48 ANATOMY AND PHYSIOLOGY 



BONES OF THE ABDOMEN 

 The five lumbar vertebrae, already described. 

 BONES OF THE PELVIC GIRDLE 



[ Hip bones 2 



The bones are j Sacrum i 



1 Coccyx i 



Hip-bone (os coxa}.- Consisting of three parts which are 

 entirely separate in the child. They are the os ilium, the os ischii, 

 and the os pubis; they unite to form a cup-shaped cavity called 

 the acetabulum, seen on the lateral surface of the bone. The 

 acetabulum is the socket of the hip-joint (Fig. 43). 



FIG. 43. HIP-BONE, EXTERIOR. (Morris.) 



The os ilium is the highest part of the hip-bone and has a broad 

 expanded portion called the wing (or ala). The medial surface 

 of the wing is the iliac fossa, which is filled with the iliac muscle; 

 the lateral surface is crossed by three curved lines (called the pos- 

 terior gluteal, the anterior gluteal, and the inferior gluteal lines}. 



The superior border is called the crest. It can be easily felt, 

 and the anterior extremity is known as the anterior superior iliac 

 spine, more often called the spine of the ilium. 



The os pubis is the anterior division of the hip-bone. It has 



