Posted by lae2 on September 01, 2011 at 23:37:01:
In Reply to: Re: Questions for the Abdominal Wall posted by ESB on August 28, 2011 at 16:09:54:
: : Answer to Questions for the Abdominal Wall
: : True/False - August 23, 2011 (selection limited by earthquake)
: : 1. The paraumbilical veins communicate with lateral thoracic vein and, thus, contribute to a portacaval shunt.
: : True—unsure of reasoning
: I think in this case, the words "shunt" and "anastemosis" are being used as synonyms for the venous connection between the portal system and the systemic system provided by the paraumbilical veins.
A shunt and an anastomosis are certainly related. For example the genicular anastomosis provides a shunt across the popliteal artery. The collateral circulation of the anterior thoracic wall provides a shunt across the descending thoracic aorta. Portacaval shunts provide shunts across the liver. Portal blood, under non-pathological conditions, passes through the liver to gain access to the caval system by way of the hepatic veins. Consider the left gastric vein. It is a tributary of the portal vein. Thus, under non-pathological conditions the left gastric vein drains into the portal vein. In the case of liver disease, portal hypertension may result. In this case the left gastric vein reverses blood flow and opens anastomotic connections with the esophageal veins. The esophageal veins provide a shunt for portal blood to enter the caval system without passing through the liver. This is a terrible condition and the afflicted ought not eat kettle cooked potato chips. Tearing of an esophageal varice may cause sudden death.
: : 11. The inferior epigastric artery enters the rectus sheath at a location inferior to the arcuate line.
: : False-the inferior epigastric artery is deep to the rectus abdominis muscles and the posterior rectus is only present above the arcuate line. Therefore, the inferior epigastric vein cannot enter the rectus sheath below the arcuate line.
: There're strange semantics involved in this question. The inferior epigastric artery runs superiorly on the posterior side of the body of the rectus abdominis from a point below the arcuate line. It enters the rectus sheath at the arcuate line, piercing the posterior layer at the point where it begins. In order to convincingly argue it as either true or false, I think I'd end up resorting to some nasty topological space arguments.
If I understand your logic, the inferior epigastric artery cannot enter the rectus sheath inferior to the arcuate line because there is no rectus sheath inferior to the arcuate line? Have you read an account of the rectus sheath stating that the rectus sheath stops at the arcuate line? Especially, have you read this in Gray's?