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iHJ:
THE CAROTID ARTERIES
IN THE PROCYONIDAE
H. ELIZABETH STORY
FIELDIANA: ZOOLOGY
VOLUME 32, NUMBER 8
Published by
CHICAGO NATURAL HISTORY MUSEUM
MAY 11, 1951
THE CAROTID ARTERIES
IN THE PROCYONIDAE
H. ELIZABETH STORY
Formerly Assistant, Division of Vertebrate Anatomy
FIELDIANA: ZOOLOGY
VOLUME 32, NUMBER 8
Published by
CHICAGO NATURAL HISTORY MUSEUM
MAY 11, 1951
iHt lift ART OF TH*
PRINTED IN THE UNITED STATES OF AMERICA
BY CHICAGO NATURAL HISTORY MUSEUM PRESS
CONTENTS
PAGE
INTRODUCTION 479
MATERIAL AND ACKNOWLEDGMENTS 480
CAROTID CIRCULATION IN THE RACCOON (Procyon lotor) 481
The Common Carotid Artery 481
The Internal Carotid Artery 481
The Circle of Willis 482
The External Carotid Artery 485
The Anterior Thyroid Artery 485
The Ascending Pharyngeal Artery 485
The Lingual Artery 488
The External Maxillary Artery 490
The Posterior Auricular Artery 492
The Superficial Temporal Artery 494
The Internal Maxillary Artery 496
The External Rete 500
The Branches of the Internal Maxillary Artery 500
The Terminal Branches of the Internal Maxillary Artery 508
CAROTID CIRCULATION IN OTHER PROCYONID GENERA 514
Bassariscus astutus 515
Nasua narica 519
Potosflavus 522
Bassaricyon alleni 526
Ailurus fulgens 528
THE PROCYONID CAROTID PATTERN 533
Internal Carotid Circulation 534
External Carotid Circulation 534
Differences from Basic Pattern 535
The Carotid Pattern in the Carnivora 536
FACTORS INFLUENCING THE PROCYONID PATTERN 544
SUMMARY 555
REFERENCES . 556
477
The Carotid Arteries in the Procyonidae
INTRODUCTION
The present study is one of a series of investigations being made
at Chicago Natural History Museum in conjunction with work on
the giant panda. More information on the vessel patterns in the
Carnivora is needed before the considerable data on the giant panda
can be evaluated. The taxonomic value of the circulatory system,
demonstrated by Davis (1941) and others, suggests the usefulness
of further study on this aspect of carnivore anatomy.
The characteristics of the carotid circulation in the Felidae have
been established (Davis and Story, 1943). The cats exhibit one ex-
treme of specialization within the superfamily Feloidea (Aeluroidea
of authors); the conditions in the other feloid families are too in-
completely known to be used for comparison. The Canoidea (Arc-
toidea of authors), to which the giant panda belongs, have been
little investigated, aside from the well-known work of Ellenberger
and Baum (1891) on the domestic dog. Accordingly, work was
begun on the arteries of the head in the raccoon, and extended to
include the other members of the raccoon family available in the
Museum collection of preserved specimens.
In order to broaden the scope of this paper, my notes on the
arteries of the head of several members of the Canidae, Ursidae,
and Mustelidae have been used to interpret the data on the Pro-
cyonidae. The Felidae, exemplifying the feloid carnivores, have been
used to emphasize both contrasts and parallels. Unfortunately, a
thorough comparison of the arteries of the head in the order Carni-
vora cannot be made without examination of many more genera
than are now available for dissection.
Simpson's (1945) classification of the Carnivora is followed, with
reservations due to certain difficulties pointed out below.
479
480 FIELDIANA: ZOOLOGY, VOLUME 32
MATERIAL AND ACKNOWLEDGMENTS
The material examined included twelve representatives of the
Procyoninae, and a lesser panda. Additional dissections were made
on a coyote, two dogs, a ferret, and a weasel. Most of these animals
were received from the Chicago Zoological Society, whose continued
co-operation is greatly appreciated. Thanks are also due the
General Biological Supply House of Chicago for the splendid em-
balming and injection done by Mr. Arnold Blaufuss. Mr. Ernest
Siegfried of the University of Chicago prepared two domestic dogs.
A few of the smaller individuals were preserved in our own laboratory.
A 9-power binocular microscope was used for much of the dissection,
making it possible to trace even the uninjected vessels to their
termini.
Frequent reference was made to the Museum's osteological
collection, from which several skulls had been selected and sectioned
in a previous study. Special thanks are due Mrs. Dorothy Foss
for careful cleaning of the foramina in key skulls.
I am deeply indebted to Mr. D. D wight Davis, Curator of
Vertebrate Anatomy in Chicago Natural History Museum, for his
helpful advice and criticism. Mr. Bryan Patterson, Curator of
Fossil Mammals, has given valuable assistance in criticizing the
manuscript.
The illustrations are intended to show the relations of the arterial
pattern to the topography of the skull. In most of the drawings,
muscles have been omitted for the sake of clarity. Structures
covered by bone or muscle are indicated by lighter shading than
structures on the surface.
The specimens dissected were all adult. The data on their
preparation are as follows:
C.N.H.M. no. 48578 Bassariscus astutus d" Gelatin injection
C.N.H.M. no. 1357 Bassariscus astutus 9 Starch injection
C.N.H.M. no. 1304 Procyon lotor 9 Starch injection
C.N.H.M. no. 1309 Procyon lotor 9 Gelatin injection
C.N.H.M. no. 1358 Procyon lotor d" Starch injection
C.N.H.M. no. 1359 Procyon lotor 9 Starch injection
C.N.H.M. no. 53935 Procyon lotor d"1 Latex injection
C.N.H.M. no. 1328 Nasua narica cf Latex injection
I. T. Sanderson Nasua narica 9 Uninjected
no. 2720M
C.N.H.M. no. 48676 Polos flavus 9 Starch injection
C.N.H.M. no. 48829 Potos flavus d" Starch injection
C.N.H.M. no. 55429 Bassaricyon alleni d1 Uninjected
C.N.H.M. no. 50815 Ailurus fulgens 9 Uninjected
STORY: CAROTID ARTERIES IN PROCYONIDAE 481
All living procyonid genera except the only slightly distinct
Nasuella, and Ailuropoda (on which detailed data were available),
are represented.
Other carnivores examined are:
C.N.H.M. no. 1312 Cam's latrans a" Latex injection
C.N.H.M. no. 1419 Cants familiaris d" Starch injection
C.N.H.M. no. 1420 Canis familiaris tf Starch injection
C.N.H.M. no. 49304 Mustela novaboracensis 9 Gelatin injection
C.N.H.M. no. 50813 Mustela putorius 9 Latex injection
CAROTID CIRCULATION IN THE RACCOON
(Procyon lotor)
The Common Carotid Artery
The common carotid arteries run forward on either side of the
trachea as far as the middle of the thyroid cartilage to the level of
the ventral crossing of N. hypoglossus. Each usually gives off no
branches until its terminal bifurcation. In one specimen there is a
minute twig to the sternothyroid muscle. In two cases out of six
the anterior thyroid arose from the common carotid instead of from
the external carotid. The common carotid artery is closely associated
with the vagus nerve and the cervical sympathetic trunk throughout
its course. At the level of the thyroid cartilage the common carotid
divides into the external and internal carotid arteries, approximately
opposite the posterior surface of the occipital condyles (fig. 82).
The internal carotid is slightly less than half the caliber of the
external carotid, bearing about the same relation to that vessel
as in the bears and pandas. In a specimen of Bassariscus astutus,
the internal carotid is three fourths the caliber of the external carotid,
and thus is apparently the largest known among carnivores.
Variations: In one individual (C.N.H.M. no. 1304) the bifurca-
tion of the left common carotid takes place far posterior, opposite
the neck of the scapula. The right common carotid in this individual
divides at the posterior border of the cricoid cartilage.
The Internal Carotid Artery
A. car otis interna runs diagonally anterodorsad beside the longus
capitis muscle to the foramen caroticum posterius, which is situated
midway between the condyloid and medial lacerated foramina. The
internal carotid has a distinct enlargement, the carotid sinus, at
its base. The average basicranial internal carotid exceeds the length
482 FIELDIANA: ZOOLOGY, VOLUME 32
of the bulla by 7 per cent. The internal carotid artery gives off
no branches outside the skull. Accompanied by the plexiform in-
ternal carotid nerve and a small vein to the sinus cavernosus, the
artery enters the anterodorsally directed carotid canal in the dorso-
medial wall of the tympanic bulla, opposite the round window. The
carotid canal arches dorsad and slightly laterad as it parallels the
promontorium. Within the canal the artery gives off fine Aa.
caroticotympanicae that accompany the two caroticotympanic nerves
onto the promontorium and anastomose with the other tympanic
arteries (fig. 83). The carotid canal arches ventrad at its anterior
end, so that in its entirety it forms an S curve. Where the carotid
canal communicates via the foramen caroticum anterior with the
foramen lacerum medium (fig. 94), the internal carotid artery receives
an anastomotic twig from the ascending pharyngeal artery, then
bends sharply dorsad to reach the floor of the cranial cavity. The
artery curves gently mesad to enter the posterior end of the sinus
cavernosus, where it takes a straight course to the tuberculum
sellae. At this point the internal carotid artery pierces the dura
mater and terminates by participating in the circle of Willis.
The internal carotid supplies a threadlike branch to the dura
mater overlying the inferior petrosal sinus. The anastomotic artery
from the orbital branch of the internal maxillary artery joins the
internal carotid opposite the dorsum sellae.
The Circle of Willis
The circle of Willis is hexagonal in outline, with considerable
irregularity in caliber and bilateral symmetry, three out of five
cases being asymmetrical. In one instance the circle took an ellipsoid
form. The internal carotid contributes the strong anterior semicircle,
and the slightly smaller basilar artery completes the circuit poste-
riorly (figs. 82 and 93).
Immediately after perforating the dura, the internal carotid
gives off the extremely slender ophthalmic artery, then breaks up
in the circle of Willis. A. ophthalmica (fig. 86) joins the strong
median branch of the internal ethmoidal and the resulting "oph-
thalmic" artery runs forward on the lateral surface of the optic
nerve into the orbit, where it terminates by anastomosing with the
rete from the ciliary arteries midway to the eyeball. The central
artery of the retina is absent.
Opposite the infundibulum the internal carotid enters the circle
of Willis and divides into three vessels, the subequal anterior and
STORY: CAROTID ARTERIES IN PROCYONIDAE 483
middle cerebrals, and the smaller posterior communicating artery.
There is no anterior communicating artery, but the anterior cerebrals
unite to form a median vessel in the longitudinal sulcus.
A. cerebri anterior arches around the optic chiasma and gives off
the internal ethmoidal1 and minute twigs to the anterior perforated
substance before it enters the longitudinal sulcus. The anterior
cerebral at once unites with its fellow and runs as a median vessel
around the genu of the corpus callosum. Here it turns backward
over the body of the corpus callosum, then divides into right and
left arteries that give off branches to the inner surfaces of the frontal
and parietal lobes, their outer surfaces along the longitudinal fissure,
and the corpus callosum, finally anastomosing near the splenium
with the posterior cerebral artery. Just before the anterior cerebral
ascends in the sulcus, it sends to the olfactory lobe a small branch,
R. bulbi olfactorii, that divides into subequal branches, one supplying
the ventral surface of the olfactory bulb, the other running in the
longitudinal sulcus, giving off twigs to the adjacent olfactory areas.
A. ethmoidalis interna (figs. 87 and 88), a medium-sized vessel,
arises from the anterior cerebral laterad of the optic nerve. The
internal ethmoidal winds toward the midline, where it runs tortu-
ously in the heavy dura beside its mate from the opposite side,
anastomosing with it, as well as with the external ethmoidal, ventral
to the olfactory lobe. The anastomosis between the two internal
ethmoidals gives rise to a median vessel that turns backward to
the optic nerves, where it divides. The resulting vessels run along
the medial surface of the optic nerves into the orbit. The true
ophthalmic joins this orbital branch.
A. communicans anterior is present as a minute vessel in one
specimen. The anterior communicating artery is a slender connec-
tion between the anterior cerebrals, which form a median vessel in
this raccoon as well as in the others. The constancy of the union
of the anterior cerebrals eliminates the necessity for a communicating
artery. In two individuals the median anterior cerebral divides at
the genu of the corpus callosum, instead of farther posteriorly.
A. cerebri media is the largest branch of the circle of Willis. It
winds dorsad between the pyriform lobe and the anterior perforated
substance to the lateral fissure, where it ramifies to the lateral surface
of the olfactory tract, the rhinal fissure, and the temporal, parietal,
and frontal lobes. The small A. chorioidea is given off by the middle
cerebral near its origin and passes backward on the cerebral peduncle
1 For use of the term "internal ethmoidal" see Davis and Story, 1943, p. 24.
484 FIELDIANA: ZOOLOGY, VOLUME 32
to the choroid fissure, where it terminates in the choroid plexus. In
three cases the choroid artery took an additional root from the
posterior communicating artery, and in one arose from it alone.
A. communicans posterior connects the internal carotid with the
terminal bifurcation of the basilar artery, and gives rise regularly
to one branch, R. hippocampi, to the hippocampal gyrus, besides
an occasional root to the choroid.
Between the first and third cervical nerve roots the vertebral
arteries form a plexus, the Rete basilaris. There is a large branch
of the vertebral at the level of the third cervical nerve root, a minute
branch at the second, and a second large branch at the first cervical
nerve. The relative caliber of these branches varies considerably,
but the rete has typically a modified diamond pattern. Posteriorly
the rete gives off the threadlike A. spinalis anterior that runs
on the ventral surface of the spinal cord, receiving anastomoses from
the arteries at each spinal nerve. Anteriorly the plexus unites to
form the basilar artery. The vertebrals sometimes unite at once,
then divide again in forming the rete.
A. basilaris extends at the midline on the medulla oblongata,
from the first cervical nerve to the anterior border of the pons, where
it bifurcates. The terminal branches of the basilar, completing the
circle of Willis, are continued into the posterior communicating
arteries at the origin of the posterior cerebrals. In its course the
basilar gives off several fine unnamed pontile rami, two pairs of
inferior cerebellar arteries on each side, the superior cerebellar,
and the posterior cerebral arteries. The basilar followed a tortuous
path in one individual and in another was small in caliber, making
the posterior half of the circle of Willis disproportionate to the large
anterior half.
A. cerebelli inferior anterior is represented by two small arteries
that arise on the pyramid opposite the root of the vagus nerve.
A. auditiva interna, a minute artery to the inner ear, is given off
as the inferior cerebellar approaches the cerebellum. A. cerebelli
inferior posterior, smaller than its companions, also arises as two
vessels, coming off either near the origin of the basilar or directly
from the rete. The two pairs of inferior cerebellar arteries anastomose
freely, supplying both the ventral and posterior surfaces of the
cerebellum.
A. cerebelli superior arises at the anterior border of the pons and
runs laterad to ramify on the anterior and dorsal surfaces of the
cerebellum.
STORY: CAROTID ARTERIES IN PROCYONIDAE 485
A. cerebri posterior arises at the level of the posterior perforated
substance and promptly divides into anterior (central) and posterior
(cortical) branches. The posterior cerebral supplies the cerebral
peduncle and the posterior and inferior surfaces of the occipital
lobe. The central and cortical branches arose independently in
three instances. A small twig, R. thalamica media, supplies the
thalamus.
The External Carotid Artery
The external carotid artery is the direct continuation of the com-
mon carotid trunk beyond the origin of the internal carotid artery.
It runs forward to the level of the anterior border of the digastric
muscle, around which it winds laterad to reach the postglenoid
process. Here the superficial temporal is given off and the trunk is
continued as the internal maxillary artery. Near the origin of the
lingual artery the hypoglossal nerve crosses the external carotid.
A branch of the superior cervical sympathetic ganglion, the external
carotid nerve, accompanies the external carotid past the digastric
muscle, and on to the internal maxillary plexus.
The external carotid gives rise to the following branches:
(1) The Anterior Thyroid Artery
The large anterior thyroid is the first branch. It supplies twigs
to the laryngeal and hyoid musculature, and the sternomastoid
muscle. The bulk of the vessel richly supplies the thyroid gland.
A branch to the sternomastoid muscle and the cervical lymph gland
usually arises opposite the thyroid cartilage, but may arise independ-
ently from the external carotid artery. A. laryngea anterior (superior)
is a small branch that takes origin either directly from the external
carotid, or from the anterior thyroid, these two origins often appear-
ing in the same animal. The anterior laryngeal artery follows the
nerve of the same name to supply the intrinsic laryngeal muscula-
ture. The anterior thyroid was absent on one side in one individual,
but this vessel on the opposite side was compensatingly enlarged.
(2) The Ascending Pharyngeal Artery
A. pharyngea ascendens (fig. 82) arises in the angle of the bifurca-
tion of the common carotid, where it crosses the anterior laryngeal
nerve and is crossed by the spinal accessory nerve. The artery
courses forward between the pharyngeal constrictor musculature
and the bulla to the level of the hamular process of the pterygoid
486 FIELDIANA: ZOOLOGY, VOLUME 32
bone, where it divides into its terminal twigs. The ascending
pharyngeal artery gives off the following branches:
(a) R. muscularis arises from the lateral wall of the ascending
pharyngeal, opposite the hypoglossal nerve, and supplies the digastric
and sternomastoid muscles.
(6) R. lymphoglandulae is given off opposite the above branch.
It ramifies to the longus capitis muscle and the cervical lymph
gland, and sends nutrient twigs to the vagus and sympathetic nerves.
(c) A. occipitalis is a small vessel that arises at the posterior
border of the bulla, and gives off at once a strong branch that runs
beside the spinal accessory nerve, supplying the nerve, the cleido-
mastoid, rectus capitis lateralis, and complexus muscles. The
occipital artery runs dorsad along the medial border of the digastric
muscle to the paroccipital process, where it breaks up. This part
of the vessel sends twigs to the digastric muscle and the superior
cervical ganglion. The terminal twigs supply the walls of the trans-
verse sinus, the atlanto-occipital capsule, and the deep axial muscula-
ture, in addition to an anastomosis with the posterior meningeal
and vertebral arteries. In three out of ten cases, the posterior
meningeal was a branch of the occipital artery. The occipital trunk
was absent in one individual, but the branches arose from the
ascending pharyngeal and were distributed as usual.
(d) A. meningea posterior, a vessel of variable caliber, takes
origin at the level of the posterior lacerated foramen. After giving
off the inferior tympanic as well as rami to Mm. longus capitis and
rectus capitis ventralis, the bulk of the posterior meningeal anasto-
moses with the occipital and vertebral arteries. The terminal
branch of the posterior meningeal, much diminished in caliber,
enters the hypoglossal canal beside the twelfth nerve and the con-
dyloid vein, supplying the walls of this canal, the adjacent dura,
and nutrient twigs to the nerve. A. tympanica inferior enters the
foramen lacerum posterior beside the internal jugular vein, runs
between the bulla and the promontorium, sending a twig to the
walls of the transverse sinus, and terminates on the promontorium
by anastomosing with the other tympanic arteries; it supplies the
periosteum of the bulla. The mastoid meningeal ramus of the
posterior auricular trunk takes over the area of dura supplied by
the posterior meningeal in Felis domestica.
The ascending pharyngeal supplies the longus capitis, rectus
capitis ventralis, pharyngeal constrictor, tensor veli palatini, and
R. anast. a. infraorbitalis
A. labialis su
A. infraorbitalis
Canal, infraorb.
A. angularis
A. maxillaris externa
A. infraorbitalis
temp. prof. ant.
A. buccinatoria
rFor. pal.ant.
. R. anast. a. pal. ant. sin.
