is curved like the cavity itself: this curve corresponds to the concavity of the 

 sacrum and coccyx, the extremities being indicated by the central points of the 

 superior and inferior apertures. A knowledge of the direction of these axes 

 serves to explain the course of the fetus in its passage through the pelvis during 

 parturition. 



Position of the Pelvis (Fig. 240). In the erect posture, the pelvis is placed 

 obliquely with regard to the trunk : the plane of the superior aperture forms an 

 angle of from 50 to 60, and that of the inferior aperture one of about 15 with 

 the horizontal plane. The pelvic surface of the symphysis pubis looks upward 

 and backward, the concavity of the sacrum and coccyx downward and forward. 

 The position of the pelvis in the erect posture may be indicated by holding it so 

 that the anterior superior iliac spines and the front of the top of the symphysis 

 pubis are in the same vertical plane. 



FIG. 241. Male pelvis. 



Differences between the Male and Female Pelves. The female pelvis (Fig. 

 .'42) is distinguished from that of the male (Fig. 241) by its bones being more 

 delicate and its depth less. The whole pelvis is less massive, and its muscular 

 impressions are slightly marked. The ilia are less sloped, and the anterior iliac 

 spines more widely separated; hence the greater lateral prominence of the hips. 

 The preauricular sulcus is more commonly present and better marked. The supe- 

 lior aperture of the lesser pelvis is larger in the female than in the male; it is more 

 nearly circular, and its obliquity is greater. The cavity is shallower and wider; 

 the sacrum is shorter wider, and its upper part is less curved; the obturator 

 foramina are triangular in shape and smaller in size than in the male. The inferior 

 aperture is larger and the coccyx more movable. The sciatic notches are wider 

 and shallower, and the spines of the ischia project less inward. The acetabula 

 are smaller and look more distinctly forward (Deny 1 ). The ischial tuberosities 

 and the acetabula are wider apart, and the former are more everted. The pubic 

 symphysis is less deep, and the pubic arch is wider and more rounded than in the 

 male, where it is an angle rather than an arch. 



16 



1 Journal of Anatomy and Physiology, vol. xliii. 



