POSTERIOR AURIS OR STYLO-MASTOID ARTERY. 251 



the transverse process of the atlas and the mastoid process of 

 the temporal bone. 



In this course it passes over the internal jugular vein and the 

 eighth pair of nerves, and under the posterior part of the 

 digastric muscle : it lies very near to the base of the mastoid 

 process, and under the muscles which are inserted into it. 

 After emerging from these muscles, it runs superficially upon 

 the occiput, dividing into branches which extend to those of 

 the temporal artery. 



The Occipital Artery sends off branches to the muscles 

 which are contiguous to it, and to the glands of the neck. 



It also gives off the following branches ; one called the Men- 

 ingeal, which passes through the posterior foramen lacerum 

 to the under and back part of the dura mater : one to the 

 exterior parts of the ear: another which passes downwards, 

 and is spent upon the complexus, trachelo-mastoideus, and 

 other muscles of the neck : and several smaller arteries. 



The artery next to be described, is sometimes sent off by the 

 occipital artery. 



6. The Posterior Auricular, or Stylo-Mastoid Artery, 



When it arises from the external carotid, comes off poste- 

 riorly from the artery, where it is involved with the parotid 

 gland, and passes backwards between the meatus auditorius 

 externus and the mastoid process. It then ascends, in a curved 

 direction, and terminates behind the ear. 



In this course it sends off small branches to the parotid gland, 

 and to the digastric and sterno-mastoid muscles. Sometimes a 

 distinct branch, which is particularly visible in children, passes 

 through an aperture in the meatus auditorius externus, and is 

 spent on its internal surface. 



It also sends off a branch which enters into the Stylo-Mas- 

 toid Foramen, constituting the proper stylo-mastoid artery ; it 

 supplies small vessels to the membrana tympani and the lining 

 membrane of the cavity of the tympanum ; to the mastoid cells ; 

 to the muscle of the stapes, and to the external semicircular canal. 

 One of these vessels anastomoses in the upper and posterior part 