_ R. anast. sphenopal.
.R. anast. a. pal. ant. sin.
. A. septi nasi median! int.
-For. paLmed.
Rr. anast.
(Rete externum)
A. masseterica
A. temp. prof. post. -j,i
R. anast. a. men. med. ^/^/
A. alv. inf..
A. meningea med.
R. tensoris tymp
A. maxillaris interna
For. orale .
A. temp, superf.
A. auric, pro .
R. m. digastricus ^
A. maxillaris externa
Meatus acusticus til.
A. auric, post.
R. gl. parotidis
R. nutriens.
R. auric. ^
A. stylomastoidea ,
Proc. mastoid. ,
R. occipitalis .
R. m.cleidomast
A. lingualis,
A. occipitalis ^
R. m. com plexus.
A. CAROTIS EXTERNA _
R. m. digastricus
Proc.paroccipitali
A. pharyngea asc. _
A. CAROTIS IXTERXA
Sinus caroticum
A. laryngea sup.
R. m. longus cap.
R. lymphogl.
R. m. stern omast
A. thyreoidea sup.
A. CAROTIS COMMCXIS
A. palatina ant.
R. anast. sphenopal.
A. palatina desc.
A. sphenopalatina
R. anast. a. pal. ant.
Tr.sphenopal.-tpalatina desc.
A. palatina post.
A. ethmoid, ext.
A. ethmoid, int.
R. m. pteryg.
A. canal, pteryg.
A. orbitalis
A. anastomotica
A. ciliaris
R. anast. a. meningea med.
R. nasopharyngeus
A. cerebri ant.
A. ethmoid, int.
A. ophthalmica
R. ant., circ. Willisi
A. anastomotica
A. canal, pteryg.
A. cerebri med.
CIRCULUS ARTERIOSUS WILLISI
A. comm. post.
R. palatinus
Rr. eustachii
R. pharyngeus
R. anast. a. carotis interna
For. lacerum med.
A. thalamica media
A. cerebelli superior
A. basilaris
A. cerebelli inf. ant.
R. nutriens
for. caroticum post.
Rr. pontis
A. cerebelli inf. post.
Rr. musculares
A. tymp. inf.
Foramen lacerum post.
A. meningea post.
R. sinus transversus
Canal, hypoglosxi
R. anast. a. vertebralis
A. spinalis ant.
A. vertebralis at N.eerc.3
FIG. 82. Ventral view of the arteries of the head in the raccoon. X 1 1A-
487
488 FIELDIANA: ZOOLOGY, VOLUME 32
levator veli palatini muscles, and nutrient twigs to the adjacent
bone, as it lies beside the bulla.
At the posterior border of the hamular process of the pterygoid
bone the ascending pharyngeal divides into its terminal branches,
the palatine and pharyngeal rami.
(e) R. palatinus runs craniad between Mm. levator veli palatini
and constrictor pharyngis anterior, giving off a twig to the velum
palatinum. The palatine branch then ramifies in the glands of the
soft palate, anastomosing with the tonsillar and posterior palatine
arteries.
(/) R. pharyngeus ascends dorsolaterally to the auditory (Eusta-
chian) tube, where it gives off several minute Rr. tubarii, the pharyn-
geotympanic artery, and a small anastomotic artery to the internal
carotid (fig. 83). The above-mentioned small arteries may arise
from a common trunk. The anastomotic artery is constant, and
joins the internal carotid near the exit of the great deep petrosal
nerve from the carotid canal. The pharyngeal branch gives off
twigs to the pharyngeal tonsil, then spends itself in the mucosa of
the nasopharynx, receiving an anastomosis from the sphenopalatine
artery.
A. pharyngeotympanica enters the middle ear medial to the tendon
of the tensor tympani muscle and anastomoses with the other
tympanic arteries on the promontorium.
(3) The Lingual Artery
A. lingualis (fig. 95), the largest branch of the external carotid,
is given off at the level of the stylohyal cartilage. It is accompanied
by the hypoglossal nerve as far as the hyoglossal muscle, beneath
which the artery turns, but the nerve remains on the lateral surface
of the muscle. The lingual artery gives off the following branches:
(a) R. m. digastricus is the first branch. It supplies the posterior
part of the digastric muscle.
(6) R. tonsillaris posterior arises at the level of the stylohyoid
and winds between the anterior and middle pharyngeal constrictors
to enter the soft palate. The posterior tonsillar artery is distributed
to the posterior and middle surfaces of the palatine tonsil, and the
adjacent glandular area of the soft palate. Twigs anastomose with
the anterior tonsillar, the ascending pharyngeal palatine ramus, the
posterior palatine, and the palatine branch of the middle meningeal
trunk. This artery is accompanied by the tonsillar branch of the
glossopharyngeal nerve. In one specimen the posterior tonsillar
STORY: CAROTID ARTERIES IN PROCYONIDAE
489
arose from the pharyngeal constrictor ramus of the ascending
pharyngeal.
R. m. pteryg. int.
A. meningea med.
R. n
N. petros.
A. stylomastoid
N. fa
R. m. digastri
R. anast. a
pharyngea
/ppoc
for. stylomasto
R. auric, n. wgu
R. nutriens
Bulla. (cut)
V. anast. V. ph
R. palatinus
R. pharyngeus
N. canalis
pterygoidei
A. pharyngea asc.
. pharyngeotymp.
R. tons. phar.
r. caroticum ant.
'or. lacerum med.
anast. a. carot. int.
petros. super}, maj.
nal. caroticum
& N. caroticotymp.
, caroticum post.
•arotis int.
carotis interna
nus cavemosus
p., N. gtossophar.
ms trans versus
men lacerum post.
tymp. inf.
anast. a. phar. asc.
I. hypoglossi
mingea post,
rticulares
A. & V. anast. vertebralis
FIG. 83. Arteries of the right auditory region in the raccoon. The floor of
the bulla and external auditory meatus have been removed. X 4.
(c) R. tonsillaris anterior arises opposite the styloglossal muscle,
to which it sends twigs, then arches mesad to reach the anterior
margin of the palatine tonsil, where it enters the rich arterial plexus
of the tonsil.
490 FIELDIANA: ZOOLOGY, VOLUME 32
(d) R. m. mylohyoideus arises at the posterior margin of the
mylohyoid muscle, which it supplies, finally anastomosing with the
submental artery from the external maxillary.
(e) R. geniohyoideus leaves the lingual anterior to the body of
the hyoid, mesad of the hyoglossal muscle, and after sending twigs
to the adjacent muscles, anastomoses with its mate from the opposite
side. The trunk thus formed runs forward, supplying the geniohyoid
muscles, to terminate at the symphysis by anastomosis with the
sublingual artery.
(/) Rr. dorsales linguae are given off at irregular intervals as the
lingual artery lies between the genio- and styloglossal muscles.
These arteries richly supply the dorsum of the tongue, their course
roughly paralleled by branches of the hypoglossal nerve.
A few millimeters beyond the entrance of the lingual nerve, the
lingual artery breaks up into its terminal branches, the sublingual
and deep lingual arteries. The smaller vessel, (0) A. sublingualis,
joins the duct of the sublingual gland, and supplies the genioglossal
muscle on its course to the symphysis. Much diminished in caliber,
the artery sends a minute twig to the frenulum, then anastomoses
with the geniohyoid branch of the lingual, and with the incisive
branch of the inferior alveolar.
(h) A. lingualis profunda, the larger branch, accompanied by
terminal twigs of the lingual nerve, enters the ventral surface of
the styloglossal muscle, coursing near the midline, approaching the
inferior surface of the body of the tongue. From the anterior border
of the genioglossus, the deep lingual lies beside the narrow lyssa
(cartilaginous median supporting rod of the tongue). The artery
breaks up into numerous small branches that go to the tip of the
tongue, forming minute anastomoses with its fellow and with twigs
derived from the dorsal lingual.
(4) The External Maxillary Artery
A. maxillaris externa1 (fig. 85) arises at the posterior border of
the external pterygoid muscle, opposite the external acoustic meatus,
immediately beyond the posterior auricular artery. The external
maxillary runs first laterally, then anteriorly between the digastric
and internal pterygoid muscles, and crosses the submaxillary duct,
emerging near the middle of the digastric in company with an
anastomotic loop between the mylohyoid and buccal nerves. The
artery follows the anteroventral border of the masseter muscle as
1 In all other procyonid genera this artery precedes the posterior auricular.
STORY: CAROTID ARTERIES IN PROCYONIDAE 491
far as the posterior angle of M. buccinator, where the vessel bifurcates
into inferior and superior labial arteries. A small sympathetic nerve
from the external carotid nerve accompanies the external maxillary
artery. In one case the posterior auricular followed the origin of
the external maxillary.
The branches of the external maxillary follow:
(a) R. m. digastricus is the first branch given off by the external
maxillary. It supplies the posterior part of the digastric muscle.
(6) R. glandulae submaxillaris arises near the lateral border of
the digastric and passes ventrad to enter the submaxillary gland.
This vessel arose from the occipital trunk in one specimen, and from
the submental in another.
(c) A. submentalis, a large branch, comes off near the anterior
border of the internal pterygoid muscle. The artery parallels the
duct of the submaxillary gland and the mylohyoid nerve as it runs
anteriorly between the mylohyoid and digastric muscles, which it
supplies. The submental artery continues along the ventromedial
border of the mandible as far as the symphysis, where it anastomoses
with its fellow of the opposite side. A delicate twig follows the
lateral border of the digastric muscle to its insertion.
(d) R. lymphoglandulae ramifies to the sub-maxillary lymph
nodes.
(e) Rr. m. masseterici are several twigs to the ventral border of
the masseter muscle.
(/) A. labialis inferior is given off opposite the third molar, and,
joined by the inferior buccal nerve, runs along the ventral border
of the buccinator muscle and the alveobuccal gland, to which it
supplies numerous twigs. The inferior labial artery terminates in
the skin of the lower lip, anastomosing with its fellow of the opposite
side.
(g) A. labialis superior is the continuation of the external
maxillary artery beyond the point at which the inferior labial arises.
The superior labial artery, in company with the superior buccal
nerve, follows the posterodorsal border of the buccinator muscle,
supplying that muscle and the platysma, and terminates by anasto-
mosing with a branch of the infraorbital artery in the vicinity of the
third premolar. The strong artery resulting from this union follows
the margin of the upper lip, anastomosing with the artery of the
opposite side, and other infraorbital twigs, and gives off a branch
to the outer surface of the septum. A. septi nasi [externi] anastomoses
492 FIELDIANA: ZOOLOGY, VOLUME 32
with septal branches of the ethmoidal, sphenopalatine, and anterior
palatine arteries (figs. 85 and 88). A. angularis,1 a large branch
of the superior labial, arises opposite the first molar, ramifies in the
superficial muscles, sends a twig toward the lateral angle of the eye
to join the lateral palpebral, and anastomoses in front of the infra-
orbital foramen with twigs from the medial palpebral and transverse
facial arteries. Terminal twigs of the angular artery accompany
the external nasal nerve.
(5) The Posterior Auricular Artery
A. auricularis posterior is a large branch arising from the anterior
part of the external carotid (fig. 84), opposite the mastoid process,
and at its origin associated with the posterior auricular nerve. The
following branches are given off:
(a) R. mm. pterygoidei et masseterici, the small first twig, arises
from the anterior wall of the posterior auricular. In one case this
artery anastomosed with the digastric ramus from the lingual artery.
(6) R. nutriens is given off at the same level as the muscular
twig but from the opposite wall of the trunk. It supplies one twig
to the digastric, runs along the posterior border of the bulla, supply-
ing the adjacent musculature, and enters a small foramen at the
paroccipital process.
(c) R. parotideus arises opposite the mastoid process and richly
supplies the parotid gland, as well as sending an anastomotic twig
to the superficial temporal. The parotid ramus gives off a slender
branch that parallels the parotid duct, supplying it and anastomosing
with the transverse facial and superficial labial arteries.
(d) R. occipitalis is a large trunk given off at the anteromedial
border of the mastoid process. A. stylomastoidea, the first branch
of the occipital ramus, joins the facial nerve, along which it runs,
giving nutrient arteries to the nerve and to the surrounding bone.
The stylomastoid artery gives off first the A. tympanica posterior,
which accompanies the chorda tympani, supplying the inner surface
of the tympanic membrane and anastomosing with the anterior
tympanic branch from the internal maxillary. Before reaching the
genu facialis, the stylomastoid sends an anastomotic twig to the
inferior tympanic. The vessel breaks up opposite the round window
of the cochlea, supplying the outer surface of the secondary tympanic
membrane, the stapedial muscle, the adjacent mastoid bone, the
1 Thisjartery is homologous to the angular artery of human anatomy. Its
thread-like dimensions in the cat caused it to be overlooked in our preceding
study. The angular artery in that paper was a misnomer for the medial palpebral.
STORY: CAROTID ARTERIES IN PROCYONIDAE
493
great superficial petrosal nerve, and the proximal portion of the facial
nerve, anastomosing with the internal auditory artery and with the
arterial plexus on the promontorium.
The occipital branch winds mesad around the mastoid process
between the insertions of the digastric and the sternomastoid muscles,
R. anast. a. temp, superf.
R. anterior
R. m. temporalis
R. auric, ant?
a. temp. /^
superf,
M. trapezius
M. rhomboideus
M. splenius
R. superf.
R. meningeus
••*" R. profundus
Capsula artic.
R. posterior
R. gl. parotidis
A. maxillaris externa'
A. auric, post.
R. occipitalis
A. lingualis/
R. m. sternocleidomast. R. m. digastricus'
A. can it is externa/
A. pharyngea asc.'
A. occipitalis'
Rr. articulares
R. m. complexus
R. sinus transversus
R. anast. a. vertebralis
A. meningea post.
A. tymp. inf.
R. m. rectus cap. vqntralis
R. anast. a. vertebralis
R. lymphogl.
R. m. longus cap.
FIG. 84. The posterior auricular and occipital arteries in the raccoon. The
left external ear has been retracted anterolaterally. X \1A..
to which it sends twigs, and continues postero-dorsad through the
insertion fibers of M. rectus capitis lateralis. The occipital branch
runs underneath the complexus, across the obliquus capitis anterior
and the biventer cervicis to the midline, where it anastomoses with
its fellow of the opposite side. A deeper branch courses through
the M. obliquus capitis anterior to the rectus capitis dorsalis complex,
one twig perforating the insertion tendon of the complexus to emerge
on the lambdoidal crest along which it runs almost to the'midline.
494 FIELDIANA: ZOOLOGY, VOLUME 32
Twigs are supplied to the surrounding axial musculature, in addition
to a well-developed R. meningeus that accompanies a large vein
through the mastoid foramen into the skull, where it supplies the
dura mater of the posterior cranial fossa. The occipital ramus has
taken over the distribution of the main occipital trunk of Felis
domestica and Homo.1
(e) R. auricularis posterior is the continuation of the main trunk
of the posterior auricular after the origin of the occipital ramus.
A medium-sized branch is distributed to the free lateral surface of
the auricle; then a larger branch supplies the posterior margin and
associated muscles. A small branch ramifies to the medial surface,
penetrating the cartilage after giving off muscular twigs. A strong
JR. auricularis anterior runs between the pinna and the temporal
muscle to the anterior border of the pinna, where it ramifies in
M. intermedius scutulorum. The posterior auricular terminates in
several superficial and deep branches to the posterior part of the
temporal muscle, one twig anastomosing with the middle temporal
branch of the superficial temporal.
(6) The Superficial Temporal Artery
A. temporalis superficialis (fig. 85) is the comparatively small last
branch of the external carotid. It takes origin at the level of the
postglenoid process, and runs in close association with the auriculo-
temporal nerve all the way to the orbit. The superficial temporal
artery winds laterad around the temporomandibular joint, then
arches anterodorsally across the zygoma and the temporal fascia to
the posterior margin of the orbital ligament, where, covered by the
scalp musculature, it divides into its terminal frontal and parietal
branches.
The superficial temporal supplies the following branches:
(a) R. articularis arises at the level of the postglenoid process
and supplies the capsule of the mandibular joint. A. auricularis
profunda, a minute medial twig from the articular ramus, runs
between the cartilaginous and bony parts of the meatus and supplies
the external surface of the tympanic membrane, as well as part of
the skin of the meatus. The deep auricular artery sends a slender
branch, A. tympanica anterior, through the petrotympanic fissure,
where it joins and supplies the chorda tympani, anastomosing with
the posterior tympanic artery.
1 For a discussion of the occipital trunk in the domestic cat and man, see
Davis and Story, 1943, pp. 13-14.
o
'S
•8
"3.
495
496 FIELDIANA: ZOOLOGY, VOLUME 32
(6) R. massetericus, the largest branch, arises at the mandibular
condyle and runs deep in the masseteric muscle, one branch (R.
dorsalis) following the curve of the zygoma, the other (R. ventralis)
turning toward the ventral border of the masseter. Twigs anasto-
mose with the external maxillary, masseteric, and buccinator arteries.
(c) A. transversa faciei, a slender vessel, arises just beyond the
masseteric ramus and runs forward across the masseter muscle,
giving twigs to the superior buccal nerve. It supplies the superficial
layer of the masseter, and anastomoses with a twig of the angular
artery external to the infraorbital foramen.
(d) A. auricularis anterior comes off opposite the transverse
facial artery and is hidden by the parotid gland throughout its course.
The anterior auricular supplies twigs to the parotid gland and to
the anterior surface of the pinna, besides anastomosing with a small
parotid twig from the posterior auricular artery.
(e) A. temporalis media, the second largest branch, takes origin
at the articular tubercle. It accompanies a temporal branch of
the auriculotemporal nerve directly dorsad, crossing the root of the
zygoma, and piercing the temporal aponeurosis to ramify in the
temporal muscle. The middle temporal artery receives an anasto-
mosis from the anterior auricular branch of the posterior auricular
artery. As the superficial temporal follows the zygomatic arch it
sends arterioles to the periosteum, forming a minute zygomatic rete
that is paralleled by companion venules. Near the center of the
zygomatic arch a twig loops across to join the transverse facial artery.
(/) A. zygomatico orbitalis is given off several millimeters after
the superficial temporal reaches the anterior part of the temporal
muscle, and is a minor anastomotic nutrient branch that follows the
zygomaticoorbital nerve and joins the lateral palpebral artery at the
lateral angle of the eye.
Shorter twigs from the superficial temporal pass to the orbital
region as the artery arches posterior to the orbital ligament. R.
parietalis, the posterior terminal branch, ramifies in the temporal
fascia in the parietal region, reaching almost to the vertex. The
anterior terminal branch, R. frontalis, winds past the medial angle
of the eye to break up into small twigs that supply the frontal
periosteum and anastomose with the medial palpebral artery.
The Internal Maxillary Artery
Beyond the origin of the superficial temporal artery the external
carotid is continued, without diminishing in size, as the internal
497
498 FIELDIANA: ZOOLOGY, VOLUME 32
maxillary artery. A. maxillaris internet, joins the auriculotemporal
nerve at the postglenoid process and winds around the medial
extremity of the mandibular condyle into the infratemporal fossa
(fig. 86). Here the internal maxillary crosses the anterior part of
N. mandibularis, runs between the external and internal pterygoid
muscles and is crossed dorsally by N. masticatorius (to masseter,
temporal, pterygoid and buccinator muscles). Beyond the foramen
rotundum the artery rests upon the dorsal surface of the internal
pterygoid muscle, and accompanies the maxillary nerve. At the
level of the palatine notch the internal maxillary terminates by
dividing into the infraorbital and sphenopalatine-descending palatine
trunks. An incipient rete surrounds the internal maxillary in the
infratemporal fossa. Many of the arteries of this region are closely
associated with branches of the cranial nerves.
