THE PELVIS. 



Each coxa, as has been stated, is composed of three portions which 

 unite at the acetabulum ; and although consolidated into one pjece, yet 

 they are separately described as if distinct. The names of these divisions 

 are ilhim, ischium, and />u^is. ' 



Ilium. — The ilium, hip, or haunch bone (os ilium), gives its name to the 

 region it occupies. It is the largest of the three bones, as well as being 

 that which is most elevated. In shape it is irregularly triangular and 

 flat, and is directed obliquely downwards, inwards, and backwards, and 

 has two faces, three borders, and three angles. Its external or superior 

 face or dorsum is marked by some muscular imprints, and is curved in 

 its widest part to form a concave space — the external iliac fossa — which 

 lodges the gluteal muscles. The internal or inferior face, or venter, offers 



Pelvis of the Mare. 



A, Tlium ; B, Pubis ; C, Ischium ; D, Foramen Ovale ; E, Tuberosity of the Ischium ; 



F, Cotyloid Cavity. 



a smooth external portion — the iliac surface — into which is implanted 

 the iliac psoas or iliacus muscle; and an internal roughened, ear-shaped, 

 irregularly diarthrodial surface, most apparent from behind — the auricu- 

 lar facet — for articulation with the sacrum. 



The anterior border, or crest oj the ilium, is slightly concave, and bears 

 a rugged lip for muscular insertion. The external border is thick and 

 roughened, and grooved for the passage of blood-vessels ; inferiorly it has 

 three nutrient foramina. The internal border is thin and concave, espe- 

 cially in its posterior part, where it constitutes the great sciatic notch; it 

 affords attachment to the sacro-sciatic ligament. The spine or ridge of 

 the same name partly belongs to it. 



The external angle, antero-superior spinous process, or point of the hip, is 

 a wide, thick, and flattened portion, bearing four tuberosities affording 

 attachments to muscles. The internal or antero-internal angle or supero- 

 posterior spinous process, is a rough tuberosity curving upwards and back- 

 wards to form an angle with the corresponding portion of the opposite 

 ilium — the summit of the croup. The inferior, posterior or cotyloid angle 

 (concurring in the formation of the acetabulum) is very large and pris- 

 matic in shape. Posteriorly, it offers a concave articular surface (acetab- 

 ular), and above this cavity is the supra-cotyloid ridge or crista Hit : an 

 elongated eminence passing backwards, sharp at its summit, smooth 



