HEAD AND NECK OF THE HORSE 51 



in undergoing a large fusiform dilatation just before it passes within 

 the mandible. 



Generally the buccinator vein is joined by a tributary from a venous 

 network that lies between the buccinator muscle and mucous lining of 

 the cheek, and commonly it is connected with the masseteric vein. 



N. BUCCINATORIUS. — The buccinator is a nerve of some size and is 

 derived from the n. mandibularis — a part of the trigeminal or fifth 

 cerebral nerve. It gains the present dissection by passing between the 

 internal pterygoid muscle and the maxillary tuber, and follows the lower 

 border of the buccinator muscle as far as the level of the first cheek-tooth. 

 Here it insinuates itself between the buccinator muscle and the mucous 

 lining of the cheek, and so gains the lips in the mucous membrane of 

 which its terminal filaments ramify. In addition numerous small 

 branches are furnished to the mucous membrane of the cheek and to 

 the ventral buccal glands ; and a connection is established with the 

 ventral buccal nerve. 



A. BUCCINATORIA. — The relatively small buccinator artery is a 

 branch of the internal maxillary, and gains the region of the cheek by 

 following the dorsal border of the buccinator nerve. Branches of the 

 artery supply blood to the pterygoid, masseter and buccinator muscles 

 and the dorsal buccal glands. 



The buccal glands (Glandula? buccales). — There are two groups 

 of these, dorsal and ventral. The dorsal glands form an elongated 

 flattened mass along the surface of the maxilla and the buccinator 

 muscle, extending forwards from the anterior edge of the mandibular 

 ramus. It is often possible to divide the group into two parts. The 

 larger portion lies underneath the masseter muscle ; while a smaller 

 and more scattered part extends in front of the masseter to within a 

 measurable distance from the angle of the mouth. 



The smaller ventral buccal glands are at present hidden by the 

 buccinator and the depressor muscle of the lower lip. They stretch 

 from the margin of the masseter to the level of the angle of the mouth. 



M. BUCCINATOR. — Though the whole of the buccinator^ muscle 

 cannot be seen until the mandible has been removed, it is necessary 

 that that portion now visible should be examined before any further 

 dissection is performed. 



The buccinator muscle may be divided into two parts. (1) The 

 buccal part (pars buccalis) is the more superficial and is limited to that 

 region of the cheek that is anterior to the masseter muscle. It is 

 1 Buccinator [L.], trumpeter. 