ASSOCIATED NERVES AND ARTERIES OF THE HEAD
IN PROCYON LOTOR
Artery Nerve
A. carotis communis accompanies vagus nerve; sympathetic
cervical trunk
A. carotis interna accompanies N. carotis interna (sym-
pathetic)
A. ophthalmica accompanies optic nerve
A. ethmoidalis interna accompanies olfactory nerve
A. spinalis anterior nutrient to spinal cord and spinal nerves
A. auditiva interna facial and auditory nerves
A. carotis externa crossed by hypoglossal nerve; paralleled
by sympathetic cervical
A. laryngea anterior accompanies N. laryngeus anterior
A. pharyngea ascendens crosses N. laryngeus anterior; crossed by
glossopharyngeal nerve
A. meningea posterior nutrient to hypoglossal nerve
A. occipitalis constant nutrient ramus to spinal ac-
cessory nerve
A. lingualis accompanies hypoglossal nerve; crossed
at base by ramus digastricus; sympathetic
cervical ganglion
A. maxillaris externa mylohyoid nerve anastomoses with N.
buccalis inferior
R. m. digastricus accompanies ramus digastricus; sympa-
thetic cervical ganglion
A. submentalis accompanies mylohyoid nerve for a few
mm.
A. labialis inferior accompanies N. buccalis inferior (facial
nerve)
A. angularis terminal twigs join N. nasalis externi
A. labialis superior accompanies N. buccalis superior (facial
nerve)
STORY: CAROTID ARTERIES IN PROCYONIDAE 499
Artery Nerve
A. auricularis posterior N. auricularis posterior (facial nerve) at
origin and for a few mm.
A. stylomastoidea nutrient to ramus auricularis; vagus nerve
and facial nerve in stylomastoid foramen
A. temporalis superficialis accompanies N. auriculotemporalis all
the way to orbit (facial nerve)
A. transversa faciei nutrient to N. buccalis superior (facial
nerve)
A. temporalis media accompanies ramus temporalis, N. auri-
culotemporalis of facial nerve
A. zygomatico-orbitalis nutrient to ramus zygomaticus, N. zygo-
matico-orbitalis (facial nerve)
A. maxillaris interna accompanies N. auriculotemporalis from
postglenoid process to foramen ovale,
there crosses N. mandibularis and is
crossed by motor root of N. trigeminus,
then accompanies N. maxillaris
Rete externum surrounds N. trigeminus, nutrient to N.
maxillaris
Rete internum absent
Ramus temporalis profundus medius N. temporalis profundus medius
A. temporalis profunda posterior N. temporalis profundus posterior
A. masseterica N. massetericus
A. meningea media N. mandibularis; nutrient to ganglion
semilunare
R. m. pterygoideus internus accompanies N. m. pterygoideus internus
from N. mandibularis
R. anastomoticus cum A. meningea
media accompanies and nutrient to N. maxillaris
Aa. ciliares longae accompanies N. ciliares longi on bulb
A. ciliaris N. opticus
A. orbitalis crosses N. maxillaris
Rete orbitalis surrounds N. maxillaris and N. opticus
A. zygomatica accompanies nutrient to N. zygomaticus
A. lacrimalis accompanies and nutrient to N. lacrimalis
A. frontalis accompanies and nutrient to N. frontalis
A. anastomotica accompanies N. maxillaris; nutrient to
N. ophthalmicus and N. maxillaris
A. canalis pterygoidei nutrient to N. canalis pterygoidei from
ganglion sphenopalatinum
A. temporalis profunda anterior accompanied at origin by N. buccinator-
ius
A. temporalis profunda media accompanies N. temporalis profundus
medius (N. mandibularis)
A. buccinatoria accompanies N. buccinatorius
A. infraorbitalis accompanies N. infraorbitalis
A. alveolaris superior posterior accompanies N. alveolaris superior pos-
terior
A. palpebralis media accompanies N. nasalis externi
A. alveolaris superior anterior accompanies N. alveolaris superior an-
terior
500 FIELDIANA: ZOOLOGY, VOLUME 32
Artery Nerve
A. palatina posterior accompanies N. palatinus posterior
A. palatina descendens accompanies N. palatinus anterior
A. palatina anterior each branch accompanied by ramus of
N. palatinus anterior
A. sphenopalatina N. sphenopalatinus from ganglion spheno-
palatinum
Terminal twigs of A. sphenopalatina. . .accompanies N. nasalis posterior superior
lateralis and N. nasalis posterior superior
medialis
The External Rete
From the foramen ovale to the orbital fissure the branches of
the internal maxillary are looped together by slender anastomotic
vessels. The loose network, or Rete externum, thus formed, is inter-
meshed with the venous pterygoid plexus. The chief arteries involved
are the posterior deep temporal, orbital, meningeal anastomotic,
middle meningeal, ciliary, proper anastomotic, and pterygoid; the
ramifications of these vessels are described below.
The external rete is hidden ventrally by the internal pterygoid
muscle and dorsally by the external pterygoid muscle, the most
dorsal and medial arterioles lying between this muscle and the
sphenoidal periosteum. The mandibular and masticatory divisions
of the trigeminal nerve pass through the rete posteriorly, and the
maxillary nerve pierces the anterior part. Periorbita separates the
rete from the ophthalmic division of the fifth cranial nerve, but
this division is joined by the main trunks of the rete as it enters
the apex of the orbital cone to become continuous with the orbital
rete. The external rete in Procyon is the same type as that found
in the domestic cat (Davis and Story, 1943), the difference being
one of degree. The basic pattern in Procyon foreshadows the com-
plex specialization found in Felis domestica. There is no internal
rete in the raccoon.
The Branches of the Internal Maxillary Artery
(1) A. alveolaris inferior arises at the anterior border of the
postglenoid process, and runs forward dorsad of the internal ptery-
goid muscle. The inferior alveolar artery is accompanied by the
vein and nerve of the same name as it passes laterad of the tendon
of M. mylohyoideus into the mandibular foramen. The artery
courses through the mandibular canal, at first directed diagonally
ventrad, to the vicinity of the root of MI, there crossing to the
STORY: CAROTID ARTERIES IN PROCYONIDAE 501
medial side of its companion nerve, to parallel the lower margin of
the corpus mandibulae. Within the canal the inferior alveolar artery
gives off twigs to the sockets and pulp cavities of the teeth and to
the adjacent bone, as well as nutrients to N. alveolaris inferior.
The artery divides at the apex of the canine root into lateral and
medial branches. The large lateral branch breaks up into rami that
emerge via the several mental foramina, with accompanying nerves
and veins, onto the external surface of the jaw, to terminate in
anastomoses with the inferior labial and submental arteries. The
smaller medial branch by-passes the canine to approach the inner
surface of the mandible, sending rami to the incisors, their alveoli,
and the surrounding bone, anastomosing at the symphysis mentis
with the corresponding vessel from the other side, with the sublingual
artery, and, after passing through small foramina below the inci-
sors, with the inferior labial. Twigs from these anastomoses supply
vibrissae and superficial musculature of the lower jaw.
(2) A. temporalis profunda posterior is a large branch that comes
off opposite the lingual nerve. The much weaker masseteric artery
is the first branch of the posterior deep temporal. A. masseterica
joins the masseteric nerve and winds around the medial end of the
mandibular condyle to the posterior margin of the coronoid process.
Here the masseteric artery divides into lateral and medial branches
that ramify in the deep fibers of the masseteric and temporal muscles
on their respective surfaces of the coronoid process. Twigs anasto-
mose with both branches of the transverse facial, with the external
maxillary, and with the anterior and posterior deep temporal arteries.
The posterior deep temporal sends a large branch to the posterior
part of the temporal muscle, and to the temporomandibular joint.
The bulk of the artery runs anterodorsally along the medial surface
of the coronoid process, supplying the temporal muscle. Twigs
arising at intervals from the main trunk anastomose with the mas-
seteric, anterior deep temporal, orbital and anastomotic arteries
(fig. 86). The delicate arterial network surrounds the internal
maxillary artery and the external pterygoid muscle, partially
paralleling the convolutions of the elaborate pterygoid venous plexus.
(3) A. meningea media1 (figs. 96 and 97) arises just anterior to
the posterior deep temporal, from the ventral wall of the internal
maxillary. The middle meningeal artery follows the posterior border
1 The intracranial distribution of the meningeal arteries was checked on dry
skulls C.N.H.M. nos. 49227 and 47386 and found to be essentially the same as
in the preserved specimens.
502 FIELDIANA: ZOOLOGY, VOLUME 32
of the mandibular nerve into the foramen ovale. Midway between
its origin and its entry into the cranial cavity, the artery crosses
the chorda tympani nerve. At this level the strong R. m. pterygoidei
interni is given off to the massive internal pterygoid muscle, one
twig anastomosing with an internal pterygoid branch farther for-
ward and another accompanying N. mylohyoideus, to anastomose
with A. submentalis. This muscle branch supplies a minute palatine
twig that accompanies the tensor veli palatini muscle ventrad onto
the hamular process of the pterygoid. The palatine twig ramifies
in the periosteum of the hard palate, anastomosing with the posterior
palatine, tonsillar, and ascending pharyngeal arteries. The middle
meningeal artery gives off a nutrient twig to the bulla and a branch,
R. tensoris tympani, that crosses diagonally over the tendon of the
tensor veli palatini to run along the medial surface of that tendon
to reach the tensor tympani muscle and anastomose with the tym-
panic arterial network.
Within the cranium the middle meningeal runs posteriorly along
the lateral surface of the semilunar ganglion to the tentorium, which
the main vessel parallels as it sends branches to the dura mater
of the posterior half of the middle cranial fossa. The branches of the
middle meningeal extend to the level of the anterior limb of the
ectosylvian gyrus, where they anastomose with the well-developed
accessory meningeal artery. The main branches occupy grooves in
the parietal bone, supplying this bone as well as the temporal.
R. petrosus superficialis arises at the level of the hiatus facialis,
which it enters beside the great superficial petrosal nerve. A. tym-
panica superior is a small vessel that is given off a short distance
laterad of the petrosal branch. The superior tympanic runs between
the tentorium and the periotic, which it supplies.
The middle meningeal receives anastomotic vessels from the
large anastomotic branch of the internal maxillary and from the
small anastomotic branch of the ciliary. These few slender anasto-
moses are the only indication of intracranial rete formation. Nu-
merous small perforating arterioles communicate with terminal twigs
of the temporal and posterior auricular arteries.
(4) A. orbitalis (fig. 86) is a large trunk that arises at the point
where the buccinator nerve crosses the internal maxillary artery.
Outside the periorbita the orbital artery sends its first small branch,
R. temporalis, to the ventral part of the temporal muscle and to
the external rete, anastomosing with the posterior deep temporal.
The orbital artery arches mesad, pierces the periorbita, and breaks
STORY: CAROTID ARTERIES IN PROCYONIDAE
503
up into the following terminal branches at the apex of the orbital
muscle cone:
Lamina cribrosa
R. anast. a. ethmoid, int.
Rr. anast.
R. ventralis a. ethmoid, ext.
R. dorsalis a. ethmoid, ext.
Aa. ciliaris brev.
A. ciliaris long.
Sinus sphenoid.
I
For. ethmoid. — 14 —
A. ciliaris
A. & N. frontalis
For. opticum
V. ophthalmica
A. ophthalmica
N. ophlhalmicus
Fissura orbiialis
A. meningea
A. anastomotica
A. ethmoid, int.
For. rotuiidum
R. anast. a. men. med.
Sella turcica
A. ophthalmica
Sinus cavernosus
Dor sum sellae
A. carotis interna
For. lacerum med.
For. caroticum ant.
Canal, caroticum
R. periostei
Si mix petrosus inf.
A. aud. int.
For. caroticum post.
V. jugularis interna
& Foramen jugulare
Canal, hypoglnssi
For. postcondyloid.
For. magnum
A. carotis interna
A. ethmoid, ext.
R. mm. oculi med. (superior)
A. & N. lacrimalis
R. mm. oculi lat. (inferior)
A. infraorbitalis
N. maxiUaris
'A. & N. buccinator.
A. temp. prof. ant.
A. orbitalis
A. & N. temp. prof. med.
'A. & \". masseter.
A. temp. prof. post.
N. lingualis
Nn. temp. prof.
•A. & N. alv. inf.
N. mylnhyoid.
A. maxillaris interna
For. orale
Ganglion semilunare
~A. meningea media
R. petros. superf.
V. vertebralis-
Sinus transversus/
V. mastoidea'
Meatus acusticus inlernus
tf~Sinus petrosus sup.
R. men. a. occip.
Teiitorium
FIG. 87. Intracranial view of infratemporal and orbital branches of the
internal maxillary artery in the raccoon, seen from above. The dissected skull
is tipped slightly ventrad, toward the right. X 2.
(a) R. muscularis lateralis (corresponding to the inferior muscular
ramus of human anatomy), supplies the lateral, inferior, and medial
recti, and part of the retractor oculi. Opposite the optic foramen
the muscular branch gives off a secondary branch that accompanies
504 FIELDIANA: ZOOLOGY, VOLUME 32
the optic nerve, participates in the loose orbital rete, and gives
off the zygomatic, supraorbital and lacrimal arteries. The zygomatic
and supraorbital arteries arise from a slender common trunk a few
millimeters anterior to the optic foramen and accompany the
zygomatic nerves to the orbital ligament. A. zygomatica, the lateral
vessel, pierces the orbicularis oculi at the lateral corner of the eye,
where it anastomoses with the orbital branch, of the anterior deep
temporal. A. supraorbitalis, the medial vessel, emerges from the
orbit near the middle of the upper eyelid, and terminates by joining
the anterior deep temporal. A. lacrimalis takes origin from the
orbital rete anteriorly, sends nutrient twigs to N. lacrimalis, and
exhausts itself in the substance of the lacrimal gland. The lateral
palpebral, from the lacrimal in Felis domestica, comes from the
anterior deep temporal in Procyon lotor.
(6) A. anastomotica (fig. 87) is the largest branch of the orbital
artery before the origin of the external ethmoidal. A long slender
branch of the anastomotic vessel follows the optic nerve to join
the orbital rete near the bifurcation of the ciliary artery; other
twigs anastomose with the external ethmoidal and the base of the
ciliary. An accessory meningeal artery, half the caliber of the
middle meningeal, is given off just outside the orbital fissure, through
which it runs along the ophthalmic division of the trigeminal nerve
posteriorly, supplying the dura of the anterior half of the middle
cerebral fossa and anastomosing with the middle meningeal at the
ectosylvian gyms as well as in the vicinity of the semilunar ganglion.
The accessory meningeal sends nutrient twigs to the frontal bone,
in addition to perforating anastomoses to the temporal arteries.
The anastomotic trunk turns posteriorly to enter the orbital fissure,
and runs backward into the sinus cavernosus. The artery extends
to the level of the posterior lacerated foramen, then doubles back
upon itself to anastomose with the internal carotid artery, thus
contributing to the circle of Willis. Opposite the dorsum sellae
the anastomotic artery sends several minute twigs, Rr. hypophysei,
to the hypophysis cerebri. The hypophyseal branches may arise
from the combined trunk of the internal carotid and anastomotic
arteries.
(c) A. ciliaris usually arises opposite the orbital fissure and
runs forward with the ophthalmic nerve, first giving off a small
anastomotic ramus. In three dissections out of ten, the ciliary arose
from the internal maxillary independently, at the anterior border
of the external pterygoid muscle. The first branch of the ciliary
STORY: CAROTID ARTERIES IN PROCYONIDAE 505
artery, R. anastomoticus, turns posteriorly, out of the orbital cone,
to run along the lateral surface of the maxillary nerve, sending
nutrient arteries to this nerve and to the semilunar ganglion. The
anastomotic branch terminates by uniting with the middle meningeal
artery at its entry to the cranial fossa.
The ciliary artery immediately sends a strong anastomosis to
the external ethmoidal artery and crosses the ophthalmic nerve and
the lateral and superior recti muscles, then curves beneath the
M. levator palpebrae superioris to reach the dorsal surface of the
optic nerve. Fine anastomotic twigs unite the ciliary with the other
orbital vessels, forming a loose network or Rete orbitalis (fig. 86)
within the orbit. The ciliary has three terminal branches:
A. ciliaris longa medialis is given off a few millimeters beyond
the ethmoidal foramen and courses forward outside the eyeball.
Anterior to the insertion of the medial rectus the medial long ciliary
artery pierces the sclera to supply the ciliary process and the iris.
A. ciliaris longa lateralis is distributed on the lateral surface of
the eyeball in like manner to its mate. The long ciliary arteries are
accompanied by the nerves of the same name.
A. ciliaris brevis medialis arises a short distance anterior to the
medial long ciliary, and is followed by the lateral long and short
ciliaries. The short ciliary arteries perforate the sclera around the
entrance of the optic nerve to supply the choroid coat, their branches
radiating from the margin of the optic papilla to the retina, taking
over the area usually supplied by the A. centralis retinae, absent
in raccoons.
(d) A. ethmoidalis externa (figs. 87 and 88), the continuation of
the orbital artery, arches across the ocular muscles, nerves, and
vessels, to the ventral surface of the medial rectus, which it parallels
as far as the ethmoidal foramen. The external ethmoidal receives
anastomotic twigs from the inferior muscular ramus and the great
anastomotic artery, then gives off the superior ocular muscular ramus,
corresponding to the "superior" of human anatomy. R. muscularis
medialis supplies both the superior and the medial recti, the levator
palpebrae superioris and part of the retractor oculi. Opposite the
levator palpebrae superioris the external ethmoidal gives rise to
the small frontal artery, which joins and gives nutrient twigs to the
nerve of the same name. Near its origin A. frontalis gives off a
twig to the periosteum, then the R. trochlearis, opposite the ethmoidal
foramen, to supply the superior oblique muscle and anastomose with
the supraorbital artery near the trochlea. The frontal artery, with
I
506
STORY: CAROTID ARTERIES IN PROCYONIDAE 507
the nerve and vein of that name, emerges at the medial angle of the
eye and unites with the orbital branch of the anterior deep temporal.
Beyond the origin of the frontal artery the external ethmoidal
is markedly increased in caliber by a strong anastomotic branch
from the ciliary artery. Just before entering the cranial cavity the
external ethmoidal gives off the small anterior meningeal. A. men-
ingea anterior enters the skull through a minute foramen, to supply
the dura of the anterior cranial fossa, and anastomose with the
accessory meningeal artery. The external ethmoidal artery and
nerves pass through the large ethmoidal foramen to the floor of the
olfactory fossa. Here the artery winds dorsad around the olfactory
lobe, giving off numerous twigs to the lamina cribrosa, and two large
dorsal and ventral branches. R. dorsalis arches across the cribri-
form plate to pass into the nasal fossa at the angle formed by the
frontal with the ethmoidal, and courses forward between the bony
roof and the mucosa of the superior nasal meatus, emerging on the
nose between the nasal bone and cartilage. This artery gives off
twigs to the dorsal ethmoidal cells, the anterior part of the nose
and the skin, a cutaneous twig anastomosing with the external artery
of the septum (from the infraorbital). R. ventralis tortuously crosses
the lamina cribrosa to enter the nasal cavity near the center of the
ethmoturbinals and immediately fans out to supply the olfactory
region, anastomosing with the posterior septal branch of the spheno-
palatine.
On the dorsal surface of the olfactory lobe the much diminished
external ethmoidal anastomoses with the slender internal ethmoidal
(from the circle of Willis), and the terminal twigs from this anasto-
mosis supply the dura and ethmoid cells of the frontal sinus.
