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DISSECTION OF THE HEAD AND NECK. 187 



the external carotid. Beneath the parotid gland it bifurcates to form 

 a pterygoid and a masseteric branch. The former passes within the 

 ramus to reach the internal pterygoid muscle. The latter emerges 

 between the ramus and the parotid gland, above the insertion of the 

 stylo-maxillaris, and penetrates the masseter. 



Veins. — The transverse facial and maxillo-muscular veins accompany 

 the arteries of the same name. The former joins the anterior auricular 

 to form the superficial temporal vein, the latter empties itself into the 

 jugular. , 



The 7th Nerve on- the face (Plate 29). This nerve appears on the 

 face a little below the articulation of the jaw, where it emerges from 

 beneath the parotid gland. Before its emergence it is joined by the 

 subzgomatic branch of the inferior maxillary division of the 5th. The 

 nerve dmdes into a variable number of branches, which anastomose on 

 the surface of the masseter and form a plexus, termed in man the pes 

 anserinus (from its resemblance to the foot of a goose). In this plexus 

 it is not possible to distinguish, among the motor fibres proper to the 

 nerve itself, those sensory fibres derived from the subzgomatic nerve. 

 This plexus is covered by the skin and the thin facial panniculus, both 

 of which receive branches from it. Below the inferior edge of the 

 masseter, branches of the plexus are continued over the submaxillary 

 vessels to supply the muscles of the cheek, lips, and nostrils, as well as 

 the panniculus and skin. The largest of these branches is the most 

 anterior, and it passes beneath the zygomaticus muscle in company with 

 the superior labial vessels. It communicates with the infra-orbital 

 nerves emerging from the infra-orbital foramen, and passes with them 

 to the upper lip. Another branch of considerable size passes beneath 

 the retractor of the lower lip, and runs in company with the inferior 

 labial artery. It reaches the lower lip, in which it is distributed along 

 with the mental nerves. 



The Subzgomatic Branch of the 5th nerve (Plate 31). The major 

 portion of this nerve joins the 7th, and is distributed with it on the 

 face ; but, before joining with that nerve, it detaches a branch which 

 passes in company with the transverse facial vessels, and is traceable as 

 far as the orbit. 



The Infra-Orbital Nerve (Plate 30). This, which is derived from 

 the superior dental branch of the superior maxillary division of the 

 5th, and is therefore sensory, emerges from the infra-orbital foramen, 

 under cover of the levator labii superioris proprius muscle. The 

 divisions of the nerve descend beneath the levator labii superioris 

 akeque nasi and the lateral dilator of the nostril, where they com- 

 municate with a branch of the 7th nerve, and are distributed in the 

 nostril and upper lip. 



Directions. — The masseter muscle on one side is now to be removed ; 



