SIDE VIEW OF THE PELVIS. 381 



ischial spine. This line corresponds in its hinder part to the origin 

 of the rectu-vesical fascia from the obturator fascia ; but in front, 

 the levator ani extends upwards between the two laminse of fascia. 

 The disposition of this part of the fascia will be better seen after 

 the hip-bone has been taken away. 



Dissection. To obtain a side view of the pelvis (fig. 143, p. 382), To JJJ e ve 

 it will now be necessary to remove the left hip-bone. The obturator 

 fascia and great sacro-sciatic ligament are first to be detached, and fascia, 

 then the bone is to be sawn through, about three-quarters of an saw bone, 

 inch outside the symphysis pubis in front, and at the articulation 

 with the sacrum behind. After the bone has been pulled somewhat 

 away from the rest of the pelvis, the ischial spine, with the recto- 

 vesical fascia attached to it, may be cut off with a bone-forceps ; and 

 the loose piece of the hip-bone may then be removed by cutting and divide 

 through the fibres of the iliacus and pyriformis muscles, and any &0 p 

 other structure that may retain it. 



A block is afterwards to be placed beneath the pelvis. The Then blow 

 bladder is to be moderately distended with air through the ureter, anddistend 

 and the urethra is to be tied. Some tow is to be introduced into other parts, 

 the rectum, also into the vagina if it is a female pelvis ; and a 

 small piece is to be placed in the pouch of peritoneum between the 

 bladder and the rectum. After the viscera are thus made prominent 

 without distension, the ischial spine and the recto-vesical fascia 

 should be raised with hooks, while the levator ani (D) and coccygeus 

 (c) muscles below it are cleaned. 



PARTS CLOSING THE PELVIS BELOW. In addition to the recto- Outlet of 

 vesical fascia, the following parts close the pelvic cavity on each closed by- 

 side, between the sacrum and the pubic symphysis. 



Behind, the student will meet with the pyriformis passing through pyriformis, 

 the great sacro-sciatic foramen, with the gluteal vessels and nerve gjus^nd 

 (fig. 142, g a and sg n) above it. Next comes the coccygeus muscle sacro-sciatic 

 (fig. 143, c) on the small sacro-sciatic ligament, between the ischial ** 

 spine and the coccyx ; one border of this muscle is contiguous to the with vessel 

 pyriformis, the other to the levator ani : and between its upper and nerves > 

 border and the pyriformis lie the great sciatic and pudic nerves, 

 with some other branches of the sacral plexus, and the sciatic and 

 pudic vessels. The greater part of the pelvic outlet is closed by by levator 

 the levator ani (D), which extends forwards from the coccygeus to ar 

 the symphysis pubis. It meets its fellow behind, but the muscles and by 

 of opposite sides are separated in front by the urethra, with the i^m g ent. r 

 vagina in the female ; and the interval between them in front is 

 closed by the triangular ligament of the perineum (H). 



The COCCYGECS MUSCLE (fig. 143, c) is flat and triangular, and Coccygeus: 

 has much tendinous substance mixed with its fibres. It arises from origin ; 

 the upper part of the inner surface of the ischial spine (fig. 139, 

 p. 369), and some fibres are attached to the adjoining part of' the 

 obturator fascia. Widening as it passes inwards, the muscle is insertion ; 

 inserted into the side, and the contiguous anterior surface of the 

 coccyx, and into the side of the lowest piece of the sacrum. 



The inner surface looks to the pelvis, and is in contact with the relations of 



surfaces 



