FACE 193 



parts. The last is small and consists of three divisions. The infraorbital canal is 



alvPoTwn.^+K^ °^ *^' f'J^^'u^ f compressed dorso-ventrally, and contains three 

 a veoh for the mcisor teeth, which mcrease in size from first to third- it also com- 

 pletes the medial wall of the large alveolus for the canine tooth. The foramen 

 mcisivnm is very small except in large skulls. The interalveolar border is wide 

 and very short The nasal process is wide at its origin and tapers to a sharp point 

 behind; the anterior part curves upward, backward, and a little inward, and forms 

 the lateral margin of the osseous nasal aperture; the posterior part extends back- 

 ward a long distance between the nasal bone and the maxilla. The palatine process 

 turns upward and outward, forming with its fellow a wide groove for the septal 

 cartilage; the posterior end is pointed and fits into a notch between the palatine 



Fig. 212. — Sagittal Section of Skull of Dog, Without Mandible. 

 A, A', Baailar and squamous parts of occipital bone; B, B', presphenoid and postsphenoid; C, C", perpendicular 

 and cnbriform plates of ethmoid bone; D, parietal bone; E, frontal bone; F. pterygoid bone; G, G', vertical and hori- 

 zontal parts of palatine bone; H, vomer; /, premaxiUa; J^, nasal bone; X, dorsal turbinate bone; L, ventral turbinate 

 bone; I, II, III, anterior, posterior and middle fossa; of cranium; 1, occipital condyle; 2, opening of condyloid canal; 

 3, eanal for intertransverse sinus of dura mater; 4, internal occipital protuberance; 5, internal opening of temporal 

 canal; 6, mastoid foramen ; 7, floccular fossa; 8, meatus acusticus internus; 9, canal for trigeminal nerve ; 10, internal 

 carotid foramen; 11, 12, openings into petro-basilar canal; 13, foramen hypoglossi; 14, petrosal crest ; 15, dorsum sella:; 

 16, hypophyseal or pituitary fossa; 17, optic foramen; 18, ethmoid foramen; 19, meatus naso-pharyngeus; 20,21,22, 

 dorsal, middle, and ventral meatus nasi; 23, incisor teeth; 24, canine tooth; 25, premolar teeth; 26, molar teeth; 27, 

 septum between frontal sinuses. 



processes of the maxillse, and supports the end of the vomer. The palatine fissure 

 is short but wide. 



The horizontal part of the palatine bone is extensive, forming about one-third 

 of the hard palate. It presents a variable number of accessory palatine foramina. 

 There is usually a pointed posterior nasal spine (Spina nasalis aboralis) at the end 

 of the median suture. The palatine canal is sometimes formed entirely in this bone. 

 The perpendicular part is even more extensive. Its lateral surface is chiefly free 

 and forms most of the medial wall of the large pterygo-palatine fossa. The max- 

 illary foramen is situated in a deep recess between this bone and the zygomatic 

 process of the maxilla. Just above it there is commonly another foramen which 

 opens into the nasal cavity. The posterior palatine and sphenopalatine foramina 

 are situated further back and a little lower; the former is ventral to the latter. A 

 horizontal plate extends from the nasal surface, meets that of the opposite bone, and 

 completes the lamina transversalis spoken of in the description of the ethmoid bone. 

 There is no palatine sinus. 



The pterygoid bones are very wide and short. They form a considerable part 

 13 



