378 ABDOMEN 



of about two and a half inches. At the point where it dis- 

 appears from view a prominent tubercle is developed on its 

 lateral lip. It is here, at the highest point of the iliac crest 

 which can be seen from the front, that the lateral outline of 

 the trunk joins the ilium. As we shall see later on, use is 

 made of this fact in subdividing the abdominal cavity 

 into regions. 



In females who have borne children the skin over the 

 lower part of the abdomen is wrinkled and scarred. 



Parts to be dissected. A dissection of the abdominal wall 

 will display the following parts : 



1. Superficial fascia. 



2. Cutaneous vessels and nerves. 



3. The external oblique muscle. 



4. The internal oblique muscle. 



5. The anterior branches of the lower six thoracic nerves and accompany- 



ing vessels ; the ilio-inguinal and ilio-hypogastric nerves. 



6. The transversus abdominis muscle. 



7. The rectus and pyramidalis muscles and the sheath of the rectus. 



8. The transversalis fascia. 



9. The inferior epigastric and deep circumflex iliac arteries. 



10. The superior epigastric and musculo-phrenic arteries. 



11. The spermatic cord. 



12. The inguinal canal. 



13. The extra-peritoneal fat. 



14. The parietal peritoneum. 



Reflection of Skin. Incisions (i) Along the middle line of the body 

 from the xiphoid process to the symphysis pubis. The knife should 

 be carried round the navel so as to surround it with a circular incision. 

 (2) From the xiphoid process transversely round the thorax, as far back 

 as the knife can be carried. (3) From the symphysis pubis laterally, 

 along the line of the inguinal ligament, to the anterior superior spine of the 

 ilium, and then backwards along the crest of the ilium (Fig. 141). 



The large flap of skin thus mapped out should be carefully raised from 

 the subjacent superficial fascia and turned laterally. If the abdominal 

 wall is flaccid, the dissection may be facilitated by inflating the abdomen. 

 Make an incision through the umbilicus, large enough to admit the nozzle 

 of the bellows or an injection-pipe fixed to a bicycle-pump, and when the 

 walls are quite tense secure the opening with twine, which should previously 

 be sewn round the lips of the incision. 



Panniculus Adiposus (Superficial Fascia). The superficial 

 fascia which is now laid bare is seen to present the same 

 appearance, and possess the same characters, as in other 

 localities. Above, it is thin and weak, and is directly con- 

 tinuous with the corresponding fascia over the chest; below, 

 it becomes more strongly marked, and acquires a greater 

 density. Towards the lower part of the abdomen the super- 

 ficial fascia develops special characters; it consists of two 



