PHYSIOLOGY, AND PATHOLOGY OF THE CHIMPANZEE. 403 



joins the inferior maxillary division before the latter separates 

 into its lingual and inferior dental nerves. The submaxillary 

 ganglion is not separate as in Man, but is fused with the 

 hypoglossal nerve. The otic ganglion was not recognised with 

 certainty. 



The ahducens emerges between the two heads of the external 

 rectus and sinks into the ocular surface of the muscle. 



Th^ facial nerve emerges from the stylo-mastoid foramen. Its 

 intra-petrous course was not traced. It divides in the parotid 

 gland into temporal, zygomatic, maxillary, buccal, mandibular, and 

 cervical divisions. The temporal branches run upwards and are 

 distributed as in Man. The zygomatic and maxillary divisions 

 eventually unite and give off from their combined trunk a 

 number of branches to the muscles of the face. The mandibular 

 and cervical divisions are as in Man. The union of the chorda 

 tympani and trigeminal nerves has already been described. 



The auditory nerve was not traced. 



The glosso-pharyngeal nerve emerges from the inner part of the 

 jugular foramen and communicates with the other nerves at the 

 upper part of the neck. It passes between the external and 

 internal carotid arteries, curves round the stylo-pharyngeus 

 muscle and disappears under the free outer edge of the hyoglossus. 

 Finally it breaks up into branches to the tongue, pharynx, and 

 tonsil. It supplies the stylo-pharyngeus. The tympanic and 

 petrosal branches were not traced. 



The Vagus Nerve (text-figs, 45 & 46) emerges from the jugular 

 foramen wherein it is lateral to the glosso-pharyngeal nerve, 

 posterior to the internal jugular vein and mesial to the accessory 

 nerve, to which it is closely adherent. Immediately below the 

 base of the skull it develops the ganglion nodosum (G.N.) on its 

 lateral aspect. The nerve separates from the ganglion again at 

 the level of the posterior border of the hard palate. At the root 

 of the neck it runs on to the posterior aspect of the common 

 carotid artery and then it entei'S the thorax on the left side. 

 The right one disappears under cover of the innominate artery 

 where the latter bifurcates into right common carotid and sub- 

 clavian arteries. The left vagus (text-fig. 45 A) only communicates 

 with the sympathetic, but the right one (text-fig. 45 B) is ex- 

 tensively used with the sympathetic. 



Branches in the Nech : — 



1. Communicating nerves to the glosFO-pharyngeal (c. ix), 

 hypoglossal (c. xii), superior cervical ganglion of tie sjmpathetic 

 (S.O.G) and cervical plexus (c.C.P). 



2. Pharyngeal nerve (a). 



3. Superior laryngeal nerve (6). 



4. Right recurrent laryngeal nerve {d). 



5. Cardiac branch of the left vagus (/"). 



6. Plexus of carotid, tracheal and cardiac branches of the 

 right vagus. 



