CEPHALIC REGION

The four autonomic ganglia of the cephalic region in
the fox squirrel are extremely small and difficult to
dissect even with a binocular dissecting microscope.
Therefore, in this work, the interpretation of these
ganglia and their connections is based entirely upon
observational microdissection. The ganglia may be

described as follows:

A. The Sphenopalatine Ganglion (Plate I-A).

 

The Sphenopalatine ganglion is the largest of the
four ganglia, averaging one millimeter in length. It is
longer than wide and lies Just inside the large Spheno-
palatine foramen closely adherent to the lateral ventral
surface of the maxillary division of the trigeminal
nerve (Plate I, 13). It seems to appear as if it were
one of the fasciculi of the nerve but upon careful
probing it defied breaking apart. It is attached to the
maxillary nerve by means of two small roots, one longer
and thinner than the other. A variable number of strands
emerge from the distal portion of the ganglion and follow
the maxillary nerve and its branches into the nasal
cavity and pharyngeal region. The large Vidian nerve
(Plate I-B) may be seen to enter the proximal border of
the ganglion after emerging from its canal (Plate 1-11)
in the pterygoid bone. This nerve, when followed caudally,
descends over the caudal border of the pterygoid plate,

4.

enters the foramen lacerum, and passes into the auditory
bulla where it is formed by the union of the large deep
petrosal and the large superficial petrosal nerves
(Plate I-C, D). The large deep petrosal nerve arises
mainly from the tympanic plexus (Plates I—E; V—B). The
large superficial petrosal nerve arises from the genicu-
late ganglion (Plate I-lO) of the facial nerve located
in the facial canal in the auditory bulla.

B. The Otic Ganglion (Plate I-F).

 

The otic ganglion is a minute oval body, about
two-thirds of a millimeter in length, imbedded in a
loose mass of fat and connective tissue located in the
region where the mandibular nerve just begins to divide
(Plate 1-15). In the majority of the specimens it was
difficult to decide without histological slides whether
a ganglion or a minute plexus was present. Only two of
the specimens exhibited a definite ganglion. It is
attached by means of two filaments to the lateral sur-
face of the mandibular nerve. In contrast to the
Sphenopalatine ganglion it is loosely placed. From its
distal border three main branches arise. Two establish
connection with the chorda tympani nerve (Plate 1-17)
and the other enters the internal pterygoid muscle
(Plate I-H). Other connections may have been present but
only these three fibers were discernible with the dis-

secting microscope.

C. The Ciliary Ganglion (Plate II-C).

 

The ciliary ganglion is about the same size as the
otic. It is located just caudad of the ventral surface
of the optic nerve (Plate 11-13). It is attached by
means of two filaments. One connects to the nasociliary
nerve (Plate II—l), a branch of the ophthalmic division
of the trigeminal nerve. The other joins the lower
division of the oculomotor nerve (Plate 11-2, 8). The
ganglion sends out three main fibers, the short ciliary
nerves (Plate II—D), that follow the optic nerve and
spread out and pierce the sclerotic coat of the eyeball
(Plate II-lO). No root from the internal carotid plexus

to the ganglion was discernible in any of the specimens.

D. The Submaxillary Ganglion (Plate III-A).

 

The submaxillary ganglion is a little less than one
millimeter in length and is found deeply imbedded in the
submaxillary gland. It lies adherent to the dilatation
or approximate origin of the submaxillary duct (Plate
III-10). Its two roots are extremely long and sinuous,
arising from the lingual nerve near the caudal border of
the sublingual gland (Plate III-B, 14). These two roots
unite just before entering the submaxillary gland. The
medial root sends fine branches to the submaxillary duct
and sublingual gland (Plate III—C). While within the
substance of the submaxillary gland the main root, before

joining the ganglion, sends a few fibers to the submaxillary

6.

vein (Plate III—8). The ganglion itself sends fine numer-
ous fibers to the submaxillary gland. In all but one
specimen the ganglion was definite. In the one specimen,
a plexus replaced the ganglion.

Just about one centimeter laterad to the two sinuous
roots of the ganglion the chorda tympani nerve joins the
lingual nerve (Plate III-4). When followed to the
auditory bulla it enters the bulla through the petro-
tympanic (Glaserian) fissure (Plate V-A, l), hooks around
the ligament of the malleus (Plate V-18), enters a small
canal, the iter chordae posterius (Plate V-l6), and
finally joins the facial nerve at the brim of the facial
canal (Plate V—lS, 17).

PLATE I. LATERAL VIEW OF THE BRAIN

A. Sphenopalatine Gln.
B. Vidian N.
C. Large Superficial Petrosal N.
D. Large Deep Petrosal N.
E. Part of the Tympanic Plexus.

~. F. Otic-Gln.. w.- “4..-...“ .. - . .3-..
G. Root to the Chorda Tympani N.

~ ~~~—~s...li..:"Ne.n¥e._tn .thealntennalattervsoiii’le ........-.~..... ..-....

1. Right Cerebral Hemisphere.

2. Posterior Perforated Substance.

3. Oculomotbr N.

4. Pons.

5. Abducens N.

6. .Trapezoid Body.

7. Auditory N.

8. Peduncle of Paraflocculus.
9. Facial N.

10. Geniculate Gln. of VII.

'11. Vidian Canal. ‘

l2. Gasserion (Semilunar) Gln.
13. Maxillary N. of v.

14. Ophthalmic N. of v.'

15. amandibular N. of v.

16. Lingual N.

17. Chorda Tympani N.

~“—.-“ . ”—4“. -n.. O .m-. é.-.‘.* Ag‘ .. ,..

PLATE I

.o-
I

n. -
ow.

I

I

o
d

l.

234...?

.24”?

 

PLATE II. CILIARY GANGLION OF THE LEFT EYE,
VENTRAL ASPECT.

A. Root from the Nasociliary N.

B. Root from the Lower Division of III.
C. Ciliary Gln.

D. Short Ciliary N.

1.. Nasociliary N.

«a»- -‘*3J_Lw“29w-wfm my“... «W'-&WM~~H-&H(W"” '
t-2.‘*Oculomotor N.

. Abducens N.
. Upper Division of III.
. Lateral Rectus M._(cut).
Inferior Rectus M. (cut).
Superior Rectus M.
Lower Division of III.

9. Inferior Oblique M. (cut).
10. Sclera of Eyeball. .
ll. Inferior Rectus M; (cut).
12. Lateral Rectus M. (cut).
13. Optic N.

14. Long Ciliary N.

0040\me

PLATE II

1..

..
"a
m

a,

.fl.

 

PLATE III.

A.
B.
C.

*“fir"r~Andand“8ubmaxi&lary“9uctrwwvnt~~*w*

l.
2.

\Om‘flmkfi-tw

10.
ll.
l2.
13.
14.
15.

THE SUBMAXILLARY GANGLION, VENTRAL VIEW.

Submaxillary Gln.

aRoots from the Lingual N.

Branches to the Sublingual Gld.

Masseter M.

Ramus of Mandible (cut).
Inferior Alveolar N.

Chorda Tympani N.

Mylohyoid N.

External Maxillary A.

Parotid Gld.

