FASCIA TRANSVERSALIS. 417 



muscle by two incisions ; one of these is to be carried through the fibres 

 attached to Poupart's ligament; the other, across the muscle from the 

 front of the hip bone to the margin of the rectus. With a little care the 

 muscle may be separated easily from the thin fascia beneath. 



The fascia transversalis (fig. 140, G ) is a thin fibrous layer between 

 the transversalis muscle and the peritoneum. In the groin or inguinal 

 region, where it is unsupported by muscles, the fascia is considerably 

 stronger than elsewhere, and is joined by fibres of the aponeurosis of the 

 transversalis muscle; but farther from the pelvis it gradually decreases in 

 strength, until at the thorax it becomes very thin. 



In the part of the fascia now laid bare, is the internal abdominal ring, 

 which gives passage to the spermatic cord, or the round ligament, accord- 

 ing to the sex; this opening resembles the finger of a glove in being visible 

 internally, but indistinguishable externally in consequence of a prolonga- 

 tion from the margin. On the inner side of the ring the fascia is thinner 

 than on the outer, and is there fixed into the pubes" and the pectineal line 

 of the hip bone, behind the conjoined tendon with which it is united. 



At Poupart's ligament the fascia is joined to the posterior margin of 

 that band along the outer half; but along the inner half it is directed 

 down to the thigh, in front of the bloodvessels, to form the anterior part of 

 a loose sheath (crural) around them. 



Internal abdominal ring (fig. 140). This opening is situate midway 

 between the symphysis pubis and the anterior superior iliac spine, and 

 half an inch above Poupart's ligament. From its margin a thin tubular 

 prolongation of the fascia is continued around the cord, as before said. 



Dissection. The tubiform prolongation on the cord may be traced by 

 cutting the fascia transversalis horizontally above the opening of the ring, 

 and then longitudinally over the cord. With the handle of the scalpel 

 the thin membrane may be reflected to each side, so as to lay bare the 

 subperitoneal fat. 



The subperitoneal fat forms a layer between the fascia transversalis and 

 the peritoneum. Its thickness varies much in different bodies, but is 

 greater at the lower part of the abdomen than higher up. This structure 

 will be more specially examined in the dissection of the wall of the abdomen 

 from the inside. 



Dissection. After the subperitoneal fat has been seen, let it be reflected 

 to look for the remains of a piece of peritoneum along the cord, in the 

 form of a fibrous thread. 



The peritoneum, or the serous sac of the abdominal cavity, projects for- 

 wards slightly opposite the abdominal ring. Connected with it at that 

 spot is a fibrous thread (the remains of a prolongation to the testis in the 

 foetus) which extends a certain distance along the front of the cord. It is 

 generally impervious, and can be followed only a very short way, but it 

 may be sometimes traced as a fine band to the tunica vaginalis of the 

 testis. 



In some bodies the process may be partly open, being sacculated at in- 

 tervals; or it may form occasionally a single large bag in front of the 

 cord. Lastly, as a rare state, the tube of peritoneum accompanying the 

 testis in its passage in the foetus may be unclosed, so that a coil of intestine 

 could descend in it from the abdomen. 



In the female the foetal tube of peritoneum remains sometimes pervious 

 for a short distance in front of the round ligament; that unobliterated 

 passage is named the canal of Nuck. 

 27 