(5) R. m. pterygoidei interni, a small vessel, springs from the
internal maxillary opposite and slightly anterior to the orbital
artery. The branch supplies the central part of the extensive
internal pterygoid muscle, sends a twig to the external pterygoid,
and anastomoses with the orbital, masseteric, and posterior deep
temporal arteries.
(6) A. canalis pterygoidei is given off ventrally immediately
after the muscular branch. It runs beneath the maxillary nerve to
the minute pterygoid canal, through which it continues posteriorly
beside the Vidian nerve, to anastomose with a twig of the ascending
pharyngeal near the auditory tube. This vessel supplies nutrient
arteries to the nerves in the pterygopalatine fossa and contributes
to the external rete.
508 FIELDIANA: ZOOLOGY, VOLUME 32
(7) A. temporalis prof undo, anterior is a well-developed trunk
arising at the same level as the A. canalis pterygoidei, but from the
dorsal wall of the internal maxillary. The anterior deep temporal
runs forward parallel to the internal maxillary artery and with N.
buccinator as far as the orbital gland. A. temporalis profunda media,
the first branch, runs mesad with the nerve of the same name to
supply the deep anterior part of the temporal muscle. A. buccina-
toria, a small vessel, arises at the posterior border of the orbital
gland, across which it runs, in company with the buccinator nerve.
The buccinator artery sends twigs to the orbital gland, the molar
alveoli, and the buccinator muscle, and anastomoses with the
superior labial artery. Beyond the buccinator artery the anterior
deep temporal ascends along the posterior border of the infraorbital
fat cushion to the orbital ligament, supplying the adjacent part of
the temporal muscle. After piercing the orbital ligament at the
external angle of the eye, the anterior deep temporal gives off the
lateral palpebral arteries, then runs along the orbital ligament,
sending numerous branches to the superior tarsal arch, the adjacent
superficial musculature and the scalp. Much diminished in caliber,
the anterior deep temporal terminates by anastomosing with the
medial palpebral, frontal and superficial temporal arteries at the
internal (medial) angle of the eye.
Aa. palpebrales laterales ramify along the free borders of the eye-
lids, their twigs forming a thick network, the tarsal arches, with
other twigs of the anterior deep temporal. These arteries anastomose
with the somewhat smaller medial palpebrals, from the infraorbital
artery, near the internal angle of the eye. In two cases the anterior
deep temporal supplied twigs to the lacrimal gland.
A small branch of the anterior deep temporal, or of its buccinator
branch, arches around the lateral border of the infraorbital fat
cushion, supplying it and the walls of the large deep facial vein.
(8) R. m. pterygoidei interni is given off midway between the
anterior deep temporal artery and the internal pterygoid muscle.
The Terminal Branches of the Internal Maxillary Artery
The internal maxillary artery divides into its terminal branches
opposite the posterior palatine notch. The larger, or lateral, branch
supplies structures external to the skull and the medial branch
structures within the skull.
(9) A. infraorbitalis (fig. 85), the lateral branch, which is the
continuation of the internal maxillary, accompanies the infraorbital
STORY: CAROTID ARTERIES IN PROCYONIDAE 509
nerve across the internal pterygoid muscle and the maxillary tubero-
sity to the infraorbital foramen. Within this foramen, the infra-
orbital artery in ramifying profusely over the external surface of the
maxilla gives rise to the following branches: A. alveolaris superior
posterior arises opposite the second molar and is distributed to both
molars. A. alveolaris superior media is given off at the level of the
pterygopalatine canal, and supplies the first molar and the fourth
premolar. An additional alveolar artery arises a few millimeters
farther forward, and passes through a foramen into the maxillary
sinus, where it ramifies to the fourth premolar. A large alveolar
artery and nerve enter a canal that runs to the canine alveolus.
The alveolar arteries are accompanied by the nerves of the corre-
sponding name. Inside the infraorbital foramen the infraorbital
artery divides into dorsal and ventral branches.
The dorsal branch,1 A. palpebralis medialis, ramifies together
with N. nasalis externi over the side of the nose, anastomosing with
the angular branch of the external maxillary and with the orbital
branch of the anterior deep temporal. Before emerging from the
infraorbital foramen the vessel gives rise to a trunk that divides at
the lacrimal canal into the medial palpebral arteries proper that
pass on each side of the medial palpebral ligament to enter the
superior and inferior tarsal arches. Aa. palpebrales mediales supply
the superficial muscles at the internal angle of the eye, as well as
the lacrimal sac and the nictitating membrane. One of these twigs
may reach the arterial plexus on the nasal mucoperiosteum. The
medial palpebral arose from A. ciliaris in one case.
The ventral branch, the continuation of the infraorbital artery,
runs forward in the muscles of the upper lip, to richly supply the
musculature of the snout in addition to an external septal (philtral)
branch. Twigs anastomose with the superior labial artery, the
sphenopalatine, the septal branch of the anterior palatine, and with
the infraorbital from the opposite side. Aa. alveolares superiores
anteriores (fig. 85) are given off to the premolars, canine and incisors,
1 Davis and Story (1943) called this vessel "A. angularis" in Felis domestica.
This term can not be used, for a careful review of dissections of the external
maxillary in the cat reveals a thread-like angular artery from the external maxillary
in addition to the so-called "A. angularis" from the infraorbital. In man, unnamed
rami from the infraorbital supply the lower eyelid and adjacent structures, but
the medial palpebral arteries proper are derived from the enormous ophthalmic
artery. The vessel in carnivores reaches the same structures that are supplied
by the two anastomosing channels in man, but the infraorbital is enlarged and the
other source dwindled. Because of this shift of proportions in carnivores an exact
homology with man is not possible. The term "medial palpebral artery" seems
most appropriate to use in the following pages.
510 FIELDIANA: ZOOLOGY, VOLUME 32
and are accompanied by the nerves of the same name, derived from
N. maxillaris.
The medial terminal branch of the internal maxillary, the com-
bined trunk of the descending palatine and sphenopalatine arteries,
is a longer vessel than in the cat and only one half the caliber of the
infraorbital. It gives off the posterior palatine artery at its base,
then crosses the body of the maxilla to reach the pterygopalatine
canal, where it divides into the subequal descending palatine and
sphenopalatine arteries.
(10) A. palatina posterior is a small vessel that accompanies the
posterior palatine nerve and large palatine vein through the posterior
palatine notch onto the hard palate. It ramifies in the palatine
glands and anastomoses anteriorly with the anterior palatine artery,
posteriorly with the palatine ramus of the ascending pharyngeal
and posterior tonsillar branch of the lingual artery.
(11) A. palatina descendens, a slightly smaller vessel than the
sphenopalatine, accompanies the anterior palatine nerves through
the pterygopalatine canal, giving off several small twigs, Aa. pala-
tinae minores, that pass through minute foramina and are nutrient
to the palatine nerves as well as the palate. The descending palatine
artery emerges on the hard palate through the posterior palatine
foramen opposite the middle of the first nerve, and from this point
takes the name A. palatina anterior (fig. 82). It gives off an anasto-
motic twig to the posterior palatine artery, then runs forward in a
groove on the hard palate to the incisive (anterior palatine) foramen.
The anterior palatine supplies the mucoperiosteum of the hard
palate, and terminates in an anastomotic network with its fellow
from the opposite side and with a branch of the sphenopalatine at
the incisive foramen. Twigs from the network circle around the
cartilage of Jacobson's organ and supply the mucosa of that struc-
ture, as well as the lining of Stenson's duct, anastomosing with the
posterior septal artery. A large median trunk, A. septi nasi mediani,
is formed by the coalescing anterior palatine arteries at the incisive
foramen. This vessel arches posteriorly to enter a well-developed
median incisive palatine foramen, and doubles back upon its course
as it reaches the inferior nasal meatus. The median septal artery
then runs forward, between the cartilaginous septum and the incisive
bone, to terminate in the rich arterial plexus supplying the snout
(fig. 88).
(12) A. sphenopalatina enters the nasal cavity through the
sphenopalatine foramen, and immediately gives off the posterior
STORY: CAROTID ARTERIES IN PROCYONIDAE 511
nasal septal artery and a pharyngeal twig. The sphenopalatine
artery runs forward along the lateral wall of the inferior nasal meatus,
accompanied by N. nasalis posterior superior lateralis, to the posterior
border of the maxilloturbinals, where it breaks up into its terminal
branches, the lateral posterior nasals and the anastomotic branch
to the anterior palatine (fig. 88). A. nasalis posterior septi gradually
crosses over to the septum, then ramifies to the ethmoturbinals, the
septum, and the vomeronasal (Jacobson's) organ, anastomosing
with the ethmoidal and anterior palatine arteries. R. pharyngeus
supplies the mucous membrane of the nasopharyngeal meatus,
anastomosing with the ascending pharyngeal. The nasal muco-
periosteum is supplied by a rich plexus of interlacing blood vessels
from the above-named anastomosing arteries and their companion
veins, forming a spongy tissue similar to that of the corpus caver-
nosus. Aa. nasales posteriores laterales are three or four vessels of
almost equal caliber that run forward upon the mucous membrane
lining the maxilloturbinals and the nasal meati, anastomosing with
branches of the ethmoidal, anterior palatine, and infraorbital
arteries, all providing high vascularization to the snout. A branch
coursing along the floor of the inferior nasal meatus, supplying the
lining of that cavity, reaches the incisive foramen, where it enters
a rich plexus from the anterior palatine arteries.
The topographical relationships of the arteries of the head to
other structures associated with the skull is indicated by the follow-
ing list of the contents of the cranial foramina.
CONTENTS OF CRANIAL FORAMINA OF CARNIVORA
(All openings of the skull in approximate order from anterior to posterior)
Anterior palatine (paired)
Nerve: Naso palatine from sphenopalatine ganglion
Artery: Anastomosis of anterior palatine with sphenopalatine
Vein: Anastomosis of anterior palatine with sphenopalatine
Remarks: Stenson's duct, confluence of nasal and buccal cavities
Median anterior palatine
Nerve: None
Artery: Median septal (anastomoses with septal artery of infraorbital)
Vein: V. comitans
Remarks: Foramen absent in Canidae and Felidae, large in Ursidae
Infraorbital
Nerve: Maxillary-
Artery: Infraorbital; medial palpebral in some forms
Vein: Venules
Remarks: Occasional subdivision for middle palpebral artery and external nasal
nerve
512 FIELDIANA: ZOOLOGY, VOLUME 32
Accessory infraorbital (unnamed)
Nerve: None
Artery: Middle palpebral
Vein: None
Remarks: Opens inside infraorbital foramen, leads to lacrimal; presence variable
Canine alveolar canal (unnamed)
Nerve: R. dentis canini
Artery: Alveolaris superior media to canine
Vein: None
Remarks: Position variable
Alveolar canals (in maxillary tuberosity; unnamed)
Nerve: R. sinus maxillaris; Nn. alveolares superiores post, and med.
Artery: Alveolares superiores post, and med.
Vein: V. comitans
Remarks: Variable in number
Lacrimal
Nerve: Lacrimal ramus of ophthalmic division of trigeminal
Artery: Branch of middle palpebral
Vein: None
Remarks: Lacrimal sac
Sphenopalatine (internal orbital)
Nerve: Lateral posterior superior nasal branch from sphenopalatine ganglion
Artery: Sphenopalatine
Vein: V. comitans
Remarks: Sometimes confluent with pterygopalatine canal
Pterygopalatine canal
Nerve: Descending palatine
Artery: Descending palatine
Vein: None
Small posterior palatine foramina (minor)
Nerve: Anterior palatine
Artery: Minor palatine
Vein: None
Remarks: Also arteries nutrient to nerve branches
Posterior palatine (major)
Nerve: Anterior palatine
Artery: Anterior palatine
Vein: None visible at 12 X.
Palatine notch (incisura palatina)
Nerve: None
Artery: Posterior palatine
Vein: Anterior palatine (groove in palate)
Remarks: Closed by ligament to form foramen
Fenestrae cribrosae
Nerve: Olfactory; ethmoidal (from ophthalmic)
Artery: Many twigs of internal ethmoidal
Vein: V. comitans
Ethmoidal
Nerve: External ethmoidal (from ophthalmic)
Artery: External ethmoidal
Vein: External ethmoidal
STORY: CAROTID ARTERIES IN PROCYONIDAE 513
Optic
Nerve: Optic
Artery: Ophthalmic
Vein: Ophthalmic
Orbital fissure (lacerum anterior; sphenorbital)
Nerve: Oculomotor; trochlear; trigeminal; abducens
Artery: Accessory meningeal; anastomotic artery
Vein: Orbital
Remarks: Sometimes confluent with foramen rotundum
Rotundum
Nerve: Maxillary branch of trigeminal
Artery: Small anastomosis to middle meningeal
Vein: Venules
Pterygoid (Vidian) canal
Nerve: Canalis pterygoideus from sphenopalatine ganglion
Artery: Canalis pterygoideus
Vein: V. comitans
Remarks: Exit lateral to orbital fissure; entrance near foramen lacerum medium
Median basisphenoid canal
Nerve: None
Artery: None
Vein: Branch to sinus cavernosus
Remarks: At suture with presphenoid; enters cranial fossa at tuberculum sellae
Alisphenoid canal
Nerve: None
Artery: Internal maxillary
Vein: None
Remarks: Sometimes confluent with foramen ovale; present in Canidae, Ursidae,
Ailurus, Viverridae
Ovale
Nerve: Mandibular; motor root of trigeminal
Artery: Middle meningeal
Vein: Venules
Canalis musculotubarius
Nerve: Minor superficial petrosal; R. tensoris tympani
Artery: Arterioles
Vein: Venules
Remarks: Auditory tube in medial half; tendon of M. tensor veli palatini in
lateral half
Lacerum medium
Nerve: None
Artery: Anastomotic artery with internal carotid
Vein: Large vein from inferior petrosal sinus, draining to pharyngeal and
pterygoid plexuses
Anterior carotid (intracranial exit of carotid canal)
Nerve: Internal carotid, division to cavernous plexus
Artery: Internal carotid
Vein: Branch from sinus cavernosus
Postglenoid
Nerve: None
Artery: None
Vein: Internal facial, from superior petrosal sinus
514 FIELDIANA: ZOOLOGY, VOLUME 32
Internal auditory meatus
Nerve: Facial; acoustic
Artery: Internal auditory
Vein: Nutrient venules
External auditory meatus
Nerve: Small branches of auriculotemporal (V3); small branches of auricular
ramus of vagus
Artery: Deep auricular
Vein: Venules
Stylomastoid
Nerve: Facial; auricular ramus of vagus
Artery: Stylomastoid; posterior tympanic
Vein: Venules
Remarks: Sometimes confluent with fossa for tympanohyal bone
Caroticum posterium (extracranial)
Nerve: Internal carotid (both divisions)
Artery: Internal carotid
Vein: Branch from sinus cavernosus
Remarks: Situated midway between foramen lacerum posterium and basi-
sphenoid
Lacerum posterium
Nerve: Glossopharyngeal, vagus, and spinal accessory
Artery: Inferior tympanic
Vein: Branch from transverse sinus
Jugular
Nerve: None
Artery: R. sinus trans versi
Vein: Internal jugular
Remarks: Enters inferior petrosal sinus at confluence with transverse sinus
Condyloid (hypoglossal)
Nerve: Hypoglossal
Artery: Posterior meningeal
Vein: Anastomotic branch from vertebral vein
Remarks: Confluent with foramen lacerum posterium in Hyaeninae
Postcondyloid (intracranial)
Nerve: None
Artery: None
Vein: Vertebral
Remarks: Empties from transverse sinus, posterolaterad to condyloid foramen
Mastoid
Nerve: None
Artery: Meningeal ramus from occipital branch of posterior auricular
Vein: Branch from transverse sinus
Magnum
Nerve: Spinal cord
Artery: Vertebral
Vein: Vertebral
CAROTID CIRCULATION IN OTHER PROCYONID GENERA
Because of the basic similarity in the arterial pattern of the follow-
ing specimens, only those vessels that present differences from
Procyon will be described.
STORY: CAROTID ARTERIES IN PROCYONIDAE 515
Bassariscus astutus (fig. 89)
The common carotid artery bifurcates at the middle of the
thyroid cartilage, approximately opposite the foramen magnum,
slightly farther forward than in Procyon. The internal carotid
artery is three fourths the caliber of the external carotid.
In the region of the carotid sinus, the internal carotid gives off
a fine arteriole to the carotid body, and another to the superior
cervical ganglion. The basicranial internal carotid is slightly shorter
than in Procyon, being approximately 65 per cent of the length of the
bulk. Within the carotid canal the artery arches gently antero-
dorsad, without deviating laterally toward the promontorium, and
then bends sharply dorsad to enter the sinus cavernosus. A caro-
ticotympanic artery is given off near the foramen lacerum medium.
The bone-enclosed portion of the internal carotid is greater than
in Procyon, as the carotid canal extends from the level of the posterior
border of the promontorium to the foramen lacerum medium.
The internal carotid gives off the ophthalmic artery before enter-
ing the circle of Willis. The ophthalmic is a small vessel, but rela-
tively much larger than that of Procyon. It gives off several small
hypophyseal twigs, and receives the anastomotic artery from the
internal maxillary, but does not give rise to a central artery of the
retina.
There is no anterior communicating artery.
The internal ethmoidal arteries remain as two vessels as far as
the anterior surface of the olfactory lobe, where they anastomose
with the external ethmoidal. There is no median anastomosis of the
internal ethmoidals.
The circle of Willis is nearly identical in pattern to that figured
for Procyon, but with the posterior half of the circle of larger caliber.
The terminal part of the posterior communicating artery has a
diminished caliber as it joins the internal carotid.
There is no collateral middle cerebral. The olfactory area is
supplied by rami from the middle cerebral instead of from the ex-
ternal ethmoidal.
At the root of the third cervical nerve, the vertebral artery gives
off a large branch that joins its fellow at the midline in a diamond-
shaped anastomosis. Two large parallel arteries run forward,
receiving small twigs from the vertebral at the second cervical nerve,
and medium-sized terminal vertebral branches at the first nerve.
Here the arteries form a second diamond, then continue as one
516 FIELDIANA: ZOOLOGY, VOLUME 32
Bassariscus astutus — continued
vessel, the basilar artery, with a caliber greater than the internal
carotid.
The common carotid gives off a branch (from the ascending
pharyngeal in Procyori) to the sternomastoid muscle and the large
cervical lymph gland before its bifurcation.
The external carotid gave off the anterior laryngeal artery at its
base in one specimen, but in the other the vessel arose from the
lingual artery. As the external carotid crosses the recessus meatus,
it sends a twig through a foramen in the floor of the meatus, to
supply the external surface of the tympanic membrane.
The ascending pharyngeal is small, with much of its usual dis-
tribution taken over by twigs of the occipital. The ascending
pharyngeal gives a nerve nutrient twig that completely encircles
the nerves emerging from the foramen lacerum posterius. The
terminal R. pharyngeus sends two small arteries into the foramen
lacerum medium, one of them to anastomose with the internal
carotid as well as supply the great deep petrosal nerve as it enters
the Vidian canal, the other twig being nutrient to the basisphenoid
bone. The other terminal branch, R. palatinus, gives off the small
pharyngeotympanic artery.
The occipital artery is relatively large and has complete occipital
distribution, supplying the splenius, the biventer cervicis and the
intrinsic axial musculature. The inferior tympanic branch also gives
off R. lymphoglandulae and R. mm. longus capitis and digastricus.
R. sinus transversus also sends a nutrient twig to the carotid canal.
Only a small part of the posterior meningeal artery enters the con-
dyloid foramen. The bulk of the posterior meningeal anastomoses
with the vertebral, with a smaller anastomosis with the ascending
pharyngeal, and a twig to the M. longus capitis.
The digastric branch of the lingual artery also supplies the sub-
maxillary gland and an adjacent lymph gland.
