86 TOPOGRAPHICAL ANATOMY OF THE 



muscle. Most commonly the artery buries itself in the substance of 

 the muscle, about the middle of the length of which it anastomoses with 

 the cranial epigastric artery. It is accompanied by the caudal 

 epigastric vein (v. epigastrica caudalis). 



A, ET V. EPIGASTRICA CRANiALis. — The cranial epigastric vessels 

 appear between the xiphoid process of the sternum and the ninth costal 

 cartilage. They follow the deep face of the rectus abdominis muscle 

 and anastomose with the caudal epigastric vessels. 



Nerves of the abdominal wall. — Within the substance of the 

 wall of abdomen are branches of the last ten intercostal, and the last 

 thoracic, ilio-hypogastric, ilio-inguinal and lateral cutaneous femoral 

 nerves. 



The last ten intercostal nerves are derived from the ventral divisions 

 of the ninth to seventeenth thoracic nerves. They appear from beneath 

 the costal arch, cross the surface of the transverse muscle, and disappear 

 under the edge of the rectus muscle, in which they terminate. Lateral 

 cutaneous branches pierce the two oblique muscles to end in the 

 cutaneous muscle and the skin. 



The hist thoracic nerve is represented in the abdominal wall by two 

 branches. The superficial branch (equivalent to the lateral cutaneous 

 ramus of an intercostal nerve) runs over the surface of the transverse 

 abdominal muscle, pierces the external oblique muscle and ends in the 

 skin of the flank. The deep branch traverses the deep face of the 

 transverse muscle and terminates in the rectus abdominis. 



The ilio-hypogastric and ilio-inguinal nerves arise from the first 

 and second lumbar nerves respectively, of which they constitute the 

 ventral branches. Each divides into a superficial and a deep branch. 

 The ramus superficialis (in series with the lateral cutaneous branches of 

 the intercostal nerves) in each case pierces the oblique muscles to reach 

 the cutaneous muscle and skin of the flank and the lateral anterior part 

 of the thigh. The ramus profundus lies between the transverse 

 abdominal muscle and the peritoneum, and consequently cannot be 

 examined until later. 



The lateral cutaneous nerve of the thigh arises by roots derived 

 from the third and fourth (often also from the fifth) lumbar nerves. In 

 the present dissection it pierces the abdominal muscles close to the 

 coxal tuber (in company with the caudal branch of the deep circumflex 

 iliac artery) to be distributed in the skin of the lateral aspect of the 

 thigh and the region of the femoro-tibial articulation. 



A. ciRCUMFLEXA ILIUM PROFUNDA. — The deep circumflex iliac 

 arises either from the aorta or the external iliac artery. After a course 



