Stomach
Things you NEED to know about the stomach
Gastric = related to the stomach.
It has the following regions: fundus, cardia, body, antrum and pylorus.
The cardiac sphincter, also called the lower oeseophageal sphincter (LOS), is the opening of the oesophagus into the stomach (not to be confused with upper oesophageal sphincter of the pharynx). The LOS is closed by the contraction of the crura of the diaphragm. The contraction of the LOS prevents reflux of gastric contents. When it can't, due to the effects of smoking, caffeine, alcohol or pathology like oesophageal or gastric cancer, reflux occurs and induces metaplasia of the lower 1/3 of the oesophagus lining.
It has ruggae, or folds, that enable it to expand to accomodate food.
It has a pH of 1.5 - 2.0, which facilitates the conversion of pepsinogen to pepsin, which itself allow the digestion of proteins.
The greater omentum hangs inferiorly from the greater curvature of the stomach.
The lesser omentum runs from the inferior edge of the liver to the lesser curvature of the stomach - within the lesser omentum layers runs the hepatic portal triad of structures.
Blood supply and nerves of the stomach
Arterial supply to the stomach
Stomach arterial supply = coeliac trunk. It has three branches that you should know about:
Left gastric artery.
Splenic artery (tortuous course over the superoposterior aspect of the pancreas - is ruptured when posterior peptic ulcers perforate).
Common hepatic artery.
Venous drainage of the stomach
The reverse of the arterial supply, but be aware: there are varations.
Be familiar with the fact the inferior mesenteric vein can drain into the splenic vein or the superior mesenteric vein. Under most circumstances, the splenic vein + superior mesenteric join to become the hepatic portal vein.
Remember: the venous drainage of the stomach is part of the hepatic portal venous drainage, because all that goodness absorbed from the stomach (and rest of GI tract) needs to filtered, metabolised and detoxified by going through the liver.