The rather large external maxillary arises before the posterior
auricular in both specimens, and differs from the artery in Procyon
in having a large buccinator ramus, which anastomoses with the
small inferior labial artery and gives off the medial palpebral, a
vessel of less than half the size of the lateral palpebral. This origin
of A. palpebralis media occurs in no other carnivore examined. A
twig from the external maxillary artery crosses the zygoma, sends
a nutrient twig to the parotid duct, and anastomoses with a terminal
twig of the superficial temporal.
A. zygomaticoorbital
A. temp, media
A. temp, superf
A. meningea
media
A. auric, post.
R. temporal is
R. meningeus
R. anast
a. vertebralis
A. occipitalis
A. carotis interna
Sinus caroticu
A.carot. comm
A. pharyngea
A. laryngea sup.
A. carotis externa
A. anastomoticaR.- mm- ^"'i med- (suP6™01")
R. anast. a. men. med. / /A. ciliana
litalis A. masseterica / / / / R- mm. oculi lat. (inferior)
. — i — .. i A_ ethmoid, ext.
A. palp, lat
_. ciliares
A. palp. med.
A. angularis
.. sac. lacrimalis
.Rr. nasales extern!
,R. alveolaria
A. infraorbitalis
A. sphenopalatina
A. palatina desc.
Tr. sphen.-pal. desc.
A. lingual is
sterna
A. temp. prof. ant. \ R. g] orbitalis
A. buccinatoria
Bassariseus
A. meningea media
A. zygomaticoorbitalis I A. temp. prof. post. R" anast a' men' med'
A. temp, superf.
A. auric, post.
R. m. temp.
R. occi
A. anastomotica
A. ethmoid, ezt.
P' lat
A. ciliaris
- Palp- med.
R. sac. lacrimalis
Aa. nasales externi
R. alveolaris
R.m.pteryg,
A. can. pteryg.
A. temp. prof. ant. .
A. buccinatoria
A. maxillaris interna
A. maxillaris externa
.
A. pharyngea asc.
A.carot. comm.
Tr. sphen.-pal. desc.
Nasua
. A. infraorbitalis
, A. sphenopalatina
A. palatina desc.
A. palatina post.
FIG. 89. Main branches of the external carotid circulation in the cacomistl,
Bassariscus astutus (XI), and in the coati, Nasua narica (X %). The extent of
the frontal sinus is indicated by diagonal lines.
517
518 FIELDIANA: ZOOLOGY, VOLUME 32
Bassariscus astutus — continued
The posterior auricular artery is very large, with its main branch
subequally dividing to supply the temporal muscle and the auricle.
The occipital ramus is represented by a slender vessel that runs
along the lambdoidal crest and by a branch to the sternomastoid
muscle. The branch to the anterior surface of the auricle is small.
The middle temporal branch is the largest one from the superficial
temporal artery. The masseteric ramus comes off opposite the deep
auricular muscle. In one individual the deep auricular artery arose
from the external carotid. The transverse facial gives a fair-sized
ramus to M. platysma, and anastomoses with the zygomatic branch
of the external maxillary.
The external rete follows the same arrangement as in Procyon
but the anastomotic vessels are smaller in proportion to the internal
maxillary artery. There is no internal rete.
The palatine twig of the middle meningeal is relatively twice the
caliber of that branch in the raccoon. Intracranially, the middle
meningeal1 runs parallel to the tentorium to the level of the posterior
limb of the ectosylvian gyrus, where it runs vertically, giving branches
that extend to the region of the Sylvian fissure. Here terminal twigs
of the meningea media anastomose with the large accessory menin-
geal.
The ciliary artery arises immediately posterior to the orbital
fissure, giving muscular, short and long ciliary rami. The short
ciliaries, which form a complex rete at the distal third of the optic
nerve, enter the optic papilla at its periphery, giving off six radially
arranged rami that supply the retina. A recurrent anastomotic
ramus from the short ciliary artery, halfway to the eyeball, is
nutrient to the optic nerve. There is no central artery of the retina.
Near its base the ciliary gives off a very small anastomotic ramus
that is nutrient to the ophthalmic division of the trigeminus and
anastomoses with the middle meningeal near the semilunar ganglion.
In one individual the ciliary trunk was doubled after the origin of
the anastomotic twig.
The orbital artery is a large trunk of the same caliber as the
ciliary, and arises a short distance anterior to that vessel. The
orbital artery gives off the anastomotic artery, the A. canalis ptery-
goidei, the lateral muscular ramus, and the lacrimal artery, after
which the trunk is continued as the external ethmoidal. The
1 The pattern of the meningeal arteries was checked on dry skull C.N.H.M.
no. 46013 and found to be identical with the preserved specimens.
STORY: CAROTID ARTERIES IN PROCYONIDAE 519
Bassariscus astutus— continued
lacrimal artery gives off the medial muscular ramus, the supra-
orbital and the zygomatic arteries. The ethmoidal rete gives off
the small anterior meningeal artery at the dorsal surface of the ol-
factory lobe, as in Felis domestica.
At the emergence of the ophthalmic nerve from the orbital
fissure the orbital artery gives off the A. anastomotica, which is
distributed mostly as the accessory meningeal (exceeding the middle
meningeal in caliber), but with a slender anastomosis with the
ophthalmic branch of the internal carotid artery and another with
the middle meningeal. There is reciprocal variation between the
anastomotic artery and the accessory meningeal, with the former
being the larger in two out of four cases. The accessory meningeal
supplies the area of dura between the coronal sulcus and the Sylvian
fissure, which its main branch parallels (fig. 96).
The anterior and middle deep temporal arteries are very large.
The buccinator artery is a small branch of the former vessel. The
lateral palpebrals, from the anterior deep temporal, greatly exceed
the medial palpebrals in size and distribution.
The internal maxillary terminates opposite the orbital fissure at
the origin of the orbital artery, in a rather weak infraorbital and the
subequal sphenopalatine-descending palatine trunk.
The most dorsal of the external nasal rami of the infraorbital
artery sends a recurrent twig through a small foramen to supply
the lacrimal sac. The infraorbital fat cushion is supplied by a
branch of the fourth and last of the series of posterior superior
alveolar arteries.
The anterior palatine artery emerges on the hard palate opposite
the anterior border of the first molar, slightly farther forward than
in Procyon.
Nasua narica (fig. 89)
The common carotid artery bifurcates at the middle of the thyroid
cartilage, approximately at the level of the occipital condyles,
exactly as in Procyon. The internal carotid is slightly more than
half the caliber of the external carotid. The basicranial internal
carotid is relatively long, exceeding the length of the bulla by 72
per cent. The carotid canal is shorter than in Procyon, arching more
sharply, with a slight lateral flexure toward the promontorium. The
two caroticotympanic arteries are given off opposite the antero-
medial border of the promontorium.
520 FIELDIANA: ZOOLOGY, VOLUME 32
Nasua narica — continued
After piercing the dura mater, the internal carotid gives off the
R. hypophysis, then enters the circle of Willis. The true ophthalmic
artery, from the hypophyseal ramus, is a threadlike nutrient twig
to the optic chiasma, terminating by anastomosis with the recurrent
loop of the internal ethmoidal.
The pattern of the circle of Willis is nearly identical with that
of Procyon, but the anterior half of the circle of Willis is more
elongated, as the large common trunk of the anterior and middle
cerebral arteries divides equally at the anterior border of the optic
chiasma. The posterior communicating artery is slightly smaller
than the middle cerebral. There is no anterior communicating artery.
The vertebral artery gives large branches at the third and first
cervical nerves, forming a basilar rete of asymmetrical diamond
shape. The basilar artery thus formed is two thirds the caliber of
the internal carotid. The posterior inferior cerebellar artery is a
single small vessel. The anterior inferior cerebellar is a large artery.
The external carotid gives off the anterior thyroid artery opposite
the second tracheal ring, farther anterior than in the raccoon. The
sternomastoid branch comes from the occipital artery.
The anterior laryngeal artery, from the external carotid, sends
an anastomotic branch to the ascending pharyngeal artery near the
superior cervical ganglion.
The ascending pharyngeal, larger than the occipital artery, gives
off a nutrient artery to the accessory nerve. The anastomotic branch
to the internal carotid at the foramen lacerum medium is small and
very tortuous.
The occipital artery, from the ascending pharyngeal at the
mastoid process, takes over the R. lymphoglandulae and R. mm.
digastricus and sternomastoideus supplied by the parent vessel in
Procyon.
The external maxillary artery arises at the lateral border of the
digastric muscle, before the posterior auricular artery, and from its
origin sends a branch across the external pterygoid muscle to the
orbital gland. The submental artery is a branch of the external
carotid just beyond the lingual artery. The terminal branches of
the external maxillary are of small caliber but anastomose in exactly
the same way as in Procyon.
The posterior auricular artery gives off the occipital ramus laterad
of the mastoid process, but the stylomastoid artery was given off
medially in one individual.
STORY: CAROTID ARTERIES IN PROCYONIDAE 521
Nasua narica — continued
The middle meningeal artery1 has a smaller intracranial distribu-
tion than in Procyon. Its branches extend only as far forward as
the posterior Sylvian gyms.
The internal maxillary and external rete are nearly identical
with the arrangement in Procyon. The ciliary artery arose beyond
the orbital trunk in one specimen. The anastomosis between the
ciliary and the ophthalmic artery takes place at the distal third of
the optic nerve.
The accessory meningeal artery from the ciliary trunk has a
more extensive distribution than in Procyon. It ramifies to the dura
mater from the level of the Sylvian (lateral) fissure as far as the
presylvian fissure, thus exceeding the area supplied by the middle
meningeal (fig. 96).
The orbital artery is a large trunk that divides at once into two
main branches. The first branch gives off the lateral muscular
ramus, the subequal anastomotic artery, and a small zygomatic
artery. The other branch of the orbital gives off the supraorbital,
the lacrimal, the medial muscular ramus, and the frontal artery and
terminates as the very large external ethmoidal. In one individual
the external ethmoidal was doubled. The increased size of the external
ethmoidal is characteristic of Nasua. The other orbital branches
could not be traced on the Sanderson specimen because of unsatis-
factory preservation. The anastomotic artery is convoluted in the
sinus cavernosus. It does not run past the hypophysis but joins
the internal carotid just inside the cranium.
The internal maxillary terminates opposite the posterior superior
alveolar process, the larger division continuing as the infraorbital ;
the smaller division forms the sphenopalatine-descending palatine
trunk.
Before bifurcating, the sphenopalatine-descending palatine trunk
gives off a branch to the internal pterygoid muscle, in addition to
the posterior palatine artery.
The descending palatine is one third the caliber of the sphenopal-
atine, and emerges as the anterior palatine opposite the second
molar.
In all other respects Nasua closely follows the arterial pattern
of Procyon.
1 The meningeal arteries followed this same pattern in two dry skulls examined,
C.N.H.M. nos. 41196 and 14011.
522 FIELDIANA: ZOOLOGY, VOLUME 32
Potos flavus (fig. 91)
The common carotid artery bifurcates at the anterior border of
the thyroid cartilage, at the level of the foramen lacerum posterius.
The internal carotid is more than half the caliber of the external
carotid. The basicranial internal carotid is extremely short (56 per
cent of the length of the bulla), despite the anterior location of the
posterior carotid foramen, since the artery originates at the level
of the posterior lacerated foramen. In the anteromedial wall of
the bulla, the internal carotid runs almost vertically until it levels
off as it approaches the foramen lacerum medium. Here the artery
receives an anastomosis from the ascending pharyngeal, then turns
sharply dorsad to enter the sinus cavernosus. Within its canal the
internal carotid gives off the caroticotympanic artery opposite the
anterior border of the promontorium.
In one specimen the internal carotids were united subdurally
by an anastomotic artery posterior to the hypophysis. The internal
carotid gives off a tortuous, small, but well-defined ophthalmic
artery and a separate twig to the hypophysis. The ophthalmic
enters the optic foramen on the lateral side of the optic nerve, makes
a turn around the nerve and runs medially inside the orbit, anas-
tomosing with the ciliary artery near the distal end of N. opticus.
The circle of Willis is the reverse of the pattern in Procyon, with
the posterior half large in caliber and elongated (fig. 93). The
anterior cerebral is half the caliber of the main middle cerebral
artery. There is a doubling of the middle cerebral, with a small
secondary middle cerebral of the same distribution, arising from the
anterior cerebral above the optic nerve. The internal ethmoidal
artery is given off near the base of the secondary middle cerebral,
and anastomoses with the external ethmoidal without uniting with
its fellow from the opposite side. There was an anterior com-
municating artery in one Potos, with the union of the anterior cere-
brals farther forward than in the other specimen.
The posterior communicating artery is only slightly smaller than
the main middle cerebral artery.
The basilar rete is in the pattern of two triangles with their
bases juxtaposed. Smaller anastomotic triangles occur along the
anterior spinal artery as it receives twigs from the vertebrals at each
nerve root.
The basilar artery is smaller than the internal carotid. The
anterior inferior cerebellar artery is represented by one large vessel
and several small pontine rami.
STORY: CAROTID ARTERIES IN PROCYONIDAE 523
Polos flavus— continued
The external carotid gives off the anterior thyroid artery and the
lingual artery opposite the foramen magnum. The anterior laryngeal
artery arises beside A. lingualis, but in one specimen was from a
trunk that gave rise to the anterior thyroid artery and submaxillary
ramus. The submaxillary ramus came from the sternomastoid
artery in one case.
The ascending pharyngeal is small, with its usual cervical branches
taken over by the occipital but its terminal branches the same as
in Procyon. The ascending pharyngeal came from the base of the
internal carotid on one side of the first specimen, and on the second,
the R. m. longus capitis came from that vessel. Two newborn
specimens (both females), C.N.H.M. nos. 52428 and 0-1333, were
examined in this region only, and the ascending pharyngeal was
found to arise from the internal carotid. This condition is seen
also in Ailuropoda and in Mustela but not in other carnivores.
The occipital artery is large, but does not reach the occiput.
Instead it breaks up at the foramen lacerum posterius into branches
to M. longus capitis and anastomoses to the vertebral artery. In
addition it gives off a nutrient branch that crosses the bulla to enter
the floor of the external meatus. The posterior meningeal artery
anastomoses with the vertebral, and does not reach the dura of the
posterior cranial fossa. A small branch of this artery runs beside
N. hypoglossus to supply the walls of the large anastomotic veins
of the foramen magnum, in addition to the atlanto-occipital joint.
The occipital arose from the base of the internal carotid in both
newborn specimens mentioned above.
The external maxillary artery is weak, and most of its terminal
area of distribution is taken over by the large buccinator artery.
The submaxillary ramus of the external maxillary anastomoses
with the above-mentioned branch of the superior laryngeal. The
bulk of the external maxillary supplies the masseter muscle. In
one specimen the external maxillary arose from the base of A.
submentalis.
The submental artery is a branch of the lingual artery, anasto-
mosing with the sublingual artery and supplying the symphysis
mentis.
The posterior auricular artery gives off a strong occipital ramus
that runs laterad of the mastoid process to a typical distribution.
The superficial temporal artery (fig. 95) is a powerful vessel
that runs with its companion vein, between the temporal fascia and
524 FIELDIANA: ZOOLOGY, VOLUME 32
Potos flatus — continued
muscle above the zygomatic arch, to emerge at the lateral angle of
the eye. The bulk of the artery continues as the lateral palpebral
arteries. The masseteric ramus is large, but the transverse facial
is quite small, anastomosing with both the external maxillary and the
buccinator arteries. The zygomatico-orbital is a short anastomotic
branch to A. zygomatica of the orbital circulation. On one specimen
the superficial temporal gave off the superior labial artery (as seen
in Bassaricyori).
The external rete of the internal maxillary artery is represented
by a few anastomotic arterioles that loop through the pterygoid
and deep temporal muscular rami.
The inferior alveolar artery has a long straight course before it
reaches its foramen, which is situated far anterior in the mandible,
only a few millimeters posterior to the last molar.
The posterior deep temporal is a very large artery that also gives
off the middle deep temporal. Rami to the internal pterygoid muscle
arise independently from the internal maxillary, the anastomosis with
A. submentalis being rather large.
Intracranially, the middle meningeal artery1 (fig. 96) is one large
trunk that is distributed more anteriorly than in Procyon, running
at right angles to the basis cranii, to supply the middle cranial
fossa, extending well beyond the anterior limb of the ectosylvian
gyrus.
The orbital artery is a powerful vessel equal in caliber to the
remaining internal maxillary trunk. The first branch of the orbital
is very small. It accompanies the maxillary nerve through the
foramen rotundum and anastomoses with the middle meningeal at
the semilunar ganglion. In one specimen the two ocular muscular
rami came off a common trunk, with the lacrimal artery as a
secondary branch of the medial muscular ramus. The external
ethmoidal, one of the terminal branches of the orbital, gives off
the frontal, the trochlear and the anterior meningeal before entering
the skull. The orbital also gives off a large deep temporal ramus;
in one specimen it also gives rise to the anterior deep temporal.
The larger division of the orbital artery, A. ciliaris, first gives
off the small accessory meningeal artery. A. meningea accessoria
runs through the orbital fissure to ramify over the dura of the
1 Sectioned skulls C.N.H.M. nos. 41606 and 8611 were examined and the
ramifications of the meningeal arteries were found to be identical with those in
the preserved specimens.
STORY: CAROTID ARTERIES IN PROCYONIDAE 525
Polos flavus — continued
anteroventral area of the anterior Sylvian gyrus. The ciliary artery
then divides into the long and short ciliary arteries that anastomose
with each other on opposite surfaces of the optic nerve, and with
the ophthalmic artery on the lateral surface. The great size of the
ciliary artery seems a compensation for the reduction of the nasal
area along with its sources of supply, and for the large eyeball.
In the adult Potos dissected, the anastomotic artery is a minute
twig from the orbital artery to the ophthalmic nerve. This tiny
arteriole runs from the orbital fissure to the Gasserian ganglion and
anastomoses with the internal carotid at the sella turcica. In the
subadult specimen the anastomotic artery was slightly larger.
The artery of the pterygoid canal arises from the internal
maxillary posterior to the orbital.
The buccinator artery is unusually large in Potos, taking over
much of the external maxillary area, as it gives off both labial
arteries and the angular. In one specimen the anterior deep temporal
came from the base of the buccinator trunk. The internal maxillary
artery terminates in three branches, the largest of which is the
anterior deep temporal; the infraorbital and the sphenopalatine-
descending palatine trunk are smaller.
The infraorbital artery breaks up at the level of the alveolar
process of the second molar. The medial palpebral arteries anas-
tomose with the frontal, superficial temporal, lateral palpebral, and
angular arteries, in a complete circuit around the eye, in addition
to supplying the lateral surface of the nose.
The short sphenopalatine-descending palatine trunk arises at the
level of the buccinator artery opposite the pterygoid process of the
superior maxilla and divides a few millimeters farther forward. The
foramina for these arteries are situated much more anteriorly than
in Procyon and the vessels are correspondingly elongated.
The main trunk of the sphenopalatine runs on the lateral wall
of the nasal cavity, as in the raccoon, but the small septal branch
arches across to the septum at once.
The posterior palatine artery, from the base of the descending
palatine, is of medium caliber and sends several rami into the area
of distribution of the anterior palatine artery, in addition to the
usual posterior branch.
The descending palatine is slightly smaller than the sphenopala-
tine and emerges as the anterior palatine artery on the hard palate
opposite the fourth premolar, farther forward than in Procyon.
526
FIELDIANA: ZOOLOGY, VOLUME 32
Potos flavus— continued
The palatine anastomoses at the incisive foramen give off a
minute artery, A. septi mediani, to the median incisive foramen.
