46 EQUINE ANATOMY. 



ligament. The anterior border is thin and rough; 

 the posterior thick and concave, and co-operates to 

 form the obturator foramen ; the internal is thick and 

 articular. The external or cotyloid angle forms the 

 bottom of the cotyloid cavity ; the internal and poste- 

 rior angles are articular. Development : one nucleus 

 of ossification. 



Ischium. — Division : Two faces, four borders, four 

 angles. The superior face is smooth and forms the 

 floor of the pelvic cavity ; the inferior is roughened for 

 muscular attachments, and presents the ischial crest. 

 The anterior border forms the obturator foramen, the 

 external the small sciatic notch, the posterior forms 

 the ischial arch, while the internal is articular. The 

 anterior external angle, or cotyloid presents a diarthro- 

 dial facet and the posterior extremity of the supra- 

 cotyloid crest ; the anterior internal angle is articulated 

 with the pubis ; the posterior external forms the ischial 

 tuberosity and the posterior internal articulates with 

 that of the opposite side. Development : two nuclei 

 of ossification. 



Thi^h. — Fp:muk. — Division: Bodv, and two Extrem- 

 ities. Body lias four faces. The ant^ouTYis smooth; the 

 posterior has a rounded, roughenec^surface, a slight 

 crest oblique above, in the middle a wide rough surface 

 for muscular attixhments, and below a wide vascular 



