THE NECK. 



Finally the superior intercostal, which, like the vertebral and thyroid axis, is a 

 branch of the first portion of the subclavian, through its profunda cervicis branch 

 anastomoses with a deep descending branch of the princeps cervicis (Fig. 172). 



The Internal Carotid Artery. The internal carotid lies posterior and to 

 the outer side of the external. It gives off no branches in the neck. Entering the 

 skull through the carotid canal, in the apex of the petrous portion of the temporal 

 bone and directly below and to the inner side of the Gasserian ganglion, it passes 

 through the inner side of the cavernous sinus and at the anterior clinoid processes it 

 bends up to divide into the anterior and middle cerebrals. Before its division it 

 gives off the posterior communicating artery, the anterior choroid artery to supply 

 the choroid plexus in the lateral ventricles, and the ophthalmic artery. The internal 



Temporal 



Posterior auricu' 

 Occipit 



Princeps cervic 

 Superficial branc 

 Deep branc 

 Internal caro 



lar 



Transverse cerv: 

 Suprasca 



tid 



Transverse facial 

 Internal maxillary 



Ascending pharyngeal 

 Facial 



Lingual 



External carotid 

 Superior thyroid 



nferior thyroid 

 'ommon carotid 



Vertebral 

 Thyroid axis 

 nnominate 



uperior intercostal 



ubclavian 



FIG. 172. Collateral circulation after ligation of the common carotid artery. 



carotid artery in the neck is normally straight, but sometimes, particularly in elderly 

 persons, it is tortuous. This may then be mistaken for aneurism. It lies about 2 cm. 

 posterior and a little to the outer side of the tonsil. As the pharynx is the side of 

 least resistance, when the vessel becomes tortuous it bulges into it, and on examina- 

 tion through the mouth a pulsating swelling can be distinctly seen in the pharynx 

 just posterior to the tonsil. The finger introduced can feel the pulsations, and 

 pressure on the carotid in the neck below causes the pulsations to cease. Thus the 

 character of the pulsating swelling can be recognized. This artery is rarely ligated, 

 but if it is desired to do so it can readily be reached through an incision 6 or 7 cm. 

 long behind the angle of the jaw. Aneurism or wounds may necessitate its ligation. 

 At its commencement it is comparatively superficial, but as it ascends it gets quite 

 deep, passing beneath the digastric and stylohyoid muscles. It should therefore be 

 ligated below the angle of the jaw and not over 3 cm. from its origin at the upper 