. zygomaticoorbitalis 1 A te su^
\ A. trans, faciei J A. palp. lat. (A. temp. prof, ant.)
, N. auricuhtemporalis / M. retract, any. oculi (cut)
' R. m.platysma
M . orbicularis oculi
A. frontal is
/ A. angularis
f A. palp. med.
A. labialis sup.
/Orificium dueti parotidei
' {. let. lab. sup.
f.maxillo-naso-labialis
M. mentalis
For. mentalis
Gl. alveobuccalis inf.
A. &V. lab. inf.
f A. maxillaris externa A. & V. submentalis
' V. anast. V. jugularis externa sin.
N. buccalis inferior
: intermed., M. sphincter colli prof.
FIG. 90. Superficial arteries, veins, and nerves of the right side of the head
in Bassaricyon alleni. Arteries are black, veins stippled and nerves unshaded. X 1.
Bassaricyon alleni (figs. 90 and 95)
Because of the rareness of this genus, our single embalmed speci-
men must serve several purposes. Only those arteries lying fairly
near the surface could be observed for the present.
The common carotid artery bifurcates at the level of the middle
of the thyroid cartilage. The internal carotid is one half the caliber of
the external carotid, and takes a diagonal course to the posterior
carotid foramen, which is situated midway between the posterior
and medial lacerated foramina. The extracranial internal carotid
is somewhat shorter than in Procyon, but not as short as in Potos.
The occipital artery arises from the base of the external carotid,
and supplies basicranial muscles and an anastomosis to the vertebral
without reaching the occiput. The posterior meningeal has a rela-
tively large caliber. The ascending pharyngeal is a small branch
of the occipital, and gives off a minute twig to the internal carotid
at the foramen lacerum medium.
STORY: CAROTID ARTERIES IN PROCYONIDAE 527
Bassaricyon alleni — continued
The external maxillary is of medium caliber, the bulk of the vessel
continuing as the submental artery, but the inferior labial is given
off as a smaller branch and the superior labial is reduced to a minute
arteriole to the superior buccal ramus of the facial nerve. The sub-
mental artery anastomoses with the sublingual and terminates at
the symphysis mentis. A small branch from the lingual artery
supplies the posterior part of the mylohyoid muscle.
The posterior auricular is a massive trunk that gives rise to
A. stylomastoidea as well as a large R. occipitalis that supplies the
occipital field.
The superficial temporal is larger than the external maxillary,
and its branches are the same as in Procyon with the exception of
the transverse facial, the largest branch. A. transversa faciei runs
across the masseter beside R. malaris of N. auriculotemporalis and
takes over the area usually supplied by the superior labial. A large
branch anastomoses with the buccinator artery. Then the artery
sends an anastomosis to the anterior deep temporal at the lateral
angle of the eye, followed by A. angularis, which anastomoses with
the medial palpebral, from the infraorbital, at the medial angle of the
eye. The transverse facial terminates in two branches supplying
the upper lip to the level of the canine tooth.
The middle meningeal and accessory meningeal arteries were
examined on skull C.N.H.M. no. 29180. The middle meningeal is
twice the caliber of the accessory, and supplies the dura posterior
to the lateral fissure.
The large anterior deep temporal artery arises just posterior to
the terminal bifurcation of the internal maxillary, and supplies the
supraorbital region as well as the temporal muscle, giving off the
lateral palpebral and anastomosing with the zygomatico-orbital
twig of the superficial temporal and with the medial palpebral.
The internal maxillary terminates in the large infraorbital and
somewhat smaller sphenopalatine-descending palatine trunk at the
posterior border of the palatine bone.
A. infraorbitalis gives off the medial palpebral and superior
alveolar arteries before passing through its foramen, where it bi-
furcates in rami to the face.
The long sphenopalatine-descending palatine trunk bifurcates
opposite the pterygopalatine canal, the sphenopalatine being much
the larger subdivision. The pterygopalatine canal opens as the
528 FIELDIANA: ZOOLOGY, VOLUME 32
Bassaricyon alleni — continued
anterior palatine foramen opposite the posterior border of the fourth
premolar in one skull, and at the posterior border of the first molar
in the other.
The medial septal artery is large.
Ailurus fulgens (fig. 91)
The common carotid artery bifurcates at the level of the thyroid
foramen, opposite the atlas. The internal carotid is over half the
caliber of the external carotid. The carotid sinus is a barely dis-
tinguishable small swelling at the base of the internal carotid. The
slightly undulating basicranial portion of the artery is rather long,
exceeding the bullar length by 6 per cent. The internal carotid
running in its canal is longer than in any other genus examined,
arching laterad in contact with the full length of the promontorium,
turning ventrad as it approaches the foramen lacerum medium,
then bending sharply dorsad to enter the sinus cavernosus. A
caroticotympanic artery is given off at the anteromedial border of
the promontorium, where it participates with the pharyngeotym-
panic in the tympanic plexus.
The internal carotid gives off a hypophyseal ramus subdurally,
and a slender ophthalmic artery just after piercing the dura. The
ophthalmic artery anastomoses with the ciliary artery at the distal
third of N. opticus.
The circle of Willis is in the form of a semicircle anteriorly and
a half-ellipse posteriorly. The anterior half of the circle slightly
exceeds the other half in caliber. The combined anterior cerebral-
middle cerebral trunk divides subequally at the optic chiasma.
The middle cerebral is accompanied by a secondary, smaller vessel
given off by the anterior cerebral. The internal ethmoidal arises
from the anastomosis with the external ethmoidal without joining
its fellow. There is no anterior communicating artery.
The posterior communicating artery is smaller than the main
middle cerebral, and gives off large hippocampal rami, and the
smaller posterior cerebral. The superior cerebellar arteries are
doubled at their origin and an anastomotic vessel bridges the tri-
angular space between them, giving off thalamic twigs.
The vertebral arteries give off small rami at cervical nerves II-
IV, with a large branch at N. cervicalis III on the left side. The
main branches of the arteries form the diamond-shaped basilar rete
at the first cervical nerve. There is a small triangular anastomosis
Fissuro orbitalis&A.. anastomotica A- meningea accessoria
For. Totundum & R. anast. a. men. med. \ 1 R- m- temporalis
A. temp. prof. post. A. massete
For. orate &
A. meningea media
A. temp, superf.
R. anterior
R. posterior
R. m. temp'
A. palp. lat.
A. ethmoid, ext.
A. ciliaris
A. palp. med.
R. sac. lacrimalis
Rr. nasales externi
R. alveolaris
. m. pteryg
A. canal, pteryg
A. alveolaris inf.
A. temp. prof. ant.
A. buccinatoria
A. maxillaris interna
A. infraorbitalis
A. sphenopalatina
A. palatina desc.
A. palatina post.
A. carot. comm. / /
A. occipitalis /
A laryngea sup
A. maxillaris externa
Potos
Fissura orbitalis&
A. meningea accessoria
For. rotundum
A. masseterica
For. ovate &
A. meningea media
R. m. mass.
R' mm-
i med. (superior)
For. oplifum
R. mm. oculi lat. (inferior)
A. temp. prof. ant.
A. ethmoid, ext.
A. buccinatoria
A. palp. lat.
A. ciliaris
A. palp. med.
R. sac. lacrimalis
A. membr. nictitans
R. nasalis externi
N. R. alveolaris
A. carot. comm?
A. laryngea
A. lingualis
A. pharyngea asc.
terna
A. maxillaris externa
A. carotis externa
R. m. digastricus
Ailurus
. infraorbitalis
A. sphenopalatina
A. palatina desc.
Tr. sphen.-pal. desc.
A. palatina post.
FIG. 91. Main branches of the external carotid circulation in the kinkajou,
Potos flavus (X 1) and in the lesser panda, Ailurus fulgens (X %). The extent
of the frontal sinus is indicated by diagonal lines.
529
530 FIELDIANA: ZOOLOGY, VOLUME 32
Ailurus fulgens — continued
where the anterior spinal artery arises, at the level of the third cer-
vical nerve.
The basilar artery is large, subequal to the internal carotid, and
gives off several pontine twigs in addition to a large anterior inferior
cerebellar artery. The posterior inferior cerebellar artery arises
from the anterior half of the basilar rete.
The external carotid artery gives off the anterior laryngeal at
its base. The anterior thyroid is a branch of the common carotid
artery.
The occipital artery is a medium-sized trunk that arises opposite
the lingual artery and immediately sends a recurrent branch to the
large cervical lymph gland and to the sternomastoid muscle. The
artery divides at the condyloid foramen into lateral and medial
branches. The lateral branch gives off rami to Mm. digastricus
and rectus capitis lateralis, as well as to the inferior tympanic
artery. The medial branch sends a twig to the transverse sinus,
a nutrient twig to the internal carotid nerve, and gives off the small
posterior meningeal artery and an articular and muscular ramus.
It anastomoses with the vertebral artery. The posterior meningeal
is a nutrient artery to the hypoglossal canal and does not enter the
posterior cranial fossa.
The ascending pharyngeal, a small artery, arises just anterior
to the occipital and sends an anastomotic twig to the internal carotid
artery at the foramen lacerum medium before making its terminal
bifurcation. The pharyngeotympanic artery is very minute. Op-
posite the carotid foramen the ascending pharyngeal gives off an
arteriole that accompanies the inferior caroticotympanic nerve and
participates in the arterial plexus on the promontorium. A similar
vessel is present in the Tibetan bear and the giant panda, but was
not found in any of the procyonines examined.
The external maxillary is a large artery that takes origin at the
lateral border of the digastric muscle at the level of the mastoid
process. The angular artery is given off opposite the fourth pre-
molar and does not anastomose with the medial palpebral. The
superior labial runs across M. buccinator widely separated from its
companion vein and anastomoses with the infraorbital opposite the
canine. A small collateral branch from the external maxillary accom-
panies the superior labial and anastomoses with the angular.
The posterior auricular is a very large vessel arising just anterior
to the external maxillary. The stylomastoid artery is given off
STORY: CAROTID ARTERIES IN PROCYONIDAE 531
Ailurus fulgens — continued
medial to the mastoid process. The strong occipital ramus is given
off at the lower border of the sternomastoid muscle dorsolaterad
of the mastoid process, supplies a well-developed meningeal ramus
through the mastoid foramen, has the usual muscular rami and
anastomoses with its fellow at the midline. The branch to the
posterior surface of the auricle is given off before the occipital ramus,
but the anterior auricular branch is given off at that level. After
the occipital branch the main trunk of the artery continues as a
temporal artery, as in the giant panda.
The superficial temporal artery is approximately two-thirds the
caliber of the posterior auricular and the bulk of the vessel pierces
the temporal aponeurosis to run between it and the temporal muscle
fibers above the zygomatic arch, giving off several strong muscular
rami in this part of its course. The masseteric and anterior auricular
rami are large. The masseteric ramus divides into a large external
branch (to the vertical part of M. masseter) that sends a slender
transverse facial to anastomose with the superior labial, and a
somewhat smaller internal branch to the deep fibers of the muscle,
as in the giant panda. The superficial temporal supplies the medial
as well as the lateral palpebral arteries.
The internal maxillary artery arches around the mandibular
articulation and presses close against the skull as it crosses the
foramen ovale and approaches the alisphenoid canal, through which
it passes to the infratemporal fossa. Consequently only the base of
the middle meningeal artery1 is exposed extracranially, and the
pterygoid rami usually from that trunk arise just anterior to it.
Intracranially, the middle meningeal (fig. 96) divides into two main
dural branches at the tentorium. The first branch supplies the
middle cranial fossa, running diagonally anterodorsad as far as the
anterior turn of the ectosylvian gyrus. Anastomoses with the ac-
cessory and anterior meningeal arteries are of extremely fine caliber.
The second branch ramifies on the posteroventral margin of the cere-
bral dura, pressed between it and the tentorium. Skulls C.N.H.M.
nos. 44875 and 36749 were examined and the former was found to
have the tentorial branch subordinated, taking origin from the
main branch. In the second skull, the ramifications followed the
same pattern as in the embalmed specimen.
1 The intracranial distribution of all meningeal arteries was checked on two
dry skulls, C.N.H.M. nos. 36749 and 44875, and found to agree with the pre-
served specimen, except for a higher bifurcation of the middle meningeal in no.
44875.
532 FIELDIANA: ZOOLOGY, VOLUME 32
Ailurus fulgens — continued
The external rete of the internal maxillary begins at the inferior
alveolar artery and extends by delicate arterial loops to connect
the posterior deep temporal, middle meningeal and pterygoid arteries.
Twigs to the internal pterygoid arise from the anastomoses and from
the internal maxillary itself opposite the otic ganglion. Unlike the
Procyoninae, Ailurus' internal maxillary artery is crossed dorsally
by both the mandibular and the masticator divisions of the trigeminal
nerve.
The inferior alveolar has a long trunk external to the mandible,
its foramen being situated far forward. The internal maxillary
gives off separately the anterior tympanic and R. mm. tensor veli
palatini and tensor tympani.
The orbital artery takes origin from the internal maxillary within
the alisphenoid canal. The anastomotic artery, the small first
branch of the orbital, runs through the orbital fissure and joins
the internal carotid artery in the inferior petrosal sinus. The
anastomotic artery gives off the accessory meningeal artery, which
enters the skull through a small foramen just anterior to the orbital
fissure. The accessory meningeal supplies the area of dura between
the coronal sulcus and the anterior limb of the ectosylvian gyrus.
The orbital next gives off the lateral muscular ramus, then the
medial muscular ramus and continues as the external ethmoidal.
The zygomatic artery comes from the lateral ramus, the lacrimal
and supraorbital from the medial ramus. The zygomatic anasto-
moses with the superficial temporal, medial terminal branch. No
separate zygomatico-orbital artery and no separate middle temporal
are visible. The external ethmoidal gives off the small frontal
artery and, just before entering the skull, the large ciliary artery.
A. ciliaris supplies the lateral and inferior recti and the retractors
as well as the usual ciliary branches, and anastomoses with the
ophthalmic.
The small anastomotic ramus, from the ciliary in Procyon, is
represented by a small nutrient artery to the maxillary nerve, at
the terminal bifurcation of the internal maxillary.
The anterior deep temporal artery is given off as the internal
maxillary emerges from the alisphenoid canal. The middle temporal
branches, usually from the orbital, come from this trunk. The
anterior deep temporal is a large artery but does not contribute to
the circulation of the orbit, and is not as strongly developed as the
adjacent sphenopalatine.
STORY: CAROTID ARTERIES IN PROCYONIDAE 533
Ailurus fulgens — continued
The terminal bifurcation of the internal maxillary takes place
at the posterior border of the superior alveolar process. The infra-
orbital artery exceeds the sphenopalatine-descending palatine trunk
in caliber. The posterior and middle superior alveolar arteries are
given off inside the infraorbital foramen. Here a branch of the
infraorbital supplies the lacrimal sac, the nictitating gland, the
orbicularis oculi and the adjacent bone, structures usually supplied
by the medial palpebral, which in Ailurus comes from the superficial
temporal instead of from the infraorbital artery. Then the infra-
orbital makes its division into a large anterior external nasal artery
and a smaller alveolar. The alveolar trunk receives the terminal
anastomosis of the superior labial artery opposite the canine tooth.
The sphenopalatine-descending palatine trunk supplies a branch
to the internal pterygoid muscle as well as to the artery of the
pterygoid canal. The posterior palatine is the next branch of the
trunk, and besides its posterior branch has anterior palatine rami
that anastomose with the main anterior palatine artery. The
sphenopalatine-descending palatine trunk winds between the internal
pterygoid muscle and the massive posterior alveolar process, to
bifurcate into its components opposite the pterygopalatine canal.
The descending palatine artery enters its diagonally directed canal
and emerges on the hard palate opposite the space between the
fourth premolar and the first molar, as the great anterior palatine.
Several skulls have the anterior palatine foramen opposite the
first molar. A. palatina anterior forms an anastomotic loop around
the incisive foramen, is joined by a sphenopalatine branch, and sends
a small branch through the median anterior palatine foramen.
The sphenopalatine artery gives a palatine ramus in addition to
its usual branches. The posterior septal branch arches over to the
septum at its origin, a short distance after the main artery emerges
from its foramen.
THE PROCYONID CAROTID PATTERN
The preceding description of the arteries of the head in the
procyonid genera has presented these vessels from the point of view
of their differences from the most familiar genus, Procyon. The
raccoon was selected for detailed description partly because of easily
accessible specimens, but subsequent dissection of the other genera
has shown the peculiar fitness of the raccoon to exemplify the
534 FIELDIANA: ZOOLOGY, VOLUME 32
family. Not only do the other genera bear a strong resemblance
to Procyon, but features in which they differ from each other can
be found combined in the collateral circulation of the raccoon.
The derivation of the characteristic patterns of each genus can
be visualized as a blocking out of parts of essentially collateral
arterial channels, compensated by an amplification of other channels.
From a comparison of the condition in Procyon with the conditions
of the other genera, it is possible to deduce the following schematic
pattern (fig. 92), from which any of the procyonid generic patterns
could have evolved. The relationships of the arteries to the cranial
foramina and to the cranial nerves are constant.
Internal Carotid Circulation
The internal carotid is large, runs in a closed canal, and enters
the circle of Willis directly. The ophthalmic is small, and anasto-
moses with the ciliary. There is no central artery of the retina. The
anastomosis (via the foramen lacerum medium) of ascending pharyn-
geal with internal carotid is small. The anastomosis (via the orbital
fissure) with the internal maxillary is of medium caliber.
External Carotid Circulation
The ascending pharyngeal and occipital arise from a common
trunk. The occipital gives off three important branches before
reaching the muscles of the occiput: (1) the posterior meningeal,
(2) the anastomosis to the vertebral artery, (3) the meningeal ramus
through the mastoid foramen.
The lingual artery is very large. It anastomoses with the ascend-
ing pharyngeal near the palatine tonsil and with the submental
branch of the external maxillary at the symphysis of the mandible.
The external maxillary is small. It anastomoses with the buc-
cinator, the transverse facial from the superficial temporal, and the
infraorbital.
The external carotid is continued as the internal maxillary.
The posterior auricular is very large. It anastomoses with the
occipital and the superficial temporal.
The inferior alveolar artery accompanies the nerve of the same
name to the mandible, where it anastomoses with the submental
artery.
The middle meningeal artery passes via the foramen ovale to
the middle cranial fossa, its branches anastomosing with a large
STORY: CAROTID ARTERIES IN PROCYONIDAE 535
accessory meningeal artery from the internal maxillary via the
orbital fissure. A nutrient artery accompanies the maxillary division
of the trigeminal nerve through the foramen rotundum and anasto-
moses with the meningeal arteries.
The bulk of the internal maxillary is divided equally into branches
supplying (1) the temporal muscle and supraorbital regions, (2) the
orbital cone, (3) the nose, palate, and infraorbital regions. These
trunks are linked by anastomotic arterioles.
(1) The superficial temporal and anterior deep temporal both
reach the supraorbital region. The posterior deep temporal is the
largest muscle branch.
(2) The orbital artery provides collateral circulation linking all
three terminal regions, and gives off the anastomotic artery to the
internal carotid. In addition to muscular rami the main orbital
divides into the ethmoidal, which supplies the olfactory region, and
the ciliary, which reaches the eyeball.
(3) The sphenopalatine supplies the internal nose; the infra-
orbital supplies the external nose and the infraorbital region. The
descending palatine supplies the palate, and anastomoses with the
preceding vessels. An additional communication is provided in a
median septal artery at the median incisive foramen.
Differences from Basic Pattern
All procyonid genera follow this basic pattern, each with its
particular variation, stated briefly below.
