DISSECTION OP THE HEAD AND NECK 183 



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

 with the mental nerves. 



The SuBZYGOMATic 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 

 alseque 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 ; 

 and in doing this, the dissector should find the branch from the inferior 

 maxillary division of the 5th nerve which enters the muscle through 

 the corono-condyloid notch. The masseter having been removed, the 

 buccinator muscle will now be fully exposed (see page 179), and the 

 dissector is to examine the alveolar vein, the buccal glands, the buccal 

 nerve and vessels, and the interior of the cheek. 



The Alveolar Vein. This vessel rests on the superior maxilla, along 

 the alveoli for the molar teeth. Inferiorly it joins the submaxillary 

 vein, and is here comparatively small. It speedily becomes of large 

 size, and it is continued round the upper extremity of the superior 

 maxilla to reach the orbit, where it will afterwards be followed. 



The Superior Buccal Gland. This consists of a string of lobules 

 resting on the anterior edge of the buccinator. The string is thickest 

 above, and thinnest below, where its lobules are placed at intervals. 

 The ducts of the lobules perforate the buccinator, and will afterwards 

 be seen opening on the cheek. 



The Buccal Artery will be found crossing the upper end of the 

 superior buccal gland. It is distributed to the buccinator muscle and 

 the other textures of the cheek. Its origin from the internal maxillary 

 artery, at the floor of the orbit, will subsequently be dissected. 



The Buccal Vein begins at the inferior edge of the masseter, where 



