304 HEAD AND NECK 



pharyngeal branches to the wall of the pharynx and 

 prevertebral branches to the prevertebral muscles. At 

 the base of the skull it gives off meningeal branches, which 

 enter the cranial cavity through the hypoglossal canal, the 

 jugular foramen, and the foramen lacerum ; and palatine 

 branches^ which pierce the pharyngeal aponeurosis above the 

 upper border of the superior constrictor and descend, along 

 the levator palati, to the soft palate. Offsets from these 

 branches are given to the auditory tube (O.T. Eustachian) 

 and to the tonsil. 



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 these structures, 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 anteriorly 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. These, 

 if traced upwards, 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 posterior to the vein 

 the rectus lateralis muscle and the first loop 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 at the level of the upper border of the 

 thyreoid cartilage. From this 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 which it reaches the interior of the cranium. 

 The internal carotid artery can therefore be very appropri- 

 ately 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 