Procyoninae
Bassariscus is very similar to Procyon, but it differs in several
ways. It has relatively the largest internal carotid, and a small
anastomotic artery. It is the only procyonid exhibiting the primi-
tive condition of basicranial origin of the large occipital artery (as
in Canidae, Mustelidae and Felidae). The occipital ramus of the
posterior auricular is very small, but the temporal ramus is large,
as in the pandas. The external maxillary artery is of medium caliber,
its angular branch giving off the medial palpebrals. The accessory
meningeal artery exceeds the middle meningeal. The ciliary artery
is exceptionally large, with a rete at its entrance to the eyeball.
The ophthalmic is of medium caliber. The ethmoidal artery is
smaller than the ciliary.
Procyon differs from the hypothetical pattern in the great size
of the occipital branch of the posterior auricular. The true occipital
536 FIELDIANA: ZOOLOGY, VOLUME 32
does not go beyond the basicranium. The mastoid meningeal ramus
of this trunk takes over the area supplied by the posterior meningeal.
All the major vessels of the head are connected by anastomoses,
providing collateral channels for every region. The external maxil-
lary arises after the posterior auricular. The anastomotic artery is
relatively large. The orbital artery is sometimes separated into
independent ciliary and larger ethmoidal trunks.
Nasua follows Procyon almost artery for artery, the chief differ-
ence being in the enlarged caliber of the arteries supplying the ol-
factory apparatus. Arteries to the eye are relatively small. The
accessory and middle meningeal arteries are equal in caliber.
Potos is farthest from the basic pattern and from Procyon, as
evidenced in the shift of the internal maxillary flow to supply the
temporal muscle and the orbit, with the olfactory trunks reduced.
The extracranial trunk of the internal carotid is unusually short.
The ophthalmic artery is well developed, but the anastomotic artery,
smaller even than in Bassariscus, is a minute nutrient to the oph-
thalmic division of the trigeminal nerve. The accessory meningeal
is small. The external maxillary is reduced, and has lost most of
its usual distribution to the enlarged buccinator artery. The
superficial temporal is large, running deep to the temporal fascia,
as seen in Ailurus. The anterior deep temporal does not reach the
supraorbital region.
Bassaricyon possesses a pattern in the buccal area intermediate
between Procyon and Potos, The other accessible arteries follow
Procyon closely, instead of Potos.
Ailurinae
Ailurus has more arterial characters in common with the giant
panda Ailuropoda than with the Procyoninae, although it falls
within the outlines of the general procyonid pattern. The giant
panda (Davis, MS.) shares more arterial characters with the bears
than with the lesser panda, and has far less resemblance to the
Procyoninae. Ailurus resembles Potos in possessing a small accessory
meningeal artery, a large superficial temporal artery, and a short
descending palatine-sphenopalatine trunk. The anastomotic artery
is very small, as in Potos and Bassariscus.
The Carotid Pattern in the Carnivora
The basic pattern of the arteries of the head (fig. 92) can best
be appreciated if the head is subdivided topographically into regions,
537
538 FIELDIANA: ZOOLOGY, VOLUME 32
each of which has more than one source of blood supply. The
arteries providing collateral circulation to these regions of the head
are as follows:
INTERNAL CAROTID CIRCULATION
Brain
A. carotis interna
A. anastomotica
A. basilaris
EXTERNAL CAROTID CIRCULATION
Meninges
A. meningea anterior
A. meningea media
A. meningea accessoria
A. meningea posterior
A. occipitalis, R. meningeus
Basicranium
A. occipitalis
A. pharyngea ascendens
Occiput
A. occipitalis
A. auricularis posterior, R. occipitalis
M. temporalis
A. temporalis profunda posterior
A. temporalis profunda media
A. temporalis profunda anterior
A. temporalis superficialis
M. masseter
A. masseterica
A. temporalis profunda posterior, R. masseter.
A. temporalis superficialis, R. masseter.
A. maxillaris externa, R. masseter.
Infratemporal fossa
Aa. temporalis profunda, Rr. anastomotici
Rr. mm. pterygoidei, Rr. anastomotici
A. meningea media, Rr. anastomotici
A. orbitalis, Rr. anastomotici
Orbit
A. orbitalis, A. ciliaris, A. ethmoidalis, Rr. musculares oculi
A. ophthalmica
Nasal and infraorbital regions
A. ethmoidalis
A. sphenopalatina
A. infraorbitalis
Cheek and supraorbital regions
A. maxillaris externa
A. temporalis superficialis
A. temporalis profunda anterior
STORY: CAROTID ARTERIES IN PROCYONIDAE 539
Palate
A. palatina anterior
A. palatina posterior
A. pharyngea ascendens
Tongue
A. lingualis, A. sublingualis, A. dorsalis linguae
A. submentalis
The terminal twigs of these main arteries anastomose freely. In
the least specialized procyonid pattern, that of Procyon, all the
anastomoses are present. When the effects of a specialization begin
to show in the vascular system, some of the anastomoses disappear
and one or another collateral artery begins to predominate. This
potentiality of collateral circulations can be applied to the interpreta-
tion of most of the procyonid patterns. The elaboration of patterns
upon a basic theme seems to be in accord with phylogenetic relation-
ships. Fundamentally, alterations are designed to transfer the flow
of blood from one area to another where basic physiological demands
are greater. Massive muscle development requires larger-calibered,
deep-lying conduits. Simplification of pattern in favor of larger-
calibered vessels seems to go hand in hand with increased body
bulk. The smaller carnivores examined usually have extensive
collateral systems; the larger carnivores have simpler patterns.
The general trends of the arterial pattern of the procyonids are
outlined below, in comparison with the conditions found in certain
other carnivores.
The ground plan of the arteries of the head consists of two
separate systems, the internal and external carotid circulations,
united by an anastomotic vessel. The condition of the internal
carotid circulation in the procyonids is essentially simple; a profusion
of collateral channels makes the external carotid circulation more
difficult to interpret.
Division of the primary common carotid trunk varies in location
among carnivores. The common carotid artery bifurcates at the
level of the middle of the thyroid cartilage in dogs, bears and pro-
cyonids, farther forward in cats and pandas. In mustelids the
bifurcation is low on the trachea. Body proportions, especially
length of neck, probably influence this condition.
Tandler (1899) analyzed the trend among feloid carnivores toward
suppression of the internal carotid but paid less attention to the
other side of the picture. The canoid carnivores observed by him
included Cam's familiaris, Cam's lupus, Ursus maritimus, and Meles
540
FIELDIANA: ZOOLOGY, VOLUME 32
taxus, in which the internal carotid is well developed. This artery
reaches its greatest caliber in the procyonids, in which it is always
at least one half the caliber of the external carotid, often much
larger, and in Bassariscus attains a caliber three fourths that of the
A. cerebri ant ,
A. ophthalmica
A. ethmoid, int.-
Bassariscus
Mustela
Procyon Cants Ursus Potos
Nasua Ailurus Ailuropoda
Felis
FIG. 93. Diagram showing four patterns of the circle of Willis in carnivores.
external. In pandas as well as bears and mustelids a large internal
carotid is characteristic. In dogs the artery is weaker, its caliber
varying in different breeds of the domestic dog, and somewhat better
developed in the coyote. The specializations of the internal carotid
in the feloid carnivores have been frequently discussed. It seems
unfortunate that the extremely specialized domestic cat is used
widely as a laboratory animal since it is far removed from the typical
carnivore carotid pattern. In many ways a generalized form such
as the raccoon would seem more suitable for studies involving head
and neck regions.
The internal carotid supplies the major flow to the anterior half
of the circle of Willis in the canoid carnivores. In those carnivores
considered in this paper, the arrangement of the circle of Willis falls
into four general patterns, ranging from a primitive canoid pattern
to a specialized feloid pattern (fig. 93). The simpler patterns A and
B have much in common, but pattern C is more complex and pattern
D is definitely specialized. In pattern A, shared by Bassariscus and
Mustela, the basilar exceeds the internal carotid in caliber, but both
STORY: CAROTID ARTERIES IN PROCYONIDAE
541
divisions of the circle are equal. The ophthalmic artery arises from
the anterior cerebral in Mustela, but from the internal carotid in
Bassariscus, Procyon, Nasua, Potos and Ailurus, although this could
not be shown on all the diagrams. Pattern B, for Procyon and Nasua,
R. anast. a. carotis interna
A. pharyngeotympanica
, A. pharyngea asc.
A. pharyngea
Canis Ursus Procyon Bassariscus Ailuropoda Panthera Felis
FIG. 94. Transition in form of the carotid canal and the foramen lacerum
medium in carnivores. Stippled parts are occupied by venous sinuses; unshaded
parts inside dotted outlines indicate space through which the internal carotid
nerves pass. Various scales.
differs from A only in the relative caliber of internal carotid and
basilar arteries, the latter being slightly smaller. In pattern C,
approximated in Canis, Ursus, Potos and the Ailurinae, the anterior
half of the circle of Willis is powerful, but much shorter than the
smaller-calibered posterior division. The ophthalmic arises from
the anterior cerebral in Canis, Ursus and Ailuropoda. The internal
ethmoidal and collateral middle cerebral arteries arise by a common
trunk from the anterior cerebral. In pattern D the specialized
arrangement of Felis domestica is shown. The anterior half of the
circle of Willis, supplied by the A. anastomotica, greatly exceeds
the posterior division. The basilar artery is weak; the posterior
communicating artery is short. The ophthalmic artery, if present,
arises from the anterior division. The internal ethmoidal arises
from the internal maxillary rete, but anastomoses with the anterior
cerebral distad to the optic chiasma.
The anastomosis of ascending pharyngeal with internal carotid
via the foramen lacerum medium1 is present in procyonids, pandas,
1 Weber (1927) defines the foramen lacerum anterior (= medium) as the fora-
men through which the internal carotid artery usually enters the skull cavity.
The foramen lacerum medium is an opening situated at the anteromedial angle
of the bulla, medial to the canalis musculotubarius, and communicates intra-
cranially either directly or indirectly with the cavernous sinus.
542 FIELDIANA: ZOOLOGY, VOLUME 32
and bears, but its insignificant caliber scarcely suggests its potenti-
ality as a collateral channel to the brain circulation, in which it
plays an important role in the Felidae. This anastomosis is well
developed in the mustelids, and variable in the domestic dog, in
which it may be large on one side, but absent on the other.
The topographical relationships of the foramen lacerum medium
and the carotid canal undergo rather confusing alterations in car-
nivores (fig. 94). In dogs and bears the foramen lacerum medium
is a large opening through which the sinus cavernosus communicates
with the pharyngeal venous plexus. The internal carotid artery
and nerves loop antero-ventrally almost to the roof of the pharynx
at the foramen lacerum medium before turning abruptly dorsad to
pass via the anterior carotid foramen into the sinus cavernosus.
The cranial opening of the foramen lacerum medium is confluent
with the distal part of the carotid canal in all arctoids observed.
In procyonids and pandas the foramen lacerum medium lengthens
to become a distinct canal, still transmitting a vein. On the other
hand, no veins were seen in the narrow foramen lacerum medium
and carotid canal of the felids. In the lion (Panthera leo) the second
segment of the carotid canal is separated from the foramen lacerum
medium by a short distance, bridged by the internal carotid artery
on its way to the circle of Willis. In the cat (Felis domestica) the
second segment of the carotid canal is no longer apparent, and the
anastomosis of the ascending pharyngeal and internal carotid arteries
runs through the foramen lacerum medium and the distal segment
of the carotid canal to enter the sinus cavernosus via the foramen
caroticum anterior.
The occipital and ascending pharyngeal arteries tend to vary
reciprocally in procyonids, pandas and bears. In dogs, Bassariscus,
mustelids, and cats, the basicranial occipital continues as the chief
artery to the nape of the neck, in typical distribution, and there are
collateral twigs from the posterior auricular to the occiput. If the
occipital does not extend beyond the basicranium, the occiput is
supplied by the posterior auricular artery. There is no apparent
mechanical explanation for this condition. If this character has
phylogenetic significance it links Bassariscus to a past shared with
a common ancestor of dogs, mustelids, and cats; perhaps this is a
primitive character once possessed by all fissipeds.
A resemblance between procyonines and pandas is seen in the
reduced size of the posterior meningeal artery with the occipital
meningeal branch, via the mastoid foramen, taking over supply of
the posterior cranial fossa.
STORY: CAROTID ARTERIES IN PROCYONIDAE 543
Changes in the buccal region in procyonids bring about a sharp
reduction of the external maxillary, as the collateral terminal twigs
of buccinator, transverse facial, and infraorbital become the im-
portant vessels reaching the external maxillary's area of distribution.
This condition is found in none of the other carnivores dissected,
although the terminal ramifications of the external maxillary in the
dogs are rather small.
In the Procyoninae and Mustelidae (as far as our material goes)
the superficial temporal is reduced in caliber, running as a slender
vessel external to the temporal fascia, scarcely more than a nutrient
to the accompanying zygomatico-orbital nerve. In the other
carnivores studied this artery is powerfully developed, running be-
neath the surface of the temporal aponeurosis. Potos, like the
pandas, has the deeper, larger trunk. The chief collateral vessel
to this region is the anterior deep temporal. It varies reciprocally
with the superficial temporal, taking over the external orbital region
in procyonids and mustelids.
The temporal and masseter muscles receive their main blood
supply from the posterior deep temporal artery in all carnivores,
with the exception of the cats. In felids an independent masseteric
artery exceeds the former vessel in caliber.
An indication of the method of origin of the external rete of the
internal maxillary artery of the Felidae is to be seen in numerous
anastomotic arterioles linking the main branches of this artery in
the infratemporal fossa of procyonines and Ailurus. Few anasto-
moses occur in this region in dogs and mustelids, none in bears and
the giant panda. Sheer muscle massiveness may be an unfavorable
condition for rete formation, as the larger felids have less rete
development than their smaller cousins.
The presence of the orbital branch of the internal maxillary in
carnivores more than balances the small size of the ophthalmic
artery (from the internal carotid), and in the procyonids leads to
gradual suppression of the ophthalmic artery to mere nutrient
dimensions.
Of the carnivores examined only the mustelids have a large oph-
thalmic artery. The central artery of the retina is absent in pro-
cyonids, bears, and pandas. In procyonids a tendency toward com-
plexity in the orbital circulation, seen elsewhere only in feloid
carnivores, brings about secondary division of the single orbital into
two arteries, with an increased caliber in the one supplying the eye
surface. This trend will be discussed further below.
544 FIELDIANA: ZOOLOGY, VOLUME 32
Many fine-calibered anastomotic arterioles link the vessels of
the orbit in dogs, procyonids, and cats. These vessels may be
safeguards in case of injury to the main arterial supply, in addition
to performing a hydrodynamic function as a means of raising or
lowering blood volume to the area.
The anastomotic trunk from the external carotid to the brain
circulation is relatively much smaller than the internal carotid in
canoid carnivores, dwindling to little more than a nutrient to the
trigeminal nerve in Potos, the Ailurinae, and Ursus americanus.
Tandler (1899) does not mention the anastomotic artery in U. mari-
timus (Thalarctos) . In Canis familiar is the anastomotic artery varies
in caliber, sometimes exceeding the internal carotid artery in supply
to the circle of Willis. The anastomotic artery in canoids appears
to vary inversely with the caliber of the internal carotid.
The external carotid circulation reaches its terminus in the
branches of the anterior part of the internal maxillary. In carnivores,
such as Canis latrans, Ursus americanus, Procyon, and Mustela, with
extensive nasal and infraorbital surface, the infraorbital and spheno-
palatine trunks carry the major internal maxillary flow. These
areas are much smaller and the flow is shifted to the orbital and
anastomotic arteries in cats, and to deep temporal muscular rami
in Potos and the pandas.
FACTORS INFLUENCING THE PROCYONID PATTERN
The shifting of importance among available collateral vessels
has been discussed above, in procyonids and in other carnivores.
Something more than the mere presence of alternate channels is
needed to bring about pattern change. The circulatory system is
functionally a passive supply system, carrying the products of
metabolism throughout the body. The organ systems of the body
wield final influence in determining the arrangement of the circula-
tory pattern; the kind of tissue being nourished places limitations
upon its supply system. Thus the circulatory system can be best
understood if approached from the functional standpoint.
It is apparent that vascular pattern is determined to a large
extent by the functional purpose of the vessel, and by the degree
of development of the functional unit supplied by the vessel.
Vessel distribution may be divided into three main categories:
(1) Branches supplying muscles and other soft parts.
(2) Branches supplying nerves, not necessarily the comitant
vessels (most variable).
STORY: CAROTID ARTERIES IN PROCYONIDAE 545
(3) Branches supplying periosteum and bone (least variable).
Of these, branches to bone are most conservative, a condition that
reflects the slow nature of the modeling of bone. A structure estab-
lished in bone is seldom subject to rapid change in adult mammals,
aside from the ability, decreased with age, to repair direct injury.
Rapid alterations in bone are associated with ontogeny and with
the post-natal growth processes of young mammals. On the other
hand, blood vessels supplying muscles and nerves are able to change
rapidly in adult life.
Muscular branches are somewhat more plastic than other vessels,
adapting readily to physiological and structural changes within a
muscle, but always conforming to the demand for adequate supply
to any area of muscle mass. Increased muscular activity develops
a local oxygen deficiency. This oxygen loss is made up by increasing
the blood volume to the area. The capillary bed of the muscle mass
is the primary agent in providing additional blood, by means of
widening the capillaries being used, and by opening other capillaries
that are collapsed during quiescence. Frequent exercise of a muscle
increases the size of its fibers; increased blood supply is a corollary
of this physiological process (Abramson, 1944). Gradual increase
in the caliber of capillaries either by expansion or coalescence brings
them to the proportions of arterioles and venules; former arterioles
attain the caliber of arteries and veins; minor arteries and veins
become sizable trunks.
Although at first glance the small Arteriae nutritiae nervi may
seem rather insignificant from the point of view of the comparative
anatomist, their importance becomes apparent when they are
followed through a series of genera. These minute vessels represent
potential channels of pattern development.
As morphological changes in the muscle-skeleton-joint apparatus
occur gradually with changing habits of an animal, alterations in
the blood supply to the region become necessary. The minute
collateral channels, already present as nutrients, are available for
development into larger vessels of a pattern more useful to the
transformed relationships of the functional unit. The basic work
of Adams (1943) on the blood supply of the sciatic nerve in the
rabbit has yielded the means and the proof of such alterations. He
found that ligation of the inferior gluteal artery, main nutrient to
the sciatic nerve, produced no change in the physiological state of
the nerve. Ligation of all macroscopic sources of supply produced
nerve degeneration in only two cases out of twelve. According to
546 FIELDIANA: ZOOLOGY, VOLUME 32
Adams, these experiments indicate the ability of the intrinsic longi-
tudinal anastomotic pathways of the sciatic nerve to accommodate
by expansion and provide adequate circulation.
Wherever changes from a basic vascular pattern occur, it is advis-
able to consider what collateral channels previously existed. A good
example of the perplexing differences that occur in one vascular
pattern is shown by the external maxillary artery and its collaterals
(fig. 95). At first glance, the pattern of Procyon seems widely
separated from that of Potos. After observation of the intermediate
pattern of Bassaricyon the transition between the vastly different
patterns of Procyon and Potos can be recognized. The entire maze
of collateral vessels is present in Procyon. In Bassaricyon the trans-
verse facial, buccinator and submental arteries increase, the superior
labial drops out, and the sublingual is reduced. The orbit in both
Procyon and Bassaricyon is supplied by a large branch of the anterior
deep temporal and a small zygomatico-orbital branch. In Potos
the trunk of the external maxillary is feebly connected with its distal
branches, which are taken over by the buccinator and the mylohyoid
ramus of the lingual artery. The orbital branch of the anterior deep
temporal has vanished, and the zygomatico-orbital dominates. The
basic relationship between the two extreme patterns is apparent
only after examining the intermediate.
