no 



THE SKELETON OF THE HORSE 



bones are not fused until the second year. The epiphyseal parts fuse with the 

 main mass at four and a half to five years of age. 



The acetabular part of the pubis ossifies from a separate center. It is most distinct in the 

 embryo at three months, and is often called the os acetabuli. Martin says that the ihum has a 

 center for the acetabular part, one for the shaft and wing, and a third for the crest. He also 

 states that there is a special center for the acetabular part of the ischium, and a transitory nucleus 

 in the symphyseal part of the pubis. 



THE PELVIS 

 The bony pelvis is composed of the ossa coxarum, the sacrum, and the first 

 three coccygeal vertebrae. The dorsal wall or roof is formed by the sacrum and 

 first three coccygeal vertebra, and the ventral wall or floor by the pubic and ischial 



Crest of ilium 



Sacral Tuber 

 spines sacrale 



Tuber coxce 



Nutrient foramen 

 Psoas tubercle 



Depression in which 

 tendon of rectus 

 femoris is attached 



Ilio- pectineal e^yiinence 



-Acetabulum 



Tuber ischii 



Pubic tubercle 



Ischium 



Fig. 88. — Pelvic Bones of Mare, Viewed from in Front and Somewh.^t from Below. 

 1, Body of first sacral segment; 2, surface on wing of sacrum for articulation with like surface on transverse process 

 of last lumbar vertebra; 3, wing of sacrum; 4, sacro-iliac articulation; 5, sacral canal; 6, promontory; 7, apex of sac- 

 rum; S, ilio-pectineal line; 9, ischiatic spine; 10, grooves for ilio-lumbar vessels; 11, grooves for iliaco-femoral vessels. 



bones. The lateral walls are formed by the ilia and the acetabular part of the 

 ischia. The defect in the skeleton here is supplied in the fresh state by the sacro- 

 sciatic ligaments and semimembranosus muscles. 



The anterior aperture or inlet of the pelvis (Apertura pelvis cranialis) is bounded 

 by the terminal line (Linea terminalis) or brim, which is composed of the base of 

 the sacrum dorsally, the ilio-pectineal lines laterally, and the pecten pubis ventrally. 

 It is almost circular in the mare, semi-elliptical in the stallion, and faces obliquely 

 downward and forward. It has two principal diameters. Of these, the con- 

 jugate or sacro-pubic diameter (Conjugata anatomica) is measured from the sacral 

 promontory to the anterior end of the symphysis. The transverse diameter 