Submaxillary V. and N. Plexus.
Submaxillary Gld. (cut).
Submaxillary Duct.
Submaxillary A. and N. Plexus.
Hypoglossal N.

Lingual N.

Sublingual Gld.

Hyoglossus M.

 

h.

 

 

10.

IV. THE GANGLIONATED CORD AND THE VAGUS NERVE OF -
THE CERVICAL REGION

Instead of the usual segmented condition as found
in the rest of the body the cervical ganglia Of the cord
become variously fused. The cervical ganglionated cord
may be said to begin with the anterior (superior) cervi-
cal ganglion located just below the auditory bulla and
ends with the stellate ganglion at the level of the first
rib. Due to the variations encountered each ganglion

will be discussed separately.

A. The Anterior (Superior) Cervical Ganglion.

 

As the cervical ganglionated cord ascends on the
right side from the middle cervical ganglion and on the
left side from the subclavian plexus, it enters the
carotid sheath (Plate VI—38) along with the vagus nerve
and common carotid artery. Just before reaching the base
of the auditory bulla it gives rise to the anterior
cervical ganglion (Plate IV-G). It is relatively con-
stant in shape and size, being pyriform, and averaging
about three milimeters in length. It is located just
behind the bifurcation Of the common carotid artery ad-
hering very closely to a mass of fibrous tissue surround-
ing the area. Its branches and connections may be grouped

as follows:

ll.

1. Caudal Fibers.

 

About five millimeters below the anterior cervical
ganglion the ganglionated cord gives off a long branch
which descends over the second and third cervical nerves,
giving off rami communicantes to the latter, and joins
the thymus gland (Plate IVeB). Since this branch was
the only discernible one from anywhere near the ganglion
that reached the region of the heart it may have con-
tained branches destined for the heart, but none were
revealed by binocular dissection. In addition, no rami
communicantes were found to connect with the fourth or
fifth cervical nerves.

From the caudal region of the ganglion a long ramus
communicans descends to reach the first cervical nerve
(Plate IV—D). Just above the origin of this ramus an
additional fiber arises which joins the anterior (superior)
laryngeal nerve of the vagus (Plate IV—F, 7).

2. Lateral Fibers.

 

Two main short branches arise from the lateral portion
of the ganglion. One connects with the spinal accessory
nerve (Plate IV-8) as it leaves the jugular foramen and
another connects with the hypoglossal nerve (Plate IV-2)
as it leaves the hypoglossal canal.

3. Medial Fibers.

 

From the medial portion of the ganglion three main
branches arise. One ramifies on the bifurcation of the
common carotid artery and forms the common carotid plexus

(Plate IV-A). A second branch ascends on the external

l2.

carotid and forms the external carotid plexus (Plate
IV-S) which anastomoses with the common carotid plexus.
The third branch is very short and connects with the
glossopharyngeal nerve (Plate IV-l4) after it leaves
the jugular foramen.

4. Cranial Fibers.

 

Three branches may be seen to originate from the
cranial portion of the ganglion. One, the internal
carotid nerve (Plate V-C), follows the internal carotid
artery into the foramen lacerum becoming plexiform as the
internal carotid plexus (Plate V—6). The second is the
largest of the three and follows the pterngpalatine
artery for a short distance and at the same time branch-
ing to form a fine plexus which follows the pterygopalatine
artery into its canal inside the auditory bulla (Plate
V-l4). The main portion of the branch turns toward the
promontory of the middle ear where it forms most of the
tympanic plexus (Plate V-B). The tympanic artery, a
branch of the pterygopalatine, follows this branch very
closely. The third branch is minute and forms a fine

plexus on the posterior meningeal artery (Plate V-l3).
B. The Middle Cervical Ganglion.

The middle cervical ganglion appeared in all six
specimens only on the right side. It exhibited great
variability in size and form. Its size ranged from
one-half to two millimeters in length and in five of the
six specimens it showed a bilobed condition with the

13.

size of the lobes varying in all five specimens (Plate
VII — figs. 1, 3, 4, 5, 6). The sixth specimen exhib-
ited a single large ganglion (Plate VII - fig. 2). In
all cases it was found on the ventral surface of the
origin of the vertebral artery (Plate VII-3). On the
left side of each Specimen the ganglion was conspicuously
absent. Instead, a plexus was found which may be desig-
nated as the subclavian plexus (Plate VI—T).

l. Branches and Connections of the
Middle CerVical Ganglion.

 

 

In all five cases the lateral one of the paired
ganglia connected with the stellate ganglion (Plate VI-H).
The medial one connected to the vagus nerve by means of
two or three filaments. Cranially, the lateral ganglion,
including the unpaired one, gave rise to the cervical
ganglionated cord (Plate VII-B). In all Six cases the
ganglia gave rise to a variable number of strands that
joined the axillary plexus (Plate VI-8). The rami com-
municantes to the sixth, seventh, and eighth cervical
nerves arose either from the ganglia or from their

branches (Plate VI-C, D).

C. The Stellate Ganglion.

 

The stellate ganglion in the fox squirrel is rela-
tively large measuring from three to five millimeters in
length. It is pyriform in shape and lies dorsad and
caudad to the subclavian artery at the level of the

origin of the first rib (Plate VI-H, S). The supreme

14.

intercostal artery lies behind the ganglion and the
phrenic nerve traverses over it (Plate VI-34, 35). In
four of the six specimens the ganglion represents a fusion
of the inferior (posterior) cervical and the first
thoracic ganglion (Plate VI-H, P, S). In the remaining
specimens, it represents a fusion of the inferior cer-
vical and the first and second thoracic ganglia. In

the cat (Reighard and Jennings 1935, p. 409) and the

rat (Greene 1935, fig. 193) the stellate ganglion repre—
sents a fusion of the inferior cervical with the first three
thoracic ganglia. The fox squirrel, therefore, differs

in this respect and resembles more closely the condition
found in the human where the stellate usually is a fusion
of the inferior cervical and the first thoracic ganglia
(Morrill 1948, p. 25).

l. Branches and Connections of the Stellate Ganglion.

 

From the cranial portion of the ganglion four main
roots arise. One traverses laterad over the subclavian
artery to the axillary artery where it joins the axillary
plexus (Plate VI-8). A second one ascends behind the
subclavian artery, variably giving off a ramus to the
eighth cervical nerve, and follows the vertebral artery
into the sixth intervertebral foramen to form the vertebral
plexus (Plate VI-E). The remaining two ascend, one dor-
sally and the other ventrally, to enclose the subclavian
artery. The ventral root, the ansa subclavia (Plate
VI-G), is larger than the dorsal root in contrast to the
rat (Greene 1935, fig. 193) and human (Morrill 1948, p. 25)

150

where the ventral root is smaller. On the right side,
after encircling the subclavian artery, these two roots
join the middle cervical ganglion whereas on the left,
they fuse and join the subclavian plexus.

From the middle portion of the right stellate
ganglion a small branch is given off and along with an
anastomotic branch from the right vagus nerve form the
right posterior (inferior) cardiac nerve (Plates VI-J;
VIII-S) which descends medially behind the innominate
artery to join the deep cardiac plexus. From the left
stellate ganglion the left posterior cardiac nerve
(Plate VI-O) arises by a fusion Of two small roots and
descends over the descending aorta to join the super-
ficial cardiac plexus. In contrast to the right cardiac
nerve it has no connection with the vagus nerve.

