THE COXAL BONE 



173 



adductor hrevis, adductor inagnus, and obturator exfernus. The posterior surface 

 is smooth and gives attachment to the cms penis or clitoridis, the sphincter urethrce 

 (urogenitalis) , the obturator internus, and the urogenital trigone (triangular liga- 

 ment). The lateral border forms part of the circumference of the obturator 

 foramen, and the medial border forms part of the pubic arch and gives attach- 

 ment to the gracilis. 



The superior ramus extends from the body of the pubis to the ilium, forming 

 by its lateral extremity the anterior one-fifth of the articular surface of the acetab- 

 ulum. It is prismatic in shape and increases in size as it passes laterally. Above 

 it presents a sharp ridge, the pecten or pubic portion of the terminal (ilio-pectineal) 

 line continuous with the iliac portion at the ilio-pectineal eminence, and affording 



Fig. 207. — Ax Immature Coxal (Innominate) Bone, showing a Cotyloid Bone. 



Th9 cotyloid bone 



attachment to the conjoined tendon [falx aponeurotica inguinalis], the lacunar 

 (Gimbernat's) hgament, the reflected inguinal ligament (fascia triangularis), 

 and the pubic portion of the fascia lata; the iliac portion of the terminal (ilio- 

 pectineal) line gives attachment to the psoas minor, the iliac fascia, and the pelvic 

 fascia. Immediately in front of the pubic portion of the line is the pectineal 

 surface ; it gives origin at its posterior part to the pectineus, and is limited below 

 by the obturator crest, which extends from the pubic tubercle to the acetabular 

 notch. The inferior surface of the ascending ramus forms the upper boundary 

 of the obturator foramen and presents a deep groove [sulcus obturatorius] for the 

 passage of the obturator vessels and nerve. The posterior surface is smooth, 

 forms part of the anterior wall of the pelvic cavity, and gives attachment to a 

 few fibres of the obturator internus. 



According to the BNA, the body [corpus ossis pubis] is the portion corresponding to the 

 acetabulum. The remainder of the bone is described as consisting of the ramus superior and 

 the ramus inferior, which meet at the symphysis. Thus the divisions according to the BNA 

 are different from those in the description above given. 



The acetabulum is a circular depression in which the head of the femur is 

 lodged and consists of an articular and a non-articular portion. The articular 

 portion is circumferential and semilunar in shape [facies lunata], vnih. the defi- 

 ciency in the lower segment. One-fifth of the acetabulum is formed by the pubis, 

 two-fifths by the ischium, and the remaining two-fifths are formed by the ilium. 

 In rare instances the pubis may be excluded by a fourth element, the cotyloid 

 bone. The non-articular portion [fossa acetabuli] is formed mainly by the 

 ischium, and is continuous below with the margin of the obturator foramen. 

 The articular portion presents a lateral rim to which the glenoid hp is 

 attached, and a medial margin to which the synovial membrane which excludes 



