The Pelvis. 269 



The inlet of the true pelvis is cordiform in shape, the 

 bloodvessels and nerves for the pelvis being contained in 

 the depression on either side of the prominence oj: the 

 sacrum. The antero-posterior diameter averages about 

 four inches in the male and four and three-quarters in the 

 female ; the transverse is four and a half in the male and 

 five and a quarter in the female; the oblique four and a 

 quarter in the male, and five in the female. The outlet, 

 also cordiform in shape, measures antero-posteriorly 

 (from the tip of the coccyx to the lower border of the 

 symphysis) three and a quarter in the male and five in the 

 female, while the transverse diameter is three and a half 

 in the male and four and three-quarters in the female. 

 The obliquity of the pelvis is such that the inlet, or supe- 

 rior strait, in the upright position, makes an angle with the 

 horizon of 55 and the outlet or inferior strait, one of 10 s ". 

 The depth of the pelvic cavity in front, i.e., at the sym- 

 physis is one and a half inches, whereas, behind, i.e., from 

 sacro-vertebral angle to tip of coccyx it is four and a half 

 inches. 



The pelvis contains the termination of the intestinal 

 canal, the bladder with the ureters, the uterus, tubes, 

 ovaries, vagina, coils of small intestine, internal iliac arter- 

 ies and veins and the sacral plexus of nerves.' On view- 

 ing the pelvis from above, after the rectum, the bladder 

 (and, in the female, the genital organs have been re- 

 moved, we see that the sacral plexus is separated from the 

 iliac arteries and veins by the pelvic fascia, and that the 

 outlet of the cavity is protected by the following muscles, 

 viz. : Behind, the pyriformis and coccygeus ; laterally, the 

 internal obturator, while in the centre of the pelvic outlet 

 is the levator ani. The latter is the chief support of the 

 pelvic contents, being attached, in front, to the symphysis 

 pubis ; behind, to the spine of the ischium, and on either 



