Stomach

• Stomach

  • Muscular sac in upper abdomen that plays crucial role in digestion.

  Function:

  • Storage of food
  • Digestion: mechanically breaks up food, mixes food to produce chyme snd controls emptying of chyme into intestine.
  • Secretion of intrinsic factor, gut hormones (gastrin + ghrelin), Hcl, microbial defense.
• Stomach location

  • Most dilated part of GIT
  • Located in upper abdomen
  • Extends from left costal region into epigastric and umbilical regions
  • Much of stomach is protected by lower ribs

  
• External features of stomach

  Stomach has

  • 3 parts: fundus, body, pylorus
  • 2 borders: lesser and greater curvature
  • 2 orifice: cardiac and pyloric orifices
  • 2 surfaces: Anterior and posterior surfaces
  • Pylorus: pyloric antrum, pyloric canal and oyloric sphincter.
• Parts of stomach

  1. Cardiac orifice: site of gastro-esophageal sphincter (opening of esophagus unto stomach). Consists of circular layer of smooth muscle (under vagal and hormonal control).
  2. Cardia: surrounds cardiac orifice.
  3. Fundus: dome-shaped. Located left to cardiac orifice. Usually full of gazes.
  4. Body: extends from fundus to level of incisura angularis
  5. Pylorus: tubular part of stomach, connects stomach to duodenum. Lies in transpylotic plane. Has a thick muscular end called pyloric sphincter.
• Pylorus of stomach

  • Has a thick muscular end called pyloruc sphincter
  • 2 areas: pyloric antrum and pyloric canal.
  • Pyloric antrum: proximal part of pylorus. Mixing and grinding area
  • Pyloric canal: distal part of pylorus leads to pyloric sphincter.
  • Pyloric sphincter: thick ring of smooth muscle that surrounds pyloric orifice.
  • cavity of pylorus is pyloric canal: contents of pyloric canal enter duodenum via pyloric orifice which opens/closes via pyloric sphincter

  
• Greater and lesser curvatures of stomach

  • Lesser curvature: concave, forms right border of stomach. Extends from cardiac orifice to pylorus.
  • Attached to liver by lesser omentum (gastrohepatic ligament)

  Greater curvature: convex, forms left border.

  • Its upper end is attached to spleen by gastrosplenic ligament.
  • Lower end is attached to transverse colon by greater omentum.

  
• Peritoneal relations of stomach

  • Stomach is lined with peritoneum on both surfaces. (Ant + post )
  • At lesser curvature the 2 layers meet to become continuous with with lesser omentum
  • At greater curvature the peritoneum lining both surfaces meet and become continuous with greater omentum.

  
• Viceral relations of stomach

  Anterior: anterior abdominal wall + diaphragm +Left lobe of liver

  Posterior (structure forming stomach bed)

  • left crus of diaphragm
  • splenic artery
  • splenic flexure of colon
  • left colic flexure
  • left kidney
  • left suprarenal
  • Pancreas

  all are separated from stomach by peritoneum of lesser sac except spleen by greater sac.
• Blood supply of stomach

  1. Along lesser curvature: Left gastric (celiac trunk) + right gastric (proper hepatic)
  2. Along greater curvature: Right gastroepiploic (gastroduodenal) + left gastroepiploic ( splenic)
  3. Along fundus: 5-7 short gastric arteries: branches of splenic

  
• Nerve supply of stomach

  • Sympathetic from celiac plexus: inhibit gastric secretion and motility
  • Parasympathetic: fiber from both vagi

  Anterior vagal trunk: fibers from left vagus: supply anteior suf except pylorus

  Posterior vagal tunk: fibers from right vagus: supply posterior suf

  Parasympathetic fibers are motor secretory: increases motility and gastric secretion.
• Venous drainage of stomach

  • Right + left gastric vein drain directly into portal vein
  • Right gastroepiploic drains into superior mesenteric
  • Short gastric + left gastroepiploic join splenic vein

  
• Stomach bed


  strcutres forming stomach bed

  
• Lymphatic drainage os stomach

  • Left gastric nodes + right gastric nodes
  • Left gastroepiploic nodes + right fastroepiploic
  • Short gastric nodes

  They all ultimately drain into celiac nodes.

  
• Stomach blood supply

  
• Gastric fundus histological slide

  
• gastric fundus histology

  
• Gastric pylorus

  
• Stomach slide description