96 Anatomy of the Rabbit. 



of the palatal surface. It is articulated in front with the palatine process 

 of the inaxilla, the suture between the two bones enclosing the greater 

 palatine foramen, the ventral termination of the pterygopalatine canal. 

 The perpendicular portion (pars perpendicularis) is the vertical plate 

 extending backward from the palatine bridge. Its medial surface is 

 divided by a low ridge into a dorsal portion, in particular relation to the 

 nasopharynx, and a ventral portion, in relation to the oral cavitv, the 

 ndge indicating the position of the soft palate. Its lateral surface is 

 partly applied to the maxilla and partly exposed to the orbit. Its 

 dorsal margin is articulated with the presphenoid and with the ethmoidal 

 process of orbitosphenoid, but a small posterior portion is free, so that 

 the anterior portion of the basisphenoid is visible from the orbit. The 

 free ventral margin forms posteriorly a thick projecting angle, the 

 pyramidal process (processus pyramidalis), the base of which is cleft 

 where it articulates with the medial and lateral laminae of the pterygoid 

 process. Between the pyramidal process and the alveolus of the last 

 cheek-tooth there is a conspicuous palatine notch (incisura palatina), 

 connecting the orbit with the palatal surface. In the entire skull only 

 the posterior portion of the lateral surface is visible from the orbit, the 

 anterior portion being concealed by the projecting bases of the posterior 

 cheek-teeth. The ridge of bone on which the alveoli of these teeth are 

 borne is separated from the palatine bone by the infraorbital groove. 

 The medial wall of the latter, formed by the palatine bone, contains the 

 orbital opening of the pterygopalatine canal and the sphenopalatine 

 foramen. 



19. THE MANDIBLE. 



The mandible (mandibula), or lower jaw, comprises the two dentary 

 bones (ossa dentalia), which, in the rabbit, as in mammals generally, 

 are united by a fibrous or fibrocartilaginous connection (symphysis 

 mandibulae) ; not coalesced, as in the human skull, to form a continuous 

 structure. As indicated above, each of the dentary bones comprises: 

 (1) a horizontal, tooth-bearing portion which, in conjunction with that 

 of the opposite side, forms the body of the mandible (corpus mandibulae) ; 

 and (2) a posterior, vertical plate, the mandibular ramus (ramus mandi- 

 bulae), for muscle attachment and articulation. The horizontal portion 

 is deep posteriorly, where it lodges the alveoli of the cheek-teeth. 

 Anteriorly, in the diastema separating the latter from the incisors, its 

 dorsal surface is rounded and depressed, the space thus formed corres- 

 ponding to a similar space in the upper jaw and serving chiefly for the 

 accommodation of the lips, which in this region encroach medially on the 

 oral cavity. The medial surface of the horizontal portion forms an 

 acute angle with that of the bone of the opposite side, except anteriorly, 

 where it bears a roughened area for articulation with the latter. Run- 

 nmg backward from the symphysis there is a broad horizontal ridge, 

 representing the mylohyoid line (linea mylohyoidea), the line of attach- 

 ment of the mylohyoid muscle. The mandibular foramen, through 

 which, in the natural condition, the inferior alveolar nerve and artery 

 gain access to the interior of the bone, lies on this surface at the junction 



