THE STOMACH By: MUTHANNA AL-LAMI

Objectives Introduction Anatomical structures Histology Anatomical relations Ligaments Blood supply ,venous drainage ,lymphatic drainage Innervation Functions

introduction The stomach, is an intraperitoneal digestive organ located between the esophagus and the duodenum.It has a ‘J’ shape. the stomach lies within the superior aspect of the abdomen. It primarily lies in the epigastric and umbilical regions, however, the exact size, shape and position of the stomach can vary from person to person and with position and respiration.

It has 4 main regions : Anatomical Structure 1- Cardia 2- Fundus 3- Body 4-Pylorus

Cardia – surrounds the superior opening of the stomach at the T11 level. Fundus – the rounded, often gas filled portion superior to and left of the cardia. Body – the large central portion inferior to the fundus. Pylorus – This area connects the stomach to the duodenum. It is divided into the pyloric antrum, pyloric canal and pyloric sphincter. The pyloric sphincter demarcates the transpyloric plane at the level of L1.

Curvatures and sphincters

Greater curvature – forms the long, convex, lateral border of the stomach. Arising at the cardiac notch. It curves to the right as it continues medially to reach the pyloric antrum. Lesser curvature – forms the shorter, concave, medial surface of the stomach. The most inferior part of the lesser curvature, the angular notch, indicates the junction of the body and pyloric region. it gives attachment to the hepatogastric ligament . LES : it lies between the esophagus and the cardia and it prevents the gastric reflex . The pyloric sphincter: lies between the pylorus and the first part of the duodenum. It controls of the exit of chyme (food and gastric acid mixture) from the stomach.

Histology of the stomach

The mucosa is the inner lining of the stomach The mucosa is the inner lining of the stomach. When the stomach is empty the mucosa has a ridged appearance. These ridges (rugae) flatten out as the stomach fills with food. The submucosa is made up of connective tissue that contains larger blood and lymph vessels, nerve cells and fibres. The muscularis propria (or muscularis externa) is the next layer that covers the submucosa. It is the main muscle of the stomach and is made up of 3 layers of muscle. The serosa is the fibrous membrane that covers the outside of the stomach. The serosa of the stomach is also called the visceral peritoneum.

Anatomical relation

Anatomical Relation Structures Superior esophagus and left dome of the diaphragm Anterior Diaphragm, greater omentum, anterior abdominal wall, left lobe of liver, gall bladder posterior Lesser sac, pancreas, left kidney, left adrenal gland, spleen, splenic artery,  transverse mesocolon

Lesser and greater omenta

The greater and lesser omenta are two structures that consist of peritoneum folded over itself. Both omenta attach to the stomach, and are useful anatomical landmarks: Greater omentum – hangs down from the greater curvature of the stomach and folds back upon itself where it attaches to the transverse colon It contains many lymph nodes and may adhere to inflamed areas , therefore playing a key role in gastrointestinal immunity and minimising the spread of intraperitoneal infections. Lesser omentum– continuous with peritoneal layers of the stomach and duodenum, this smaller peritoneal fold arises at the lesser curvature and ascend to attach to the Liver.

Ligaments of stomach

Blood supply

Common hepatic or proper hepatic artery – Blood supply Left gastric artery –supplies the cardia of the stomach and distal esophagus . Splenic artery – gives two branches (left gastroepiploic ,short gasteric arteries ) which supply the greater curvature of the stomach Common hepatic or proper hepatic artery – Two major branches : right gastric –supplies a portion of lesser curvature . Gastrodudenal artery –gives rise to right gastroepiploic artery which supply greater curvature in conjugation with left gastroepiplic artery .

Venous drainage

Lymphatic drainage

Lymph from proximal portion of the stomach drains along the lesser curvature into superior gastric lymph nodes . Distal portion of lesser curvature drains through the suprapyloric nodes . Proximal portion of the greater curvature is supplied by the lymphatic vessels that traverse the pancreaticosplenic nodes . Antal portion of the greater curvature drainds into the subpyloric and omental nodal groups .

Innervation

The stomach receives innervation from several sources: (1) sympathetic fibers via the splanchnic nerves and celiac ganglion (synapse) supply blood vessels and musculature. (2)parasympathetic fibers from the medulla travel in the gastric branches of the vagi. (3) sensory vagal fibers include those concerned with gastric secretion.

Function The main functions of stomach: temporary storage for food, which passes from the esophagus to the stomach where it is held for 2 hours or longer mixing and breakdown of food by contraction and relaxation of the muscle layers in the stomach digestion of food production of enzymes

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