Anatomy of the Stomach
Knowing about the anatomy of the stomach will aid in the understanding of various procedures, illnesses and the functioning of the digestive system. Knowledge about anatomy can help a person make wise health and lifestyle decisions.
The stomach is a complex organ with various parts that serve different functions. There are four main sections identified in the stomach; the cardia, the fundus, the corpus and the pylorus.
The cardia is the beginning of the stomach and is the section of the stomach where food enters from the esophagus through a one way valve called the esophageal sphincter. The cardia also contains glands that secrete mucus. In a healthy stomach and digestive system the esophageal sphincter as well as the angle of the cardia will prevent food from passing back up into the esophagus.
The fundus is the upper most portion of the stomach that curves upward from the cardia and forms a curve at the top of the stomach much like the top portion of a lima bean. The fundus allows for the collection of stomach gasses and also stores undigested food. Cells in the fundus secrete mucus and produce hormones that assist in digestion.
Corpus or Body
The corpus is the main body of the stomach with an inner small curve called the lesser curvature and an outer larger curve called the greater curvature. Inside the corpus are folds and ridges formed by the internal wall of the stomach. These are called rugae or rugal folds. One particular fold that travels down the inside of the lesser curvature is called the gastric canal. These rugae fold and stretch around food as it enters the stomach.
Where the body of the stomach begins to narrow down, this area is identified as the pylorus. The pylorus is divided into the pyloric antrum nearer the corpus and the pyloric canal which empties into the duodenum. There is also a sphincter valve at the end of the pyloric canal that opens to allow the digested food to enter the duodenum where the food will be further processed.
Cardial Notch and Angular Notch
In addition to these four major parts of the stomach there are other anatomical characteristics that are identified. There are two notches; one is the cardial notch formed where the cardia bends toward the fundus and the other is the angular notch which is formed as the pylorus bends away from the corpus.
The Stomach Wall
The stomach wall consists of multiple layers of connective tissue and muscle. The mucosa layer, the most internal layer, contains the gastric glands that secrete mucus and gastric juice. The next layer, the sub mucosa is where the nerve bundles lie. Moving outward there are three layers of smooth muscle tissue that form the muscularis externa which is responsible for the movements of the stomach and finally the outermost layer is the serosa which encloses the stomach organ and is connected to the lining of the abdominal cavity.
The following illustration is on the National Cancer Institute website and is part of a training module from Surveillance, Epidemiology and End Results (SEER) Program
The function of the stomach is to store food and partially digest food in order for our bodies to extract the needed nutrients. However the stomach is only one part of the digestive system and works in concert with the entire gastrointestinal tract.
Digestive System Overview
The digestive system begins at the mouth where food is chewed and broken down through saliva and enzymes in your mouth. The chewed food travels down the esophagus and into the stomach where it is further digested into chyme which then continues into the duodenum and small intestine for further digestion and extraction of nutrients before traveling into the larger intestine and out the rectum.