The stomach is a muscular organ which acts as a reservoir for ingested food particles and serves to break down foodstuffs mechanically and support the process of digestion before that stuff is passed on into the duodenum. located between the esophagus and the duodenum.
The stomach has a ‘J’ shape, & structures a lesser & greater curvature. The anterior & posterior surfaces are smoothly rounded with a peritoneal covering to it. The stomach has an important anatomical part. The 4 main sections of the stomach are the cardia, fundus, body, and pyloric part.
There are 2 sphincters of the stomach ( inferior oesophageal sphincter and pyloric sphincter) and there location to each orifice. Usually, their work is to control the passage of material entering & exiting the stomach.
Mucus producing epithelial cells are present in gastric and thus turned over rapidly. In the pyloric part of the stomach, there is present mucus-secreting glands beside these most of the specialized cells such as parietal and chief cells are found in the gastric crypts. The gastric has also numerous endocrine cells too.
Parietal cells, also called Oxyntic Cell or Delomorphous Cell that are the source of HCL, intrinsic factor & most of the water in the stomach juices. These cells are located in glands in the lining of the fundus and cardiac of the stomach , in the body of the stomach, and line the crypts, being more abundant distally.
The gastric chief cells (or peptic cell, or gastric zymogenic cell)are those in lies principally proximally in gastric crypts of the stomach that releases pepsinogen ( it activate in the stomach to produce the digestive proteases, pepsin) & gastric lipase & is the cells responsible for the secretion of chymosin in ruminant
The stomach has numerous endocrine cells. In the gastric antrum, the mucosa contains G cells and that produce gastrin. Throughout the body of gastric, enterochromaffin-like ( ECL) cells are abundant and those produce histamine which helps in facilitate gastric acid secretion. Besides these, there are large numbers of somatostatin producing D cells throughout the gastric, & somatostatin has a negative regulatory role and peptides as well as neuropeptides produced in the stomach as well.
Blood supply to the stomach
The stomach has an arterial supply on both lesser and greater curvatures. A branch from a celiac trunk called the left gastric artery supply the lesser curvature and forms an anastomosis with the right gastric artery which is the branch of common hepatic artery and it’s a branch from the celiac trunk. A branch from a hepatic artery called the gastroduodenal artery that passes behind the 1st part of the duodenum and here it gives two branches superior pancreaticoduodenal artery and right gastroepiploic artery.
The superior pancreaticoduodenal artery supplies the duodenum and pancreatic head whereas and that form the anastomosis with the inferior pancreaticoduodenal artery which is the branch of the superior mesenteric artery whereas the right gastroepiploic artery that runs and supplies the greater curvature of the stomach and form anastomosis with the left gastroepiploic artery which is the branch of the splenic artery and the splenic artery is the branch from the celiac trunk. And the fundus of the stomach is supplied by the short gastric artery also called as the vasa brevia and those arise from the terminal of the splenic artery.
The veins draining the stomach run parallel to the arteries. They ultimately drain into three large vessels called the hepatic portal, splenic, and superior mesenteric veins. The left gastric vein also called coronary vein runs up the lesser curve towards the esophagus and then passes left to right to join the portal vein and finally this vein markedly dilated in portal HTN.
Lymphatic supply to stomach
The stomach lymphatic vessels travel with the arteries along the greater & lesser curvatures of the stomach. Lymph fluid drains into the gastric and gastro-omental lymph nodes found at the curvatures and the efferent lymphatic vessels from these nodes connect to the coeliac lymph nodes, that are located on the posterior abdominal wall of the stomach . The lymphatic supply to stomach has its value in the surgery of stomach cancer.
Nerve supply to the stomach
The stomach receives its innervation from the autonomic nervous system ( ANS) :
Parasympathetic innervation:- It arises from the anterior & posterior vagal trunks, whoch derived from the vagus nerve i.e. X th cranial nerve.
Sympathetic innervation:- Its arises from the T6-T9 spinal cord segments & passes to the coeliac plexus via the greater splanchnic nerve.