66 



THE SKELETON OF THE HORSE 



divided into parietal, frontal, nasal, and premaxillary regions. The parietal region 

 extends from the occipital crest to the parieto-frontal or coronal suture. It is 

 marked medially by the external sagittal crest, which bifurcates in front, the 

 branches becoming continuous with the frontal crests. The latter curve outward 

 to the root of the supraorbital process. The frontal region is the widest part of 

 the surface, and is smooth and almost flat. It is l)ounded in front l)y the naso- 

 frontal suture. On either side of it is the root of the supraorbital process, pierced 



Fig. .33. — Cranial and Orbital Regions of Skull of Horse, Lateral View. The Zygomatic Arch and 

 Supraorbital Processes Have Been Sawn Off. 

 1, Occipital condyle; 2, condyloid fossa; 3, paramastoid or styloid process; 4, occipital crest; 5, external 

 occipital protuberance; 6, external auditory meatus; 7, mastoid process; 8, hyoid process; 9, stylomastoid fora- 

 men; 10, muscular process; 11, foramen lacerum anterius; 12, postglenoid process; 13, glenoid cavity; 14, tem- 

 poral condyle; 15, Vidian groove; 16, alar canal of pterygoid process indicated by arrow; 17, temporal foramen; 

 IS, ethmoidal foramen; 19, optic foramen; 20, .foramen lacerum orbitale; 21, maxillary foramen; 22, spheno- 

 jjalatine foramen; 23, posterior palatine foramen; 24, supraorbital foramen (opened); 25, lacrimal fossa; 26. 

 depression for origin of obliquus oculi inferior; 27, facial crest; 28. maxillary tuberosity; 29, alveolar tuberosity; 

 30, hamulus of pterygoid bone; S.o.. supraoeeipital; P, parietal; S, squamous temporal; B.o., basioccipital; 

 5.S., basisphenoid; .4 J., temporal wing of sphenoid; ,4. o., orbital wing of sphenoid; P;. p., pterygoid process of 

 sphenoid; P.p., perpendicular part of palate hone; F,F', facial and orbital parts of frontal bone; L,L', orbital 

 and facial parts of lacrimal bone; .1/. faci.nl i)art of malar bone; M.x.. maxilla; a. jjarieto-occipital suture; b, 

 parieto-temporal or squamous suture; c.cl. siiheno-squamous suture; e, palato-frontal suture; /, fronto-lacrimal 

 suture. 



by the supraorbital foramen. The nasal region is convex from side to side, wnde 

 behind, narrow in front. Its profile is in some cases nearly straight; in others it 

 is undulating, with a varial)ly marked depression about its middle and at the an- 

 terior end. The premaxillary region presents the osseous nasal aperture (Apertura 

 nasalis ossea) and the foramen incisivum. 



The lateral surface (Norma lateralis) may be divided into cranial, orbital, and 

 maxillary or preorl)ital regions. 



