124 



DISSECTION OF THE POPLITEAL SPACE. 



Sacro-sciatic 

 ligaments : 



large, 



and small ; 



form two 

 foramina ; 



small, with 

 contents ; 



large, and 

 parts pass- 

 ing through 

 it. 



The SACRO-SCIATIC LIGAMENTS pass from the sacrum and coccy? 

 to the ischium : they are two in number, and are named great anc 

 small. 



The great or posterior ligament (fig. 50, P) is attached above tc 

 the posterior inferior iliac spine, and to the side of the sacrum and 

 coccyx ; and below, to the inner margin of the ischial tuberosity 

 sending forwards a prolongation along the ramus of the bone : somt 

 of the superficial fibres are continued over the tuberosity into the 

 long head of the biceps. 



It is wide next the sacrum, and becomes narrower below ; but it 

 is somewhat expanded again at the tuberosity. On the cutaneous 

 surface are the branches of the sacral nerves ; and the glutens maxi- 

 mus conceals and takes origin from it. Branches of the sciatic 

 artery and a cutaneous nerve from the sacral plexus perforate it. 



The small or anterior ligament passes from the sacrum and coccyx 

 to the ischial spine, but this band will be more fully seen in the 

 dissection of the pelvis. 



These ligaments convert the deep sacro-sciatic notch of the dried 

 pelvis into two foramina. Between their insertion into the spine 

 and tuberosity of the hip-bone is the small sacro-sciatic foramen, 

 which contains the internal obturator muscle with its nerve and 

 vessels, and the pudic vessels and nerve. And above the smallei 

 ligament is the large sacro-sciatic foramen, which gives passage to 

 the pyriformis muscle, with the gluteal vessels and the superior 

 gluteal nerve above it, and the sciatic and pudic vessels and nerves, 

 the inferior gluteal nerve, and the nerves to the obturator internus 

 and quadratus femoris below it. 



SECTION II. 



THE POPLITEAL SPACE AND THE BACK OF THE THIGH. 



Directions. 



Position 



Take the 

 skin from 

 over the 

 ham. 



Seek the 



cutaneous 



nerves. 



Directions. The ham or popliteal space should be taken after the 

 buttock, in order that it may be seen in a less disturbed state than 

 if it were dissected after the examination of the muscles at the back 

 of the thigh. When this space has been learnt, the student will 

 return to the dissection of the thigh. 



Position. The limb should be raised on blocks into the hori- 

 zontal position. 



Dissection (fig. 51, p. 126). To remove the skin from the 

 popliteal region, let a longitudinal incision be made behind the knee 

 from a distance of six inches above to four inches below the joint. 

 At each extremity of this cut make a transverse incision, and raise 

 the skin in two naps, the one being turned outwards and the other 

 inwards. 



In the fat are some small cutaneous nerves, viz., one or two twigs 

 in the middle line of the limb from the small sciatic nerve beneath 