In two cases the rami communicantes arising from the
stellate ganglion differed on both sides. The right
stellate gave off rami directly to the second and the
first thoracic nerves (Plate VI-lO), whereas the left
ganglion gave off a ramus to the first thoracic nerve
and a ramus to an anastomotic root which connected the
first and second thoracic nerves (Plate VI-R). The
condition of this left stellate was found on both sides

in the remaining four specimens.

16.

V. THE AUTONOMIC PLEXUSES OF THE CERVICAL REGION

The cranial plexuses of the cervical region are
formed mainly from branches of the anterior cervical
ganglion. In the lower cervical region the plexuses
are formed by branches from the cervical ganglionated
cord and the middle cervical and stellate ganglia. They

may be grouped as follows:

A. The Tympanic and Internal Carotid Plexuses.

 

The tympanic plexus consists of a linear network of
anastomotic fibers located on and within the groove of
the promontory of the middle ear (Plate V-B, 4). It is
formed mainly by a branch from the anterior cervical
ganglion and the tympanic (Jacobson's) nerve from the
petrous ganglion of the glossopharyngeal nerve (Plate
V-G). From the cranial portion of the plexus which dips
down in front of the promontory, the large deep petrosal
nerve arises (Plate I-D) and ascends on the inner wall
of the auditory bulla. Just before the large deep
petrosal nerve ascends, the internal carotid plexus
located in the foramen lacerum (Plate V-5) anastomoses
with the tympanic plexus. The internal carotid plexus
is formed from the internal carotid nerve originating

from the anterior cervical ganglion (Plate V-6).

17.

B. The Common Carotid Plexus and its Subdivisions.

 

At the bifurcation of the common carotid artery,
just caudad of the auditory bulla, a thick network of
fibers, the common carotid plexus, may be seen adhering
to the artery (Plate IV-A). It originates by several
fibers from the anterior cervical ganglion and sends
subordinate plexuses which follow the branches of the
common carotid artery including the anterior thyroid,
external carotid, posterior auricular, lingual, external
maxillary, and submaxillary arteries (Plates IV-l, 4, 5,
6; III-ll).

C. The Subclavian Plexus and its Subdivisions.

 

The subclavian plexus is found only on the left side,
the right side being replaced by the middle cervical
ganglion from which identical subordinate plexuses arise.
The subclavian plexus is a dense network of fibers formed
mainly from the cranial branches of the left stellate and
lateral branches of the left vagus nerve including the
lower portion of the cervical ganglionated cord (Plate
VI-T). It lies ventrad to the lateral surface of the
esophagus and longus colli muscle and just mediad to the
origin of the vertebral artery (Plate VI-S, 36, 39). It
sends rami communicantes to the sixth, seventh, and eighth
cervical nerves (Plate VI-T).

Along with a branch from the stellate ganglion the

subclavian plexus sends subordinate plexuses to the

18.

axillary artery (Plate VI-8) and to the cervical axis
(Plate VI-6) following their branches into the lower

cervical region and upper limb.

PLATE IV.

A.
i
B:

E
.

C.““

D.
E.
F.

VENTRAL VIEW OF THE RIGHT AUDITORY BULLA AND
ADJACENT STRUCTURES PULLED LATERALLY.

CommOn CarOtid Plexus. t
Branch to the Thymus Gld. l
UefiitamWEETEBEa? “"‘"”"‘“""‘""' M
Ramus Communicans to C-1.
Vagus N.

Branch to the Anterior Laryngeal N.
Anterior Cervical Gln. (dorsal surface).

Ganglion Nodosum of X.

Lingual A. and N. Plexus.

Hypoglossal N.

Pharyngeal Branch of X.

Posterior Auricular A. and N. Plexus.

External Carotid A. and N. Plexus (dorsal
surface).

Anterior Thyroid A. and N. Plexus.
Anterior Laryngeal N.

Spinal Accessory N.“

Common Carotid A. (dorsal surface).
First Cervical N.

Hypoglossal Canal.

Jugular Foramen.

Internal Carotid A. and N. Plexus.
Glossopharyngeal N.

Auditory Bulla.

C
. ,._ J~._.--.~) 'l-I- W ' "”1 "‘M“-".’:" ' ‘
J

N- ”1“.“ (l

 

 

PLATE V. INTERNAL VENTRAL VIEW OF THE LEFT

A..

B.

\OCDNONUl-F-‘UO

10.
ll.
l2.
l3.
14.

15.

16..

17.
18.
19.

720.

‘3121-

22.

23.

AUDITORY BULLA.

Chorda Tympani N.
Tympanic Plexus.

C WWW.» -a

Ganglion Nodosum of X.
Anterior Cervical Gln.
Branch to the Tympanic Plexus.

Tympanic (Jacobson's) N. from the
Petrous Gln. of IX.

Petrotympanic (Glaserian) FisSure.
Canal in the Glaserian Fissure.
Auditory Bulla (cut).

Promontory of the Middle Ear.
Foramen Lacerum.

Internal Carotid A. and N. Plexus.
Hypoglossal Canal. .
Spinal Accessory N.

Hypoglossal N.

Glossopharyngeal N..and Petrous Gln.
External Carotide.

Jugular Foramen.: ,,

Posterior Meningeal A. and N. Plexus.

Pterygopalatine A. and N. Plexus in
its Canal.

VII N. in the Facial Canal.

Canal (iter chordae posterius) for
the Chorda Tympani N.

Facial N. .
Ligament of the Malleus (cut).
Epitympanic Recess.

Incus.

“Handle of the Malleus. .. 4e-wl

Attachment of the Handle of the
Malleus.

Tympanic Membrane.

 

 

 

V

.I 314

PIA

 

«a

l6.

l7.
l8.

l9.

"?EATE"VI?“

- .-

Cervical Ganglionated
Cord.

Right Vagus N.

Ramus Communicans to
C-7. '

Paired Middle Cervical
Gln. with Rami to

C-6 & C-7.

Branch to the Vertebral
Plexus.

Right Recurrent
Laryngeal N.

Ansa Subclavia.

Right Stellate Gln.
Right Posterior
Cardiac M.

Right Common Carotid A.
Fourth Cervical N.
Thyroid Gld.
Trachea.

Longus Colli M.
Cervical Axis and N.
Plexus. '

Sixth Cervical N.
Axillary A. and N.
Plexus.

First Rib (cut).
First Thoracic N.
Innominate A.
Aortic Arch (cut).
Right Phrenic N.
(cut).

Right Precava.
Azygos V.

Right Auricular
Appendage.

Right Phrenic N.
Postcava.
Esophagus

K.
L.
M.
N.

O.
P.
R.

S.
T.

U.

20.

21.
22.
23
24.
250
26.
27
28.

29.
30.

31.
32.
33.

34.

35.”

36.
37

_ 38.

39-

VENTRALHVIEWWOF-THE NEGMrAND-THGRAX. »-~

Deep Cardiac Plexus.
Thoracic Cardiac N.
Right Vagus N.
Superficial Cardiac
Plexus. .

Left Posterior Cardiac
N.

