232 THE SKELETON. 



i 



Its inner border is thick, rough, slightly everted, forms part of the outlet of 

 the pelvis, and serves for the attachment of the crus penis. Its outer border 

 is thin and sharp, and forms part of the inner margin of the obturator foramen. 



The Pules forms the anterior part of the os innominatum; it is divisible into 

 a horizontal ramus or body, and a perpendicular ramus. 



The body, or horizontal ramus, presents for examination two extremities, an 

 outer and an inner, and four surfaces. The outer extremity, the thickest part of 

 the bone, forms one-fifth of the cavity of the acetabulum ; it presents, above, 

 a rough eminence, the ilio-pectineal, which serves to indicate the point of junc- 

 tion of the ilium and pubes. The inner extremity is the symphysis; it is oval, 

 covered by eight or nine transverse ridges, or a series of nipple-like processes 

 arranged in rows, separated by grooves ; they serve for the attachment of the 

 interarticular fibro-cartilage, placed between it and the opposite bone. The 

 upper surface, triangular in form, wider externally than internally, is bounded 

 behind by a sharp ridge, the pectineal line, or linea ilio-pectinea, which, run- 

 ning outwards, marks the brim of the true pelvis. The surface of bone in 

 front of the pubic portion of the linea ilio-pectinea, serves for the attachment 

 of the Pectineus muscle. This ridge terminates internally at a tubercle, which 

 projects forwards, and is called the spine of the pubes. The portion of bone 

 included between the spine and inner extremity of the pubes is called the crest; 

 it serves for the attachment of the Rectus, Pyramidalis, and conjoined tendon 

 of the Internal Oblique and Transversalis. The point of junction of the crest 

 with the symphysis is called the angle of the pubes. The inferior surface pre- 

 sents, externally, a broad and deep oblique groove, for the passage of the obtu- 

 rator vessels and nerve ; and internally, a sharp margin, which forms part of 

 the circumference of the obturator foramen. Its external surface, flat and com- 

 pressed, serves for the attachment of muscles. Its internal surface, convex from 

 above downwards, concave from side to side, is smooth, and forms part of the 

 anterior wall of the pelvis. 



The descending ramus of the pubes passes outwards and downwards, becom- 

 ing thinner and narrower as it descends, and joins with the ramus of tho 

 ischium. Its external surface is rough for the attachment of muscles ; the Ad- 

 ductor Longus above, the Adductor Brevis below; the Gracilis along its inner 

 border, the Compressor Urethra towards its internal aspect ; and a portion of 

 the Obturator Externus where it enters into the formation of the foramen oi 7 

 that name. Its inner surface is smooth. Its inner border is thick, rough, and 

 everted, especially in females. In the male it serves for the attachment of tho 

 crus penis. Its outer border forms part of the circumference of the obturator 

 foramen. 



The cotyloid cavity, or acetabulum, is a deep, cup-shaped, hemispherical de- 

 pression; formed, internally, by the pubes, above by the ilium, behind and 

 below by the ischium; a little less than two-fifths being formed by the ilium, a 

 little more than two-fifths by the ischium, and the remaining fifth by the pnl >(-;. 

 It is bounded by a prominent uneven rim, which is thick and strong above, and 

 serves for the attachment of a fibro-cartilaginous structure which contracts its 

 orifice, and deepens the surface for articulation. It presents on its inner sid-> a 

 deep notch, the cotyloid notch, which transmits the nutrient vessels into the 

 interior of the joint, and is continuous with a circular depression at the bottom 

 of the cavity : this depression is perforated by numerous apertures, lodges a 

 IIKISS of fat, and its margins serve for the attachment of the ligumentum teres. 

 The notch is converted, in the natural state, into a foramen by a dense liga- 

 mentous band which passes across it. Through this foramen the nutrient ves- 

 sels and nerves enter the joint. 



The obturator or t/u/roid foramen is a large aperture, situated between the 

 ischium and pubes. In the male it is large, of an oval form, its longest diameter 

 being obliquely from above downwards; in the female it is smaller, and more 

 triangular. It is bounded by a thin uneven margin, to which a strong mem- 



