CAROTIDS, AND THEIR BRANCHES. 203 



along the posterior belly of the digastricus between the trans- 

 verse process of the atlas and the mastoid portion of the tempo- 

 ral bone, being covered by the several muscles which are If* 

 serted into the latter, as the sterno-mastoid, the splenius, and 

 the trachelo-mastoid. It is covered, for some distance, by the 

 insertion of the splenius capitis, and becomes at length super- 

 ficial at the posterior margin of this muscle. The occipital 

 artery is distributed as follows: 



Shortly after its origin, it sends branches to the digastric 

 muscle behind, to the upper part of the sterno-mastoid and to 

 the lymphatic glands of the upper part of the neck. While en- 

 closed by the muscles on the back of the neck, it also sends 

 branches to them, and anastomoses thereby with the vertebral 

 artery; occasionally, one of these branches is of considerable 

 magnitude, and has been found descending very low on the 

 back, between the splenius and the complexus muscles. It also 

 sends a small branch to the dura mater, through the mastoid 

 foramen generally, but sometimes through the posterior fora- 

 men lacerum. When the stylo-mastoid artery is wanting, it 

 also detaches a branch through the stylo-mastoid foramen to 

 the internal parts of the ear. 



The occipital artery, having become superficial at the inter- 

 nal margin of the splenius on the occiput, ascends on the latter 

 bone towards the vertex in a tortuous manner, sending off, on 

 each side, many small ramifications. It ends by anastomosing 

 with the posterior temporal artery. 



The Posterior Auricular Artery (Art. Jluricularis Posterior) 

 arises a little above the last, at the lower edge of the parotid 

 gland, from the external carotid, and is one of its smallest 

 branches. It ascends backwards enclosed by the parotid gland, 

 and afterwards between the meatus auditorius externus and the 

 mastoid bone : at the latter place, it sends a ramification to the 

 internal side of the external ear; it then ascends and is distri- 

 buted, by small branches, on the contiguous integuments of the 

 side of the head. While still involved in the parotid gland, it 

 sends some small ramifications through the meatus externus to 

 its lining membrane and the membrana tympani. It then de- 

 taches a branch through the stylo-mastoid foramen, from which 

 the whole artery is also named Stylo-Mastoid; but this branch, 



