Stomach-anatomy

• 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 stomach gradually converts food into and passes into the duodenum
• Gross anatomy of stomach

  • Location in upper left part of abdomen
  • Size - 10 inches long
  • Capacity - 30 ml in newborn, 1.5-2 litres in adults
  • Shape - 'J' shaped when empty
  • External features - cardiac and pyloric ends, lesser and greater curvatures, anterior and posterior surfaces

  
• Stomach development


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

  2. Has dorsal mesogastrium and ventral mesogastrium

  3. Rotates 90 degrees around longitudinal axis

  4. Cranial and caudal ends originally lie in the midline

  5. Stomach rotates around an anteroposterior axis
• Parts of stomach


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

  
• Relations of stomach


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

  
• Interior of stomach


  • Gastric rugae (folds of mucous membrane)
  • Gastric pits (depressions opening into gastric glands)
  • Gastric canal (groove along lesser curvature)
• Arterial supply of stomach

  • Left gastric artery
  • Right gastric artery
  • Right gastroepiploic artery
  • Left gastroepiploic artery
  • Short gastric artery
• Venous drainage of stomach

  • Drains into superior mesenteric, splenic and portal veins

  
• Nerve supply of stomach

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

  • Drains to right gastric, left gastric, right gastroepiploic, left gastroepiploic, short gastric nodes
  • Left gastroepiploic and short gastric nodes drain into pancreaticosplenic nodes
  • Right gastric, left gastric, right gastroepiploic nodes drain to hepatic nodes
  • Pancreaticosplenic, hepatic nodes drain to coeliac nodes
• Gastric canal along lesser curvature is a common site for peptic ulcer occurrence
• Gastric pain is referred to the epigastric region

  Due to nerve supply from T6 to T9 spinal segments
• A hiatal (hiatus) hernia is a protrusion of part of the stomach into the thorax through the esophageal opening of the diaphragm
• Pylorospasm is characterized by failure of the smooth muscle fibers encircling the pyloric canal to relax normally, resulting in food not passing easily from stomach to duodenum
• A posterior gastric ulcer may erode through the stomach wall into the pancreas, resulting in referred pain to the back, and erosion of the splenic artery can result in severe hemorrhage into the peritoneal cavity