66 



THE SKELETON OF THE HORSE 



and nasal, are smooth and rounded. The dorsal border is free, thick, and smooth ,- 

 it concurs with the free margin of the nasal bone in forming the naso-maxillary 

 notch (Incisura nasomaxillaris) . The ventral border is dentated and joins the 

 maxilla; at its anterior end it forms with the latter the alveolus for the permanent 



canine tooth.^ The posterior ex- 

 t i^ F^ tremity fits into the interval be- 

 a./lV OT tween the nasal bone and the 

 maxilla. 



The palatine process (Pro- 

 cessus palatinus) is a thin plate 

 which forms the anterior part of 

 the basis of the hard palate. Its 

 nasal surface (Facies nasalis) has 

 a longitudinal ridge which forms 

 with that of the other side a groove 

 for the septal cartilage; lateral to 

 the ridge there is a groove for the 

 vomero-nasal organ. The palatine 

 surface (Facies palatina) is flat. 

 The medial border is serrated and 

 meets its fellow at the median pala- 

 tine suture. The lateral border is 

 separated from the maxilla and the 

 nasal process by the palatine fis- 

 sure (Fissura palatina). The pos- 

 terior extremity fits into the inter- 

 val between the vomer and the 

 palatine process of the maxilla. 



Development. — The premax- 

 illa ossifies from a single center. 

 Fusion of the two bones is com- 

 plete at the end of the third or 

 the beginning of the fourth year. 



-7.3 



The Palatine Bones 



The palatine bones (Ossa pala- 

 tina) are situated on either side of 

 the choanse or posterior nares, and 

 form the posterior margin of the 

 hard palate. Each is twisted so as 

 to form a horizontal and a perpen- 

 dicular part. 



The horizontal part (Pars hori- 

 zontalis) is a narrow plate which 

 forms the posterior part of the 

 hard palate. It presents smooth 

 nasal and palatine surfaces (Facies 

 nasahs, palatina). The medial border meets its fellow at the median palatine 

 suture, on the nasal aspect of which is the nasal crest. The anterior border joins 

 the palatine process of the maxilla at the transverse palatine suture, and forms with 

 it the anterior palatine foramen (Foramen palatinum anterius). The posterior 

 border is concave and free; it gives attachment to the aponeurosis of the soft palate. 



' The alveolus for the temporary canine is commonly formed in the maxilla alone. 





Ll 



Fig. 43.- 



Half 



-Upper Jaw of Horse About Four and 

 Years Old; Ventral View. 

 1, 1, Choanse or posterior nares; 2, vomer; 3, horizontal 

 part of palatine bone; 4, anterior'palatine foramen; 5, palatine 

 groove; 6, transverse palatine suture; 7, median palatine suture; 

 8, palatine process of maxilla; 9, palatine process of premasilla; 

 10, foramen incisivum; 11, malar bone; 12, maxilla; 13, anterior 

 end of facial crest; 14, interalveolar space; 7. i— 3, incisor teeth; 

 C, canine tooth; P.l, first premolar or "wolf" tooth. The 

 opening lateral to 9 is the palatine fissure. 



