SECTION III 

 PELVIC GIRDLE AND LOWER LIMB 



THE pelvic girdle consists of three bones firmly joined together, 

 with two of which the two femurs articulate by means of ball- 

 and-socket joints ; the pelvic girdle and lower limb are analogous 

 to the shoulder girdle and upper limbs (see comparison in 

 Section I.). 



The bones forming the pelvis are the two innominate bones, 

 joined together in front at the symphysis pubis and articulating 

 with the sacrum behind. 



The Innominate Bone is a large, flat irregular-shaped bone 

 -consisting of three parts, which at birth are distinct, but in 

 adult life become fused together in the same way that epiphyses 

 fuse with the shafts in long bones. The three parts are re- 

 spectively the ilium, ischium, and pubis, which join together to 

 form the acetabulum, a deep socket which receives the head of 

 the femur. 



The Ilium forms a fan-shaped expansion, the top edge of 

 which, the crest of the ilium, is thickened to give attachment to 

 muscles. About two inches from the anterior end is a rough 

 tubercle, which is the highest point of the crest, and can easily 

 be felt in the living subject. The crest forms an S- shaped curve, 

 the anterior half being convex outwards. The ends are termed 

 respectively the anterior and posterior superior spines. The 

 anterior margin of the ilium extends from the anterior superior 

 spine to the margin of the acetabulum, of which the ilium forms 

 the upper two-fifths. Halfway down the anterior margin is a 

 rough tubercle called the anterior inferior spine. 



The posterior margin extends from the posterior superior 

 spine to the posterior margin of the acetabulum. A little way 



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