768 THE VASCULAR SYSTEM. 
part of the roof of the nose, the roof of the pharynx, the sphenoidal sinus, and the lower 
part of the Eustachian tube, and anastomoses with the Vidian branch of the internal 
carotid. 
(f) The spheno-palatine branch (a. spheno-palatina) springs from the termination of 
the internal maxillary artery. It passes inwards through the spheno-palatine foramen 
into the nasal cavity, where it divides into many branches. One of these, the internal 
nasal or naso-palatine, which is sometimes looked upon as the continuation of the artery, 
crosses the back part of the roof of the nose, and descends in a groove on the vomer to 
the incisive foramen where it anastomoses with the termination of the posterior palatine 
artery and with the septal branch of the superior coronary. The outer or external nasal 
branches of the spheno-palatine artery supply the greater part of the outer wall of the 
nasal fossa and the cavity of the antrum, anastomosing with branches of the infraorbital, 
ethmoidal, and lateral nasal arteries. Branches are also distributed to the ethmoidal cells, 
to the sphenoidal sinus, and to the upper part of the pharynx. 
THE INTERNAL CAROTID ARTERY 
The internal carotid artery (a. carotis interna, Figs. 554, 556, and 559) com- 
mences at the termination of the common carotid, opposite the upper border of the 
Supra-orbital 
Ethmoidal 
arteries 
artery 
Ophthalnic 
Optic nerve 
artery 
Stalk of Pituitary body 
Post. communicating arteries 
Post. cerebral arteries 
Sup. cerebellar artery 
=f Z = q / Frontal artery 
Basilar artery___.-——— a 
op i Nasal artery 
2 @ yA -. Ciliary arteries 
Vertebral arteries 
Internal carotid artery 
Ascending pharyngeal 
artery 
Ascending palatine artery 
Stylo-glossus muscle 
Stylo-pharyngeus muscle 
Posterior auricular artery 
Occipital artery _ 
Facial artery 
Lingual artery 
Facial artery 
External carotid artery 
Superior thyroid artery — 
Common earotid 
artery 
Vertebral artery 
Profunda 
cervicis artery ~ 
Superior inter- 
costal artery == Thyroid axis artery 
Anastomosis —Subclavian artery 
with first 
aortic inter- ~~ 
costal artery 
—— Internal inainmary artery 
————Innominate artery 
Fic. 556.—THE CAROTID, SUBCLAVIAN, AND VERTEBRAL ARTERIES AND THEIR MAIN BRANCHES. 
thyroid cartilage, and terminates in the middle fossa of the skull, close to the 
commencement of the fissure of Sylvius, where it divides into the middle and 
anterior cerebral arteries. 
Course.—It passes through the carotid and submaxillary triangles, traverses 
the carotid canal of the temporal bone, crosses the upper part of the foramen lacerum 
medium, and runs in the outer wall of the cavernous sinus in the middle fossa of the 
skull. 
At its origin it lies behind and to the outer side of the external carotid, but as 
