178 AURICULAR GROUP. 



the masseter in appearance and direction, and was named by Winslow 

 the internal masseter. 



Relations. By its external surface with the external pterygoid, the 

 inferior maxillary nerve and its branches, the internal maxillary artery 

 and branches, the internal lateral ligament, and the ramus of the lower 

 jaw. By "its internal surface with the tensor palati, superior constrictor 

 and fascia of the pharynx, and by its posterior border with the parotid 

 gland. 



Fig. 84.* 



Actions. The maxillary muscles are the active agents in mastica- 

 tion, and form an apparatus beautifully fitted for that office. The 

 buccinator circumscribes the cavity of the mouth, and with the aid of 

 the tongue keeps the food under the immediate pressure of the teeth. 

 By means of its connection with the superior constrictor, it shortens 

 the cavity of the pharynx, from before backwards, and becomes an im- 

 portant auxiliary in deglutition. The temporal, the masseter, and the 

 internal pterygoid are the bruising muscles, drawing the lower jaw 

 against the upper with great force. The two latter by the obliquity 

 of their direction, assist the external pterygoid in grinding the food by 

 carrying the lower jaw forward upon the upper ; the jaw being brought 

 back again by the deep portion of the masseter and posterior fibres of 

 the temporal. The whole of these muscles, acting in succession, pro- 

 duce a rotatory movement of the teeth upon each other, which, with 

 the direct action of the lower jaw against the upper, effects the proper 

 mastication of the food. 



8. Auricular Group. Attollens aurem, 

 Attrahens aurem, 

 Retrahens aurem. 



* The two pterygoid muscles. The zygomatic arch and the greater part of 

 the ramus of the lower jaw have been removed in order to bring these muscles 

 into view. 1. The sphenoid origin of the external pterygoid muscle. 2. Its 

 pterygoid origin. 3. The internal pterygoid muscle. 



