anatomy stomach

• Stomach


  Specialized for the accumulation of ingested food, which it chemically and mechanically prepares for digestion and passage into the duodenum
• Functions of stomach


  • Storage of food
  • Digestion
  • Mixing of food into chyme
  • Acid secretion
  • Enzyme secretion
  • Hormone secretion
  • Absorption
  • Periodic release of chyme into the duodenum
• Chyme


  Semiliquid mixture that the gastric juice gradually converts the mass of food into, which passes fairly quickly into the duodenum
• Gross anatomy of stomach

  • Location - upper left part of abdomen
  • Shape - 'J' shaped when empty
  • Size - 10 inches long
  • Capacity - 30 ml in newborn, 1.5-2 litres in adults
  • Ends - cardiac and pyloric
  • Orifices - cardiac and pyloric
  • Curvatures - lesser and greater
  • Surfaces - anterior and posterior

  
• Cardiac end


  Upper end where esophagus continuous with stomach, located at T11 vertebra, presents cardiac orifice

  
• Pyloric end


  Lower end where stomach continues as duodenum, located at L1 vertebra, presents pyloric sphincter (pylorus) with pyloric orifice
• Lesser curvature


  Concave, shorter than greater curvature, gives attachment to lesser omentum, related to right and left gastric vessels
• Greater curvature


  Convex, longer than lesser curvature, gives attachment to greater omentum, gastrosplenic and gastrophrenic ligaments, related to right and left gastroepiploic vessels
• Parts of stomach


  • Cardia
  • Fundus
  • Body
  • Pyloric part (pyloric antrum and pyloric canal)

  
• Cardia


  Part surrounding the cardiac orifice
• Fundus


  Dome shaped part, situated above the level of cardiac orifice, contains undigested food and filled with gas
• Body


  Largest part lies between fundus and pyloric antrum
• Pyloric antrum


  Situated between body and pyloric canal
• Pyloric canal


  Narrow, tubular part, at its right end presents pyloric sphincter (pylorus) which guards pyloric orifice
• Relations of stomach


  • Anterior surface - related to anterior abdominal wall, diaphragm, left lobe of liver, left costal margin, left lung and left pleura
  • Posterior surface - related to lesser sac, diaphragm, left kidney, left suprarenal gland, splenic artery, splenic flexure of colon, pancreas, and transverse mesocolon

  
• Gastric rugae


  Folds of mucous membrane that disappear when the stomach is distended
• Gastric pits


  Depressions which open into the lumen of stomach, each receives openings of 2 to 3 gastric glands
• Gastric canal


  Groove formed temporarily by the gastric rugae along the lesser curvature during swallowing, where saliva, small quantities of masticated food and other fluids drain to the pyloric canal when the stomach is mostly empty
• Arterial supply of stomach

  • Left gastric artery (branch of coeliac trunk)
  • Right gastric artery (branch of hepatic artery)
  • Right gastroepiploic artery (branch of gastroduodenal artery)
  • Left gastroepiploic artery (branch of splenic artery)
  • Short gastric arteries (branches of splenic artery)
• Venous drainage of stomach


  Veins drain into superior mesenteric, splenic and portal veins
• Nerve supply of stomach

  • Parasympathetic - anterior and posterior vagal trunks
  • Sympathetic - arise from T6 to T9 spinal segments, distributed via coeliac plexus, hepatic plexus and greater splanchnic nerves
• Lymphatic drainage of stomach

  Lymph drains to right gastric, left gastric, right gastroepiploic, left gastroepiploic, short gastric nodes, then to pancreaticosplenic and hepatic nodes, and finally to coeliac nodes
• Development of stomach


  1. Appears as a fusiform dilation of the foregut in week 4

  2. Has dorsal mesogastrium and ventral mesogastrium

  3. Rotates 90⁰ around its longitudinal axis - results in the left side facing anteriorly and its right side facing posteriorly

  4. Cranial and caudal ends originally lie in the midline

  5. Stomach rotates around an anteroposterior (a-p) axis - caudal end moves to the right and upward, cranial end moves to the left and slightly downward
• Gastric canal along lesser curvature


  Common site for occurrence of peptic ulcer
• Gastric pain is referred to the epigastric region
• Hiatal (hiatus) hernia


  Protrusion of part of the stomach into the thorax through the esophageal opening of the diaphragm
• Pylorospasm


  Failure of the smooth muscle fibers encircling the pyloric canal to relax normally, resulting in food not passing easily from the stomach into the duodenum and the stomach becoming overly full, usually resulting in discomfort and vomiting
• Posterior gastric ulcer


  May erode through the stomach wall into the pancreas, resulting in referred pain to the back. Erosion of the splenic artery results in severe hemorrhage into the peritoneal cavity