Left Second Thoracic
Gln.

Ramus Communicans.
Left Stellate Gln.
Subclavian Plexus with
Rami to C 6, C- 7,&

C-8.

Left Recurrent
Laryngeal N.

Pulmonary Arch.
Ligamentum Arteriosum.
Right Ventricle.
Left Ventricle.‘
Thoracic.Aorta.
Left Pulmonary V.
Left Bronchus.
Left Pulmonary A.
Left Auricular
Appendage.

Left Phrenic N.

,LeftrPrecava.
jDescending Aorta.
Third Rib (cut).

Left Subclavian A.
(cut).

Supreme Intercdstal A.
Left Phrenic N.

(cut).

Vertebral A.

Left Common Carotid A.
Carotid Sheath.
Esophagus.

TE VI

LA

P

l

 

 

 

 

 

 

      

 

 

  

lr'll)

. n. 1...... . . ..-.....
u I \ .l o .. s i... .0....un .
i I .

. e
"

4.1 5.3.3.... ....
14;..-
b It. ..a .
s “
A

"fl.”

11» .l .. . 11. ..

    

 

PLATE VII. VARIATIONS IN THE MIDDLE CERVICAL GANGLION.

. B. Cervical Ganglionated Cord.
M *Mmeéaemcahfifilmh - “-4... Nil-n. MthMu‘A—p- = 1..
D. Ansa Subclavia.

7 , HA. Right.Vagus N. . - - g

E. Right Recurrent Laryngeal N.

1. Right Subclavian A.

2. Innominate A.

3. Right Vertebral A.

4. Right Common Carotid A.

 

23.

VI. THE GANGLIONATED CORD OF THE THORACIC REGION

The ganglionated cord of the thoracic region begins
at the level of the first rib and extends to just caudad
of the twelfth rib where the cord, after giving off the
splanchnic nerve and passing under the central tendon of
the diaphragm, enters into and among the fibers of the
psoas muscles. It is retro-peritoneal and from the ninth
to the twelfth rib it is in relation to the azygous vein,
the thoracic duct, the esophagus, and the thoracic aorta.
Continuing cephalad, the cord begins to diverge from the
median axis of the body and ends with the stellate
ganglion, near the commencement of the subclavian artery
where the supreme intercostal artery is given off. The
ganglia of the cord greatly diminish in size beginning at
the level of the sixth intercostal artery down to the
level of the eleventh intercostal. A few of these ganglia
can hardly be distinguishable (Plate VIII).

A. Communications with the Thoracic Nerves.

 

Each ganglion of the cord lies directly on the sur-
face of each corresponding intercostal nerve and artery
near their stems. Just below each ganglion a long ramus
communicans is given off to each of the corresponding
thoracic nerves (Plate VIII-G). Generally the second
thoracic ganglion (Plate VI-P) gives off an additional
ramus to an anastomotic root which connects the second

and the first thoracic nerves.

24.

B. Medial Branches of the Cord.

 

Just craniad to the twelfth thoracic ganglion, a
large splanchnic nerve (Plates VIII—K; IX—D) arises and
descends for a short distance, turns medially, and
pierces the crura of the diaphragm to join the aortico-
renal ganglion. No lesser or least splanchnic nerves
were discernible in the fox squirrel.

From the ninth, tenth, and eleventh ganglia fine
filaments arise which traverse medially along the cor-
reSponding intercostal artery toward the ventral sur-
face of the thoracic aorta where they ramify. From the
sixth, seventh, and eighth ganglia identical filaments
are given off which, in addition, branch to contribute
to the esophageal plexus and anastomotic filaments to
the vagus nerves. From the fifth and sixth ganglia
additional filaments arise to enter the pulmonary
plexuses (Plate VIII-F). From the third, fourth, and
fifth ganglia fine filaments are given off which follow
the intercostal arteries medially and contribute to the
deep cardiac plexus located between the aortic arch and
the bifurcation of the trachea (Plate VIII—P). The
second thoracic ganglion does not seem togive Off any

medial branches.

25.

VII. THE COURSE OF THE VAGUS NERVES IN THE
THORACIC CAVITY

A. The Left Vagus Nerve.

 

The left vagus nerve in the thoracic cavity may be
said to begin at the level of the first rib where it
contributes to the subclavian plexus (Plate VI-T). It
then descends ventrad to the esophagus and the left
longus colli muscle. Upon reaching the base of the left
subclavian artery it curves ventrad over the aortic
arch. The left vagus then continues dorsad to the left
pulmonary vessels and bronchus and after coursing med—
ially for a short distance, it comes into close relation
with the left side of the esophagus and anastOmoses with
the right vagus nerve. Upon entering the abdomen it
enters the concavity between the termination of the
esophagus and the lesser curvature of the stomach where
it anastomoses with branches from the right vagus and
forms the left gastric plexus (Plate VIII-M). Its
branches may be described as follows:

1. The Left Recurrent Laryngeal Nerve (Plate VI-U).

 

The left recurrent laryngeal nerve arises just
ventrad to the base of the left subclavian artery and
descends to loop under the ligamentum arteriosum (Plate
VI-2l). While it ascends toward the trachea it con-
tributes to the bulk of the deep cardiac plexus. Upon
reaching the left side of the trachea it continues to

26.

ascend and gives off branches to the trachea, esophagus,
and anastomotic branches to the cervical ganglionated
cord. It then terminates within the larynx as the
inferior laryngeal nerve.

2. Branches to the Thoracic Plexuses.

 

At the level of the first rib the left vagus gives
off distinct filaments which connect with the left cer-
vical ganglionated cord to form part of the subclavian
plexus. After giving off the left recurrent laryngeal
nerve the vagus contributes a few filaments to the super-
ficial cardiac plexus (Plate VI-N). At the origin of the
left bronchus it branches to form the left pulmonary
plexus and descends toward the dorsal surface of the
esophagus to contribute to the esophageal plexus and

communications with the right vagus nerve (Plate VIII-H).

B. The Right vagus Nerve.

 

The thoracic portion of the right vagus may be
said to begin at the level of the first rib in front of
the right subclavian artery where the right recurrent
laryngeal nerve arises (Plate VI-F). It then descends
laterad to the trachea and comes into close relation with
the right side of the esophagus. Upon reaching the
cardiac stomach it branches and anastomoses with branches
from the left vagus to form the right gastric plexus
(Plate VIII-L). Its branches may be described as

follows:

27.

l. The Right Recurrent Laryngeal Nerveg(Plate VI-F).

 

At the ventral surface of the root of the right
subclavian artery the recurrent laryngeal nerve arises
and turns dorsomediad to the innominate artery and ascends
on the right lateral surface of the trachea giving off
branches to the trachea and continuing up into the
larynx. In contrast to the left recurrent nerve it does
not contribute to the deep cardiac plexus.

