488 



CAROTID ARTERY. 



in the substance of that muscle with the branches 

 which it receives from the superior thyroid. 



The stern o-mastoid muscle very frequently 

 receives a large branch at this part arising dis- 

 tinctly from the external carotid. This Professor 

 Harrison considers should be classed among 

 the regular branches of the external carotid, 

 and he has described it under the name of a. 

 sterno-tnastoidca.* 



While the occipital artery is covered by the 

 sterno-mastoid, trachelo-mastoid, and splenius, 

 it gives branches to these muscles, some of 

 which descending anastomose with branches of 

 the cervicalis profunda and the vertebral ; 

 those which ascend are distributed to the supe- 

 rior attachments of these muscles ; amongst 

 them there is one branch occasionally found 

 which penetrates into the cranium by the mas- 

 toid hole, and is distributed to the dura mater, 

 under the name of posterior meningeal of the 

 occipital. 



When the occipital artery comes out from 

 beneath the splenius muscle it divides into 

 those branches which are distributed over the 

 posterior surface of the occipital bone, sup- 

 plying the occipito-frontalis and the scalp, to- 

 gether with the pericranium, and anastomosing, 

 as already mentioned, with the opposite occi- 

 pital, posterior auris, and temporal. One of 

 these branches frequently enters the cranium 

 by the parietal hole, and spreads over the dura 

 mater. 



The occipital artery sometimes gives small 

 twigs, which enter the cranium by the foramen 

 lacerum posterius and the anterior condyloid 

 foramen. 



2d. A. posterior auris, v. auricularis pos- 

 terior, arises immediately after the occipital, 

 in the substance of the parotid gland ; it is 

 generally a much smaller vessel than the latter, 

 from which it is mostly separated by the stylo- 

 hyoid muscle : sometimes it comes from the 

 occipital. It passes upwards and backwards 

 under the parotid gland between the mastoid 

 process of the temporal bone and the cartila- 

 ginous tube of the ear ; it first sends branches 

 to the parotid gland, the stylo-hyoid muscle, 

 the posterior belly of the digastric and the 

 external ear; it then gives off the stylo- 

 mastoid artery, which, among other branches 

 to the external ear, gives off one to be dis- 

 tributed to the membrana tympani. Then 

 the stylo-mastoid traversing the aqueduct 

 of Fallopius finds its way into the cavity of 

 the tympanum, on the lining membrane of 

 which, and its prolongation into the mastoid 

 cells, its branches are expended, where it anas- 

 tomoses with a branch of the middle menin- 

 geal, which enters the hiatus Fallopii, and 

 arrives in the tympanum along with the chorda 

 tympani nerve. Sometimes the stylo-mastoid 

 artery comes from the middle meningeal. 



When the posterior auris gets to the front of 

 the mastoid process it divides into two branches, 

 one of which is anterior and the other pos- 

 terior ; the former spreads its branches over all 



* Surgical Anatomy of the Arteries of the Human 

 JJody, vol. i. 



parts of the internal surface of the ear; the 

 latter ascends in front of the mastoid process, 

 passes under the posterior auris muscle, and 

 divides into many branches, which are distri- 

 buted to the occipito-frontalis and temporal 

 muscles, integuments, &c. 



These branches anastomose with the temporal 

 and occipital arteries.* 



While traversing the parotid gland the ex- 

 ternal carotid gives several small branches to 

 the masseter and pterygoid muscles, to the 

 substance of the gland itself, and a few to the 

 front of the external ear ; occasionally it gives 

 origin to the transversalis faciei in this course. 



Behind the neck of the condyle of the lower 

 jaw the external carotid divides into its two 

 superior and terminal branches, the temporal 

 and internal tnaxitiary. 



\. Temporal artery, (a. temporalis.) The 

 temporal artery ascends at first a little obliquely 

 outwards between the ram us of the jaw and 

 the tube of the ear, covered by the parotid 

 gland ; crossing the zygoma at its posterior 

 part, and passing under the anterior auris 

 muscle, it mounts up over the temporal apo- 

 neurosis, and becomes subcutaneous for the 

 remainder of its course. 



Immediately after its origin the temporal 

 gives off anteriorly a very considerable 

 branch, which is called the transversalis J'uciei : 

 this artery sometimes arises from the trunk of 

 the external carotid ; it passes forward over the 

 neck of the condyle of the lower jaw, and, 

 crossing the masseter muscle, runs superior to 

 the duct of Steno, which it accompanies across 

 the face; it anastomoses with the labial, buccal, 

 and infra-orbital arteries. The branches which 

 the transversalis faciei usually gives off are 

 distributed to the parotid gland and its duct, 

 the masseter, zygomatic, and orbicularis pal- 

 pebraium muscles, and the integuments. I 

 have seen an instance in which this artery arose 

 from the external carotid opposite the angle of 

 the jaw, beneath which it passed forwards, and 

 joined the labial at the anterior edge of the 

 masseter muscle. 



When the temporal artery has arrived at the 

 zygoma, it gives a branch called middle tem- 

 poral, which pierces the temporal aponeurosis, 

 and ascends in the substance of the temporal 

 muscle, to which it is distributed, and which 

 anastomoses with the deep temporal arteries. 



Having given off a few small branches to 

 the parotid gland, integuments, and external 

 ear, the temporal artery ascends on the temporal 

 aponeurosis, and divides into two branches, 

 the anterior and posterior. The anterior branch 

 ascends in a serpentine course towards the 

 forehead, and sends off many branches, which 

 are distributed to the occipito-frontalis, the 

 orbicularis palpebrarum, and integuments, and 

 which anastomose with the superciliary and 



* [The surgical anatomist cannot fail to notice 

 the relation of the posterior auris artery to the portio 

 dura nerve, as it lies superficial to and nearer the 

 mastoid process than that nerve, so as to be consi- 

 derably, although not necessarily, endangered when 

 the operator proceeds to divide the nerve at its 

 emergence from the stylo-mastoid foramen. ED.] 



