ABDOMINAL WALL 381 



Towards the pubes the finger can be pushed downwards behind the 

 fascia of Scarpa and along the spermatic cord into the perineum. No 

 barrier opposes the passage of the finger in this direction. The continuity 

 of the fascia of Scarpa and the fascia of Colles is thus demonstrated. 



If the dissector now recalls the fact that in the urethral 

 triangle of the perineum the fascia of Colles is attached 

 laterally to the margins of the pubic arch, and posteriorly to 

 the base of the urogenital diaphragm, whilst above the level of 

 the pubic crests it is continuous with the fascia of Scarpa on 

 the front of the abdominal wall, he will have little difficulty in 

 understanding the course which urine takes when extrava- 

 sated from a rupture of the urethra in front of the urogenital 

 diaphragm. The effused fluid is directed upwards into the 

 scrotum over the penis, and along the spermatic cords to the 

 front of the abdomen. From the abdomen it cannot pass 

 downwards to the front of the thighs, owing to the attachment 

 of Scarpa's fascia to the fascia lata. Unless vent be given 

 to it by early and free incisions, it will continue to ascend 

 over the abdomen. 



Cutaneous Nerves. A dissection must now be made of 

 the cutaneous nerves of the abdomen. These are arranged 

 on the same plan as the cutaneous nerves of the thorax. We 

 have therefore to look for an anterior and a lateral series. 



( i. Anterior cutaneous nerves. 

 J 2 - 



Anterior series J 2 ' Anterior cutaneous branch of the ilio - hypogastric 



I 3. The ilio-inguinal nerve. 



Lateral cutaneous nerves. 



Lateral series. -( 2. Lateral cutaneous, branch of the last thoracic nerve. 

 Lateral cutaneous branch of ilio-hypogastric nerve. 



Va- 

 ries. -I 2. 



1 3- 



The anterior cutaneous nerves are the small terminal twigs 

 of the lower five or six thoracic nerves. They pierce the 

 aponeurotic sheath of the rectus muscle at variable points, 

 some close to the median line and others a little distance 

 from it. After entering the superficial fascia they run for a 

 short distance laterally. 



To find these nerves, the best plan to adopt is to divide the superficial 

 fascia along the middle line, and reflect it cautiously laterally. The small 

 arteries which accompany the nerves serve as guides. 



The anterior cutaneous branch of the ilio-hypogastric lies 

 in series with the preceding. In the dissection of the 

 superficial fascia it has been seen piercing the aponeurosis 



