72 



EQUINE ANATOMY. 



of the opposite side. Development : one nucleus of 

 ossification. 



Pterygoid. — Two faces and two extremities ; the in- 

 ferior extremity has a tendinous pulley. Develop- 

 ment: one nucleus of ossification. 



Zygomatic. — Division : Two faces^ two borders, a 

 base and an apex. The external face has two portions, 

 one anterior orbital, one posterior convex ; the in- 

 ternal face forms the maxillary sinuses. The anterior 

 border is articular, the posterior shows the zygomatic 

 crest ; the base is articular, the apex at the zygomatic 

 arch forms the jugal bridge. Development : one 

 nucleus of ossification. 



Lachrymal. — Division : Two faces and a circum- 

 ference. The external face has two regions, one su- 

 perior or orbital, w^ith the orifice of the lachrymal 

 duct and the lachrymal fossa, and one inferior or facial 

 with tlie lachrymal tubercle. The internal face forms 

 the maxillary and frontal sinuses. The circumference 

 is articular. Development : one nucleus. 



Nasal. — Two faces, two borders, abase and an apex. 

 Tiie external face is smooth; the internal or pos- 

 terior has a crest for the turbinated bone. The ex- 

 ternal border articulates above, but is free below to 

 form the nasal spine ; the internal is articular, as is the 

 base. Development : one nucleus of ossification. 



