958 



THE ORGANS OF DIGESTION. 



exactly correspond to their arteries, and are usually single. The superficial epi- 

 gastric anastomoses with the deep epigastric, and both with the internal mammary. 



Pressure upon the vena cava inferior forces blood into the superficial epigas- 

 tric vein. A dilatation of the superficial abdominal veins to the size of the little 

 finger (caput Medusae) may thus be caused by cirrhosis of the liver. This is 

 explained by the anastomosis between the superficial epigastric vein and the 

 portal system : the superficial veins communicate with the deep epigastrics and 

 these with the portal system by means of a little vena parumbilicalis running in 

 the falciform ligament of the liver. 



Depending upon the seat of obstruction, whether in the vena cava inferior or 

 in the portal system, the course of the blood-stream in the dilated veins may be 

 in one of two directions : toward the umbilicus in the former case, and from it in 

 the latter. 



The deep veins are the venae comites of the deep epigastric and deep circum- 

 flex-iliac arteries. They communicate with the superficial set, the internal mam- 

 mary, the portal system, and behind the sheath of the Rectus with a plexus in 

 the parietal peritoneum. 



The superficial lymphatic vessels above the umbilicus empty into the axillary 

 glands, below the umbilicus into the inguinal glands. The deep lymphatics prob- 

 ably empty above into the sternal glands arid below into the iliac glands. 



M. rectus abdominii 



M. obliquus 

 externus 



Peritoneum 



M. quadratm 

 lumborum 



Posterior M. latissimus dorsi 



layer Lumbar aponeitrosis, anterior layer 



Middle layer 



FIG. 576. Horizontal section of the posterior abdominal wall through the second lumbar vertebra, right 

 side. (Tillaux.) 



The nerves supplying the whole musculature are the lower five intercostal, 

 the anterior part of the first lumbar, viz. the ilio-hypogastric and ilio-inguinal. 

 Twigs from the lower seven intercostal and from the ilio-hypogastric and ilio- 

 inguinal furnish the sensory supply. 



