CAVITY OF PELVIS. 223 



spread in all directions; and circumscribed abscess of 

 the vulvo-vaginal gland, which would be seen as an 

 oval projection on the side of the vestibule. 



The sacro-coccygeal region offers for surgical consid- 

 eration a common arrest of development of the neural 

 arches of the sacrum, constituting spina bifida ; and the 

 nerves (cauda equina) are in this region usually connected 

 with the sac. Hence, if the operation of puncture be 

 deemed advisable, it should always be made on one side 

 of the sac, and at its lowest part. 



CAVITY OF PELVIS. 



The pelvic cavity contains those viscera, the inferior 

 relations and apertures of which have been described in 

 the preceding section viz., the bladder, rectum, and 

 vagina, with its appendages, the superior surface of the 

 perineum forming its inferior boundary. The soft parts 

 lining its bony walls, the obturatores interni, pyriformes, 

 and levatores ani muscles, are invested with the reflexion 

 of the pelvic fascia, upon which lie the peritoneum and 

 subperitorieal cellular tissue, the arrangements of which 

 are of considerable importance surgically. 1 



The pelvic fascia, which is continuous with the fascia 

 iliaca, is itself a continuation of the transversalis fascia. 

 It is attached to the brim of the true pelvis, and round 

 the margin of the obturator internus muscle. At a 

 curved line between the spine of the ischium and the 

 pubes, this fascia splits to inclose part of the origin of 

 the levator ani muscle, the external lamina of which 

 (obturator fascia) is applied to the inner surface of the 



1 The surgical anatomy of the uterus and ovaries will be better 

 studied in special works on obstetrics. 