2. Branches to the Thoracic Plexuses.

 

At the origin of the right recurrent laryngeal nerve
the vagus gives off a short communication to the right
posterior cardiac nerve which contributes to the deep
cardiac plexus. In addition, the vagus itself sends two
or three branches, the thoracic cardiac nerves, to con-
tribute to the same plexus (Plates VI—L; VIII-R). Un—
like the left vagus it sends several branches directly
to the trachea. At the level of the origin of the right
subclavian artery it is connected to the middle cervical
ganglion by means of a variable number of fine fila-
ments (Plate VII - figs. 1-6). After giving off the
right pulmonary plexus on the right bronchus the right
vagus descends on the ventral surface of the esophagus
where it contributes to the esophageal plexus and com-

munications to the left vagus nerve (Plate VIII-H).

28.

VIII. THE AUTONOMIC PLEXUSES OF THE THORACIC REGION

A. The Deep Cardiac Plexus(Plates VI-K; VIII-P).

 

The deep cardiac plexus consists of a closely woven
network of fibers located between the bifurcation of the
trachea and the aortic arch. It is made up of fibers
contributed directly by the left recurrent laryngeal, the
thoracic cardiac nerves of the right vagus, andthe
right posterior cardiac nerve of the stellate ganglion.

A few filaments from the third, fourth, and fifth ganglia
of the thoracic ganglionated cord also contribute to the

plexus.

B. The Superficial Cardiac Plexus (Plate VI-N).

 

The superficial cardiac plexus is a thin network of
fibers located in a space bounded by the concavity of
the pulmonary arch, the left auricular appendage, and
the base of the left precava. It is made up of branches
contributed by the left posterior cardiac nerve of the
stellate ganglion and variably by the left vagus and

recurrent laryngeal nerves.

C. The Pulmonary Plexuses (Plate VIII-F).

 

The right and left pulmonary plexuses lie at the
roots of the right and left brdfihi and follow the cor-
responding pulmonary vessels and secondary bronchi into

the lungs. They are made up of fibers arising from the

29.

right and left vagi and a few filaments from the fifth

and sixth ganglia of the thoracic ganglionated cord.
D. The Esophageal Plexus (Plate VIII-R).

At the level of the eighth rib the two vagi come
into close relation with the esophagus giving off
anastomotic branches that seem to enclose the eSOphagus
in this region. This plexus also receives a few fila-
ments from the sixth, seventh, and eighth ganglia of
the thoracic ganglionated cord.

.J.

A.
B.
C.
D.

F.
G.
H.
J.
K.
L.

130
l4.

16.
17.

9“?”

PLATE VIII.

THE VAGUS NERVES AND GANGLIONATED CORD

OF THE THORACIC CAVITY WITH THE HEAET'PUSEED'

TOWARD THE LEFT SIDE..~IW-LAWL.

Right Vagus N.
Stellate Gln.

Second Thoracic Gln.
Thoracic Ganglionated
Cord.

Branch to the Deep
Cardiac Plexus.

Right Pulmonary Plexus.
Ramus Communicans.
Esophageal Plexus.
Twelfth Thoracic Gln.
Splanchnic N.

Right Gastric

Plexus.

Longus Colli M.

Right Subclavian A.
Supreme Intercostal A.
Third Rib (cut).
External Intercostal M.
Fifth Intercostal N.
Sixth Intercostal A.
Azygos V.

Thoracic Duct.

Fundus of Stomach.
Pylorus of Stomach.
Esophagus.

Diaphragm (cut).

Right Phrenic N.
Postcava.

Thoracic Aorta.

Left Phrenic N.

M.
N.
O.
P.
R.
S.

U.
V.

18.

20.
21.
22.
23.
24.
25.
26.

27.
28.
29.
30.
31.
320

Left Gastric Plexus.
Left Vagus N.

Left Vagus N.

Deep Cardiac Plexus.
Thoracic Cardiac N.
Right Posterior
Cardiac N.

Left Posterior
Cardiac N.

Left Vagus N.

Left Recurrent
Laryngeal N.

Right Recurrent
Laryngeal N.

Pericardium.

Right Pulmonary A.
Right Precava.
Right Auricle.
Left Ventricle.
Right Ventricle.
Aortic Arch.
Innominate A.

Left Cardiac Lobe
of Lung (cut).
Left Subclavian A.
Left Common Carotid
Trachea.

Left Phrenic N.
Esophagus.

Right Common
Carotid A.

o-—':o—--' 10‘1
I'
’

h lrh—I-MW u..- -

   
    

 

__ AH ’-

 

HW ”W" «.1 “an“ 59-; . .
. x ..
#5

“WWW

“s
W». .
‘ i ° --.-:2{ '11.

'A
‘
r
u
:"o
I- 19"
' n
2" -~'.'
'I I

“L-‘J

'\'

x .
\
. . ‘
M
.
\O. ““‘

I

.I
'l

 
    

   
 
 
  

W\\ l 3*" a

 

 

 

 

 

--'—~v—-._

 

31.

IX. THE COLLATERAL GANGLIA OF THE ABDOMINAL REGION

A. The Coeliac Ganglia.

 

The coeliac ganglia are flat, somewhat semilunar-
shaped masses that lie on both sides of the origin of the
coeliac artery. They are connected to each other by
plexiform fibers which follow the coeliac artery and
contribute to the coeliac plexus. The right coeliac
ganglion lies dorsad to the postcava and ventrad to
the right crus of the diaphragm whereas the left
coeliac lies dorsad to the omental bursa and stomach and
ventrad to the left crus of the diaphragm (Plate IX-H, L).
The length of the ganglion varies from a little under
seven millimeters to such a small size as to be indis-
tinguishable as a ganglion (Plate XI - figs. l-6). The
measurable average length in the six specimens was found
to be around four and a half millimeters. Based upon
this average measurement the coeliac ganglion may be con-
sidered the largest autonomic ganglion in the fox squirrel.
In one case the right coeliac ganglion gave off an ac-
cessory ganglion that contributed a few fibers to the
right renal plexus (Plate XI - fig. 2-C). Although the
size of the ganglion varies to a great extent, the paired
condition seems to be persistent. In the rat, another
rodent, the coeliac ganglion is not paired (Greene 1935,
p. 135) whereas in the cat (Field and Taylor 1950, plate

49) it may or may not be paired. In man (Gray 1936,

32.

p. 974) the paired condition resembles that of the fox

squirrel.

B. The Aorticorenal Ganglia.

 

Although variable in size and position, the aortico-
renal ganglia in the fox squirrel can always be recog-
nized because of the constancy of the splanchnic nerves
to enter directly into the ganglia (Plates IX-G, D;

XI - figs. 1-6 -A, G). In the majority of cases they
appeared to be segmented off from the coeliac ganglia.
In one case the right aorticorenal gave off a small
accessory ganglion which contributed a few filaments to
the right adrenal plexus (Plate XI - fig. 6-C). The
relations of the ganglia are the same as those for the
coeliac with the exception of the phrenic arteries which
lie immediately dorsad. According to Greene (1935,

p. 135) the aorticorenal ganglion is absent in the rat.
In the cat, Field and Taylor (1950, plate 49), Reighard
and Jennings (1935, p. 413), and Davison (1947, p. 299)
do not mention the possible existence of this ganglion.
The aorticorenal ganglion of the fox squirrel resembles
more closely the condition found in man where the gang-
lion is usually, but not always, distinguishable
(Morrill 1946, p. 89).

