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 bounded in front by 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 

 occijntai inotuberance; 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; 

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

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

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

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

 B.S., basisphenoid; A.t., temporal wing of sijhenoid; A.o., orbital wing of sphenoid; Pt.p.. pterygoid process of 

 sjjhenoid; P.p., peri)endiciilar i)art of i)alate lione; F,F' , facial and orbital parts of frontal bone; L,L', orbital 

 and facial jiarts of lacrimal bone; M. facial part of malar bone; M.x., maxilla; a. ])arieto-occipital sutiue; b, 

 jfarieto-temporal or s<|uamous suture; c,(l, si)heno-squamous suture; e, palato-frontal suture; /, fronto-lacrimal 

 suture. 



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

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

 is undulating, witli a varial)ly marked depression al)out its middle and at the an- 

 terior end. Tlie 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 preurbital regions. 