An example of the influence that muscular development (as a
result of changing food habits or other factors) may exert on vascular
pattern is seen in the transformations in the superficial temporal
and anterior deep temporal arteries. The superficial temporal is at
first a large artery buried beneath the temporal aponeurosis, with a
slender zygomatico-orbital branch accompanying the nerve of the
same name to the orbit. The anterior deep temporal is a relatively
small vessel terminating in the same region. The temporal muscle,
in the role of most powerful agent for closing the jaws, is subject
to the greatest demands for adaptability in response to changing
food habits. Additional surface for origin of the temporal muscle
is provided through growth of the sagittal and lambdoidal crests
of the parietal, and dorsal and lateral expansion of the frontals.
The latter process is accompanied by increase in the pneumatic
space (so-called frontal sinus, figs. 88, 89, and 91) continuous through
the frontal, maxillary and nasal bones. In elongated heads, increase
in the mass of the temporal muscle tends to lie in the anteroposterior
plane, but temporal expansion appears greater in the horizontal
plane in short, broad skulls. Changes in the histological structure
Aa. palp. lat.
A. angularis
A. labialis sup.
A. labialis inf.
A. zygomaticoorbitalis
^. buccinatoriaW A. temp.
prof. ant. \ A. temp, superf.
A. maxillaris interna
-,-,-, ,^_ ^. _ A. auric, post.
k.A. trans, faciei ^^^H^^^A
A. maxillaris external |^L^ ,&• carotis externa
R. m. mass.
A. lingualis
A. sublingualis
Procyon
A. dorsalis ling.
Aa. palp. lat.
A. angularis
A. labialis sup.
A. zygomaticoorbitalis
A. labialis inf.
A. submentalis
— ^.
A. sublingualis
A. temp, superf.
A. maxillaris interna
A. auric, post.
A. carotis externa
A. lingualis
dorsalis ling.
Aa. palp. lat.
A. angularis
. zygomaticoorbitalis
/
A. labialis sup.
A. labialis inf.
A. temp, superf.
A. maxillaris interna
A. auric, post.
. carotis externa
A. sublingualis
A. dorsalis ling.
Potos
FIG. 95. Three arrangements of the external maxillary artery and its collateral
vessels. Dotted lines indicate arteries that have disappeared as others increased
in distribution.
547
548 FIELDIANA: ZOOLOGY, VOLUME 32
of that part of the temporal muscle supplied by the superficial
temporal may be correlated with the caliber of the artery. This
part of the muscle is more tendinous than fleshy in those long-skulled
carnivores (Bassariscus, Procyon, Nasua, Mustela), with a weak
superficial temporal. The transition to tendinous fibers (resulting
from changing stresses within the muscle) is accompanied by reduc-
tion of the superficial temporal in caliber; its main muscular branch
no longer extends to the orbit, and the zygomatico-orbital branch,
a weak vessel superficial to the temporal fascia, is the remaining link
to the orbital circulation. Meanwhile, as deeper areas of the temporal
muscle become bulkier, the anterior deep temporal increases its size
to accommodate the enlarged fleshy fibers, and finally takes over the
terminal orbital branches of the superficial temporal artery. The
anterior deep temporal remains short in those carnivores (dogs,
bears, Potos, pandas, and cats) in which the superficial temporal is
a large artery supplying heavy fleshy fibers in the temporal muscle.
The anastomotic artery and the accessory meningeal often asso-
ciated with it begin as nutritiae nervi and gradually increase in
importance in many carnivores. The development of the anastomotic
artery has already been discussed (Davis and Story, 1943) but the
meningeal arteries (fig. 96) in carnivores have been neglected. The
accessory meningeal may equal the middle meningeal in distribution,
and in the extreme case of the giant panda may even take over
completely. There may be some correlation between cranial form
and the pattern of dural arteries, since longer crania tend to have
two well-developed meningeal arteries, but shorter, more rounded
crania are supplied by one main artery. The frontal bone always
receives nutrients from the accessory meningeal; the parietal and
temporal bones receive from the middle meningeal. The similarity
in pattern among long-headed procyonids (Bassariscus, Procyon,
Nasua) does not necessarily imply lack of relationship to other
procyonids (Bassaricyon, Potos) for the basic pattern is still present
in both, but altered to a degree conforming to the differing propor-
tions. Endocranial casts of carnivores with elongated crania, such
as the mustelids Lutra, Tayra, Taxidea, and Mustela, show the
presence of two well-developed meningeal arteries. The dura of
the shorter, more rounded brains of bears, pandas, and the brachy-
cephalic dogs are supplied by one powerful artery, but even here a
weak accessory meningeal is always present. The superficial resem-
blance of these arteries in Potos, Ailurus, and Felis cannot be regarded
as more than coincidental due to the similar cranial proportions of
these genera.
X
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550
STORY: CAROTID ARTERIES IN PROCYONIDAE 551
The relations of the meningeal arteries with the fifth nerve,
going hand in hand with the development of the anastomotic artery,
are shown in the accompanying diagram (fig. 97) . The necessity of
adequate nutrition for the continued functioning of nerves appears
to be an important factor in the constancy of the association of these
arteries, regardless of their varying caliber, with the divisions of
the fifth nerve as they leave the skull via their specific foramina; the
ophthalmic division, via the orbital fissure, is accompanied by the
anastomotic artery and the accessory meningeal; the maxillary
division, via the foramen rotundum, is supplied by a nutrient
anastomotic branch; the mandibular division, via the foramen ovale,
is associated with the middle meningeal. All three arteries are linked
by anastomoses surrounding the semilunar ganglion of the trigeminus.
The extracranial relationships are constant also: N. ophthalmicus
with A. orbitalis, N. maxillaris with A. infraorbitalis, N. mandibularis
with A. alveolaris inferior, N. masticatorius with A. masseterica.
These topographical relationships are constant in all carnivores
seen; variation lies only in the caliber of the vessels. The anasto-
motic artery is essentially one of the nutrient arteries of the tri-
geminus, enlarged in Procyon to moderate importance, in Felis
domestica to great size in order to perform a specialized function.
In Potos and in Ursus americanus the anastomotic artery has not
developed beyond its primary function of nutrition for the fifth nerve.
The proportions of the olfactory and masticatory apparatuses
vary in the procyonids (fig. 98). Two divergent trends are present,
one in the direction of nasal expansion, the other toward nasal
reduction. In those forms with a large nasal development, such as
Procyon and Nasua, the vessels to this region are powerfully de-
veloped; relatively weaker vessels supply the orbit. In the shorter-
faced forms (Bassariscus, Bassaricyon, and Potos) the proportions
of nasal versus orbital area are nearly reversed and vascular supply
is likewise altered. The masticatory muscles (temporal, zygomatico-
mandibular, masseter and pterygoids) are well developed in all the
procyonids, but appear to increase in the horizontal plane in the
shorter-faced forms. In the latter, the vascular supply to the nasal
region is not extensive but the arteries to the masticatory muscles
are very large. The variability of the arterial pattern of the face
in procyonids may be due to functional necessities accompanying
changes in facial proportions.
Ontogenetically, the eye and the olfactory apparatus are con-
sidered as parts of the brain; this primary relationship of olfactory
552 FIELDIANA: ZOOLOGY, VOLUME 32
and visual apparatuses accounts for the intimate association of the
vascular trunks to these structures. The intracranial arteries (from
internal carotid) to these sensory regions are augmented by a large
trunk from the extracranial main vascular channel (external carotid).1
The close approximation of the internal ethmoidal and (internal)
ophthalmic arteries has already been mentioned by such authors
as Hiirlimann, Norris, and Tandler. The external ethmoidal and
ciliary arteries (sometimes termed external ophthalmic) are jux-
taposed branches of the external carotid. As the unequal growth
of the sense organs brings a divergence in volume, functional demands
change and a corresponding shift in the vascular supply occurs.
Two sets of arterial channels are available for reciprocal variation:
extracranial versus intracranial, and ethmoidal versus ciliary-oph-
thalmic. In mammals with a partially membranous orbit the extra-
cranial channel tends to dominate. The relative caliber of ethmoidal
and ciliary arteries varies with the relative size of the olfactory and
visual apparatuses. In the Anthropoidea, which have a closed orbit,
the intracranial channel takes over. The end stage of this trend is
seen when a large ophthalmic from the internal carotid supplies the
other orbital and ethmoidal structures in addition to the highly
developed eye. Weidenreich has discussed the decisive role of the
brain in the transformation of the primate skull. The structural
modifications of the skull have rendered the phylogenetically earlier
vascular channels untenable and a major shift in proportions of the
main channels has taken place. Thus the factors operating upon
skull transformation wield an influence on vascular supply.
The single orbital artery found in seven out of ten dissections of
Procyon, and in Potos and Ailurus, represents the primitive condition,
in which the olfactory and visual organs are nourished by a single
large trunk that bifurcates distally into ciliary and external ethmoidal
arteries. The single orbital artery is found also in the dogs, the bears
and giant panda, and the mustelids. Among the dogs examined,
the ethmoidal (olfactory) division considerably exceeds the ciliary
(visual) division in Cam's latrans, but the two divisions are equal
in Cam's familiaris. The skull of C. latrans is narrow and long-nosed,
and the orbit small, but the shorter skulls of certain domestic breeds
have larger orbits; the arterial pattern parallels these proportions.
Correlation of skull form and vascular proportions is again apparent.
1 The ontogeny of this region in man cannot be taken as a guide, for cranial
expansion in primates has produced a wide difference from the basic mammalian
pattern. The ontogeny of the arteries of the head has not been satisfactorily
traced in a carnivore.
553
554 FIELDIANA: ZOOLOGY, VOLUME 32
In Procyon the orbit is in an unstable condition, the eyeball
varying considerably in proportion to the volume of the orbit and
in lesser degree relative to brain volume. The variability in the
pattern of the orbital vascular supply of the raccoon, described above,
reflects the dynamics of transformations in the orbital region of the
skull. The basic pattern of a single orbital artery is gradually being
changed to a duplex pattern in procyonines. The ciliary artery is
separated from the original orbital (ethmoidal) trunk in Bassariscus
and Nasua and is an independent vessel in three out of ten Procyon
dissections. In Bassariscus the volume of the eye is greater in rela-
tion to brain volume than in Procyon; the ciliary, a powerfully
developed vessel, slightly exceeds the combined caliber of the other
orbital arteries. Among carnivores dependent on keen vision, this
trend toward massiveness in the ciliary artery reaches a climax in
Felis domestica, in which the eye is very useful. In Felis the huge
ciliary artery maintains its strength and individuality through the
complexity of the surrounding external rete that supplies all other
vessels to the orbit.
Feeding habits and the masticatory apparatus as an influencing
factor on skull form have been discussed recently by Sicher (1944).
The influence of relative brain size on skull transformations has
been brought out by Weidenreich (1941) and others. The relative
proportion of facial area (olfactory, visual and masticatory ap-
paratuses) to cranial area influences the vascular pattern of both
main areas of the skull. Since there is a definite correlation between
relative size of brain, mass of extracranial structures, and propor-
tionately adequate vascular supply, trends in the vascular pattern
within closely knit phylogenetic groups, such as the Felidae, clearly
are associated with changes in skull contour brought about by
facial and cranial development. In the Felidae a gradual shift in
the source of blood supply to the brain has occurred (Davis and
Story, 1943), with the external carotid taking over the functions of
the internal carotid of other forms. The larger cats, with a powerful
infraorbital artery supplying their facial area, show a diversion of
part of the external carotid flow to reach the brain, but retain a
functional internal carotid of small caliber. In the domestic cat,
on the other hand, the facial region of the skull is relatively much
smaller compared to the brain cavity. Extreme transformation in
function of the carotids occurs in Felis domestica, in which only a
moderate-calibered infraorbital artery supplies the facial area, with
the balance of the external carotid going to the brain via the external
rete; the true internal carotid is vestigial.
STORY: CAROTID ARTERIES IN PROCYONIDAE 555
The Procyonidae are a less closely knit group than the Felidae,
but there is apparent correlation throughout the family between
general proportions of the head and vascular supply. The propor-
tions of the internal and external carotid circulations are the reverse
of the feloid condition and are probably nearer the primitive condition
for carnivores. The extracranial structures, supplied by the external
carotid, make up the greater part of the head. The brain is ade-
quately supplied by the large internal carotid and the basilar artery
(from the vertebrals) ; collateral sources of supply are not essential
to maintain brain metabolism. The external and internal carotid
circulations are thus nearly independent of each other, yet a slender
connection through the anastomotic artery of varying caliber is
always present, available as a collateral channel if functional demands
change.
SUMMARY
The arteries of the head in the raccoon, Procyon lotor, are described
in detail. In the other procyonid genera, Bassariscus, Nasua, Potos,
and Ailurus, vessels differing from those in Procyon are described.
Brief notes on Bassaricyon are included.
A basic similarity exists among all the procyonid genera. The
arterial pattern of Procyon provides many collateral arteries to each
region of the head, and in this respect approximates a hypothetical
pattern from which any one of the procyonid generic patterns could
have been derived.
The forces modelling the structure of the head in procyonids
apparently influence the developmental trends of the passive circula-
tory system. Differences among the various genera have been
brought about by shifts between available collateral vessels. Some
of the factors involved in these shifts appear to be muscular develop-
ment, nerve arrangement, skull proportions and size of brain and
sense organs. None of these factors can with certainty be said to
predominate, for there is a continuous interplay of influences. Per-
haps some factors have been overlooked, but those enumerated
above call for further investigation along comparative embryological
as well as gross morphological lines.
The ground plan in the Procyonidae consists of a large internal
carotid artery, with a small anastomotic artery connecting this intra-
cranial trunk with the larger extracranial trunk, the external carotid.
The extracranial trunk breaks up, in the infratemporal fossa, into
556 FIELDIANA: ZOOLOGY, VOLUME 32
branches to the masticatory apparatus, the orbit, and the olfactory
apparatus.
Two trends in head proportions are present in procyonids: (1)
toward elongation of the olfactory and masticatory regions, with
apparent reduction of the eye (Procyon, Nasua) and (2) toward
shortening the olfactory and masticatory regions, with apparent
increase in eye development (Bassaricyon, Potos). Bassariscus is
intermediate, with little reduction in nasal area but with a large
eye. Vascular changes parallel these transformations of skull contour.
Despite skull changes, arteries passing through cranial foramina
and those accompanying nerves are constant in location; variations
are in caliber.
Numerous arterioles anastomose around the internal maxillary
artery in the infratemporal fossa of procyonids. This tendency may
foreshadow, structurally, the external rete of the Felidae.
On the basis of arterial pattern, intergeneric relationships are
indicated as follows: Procyon and Nasua are very close, Bassariscus
and Bassaricyon intermediate between Procyon and Potos; Potos has
some resemblance to Procyon but parallels Ailurus; Ailurus resembles
Ailuropoda more than it does the other procyonid genera.
Many features shared with other carnivores are present in the
raccoons, and it is difficult to point out a sharply delineated pro-
cyonid pattern. Limitations of material prevent a comprehensive
comparison of the Carnivora, but the available data have been
checked against the procyonids.
The Procyoninae (Bassariscus, Procyon, Nasua) share many
characters with the Ailurinae, Mustelidae, Canidae, and Ursidae, in
the order named. The Ailurinae (Ailurus, Ailuropoda) share
characters with the Procyoninae, Ursidae, Canidae and Mustelidae.
Ailuropoda shares more with the Ursidae than with Ailurus or the
Procyoninae. Potos has more in common with Ailurus than with
the Procyoninae. Bassariscus has fewer dog and bear characters
than the other procyonines. Because the Procyonidae overlap the
other canoid carnivores in their carotid circulation, the family gives
a cross sectional view of this system in the Canoidea.
REFERENCES
ABRAMSON, D. I.
1944. Vascular responses in the extremities of man in health and disease.
Univ. of Chicago Press; x+412 pp., 58 figs.
STORY: CAROTID ARTERIES IN PROCYONIDAE 557
ADAMS, W. E.
1943. The blood supply of nerves. II. The effects of exclusion of its regional
sources of supply on the sciatic nerve of the rabbit. Jour. Anat., 77, pp.
243-250, 2 figs., 3 pis.
DAVIS, D. D.
1941. The arteries of the forearm in carnivores. Field Mus. Nat. Hist., Zool.
Ser., 27, pp. 137-227, 44 figs.
MS. A monographic study of the giant panda.
DAVIS, D. D. and STORY, H. E.
1943. The carotid circulation of the domestic cat. Field Mus. Nat. Hist.,
Zool. Ser., 28, pp. 1-47, 9 figs.
ELLENBERGER, W. and BAUM, H.
1891. Systematische und topographische Anatomie des Hundes. Berlin: Parey;
xxiv+646 pp., 208 figs., 37 pis.
SICKER, HARRY
1944. Masticatory apparatus in the giant panda and the bears. Field Mus.
Nat. Hist., Zool. Ser., 29, pp. 61-73, 5 figs.
SIMPSON, G. G.
1945. The principles of classification and a classification of the Mammalia.
Bull. Amer. Mus. Nat. Hist., 85, xvi+350 pp.
TANDLER, JULIUS
1899. Zur vergleichenden Anatomie der Kopfarterien bei den Mammalia.
Denkschr. K. Akad. Wiss. Wien, 69, pp. 667-784, 17 figs., 8 pis.
WEBER, MAX
1927. Die Saugetiere. Einfiihrung in die Anatomie und Systematik des
Recenten und fossilen Mammalia. Bd. 1. Anatomischer Teil [2nd ed.].
Jena: G. Fischer; xv+444 pp., 316 figs.
WEIDENREICH, FRANZ
1941. The brain and its role in the phylogenetic transformation of the human
skull. Trans. Amer. Phil. Soc., n.s., 31, pp. 321-442, 56 figs.
INDEX
Ailurns fulgens, carotid arteries of, 528,
fig. 91
arteries of the head in the raccoon, 487,
fig. 82
arteries of the right auditory region in
the raccoon, 489, fig. 83
auricular artery, posterior, in Procyon
lotor, 492, fig. 84
Bassaricyon alleni, carotid arteries of,
526, figs. 90, 95
Bassariscus astutus, carotid arteries of,
515, fig. 89
carotid artery, in Procyon lotor, 481
common, 481
external, 485
internal, 481
carotid canal, transitions in form, 542,
fig. 94
carotid pattern, procyonid, 533, fig. 92
circle of Willis, patterns in carnivores,
482, 540, fig. 93
in Procyon lotor, 482
cranial foramina, in Garni vora, 511
lingual artery, in Procyon lotor, 488, fig.
95
maxillary artery, external, in Bas-
saricyon, 546, fig. 95
in Polos, 546, fig. 95
in Procyon, 490, figs. 85, 95
maxillary artery, internal, 496, fig. 86
branches of, 500, 508, fig. 87
proportions to skull and orbit, 533,
fig. 98
Meningeal arteries, 549
of Ailurus, 549, fig. 96
of Bassariscus, 549, fig. 96
of Felis, 549, figs. 96, 97
of Nasua, 549, fig. 96
of Potos, 549, fig. 96
of Procyon, 549, 550, figs. 96, 97
of Ursus, 550, fig. 97
Nasua narica, carotid arteries of, 519,
fig. 89
nerves associated with arteries, 498
nose, arterial supply, 506, fig. 88
pharyngeal artery, ascending, in Pro-
cyon lotor, 485
Potos flavus, carotid arteries of, 522,
fig. 91
Procyon lotor, carotid circulation, 481
rete, external, 500
temporal artery, superficial, 494, fig. 85
thyroid artery, anterior, in Procyon,
485
557A
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