132 



PRACTICAL ANATOMY. 



FIG. 60. THE PELVIS. 



A A, atitero-posterior diameter; B B, transverse diameter; 

 C C, two oblique diameters ; 1, sacro-iliac ligament ; 2, anterior 

 or lesser sacro-sciatic ligament; 3, posterior or great sacro-sciatic 

 ligament. 



terminates at the outlet or inferior strait, which is very 

 irregular, and formed laterally by the tuberosities of 



the ischia and pos- 

 teriorly by the tip of 

 the coccyx. Be- 

 tween the tuberosi- 

 ties of the ischia 

 anteriorly is the 

 pubic arch, formed 

 by the rami of the 

 ischia and pubes. 

 The superior strait 

 measures about five 

 inches transversely 

 and about four inches antero-posteriorly. The true 

 pelvis is about four and a half inches in diameter. The 

 inferior strait measures about four inches transversely 

 and about four and i 



a half inches ante- j 



ro-posteriorly. The 

 deptli of the true 

 pelvis is about two 

 inches anteriorly, 

 about four and a 



half inches posteri- 

 orly. The axis of 

 the true pelvis is a 

 line equidistant be- 

 tween the anterior 

 and posterior walls 



f .1 ] '"PV, 



OI tne DelVlS. J_ne 



pelvis is tilted up- 



ward and forward, so that the promontory of the sacrum 



is about four inches higher than the upper border of the 



FIG. 61. THE Axis OF THE PELVIS. 



a b, plane of the superior strait (brim) ; o i, plane of the 

 inferior strait (outlet) ; c, the point where these two planes 

 would meet, if prolonged ; m n, a horizontal line ; ef, axis of 

 brim ; g k, axis of cavity : p q r s t, various points taken on the 

 sacrum to show the plane of the cavity at each point. 