C. The Anterior (Superior) Mesenteric Ganglion.

 

The anterior mesenteric ganglion is a thick pyramidal-

shaped mass that is closely adherent and caudad to the

33-

base of the anterior mesenteric artery. Its shape and
size is relatively constant measuring approximately
three and a half millimeters in length. It connects
with both coeliac ganglia by means of two large strands,
variable in thickness, arising from its lateral tips
(PlatesIX-N; XI - figs. 1-6). In two cases a small
accessory ganglion was found to branch off, one from the
ganglion and the other from the right connecting strand
(Plate XI - figs. 1, 6-C). Both ganglia contributed a
few filaments to the renal plexuses. In none of the
specimens did the ganglion exhibit any complete or
partial fusion with the coeliac in contrast with both
the human (Ranson and Clark 1947, p. 134) and the cat
(Field and Taylor 1950, plate 49) where the ganglion is
often found fused with the coeliac ganglia. In the

rat (Greene 1935, p. 135) (Hunt 1931, p. 112) the an-

terior mesenteric ganglion is apparently absent.

D. The Posterior (Inferior) Mesenteric Ganglion.

 

Just craniad to the origin of the posterior mesen-
teric artery lies the posterior mesenteric ganglion. It
is relatively constant in size, measuring about three and
a half millimeters in length. Its shape is extremely
variable. Its longitudinal axis may vary from horizontal
to vertical (Plate XI - figs. 7, 8, 9). In two cases it
exhibited a bilobed condition (Plate XI - figs. 10, 12).
In another case it appeared to be almost circular (Plate

XI — fig. 11). In still another case a small accessory

34.

ganglion was found to arise from one of its anterior
roots (Plate XI - fig. 8-C). Besides its relation to the
posterior mesenteric artery and abdominal aorta the
lumbar lymph trunks, which are ventrad to the postcava,
lie immediately dorsad to the ganglion (Plate X-6). In
relation to the size of the animal the posterior mesen-
teric ganglion is larger than that found in the cat or
man. In the rat it is apparently absent (Greene 1935,

p. 135). In the cat (Reighard and Jennings 1935, p. 413)
(Field and Taylor 1950, plate 49) it is small and may be
paired while in man it is generally absent (Gray 1936,

p. 976) -

.11-- PLATE IX,

g3.

)u

We; W-ai- gal-,3: me*-.W -L. -.. -..¢-p~ -.- ".- —v--*~‘- ""-

A.
B.

\OCDNmUl-PUJ
O

10.
ll.
12.
13.
14.

15.

ABDOMINAL REGION, RIGHT VENTRAL ASPECT.

CQLLATERAL.GANGLIA AND PLEXUSES OF THE

. w‘ -h‘n--O

Abdominal Ganglionated Cord.

Ramus Communicans.

Twelfth Thoracic Vertebral Gln.
Splanchnic N.

Adrenal Plexus and A.

Renal Plexus.-

Aorticorenal Gln.

Right Coeliac Gln.

Phrenic Plexus and Inferior Phrenic A.
Branches of the Right Vagus N. .
Left Coeliac Gln.

Anterior Mesenteric Plexus.’
Anterior Mesenteric Gln.

Psoas M. (cut).

Adrenal Gld.

Right Kidney.

Ureter.

Postcava.

Right Renal A.

Right Crus of the Diaphragm.
Inferior Phrenic A.
Coeliac A. and N. P1exus..
Diaphragm (cut).

Small Intestine (cut).
Anterior Mesenteric A.
Cisterna Chyli.

Abdominal Aorta.

Left Renal A.

G}. -

 

. 1
‘W

“- v.‘ . (I
"“ 1n ' I
3' 4:131an

 

 

.,-.. _

PLATE X. THE POSTERIOR MESENTERIC GANGLION AND

‘.

4» *Mwi x- . a-..

-. v ‘_

PLEXUS, FEMALE.“

-«._...._-.-.-.- . “-a- “i‘. ,_ -.

Posterior Mesenteric Plexus.
Posterior Mesenteric Gln.
Ganglia of the Aortic Plexus.
Left Lumbar Ganglionated Cord.

Left Colic A.

Colon.

Lumbar Aortic Lymph Node.
Anterior Hemorrhoidal A.
Posterior Mesenteric A.
Lumbar Lymph Trunk.
Postcava.

Lumbar Aorta and Aortic Plexus.
Psoas M. (cut).

Iliolumbar A. and N. Plexus.
Uterine A. and N. Plexus.

X

.11“
”HI:

A

"T

 

 

         

 

 

'. '." 0 ”We

       

       

 

¢M_ .5 . r. / ///:,/:./// //V/M//%x
:. ._ IQM‘ . .m. . . .77: . I D”/ -,
‘I‘ : ll’../....:

7.
.W.///// I/I/ztamiifi/‘lll/I. rifl/flfé’gg/ I4 I

‘

        

 

 

5“

 

  

V qua-l 1. ... t 11‘ y . .1 \)1‘ ‘.
325:7). IPJEEE
"' .‘
I‘ ‘ I
4‘ ‘. .I‘ .l V! rfil 5.“
. . 1‘ II x..n...)¢.rn.uu...swhhpx.h..lutv M..-

x.) .1.
. U .I .1"..‘

.. ‘ le‘l‘il‘ 4“.

 

‘1‘!

 

 

 

 

 

PLATE XI. VARIATIONS IN THE ABDOMINAL
COLLATERAL GANGLIA.

.7.1.---1.n‘ u-‘
1'-- -u. 0:. '

. —o—- 'fli w

Figur‘ '9 3‘1"“5‘4“ *Thezcfieflflc-rflomic PITena‘l“;*and“A‘n'CET’i or“ - ‘ ‘
Mesenteric Ganglia.

Figures 7 - 12. The Posterior Mesenteric Ganglion.

A. Right Splanchnic N.

B. Right Aorticorenal Gln.
C. Accessory Ganglia.

D. Anterior Mesenteric Gln.
E. Left Coeliac Gln.

F. Left Splanchnic N.

G. 'Right Coeliac Gln.

H. Left Aorticorenal Gln.

J. Accessory Gln. of the
Aortic Plexus.

PLATE XI

  

.. —-~- - A —- - ,... W 5. . ‘
- . -figrpmgfiwmwm 1..., - M.‘, gm.” 1% mg;

 

38.

X. THE GANGLIONATED CORD OF THE ABDOMINAL REGION

The ganglionated cords of the abdominal region con-
sist of two long chains of six pairs of vertebral ganglia
extending from the first lumbar vertebra to the center of
the pelvic brim where the sixth and largest lumbar
vertebra lies (Plate XII-D). The ganglia lie ventrally
between the intervertebral discs of the vertebral col-
umn and are imbedded among the fibers of the origin of
the psoas muscles. The abdominal aorta covers most of
the cords and are thus retroperitoneal. From the upper
three lumbar vertebrae, the three tendinous origins of
the diaphragm cover a portion of the chains. The four
lumbar vessels from the aorta and postcava are in im-
mediate relation with the ganglia and cords, traversing
dorsad and caudad to each of the four ganglia. The
branches and connections of the ganglionated cord may be
grouped as follows:

A. Branches to the Aortic Plexus and Posterior Mesenteric
Ganglion.

 

From each of the second, third, fourth, and fifth
ganglia of the cord single filaments arise which follow
the four lumbar arteries and upon reaching the aorta
anastomose and contribute to the aortic plexus (Plate
XII-3, E). In addition, from the fourth ganglion and that
part of the cord connecting the fourth and fifth ganglia,

two filaments arise which traverse ventrally over the

39-

lower part of the abdominal aorta and establish anastomotic
connections with the cranial roots of the posterior
mesenteric ganglion. These two filaments may be spoken

of as the "lumbar splanchnics" (Plate XII-C) correspond—
ing to the human lumbar splanchnics of which Morrill

(1946, p. 90), gives an account. According to Morrill,

the lumbar splanchnics correspond to the thoracic splanch-
nics since they also contain afferent fibers which pass

without interruption into the pelvic viscera.

