_1_, Vertebral artery; _2_, muscular branches of _1_; _3_, branches of
_1_ to the rete mirabile, _4_; _5_, branches of internal maxillary
artery to rete; _6_, branch of internal maxillary artery entering
cranium through foramen ovale; _7_, condyloid artery; _8_, emergent
artery from rete, distributed like internal carotid artery of horse;
_9_, _9′_, longitudinal vertebral sinuses; _a_, cribriform plate;
_b_, optic foramina; _c_, for. lacerum orbitale + rotundum; _d_,
foramen ovale; _e_, occipital condyle; _f_, _g_, _h_, first, second,
and third cervical vertebræ. (After Leisering’s Atlas.)
]
2. The =external maxillary artery= is smaller than that of the horse,
but pursues a similar course. The =lingual artery= is large, and often
arises separately from the common carotid; it gives off a branch to the
submaxillary gland, and the =sublingual artery=. After turning around
the jaw the facial gives off the two =labial arteries=. The =superior
labial= is large; it usually gives off a branch which runs forward
almost parallel with the lateral nasal. The =angular artery= is absent
or rudimentary, and the =lateral= and =dorsal nasal arteries= spring
from branches of the internal maxillary.
3. The =external carotid artery= passes upward between the
stylo-hyoideus and the great cornu of the hyoid bone, turns forward
across the external face of the latter, and divides into superficial
temporal and internal maxillary arteries. It gives off the following
collateral branches:
(1) Branches to the parotid and submaxillary glands.
(2) The =pharyngeal artery=, which, however, often arises from the
occipital.
(3) The =posterior auricular=, which resembles that of the horse and
sends a stylo-mastoid branch into the tympanum. It may arise from the
superficial temporal.
(4) The =masseteric artery= resembles that of the horse, but is smaller.
The =superficial temporal artery= is large and presents the following
special features: (1) Its transverse facial branch passes into the
central part of the masseter. (2) It gives off a branch which
corresponds to the posterior meningeal artery of the horse, enters the
temporal canal, and ramifies in the dura mater, giving off twigs to the
external ear, the temporal muscle, and the frontal sinus. (3) It usually
gives off the anterior auricular artery. (4) Branches are supplied to
the frontalis muscle and the eyelids, (5) A large branch passes around
the outer side of the base of the horn-core, supplies the matrix of the
horn, and anastomoses across the back of the frontal eminence with the
artery of the opposite side.
The =internal maxillary artery= is less curved than in the horse and is
entirely extraosseous, since the alar canal is absent. The principal
differential features in its branching are as follows:
(1) The =ophthalmic artery= forms a rete mirabile within the periorbita.
Its frontal branch enters the supraorbital canal and ramifies chiefly in
the frontal sinus.
(2) Several branches take the place of the internal carotid artery. One
of these enters the cranial cavity through the foramen ovale and several
small ones pass through the foramen which represents the foramen
rotundum and foramen lacerum orbitale of the horse. They concur with the
vertebral and condyloid arteries in the formation of an extensive =rete
mirabile= on the cranial floor around the sella turcica. From each side
of the rete an artery arises which is distributed in general like the
internal carotid of the horse.
(3) The =malar artery= is large; it arises by a common trunk with the
infraorbital and gives off the =dorsal nasal= and the =angular artery of
the eye=.
(4) The =infraorbital artery= is large and emerges from the infraorbital
foramen to form the =lateral nasal artery=.
(5) The =palatine artery= is smaller than in the horse and usually
arises by a common trunk with the sphenopalatine. It passes through the
palatine canal and along the palatine groove, enters the nasal cavity
through the incisive fissure, and does not go to the upper lip. It forms
a rete mirabile about the naso-palatine canal and terminates in the
mucous membrane of the anterior part of the nasal cavity.