GREAT VESSELS AND NERVES OF NECK 211 



Dissection. After the ascending pharyngeal artery has been 

 examined, the internal carotid artery, the glosso-pharyngeal, 

 vagus, accessory, and hypoglossal nerves, and the superior 

 cervical ganglion, with their various connections and branches, 

 must be dissected. A dense and tough fascia envelops them, 

 and a great amount of patience is required to trace the branches 

 of the nerves through it. One nerve the pharyngeal branch 

 of the vagus which proceeds downwards and forwards, upon 

 the superficial or lateral aspect of the internal carotid, is especially 

 liable to injury, and must therefore be borne in mind from the 

 very outset of the dissection. The internal laryngeal and the 

 external laryngeal nerves have been previously displayed in the 

 anterior triangle of the neck. If they are traced upwards, they 

 will lead to the superior laryngeal branch of the vagus, which 

 lies in relation with the deep aspect of the internal carotid artery. 

 Near the base of the skull all the nerve-trunks will be found 

 making their appearance, close together, in the interval between 

 the internal jugular vein and the internal carotid artery ; whilst 



erior to the vein the rectus lateralis muscle and the first 

 of the cervical plexus will be seen. 



Arteria Carotis Interna. The internal carotid artery is 

 one of the two terminal branches of the common carotid, 

 and it commences, therefore, at the level of the upper border 

 of the thyreoid cartilage. From that point it proceeds upwards 

 in the neck, in a vertical direction, until it reaches the 

 base of the skull; there it disappears from view by entering 

 the carotid canal of the petrous portion of the temporal bone. 

 Through the carotid canal it reaches the interior of the 

 cranium. The internal carotid artery can therefore be very 

 appropriately divided into three parts viz., (i) a cervical; 

 (2) a petrous; and (3) an intracranial. The cervical part 

 alone comes under the notice of the student in the present 

 dissection. 



In the first part of its extent the internal carotid artery 

 lies in the carotid triangle, and is therefore comparatively 

 superficial. It is covered by the integument, platysma, and 

 fascia, and is overlapped by the sterno-mastoid muscle and 

 the anterior border of the internal jugular vein. It is crossed 

 by the hypoglossal nerve, the occipital artery and its sterno- 

 mastoid branch, and the lingual and common facial veins. The 

 descendens hypoglossi descends on its superficial surface. 



As it proceeds upwards, it passes under cover of the lower 

 end of the parotid gland and then at a higher level under 

 cover of the posterior belly of the digastric, the stylo-hyoid, 

 the stylo-pharyngeus, and the styloid process, which separate 

 it from the postero-medial surface of the parotid gland. It 

 in 14 a 