B. Connections to the Lumbo-Sacral Plexus.

 

In order to show the connections of the cord to the
lumbo—sacral plexus parts of the psoas muscles had to be
cut away, for the connections are very fine and deeply
imbedded among the muscle fibers. The rami communicantes
from the first and second ganglia connect with the ventral
root from which the iliohypogastric nerve arises (Plate
XII-10). The third ganglion gives off a ramus commun-
icans to the ventral root from which the ilioinguinal
nerve arises (Plate XII-l2). From the fourth ganglion a
ramus communicans connects with the ventral root from
which the femoral nerve arises (Plate XII-15). In addi-
tion, the fourth ganglion gives off a moderately thick
strand to the base of the ilioinguinal nerve. The fifth
and sixth ganglia establish ramal connections with the
two roots that contribute to the make-up of the sciatic
stem (Plate XII-17).

PLATE XII.

15-
16.
17.

THE GANGLIONATED CORD OF THE ABDOMINAL

REGION, VENTRAL ASPECT.

*‘-M , .7... 0..

Posterior Mesenteric Gln.
Sixth Lumbar Vertebral Gln.
Lumbar Splanchnic Nerves.

Left Lumbar Ganglionated Cord.
Fourth Lumbar Vertebral Gln.
Ramus Communicans

Anterior Mesenteric A.

Left Renal A. ‘

Lumbar Aorta and N. Plexus.
Posterior Mesenteric A.

Postcava. .

Sixth Lumbar Vertebra.

Right Lumbar A.

Tendinous Origin of the Diaphragm.

.Psoas Muscles (cut).

Iliohypogastric N.
Second Lumbar Vertebra.
Ilioinguinal N.

Left Lumbar A.

Lateral Cutaneous N.
Femoral N.

Obturator N.

Sciatic N.

PLATE XII

oza'

“"In.-xw..'..;,,

U , 1) .v’\?-\'L“ A

 

 

41.

XI. THE AUTONOMIC PLEXUSES OF THE ABDOMINAL REGION

All the plexuses of the abdomen may be conveniently
designated as-subdivisions of the coeliac plexus. The
reason for this interpretation is that all the plexuses
are connected to the coeliac either directly through
fibers or indirectly through collateral ganglia and
their branches. These subdivisions fall into two cate-
gories. Those that are paired and those that are unpaired.

The following plexuses are paired: ~

A. The Gastric Plexuses (Plate VIII-L, M).

 

The gastric plexuses consist of a very thick net-
work of fibers bounded by the lesser curvature of the
stomach and are made up of branches from the vagus
nerves and filaments from the plexus on the coeliac

artery (Plate IX-9).

B. The Phrenic Plexuses (Plate IX-J).

 

These plexuses are found in the proximal regions of
the origins of the crura of the diaphragm and are formed

from filaments from the right and left coeliac ganglia.

C. The Adrenal Plexuses (Plate IX—E).

 

The adrenal plexuses are located in the vicinity of
the hiluses of the adrenal glands and are made up of

fibers contributed by the right and left aorticorenal

42.

ganglia. A few fibers arising from the aorticorenal

branches to the kidneys may also contribute to the plexuses.

D. The Renal Plexuses (Plate IX—F).

 

The right renal plexus is located just at the hilus
of the right kidney and is made up of fibers from the
aorticorenal ganglion and occasional filaments arising
from the proximal portion of the main connection between
the anterior and posterior mesenteric ganglia. The left
renal plexus is generally made up of fibers from the

left aorticorenal ganglion.

E. The Uterine Plexuses (Plate X-ll).

 

The uterine plexuses are derived from a few fibers
arising from the posterior mesenteric ganglion and from
the aortic plexus. After pursuing the uterine arteries
they divide into subordinate plexuses supplying the
ovaries, cornua, body of the uterus, and vagina. These
plexuses are very minute and are difficult to located

with the unaided eye.

F. The Spermatic Plexuses (Plate XIII).

 

The Spermatic plexuses were well developed in all
three male specimens. The plexuses arise mainly from
the lateral portions of the posterior mesenteric ganglion.
As several large strands, they follow closely the course
of the Spermatic vessels, the caudal portion of the

ureters, and the vasa deferentia, giving off fine filaments

1+3.

to the structures named and also anastomotic fibers to
the hypogastric plexus (Plate XIII-B, C, F). Upon
reaching the neck of the bladder these strands branch and
form a dense network of fibers (Plate XIII-E) which are
distributed to the trigone, urethra, prostate gland,
penis, and associated glands. Just caudad of the trigone
and imbedded in the surface of the prostate gland sev-
eral ganglia of moderate size can be discernible. 0f

the three male specimens, one exhibited both ganglia on
the right; one showed both ganglia on the left side; and
the other had one ganglion on either side. These unnamed
ganglia may be conveniently designated as the ganglia of
the prostate gland (Plate XIII-D).

The following Plexuses are unpaired:

A. The Hepatic, Splenic, and Pancreatic Plexuses (Plate IX-9).

 

These plexuses arise from branches given off mainly
by the coeliac ganglia. The branches follow the cor-
responding branches of the coeliac artery and form fine
plexuses on the surfaces of the corresponding viscera.
These plexuses are difficult to observe without histological
slides.

B. The Aortic Plexus (Plate X—8).

 

The aortic plexus may be described as a dense net-
work of fibers adherent to the abdominal aorta and
extending from the base of the left renal artery down to

the region of bifurcation of the aorta near the pelvic

44.

brim. The plexus itself sends minute filaments to

supply all the aortic and postcaval branches below the
left renal artery. It is made up of fibers contributed

by the connection between the third and fourth ganglia

of the cord; from fibers arising from the connections
between the anterior and posterior mesenteric ganglia; and
from a few filaments arising from the posterior mesenteric
ganglion itself. In one case, Just between the origin

of the posterior mesenteric artery and the left iliolumbar
artery, two small accessory ganglia were found on the
ventral surface of the aorta. They were fused perpendic-
ularly to each other and sent connective filaments to

the uterine plexus, poSterior mesenteric ganglion, and

to the ganglionated cord. Just about five millimeters
above these two ganglia, a third ganglion was discernible
that connected to the fused ganglia and also sent fila—
ments to the ganglionated cord (Plate X-C). In one

other caSe, one ganglion was found Just a few centimeters
below the anterior mesenteric ganglion (Plate XI - fig.
6-J). These ganglia may be considered as the ganglia of

the aortic plexus.

