FORM OF THE PELVIS. 



97 



THE PELVIS. 



The ossa innominata with the sacrum and coccyx form the osseous walls 

 of the pelvis. 



This part of the skeleton may be considered as divided into two parts at 

 the level of the upper border of the symphysis pubis, the sacral promontory 

 and the ilio-pectineal lines. The circle thus completed constitutes the brim 

 or inlet of the lower or true pelvis; the space above it, between the iliac 

 fossae, belongs really to the abdomen, but has been called the upper or false 

 pelvis. The inferior circumference, or outlet of the pelvis, presents three 

 bony eminences, the coccyx and the tuberosities of the ischium. Between 

 the tuberosities of the ischium in front is the pubic or subpubic arch, which 

 bounds an angular space extending forwards to the symphysis, and is formed 

 by the descending rami of the ossa pubis and the ascending rami of the 

 ischia. The interval between the sacrum and coccyx and the ischium on 

 each side is bridged over in the recent state by the sacro-sciatic ligaments, 

 which therefore assist in bounding the outlet of the pelvis. 



Fig. 87. 



Fig. 87. 



VIEW OP THE PELVIS 

 OP A MIDDLE-AGED 

 MAN, AS SEEN FROM 



BEFORE, IN THE 

 ERECT ATTITUDE OF 

 THE BODY. ^ 



1, 2, anterior ex- 

 tremities of the 

 crest of the ilium in 

 front of the widest 

 transverse diameter 

 of the upper or false 

 pelvis ; 3, 4, aceta- 

 bula; 5, 5, thyroid 

 or obturator fora- 

 mina ; 6, subpubic 

 angle or arch. 



Fig. 88. 



VIEW OF THE PELVIS 

 OF A MIDDLE-AGED 

 WOMAN. J 



Similarly placed with 

 that shown in the 

 preceding figure, and 

 designed to illustrate, 

 by comparison with 

 it, the principal dif- 

 ferences between the 

 male and female pel- 

 vis, viz. , the greater 

 distance in the female 

 between the aceta- 

 bula, the wider and 

 shallower true pelvis, 

 the triangular form 

 of the obturator fo- 

 ramen, the greater 



width between the tuberosities of the ischium, and the greater width of the sub-pubic 

 arch. The numbers indicate the same parts as in the preceding figure. 



Fig. 88. 



