THE STOMACH

• Stomach begins as a mere dilation of the primitive gut tube.
• It undergoes two basic processes: differentiation and rotation.
• Initially tube attaches to dorsal and ventral walls via dorsal and ventral mesenteries.

1. Ventral Mesentery eventually becomes lesser omentum.
2. Dorsal Mesentery (Dorsal Mesogastrium) eventually becomes greater omentum.
   

• Rotation: Then the whole structure rotates 90 to the right, dragging the mesentery along with it.
• The dorsal mesentery becomes the left side of the body, and the posterior of the stomach becomes the left lateral aspect.
• Differential Growth: Then differential growth produces the fundus, the greater curvature, and the lesser curvature of the stomach.

• LOCATION: The pylorus of the stomach at the level of L1, in the transpyloric plane. Generally in the right epigastric region, but the location varies depending on position, weight, physiology, etc.

• Cardia: Superior part nearest the esophagus.
• Fundus: That part of the stomach that is actually superior to the abdominal esophagus.
• 1. Gastric Bubble is located here in radiographs, if person is upright.
  2. Cardiac Notch is a radiographic feature of being able to see the fundus part of the stomach.
• Body: The main part of the stomach consisting of the greater and leser curvatures.
• 1. Greater Curvature: Inferior border of stomach body.
  2. Lesser Curvature: Superior border of stomach body.
• Pyloric Region: The most distal part of the stomach, at level of L1, leading into duodenal cup.
• 1. Gastrocolic Ligament: On greater curvature of stomach, attaching to transverse colon. It is part of the greater omentum.

• Gastric Canal:
  
• 1. Impression along the lesser curvature of the stomach, on the interior.
  2. Rugae here are more longitudinal, to guide food to the pylorus.
     

• Cardiac Opening: The opening at the proximal end, aka the esophogastric junction.

1. No true sphincter here.
   

• Rugae: Mucosal folds of internal wall of stomach. They increase the surface area available for digestion.
• Pyloric Antrum:

1. Pyloric Canal: The distal region of the body, in the pyloric zone, leading to pylorus.
2. Pyloric Sphincter: At the pylorus, it is a true sphincter controlling flow of chyme into the duodenum.
   

1. The left lobe of the liver overlies the anterior portion of the stomach.
2. Spleen is lateral to the stomach, just off the greater curvature.
3. The greater omentum is inferior to the stomach (just off greater curvature), and the transverse colon lies directly deep to it.
4. Posterior to Stomach:
   

• The lesser peritoneal sac.
• The pancreas, with the duodenum surrounding it.
• Bed of the Stomach: Those organs upon which the stomach lies.

1. The pancreas,
2. spleen,
3. transverse colon,
   
4. a portion of the kidney and suprarenal glands.
   

• Gastric Bubble can be seen in stomach on X-rays, in the fundus region.
• Stomach Carcinoma is usually in the pyloric region or lower body, close to the pyloric lymph nodes.
• Gastric (Peptic) Ulcers: Acid secretion in stomach.
• Gastroduodenal Artery, posterior to pyloric area, can be affected by an ulcer if the wall is eroded.

• Pyloric Lymph Nodes drain to the Celiac Nodes.
• Right and Left Gastric Arteries supply the lesser curvature of the stomach. They come off of the Celiac Trunk, via the common or proper hepatic arteries.
• Right Gastroepiploic supplies greater curvature, from the gastroduodenal, from the proper hepatic.
• Left Gastroepiploic supplies greater curvature, from the Splenic Artery, from the Celiac Trunk.

Category: Anatomy Notes