C. The Anterior (Superior) Mesenteric Plexus(Plate IX-M).

 

The anterior mesenteric plexus consists of a dense
network of fibers concentrated around the anterior
mesenteric artery. Upon entering the intestinal mesen-
tery the plexus sends out numerous fine filaments that

follow the terminal branches of the artery into all parts

45.

of the small intestine, including a part of the proximal
portion of the large: intestine. It is made up of a
number of large fibers arising from the anterior mesen-

teric and coeliac ganglia.

D. The Posterior (Inferior)Mesenteric Plexus (Plate X-A).

 

The posterior mesenteric plexus is a linear network
of fibers that begins at the base of the posterior mesen-
teric artery, spreads, and extends along the dorsal
border of the large intestine and along with the arterial
branches it is distributed to the distal part of the
large intestine, including the upper part of the rectum.
The bulk of the plexus in the fox squirrel is made up of
fibers originating from the posterior mesenteric gang-
lion in contrast to the human in which the bulk of the
plexus is made up of fibers from the aortic plexus

(Morrill 1946, p. 88) (Gray 1936, p. 976).

PLATE XIII. VENTRAL VIEW OF THE MALE HYPOGASTRIC
REGION SHOWING THE SPERMATIC PLEXUSES.

a
‘!

g A. Posterior Mesenteric Gln. t
..,-- 1.3...Wmm, the. spamsiam wandouW-Ws-‘é 7
C. Branch to the Ureter. ?
D. Ganglia of the Prostate Gld.
E. Plexus of the Neck of the Bladder.
F. Hypogastric Plexus.

1. Postcava.
2. Spermatic V.
Spermatic A.

Ureter.

Iliolumbar A. and V.
Internal Inguinal Ring.
Prostate Gld.

Urethra and N. Plexus.

\OCDNmUl-P‘UO

Common Iliac V.

10. Common Iliac A.

ll. vas Deferens and N. Plexus.
l2. Bladder (cut).

13. Rectum (cut).

14. Posterior Mesenteric A.

15. Lumbar Aorta and N. Plexus

fl”

PLATE XIII

‘12.} :PW

‘Ffi’u‘fl

6

. I ' ' . a I
fildw-N 3V 1‘

 

3'
3
.-

P

.a‘x. ; .
”:30
.1 is. '.

 

47.

XII. THE HYPOGASTRIC PLEXUS AND THE
PELVIC VISCERAL NERVES

The hypogastric plexus is a continuation of the
aortic plexus commencing at the caudal bifurcation of
the aorta. It receives fibers mainly from the first and
second sacral vertebral ganglia (Plate XIV-G). It
appears as a group of plexiform fibers enclosing the
origin of the common iliac vessels and anastomoses with
the uterine and Spermatic plexuses (Plate XIII-F).

At the level of the third and fourth sacral verte-
brae the posterior caudal trunk (Plate XIV-4), a part
of the caudal or sacral plexus, gives rise totwo groups
of fibers, the pelvic visceral nerves (Plate XIV-D),
which directly enter the pelvic viscera and bypass the
caudal ganglionated cord. These nerves variably anastomosed
with the hypogastric plexus and were thus not very def-
inite.

48.

XIII. THE GANGLIONATED CORD OF THE PELVIC REGION

Most of the pelvic and caudal musculature had to
be cut away in order to observe the cord. Both gang-
lionated cords commence on the ventral surface of the
promontory of the sacrum and begin to converge and
decrease in size toward the caudal vertebrae where they
eventually become so minute that for purposes of gross
dissection they may be said to disappear (Plate XIV).
The terminal portion of the abdominal aorta, the middle
sacral artery, comes into immediate relation with both
cords and extends into the tail. In one case, at the
caudal portion of the right side of the sixth lumbar ver-
tebra an extra ganglion was observed in the ganglionated
cord. In other words, on the right side there were
seven lumbar vertebral ganglia instead of the usual
six (Plate XIV-A). Except for this one situation, the
sacral vertebral ganglia generally conform to the number
of sacral vertebrae. Each ganglion gives off a ramus
communicans to all the roots of the sacral plexus and
to the sacral roots of the posterior caudal trunk. On
the third sacral vertebra, the two ganglia are found to
be connected to each other by a couple of fine filaments
whereas the rest of the ganglia are quite separate
from each other (Plate XIV-F). This latter condition

persisted in all six specimens.

PLATE XIV. THE GANGLIONATED CORD OF THE PELVIC REGION.

V A. Extral Sixth Lumbar Vertebral Gln.
B. Ramus Communicans. .
3 C. Second Sacral Vertebral Gln., ' :1
WW 9 nag...» aoq“«“IMW._-v WAW orb-”O -’
D. Pelvic Visceral Nerves.
E. Ramus Communicans.
F. Third Sacral Vertebral Gln.

G. Fibers to the Hypogastric Plexus.

l. Sciatic N.

2. Pudendal N.

3. First Caudal Vertebra.
4. Posterior Caudal Trunk.
5. Second Sacral Vertebra.
6. Sixth Lumbar Vertebra.
7. Middle Sacral A.

“I Mfi‘

' PLATE IN

V

 

 

 

 

500

XIV. LIST OF REFERENCES

Burt, W. H. 1946. The Mammals of Michigan. The Univer-
sity of Michigan Press, Ann Arbor, Michigan.

Davison, A. and Stromsten, F.A. 1947. Mammalian Anatomy,
with Special Reference to the Cat. The
Blakiston Co., Philadelphia and Toronto.

Field, H. E. and Taylor, M. E. 1950. An Atlas of Cat
Anatomy. The University of Chicago Press,
Chicago, Illinois.

Gray, Henry. 1936. Anatomy of the Human Body. Lea and
Febiger, Philadelphia.

Greene, E. C. 1935. Anatomy of the Rat. Transactions
of the American Philosophical Society,
Philadelphia.

Hunt, H. R. 1924. A Laboratory Manual of the Anatomy
of the Rat. The Macmillan Co., New York.

Morrill, C. V. 1946. Anatomy of the Abdomen and Pelvis.
Edwards Brothers, Inc., Ann Arbor, Michigan.

1948. Anatomy of the Neck and Head.
Edwards Brothers, Inc., Ann Arbor, Michigan.

 

Ranson, S. W. and Clark, S. L. 1947. The Anatomy of
the Nervous System. W. B. Saunders Co.,
Philadelphia and London.

Reighard, J. and Jennings, H. S. 1935. Anatomy of the
Cat. Henry Holt and Co., Inc., New York.

. 51.
XV. CURRICULUM VITAE “x.

Nicholas James Mizeres was born in Pittsburgh,
Pennsylvania, in 1924. His early education was obtained
in Canton, Ohio, where he was graduated from McKinley
High School in 1942. The following year he entered the
service of the Army of the United States, where he spent
the next three years in the states and overseas.

In 1948 he was graduated from Kent State University
in Ohio with a Bachelor of Science degree. While at
that institution, he was an undergraduate assistant in
comparative and mammalian anatomy.

At the present time he is a graduate student in the

Zoology Department at Michigan State College.

 

1.3M
« «U
4

’1'

"59

MIC

\

IT {113111111 fijlifllfiilmflfiflflfiflfS