506 ARTERIES OF THE HEAD AND XECK. 



Varieties. — ^?r////«. — The facial artery not unfrequently arises by a common 

 trunk with the lingual. Occasionally it arises above its usual i^osition, and then 

 descends beneath the angle of the jaw to assume its ordinary course. 



Size. — This artery varies much in size, and in the extent to which it is distri- 

 taited. It has been observed, very rarely, however, to end as the submental, not 

 Teaching the side of the face ; in some cases it supplies the face only as high as 

 the lower lip. The deficiency of the facial artery is most frequently compen- 

 sated for by an enlargement of the nasal branches of the ophthalmic at the 

 inner side of the orbit ; occasionally by branches from the transverse facial or 

 imternal maxillary ai'teries. 



Branches;. — The /ixccndiiif/ pnlatiiu- artery is in some instances transferred to 

 the externa! carotid. This branch varies in size and the extent to which it 

 reaches. Not unfrequently it is expended without furnishing any branch to the 

 ^oft palate. AMien it is thus reduced in size, the phalangeal artery takes its 

 3)lace on the soft palate. 



The tomiUar branch is not unfrequently altogether wanting. 



I'hQ.siihintntal branch has been observed to take its rise from the lingual artery. 

 On the other hand, the facial artery, instead of the lingual, has been found to 

 furnish the branch which supplies the sublingual gland. 



4. Occipital Artery. — The occipital artery, arising from the 

 posterior part of the external carotid, usually opposite the facial or a 

 little higher up, is directed upwards and backwards, beneath the pos- 

 terior belly of the digastric muscle, to the interval between the trans- 

 verse process of the atlas and the mastoid process of the temporal bone. 

 From that point it turns horizontally backwards along the skull in the 

 occipital groove of the temporal bone, internal to the mastoid process 

 and the sterno-mastoid, splenius, digastric and trachelo-mastoid muscles, 

 and resting on the superior oblique and complexus muscles. Lastly, 

 changing its direction a second time, and piercing the cranial attach- 

 ment of the trapezius, it ascends beneath the integument on the back 

 of the head accompanied by the great occipital nerve, and divides into 

 numerous branches upon the upper and back part of the cranium. 

 "While in the neck, the occipital artery crosses over the internal carotid 

 artery, the vagus, and s[)inal accessory nerves, and the internal jugular 

 vein ; and the hypoglossal nerve turns from behind over it at its origin. 



Branolies. — (a) Small miixeiilur oSsets to the digastric and stylo-hyoid muscles, 

 and one of larger size to the sterno-mastoid. This last is so regular a branch that 

 it is known as the xfcrno-maxiold branch. 



(Ji) An (luvicular branch to the back part of the concha of the ear. and two 

 or three other muscular branches to the splenius and trachelo-mastoid. 



(i") Tlie nicniiificdl branch. This rmis up with the internal jugular vein, enters 

 the skull through the foramen jugulare, and ramifies in the dura mater of the 

 posterior fossa of the base of the skull. 



(r/) The rrrricdl branch, rtuniix cn-i-irtili.'< j)rinerj)x. To the upper and back part 

 of the neck the occipital artery furnishes a branch thus designated. Descending 

 a short way, this vessel divides into a superficial and a deep branch. The former 

 ramifies beneath the splenius, sending oftsets through that muscle to the trape- 

 zius ; while the deep branch passes beneath the comjjlexus, and anastomoses with 

 branches of the vertebral artery, and with the deep cer\'icai artery. The size of 

 this branch varies very much. 



(e) The .superficial or cranial branches. These pursue a tortuous course between 

 the integument and the occipito-frontalis muscle ; and in proceeding upwards on 

 the skull they separate into diverging branches, which communicate with the 

 branches of the opposite artery, as well as with those of the posterior auricular 

 arteiy, and of the temporal artery at the vertex and side of the skull. 



A small twig, the iiiaKtoid branch, enters the skull through the mastoid foramen, 

 and ramifies in the dura mater. 



