Anatomy of the Stomach Quiz

Anatomy of the Stomach & Duodenum

• The stomach is the most dilated part of the gastrointestinal tract (GIT).
• Located in the left hypochondrium, epigastric, and umbilical regions of the abdomen.
• Situated at the level of vertebrae T10 to L3.
• Adult stomach capacity is approximately 2 liters.

Shape of the Stomach

• Typically J-shaped, with a vertical long axis.
• Can be steer-horn shaped, with a horizontal long axis, depending on factors.
• Factors influencing shape include:
  • Distension (empty stomach is more vertical.)
  • Body build (obese people tend toward horizontal)
  • Respiration phase (more vertical during inspiration).
  • Body position (more vertical in standing).

External Features of the Stomach

• Orifices:
  • Cardiac orifice: junction of the esophagus and stomach.
  • Pyloric orifice: junction of the stomach and duodenum.
• Borders:
  • Greater curvature: along the convex side.
  • Lesser curvature: along the concave side.
• Surfaces:
  • Anterior surface.
  • Posterior surface.
• Parts:
  • Cardia (surrounds the cardiac orifice).
  • Fundus (dome-shaped, above the cardiac orifice).
  • Body (extends from fundus to angular notch).
  • Pyloric part:
    • Pyloric antrum (widest part).
    • Pyloric canal (narrow, distal to antrum).
    • Pylorus (distal part, with pyloric sphincter).
• Notches:
  • Cardiac notch.
  • Angular notch.

Orifices of the Stomach

• Cardiac Orifice (more fixed end):
  • Located at the junction of the esophagus and stomach.
  • Located behind the left 6th costal cartilage, 2-4 cm from the median plane at the level of T10 or T11 vertebra.
  • Contains the gastroesophageal sphincter, a physiological sphincter.
  • It's composed of smooth muscles of the right crus of the diaphragm encircling the lower esophagus.
  • Function: prevents gastric reflux.
• Pyloric Orifice (less fixed end):
  • Located at the junction of the stomach and duodenum.
  • Situated at the transpyloric plane (L1), 1.25 cm to the right of the median plane.
  • Position indicated by:
    • Circular groove (pyloric constriction).
    • Prepyloric vein of Mayo (useful for surgical identification).
  • Has a thick anatomical sphincter.

Borders of the Stomach

• Lesser Curvature:
  • Runs from the cardiac orifice to the pylorus.
  • Has an angular notch.
  • Attached to the liver by the lesser omentum.
• Greater Curvature:
  • Runs from the cardiac notch to the pylorus.
  • Attached to the diaphragm by the gastrophrenic ligament.
  • Attached to the spleen by the gastrosplenic ligament.
  • Attached to the transverse colon by the greater omentum.

Parts of the Stomach

• Cardia: Area surrounding the cardiac orifice.
• Fundus: Dome-shaped, left of cardiac orifice, often filled with gas.
• Body: Extends from the fundus to the angular notch.
• Pyloric Part: Divided into antrum, canal, and pylorus, with a thick muscular pyloric sphincter.

Relations of the Stomach

• Anterior Relations:
  • Anterior abdominal wall.
  • Left costal margin.
  • Left pleura and lung.
  • Diaphragm.
  • Left lobe of the liver.
• Posterior Relations:
  • Left crus of the diaphragm.
  • Left suprarenal gland.
  • Upper part of the left kidney.
  • Splenic artery.
  • Pancreas.
  • Transverse mesocolon.
  • Transverse colon.
  • Spleen.
  • Stomach separated from these structures by the lesser sac.

Clinical Notes

• Perforating ulcer in the posterior wall of the stomach can result in:
  • Peritonitis .
  • Referred back pain due to pancreatic invasion.
  • Erosion of the splenic artery leading to severe peritoneal hemorrhage.

Arterial Supply of the Stomach

• Branches from the celiac trunk (branch of abdominal aorta at T12 level).
• Left Gastric Artery:
  • Branches from the celiac trunk.
  • Passes upward to reach the esophagus then descends along the lesser curvature.
  • Supplies the lower third of the esophagus and the upper right part of the stomach.
• Right Gastric Artery:
  • Branch of hepatic artery.
  • Runs to the left along the lesser curvature.
  • Supplies the lower right part of the stomach.
• Short Gastric Arteries:
  • Branches from splenic artery.
  • Supplies fundus of stomach.
• Left Gastro-omental Artery:
  • Branch of the splenic artery at hilum of spleen.
  • Supplies stomach along the upper part of the greater curvature.
• Right Gastro-omental Artery:
  • Branches from the gastroduodenal artery
  • Supplies the stomach along the lower portion of the greater curvature.

Venous Drainage of the Stomach

• Left and right Gastric Veins: drain directly into the hepatic portal vein.
• Short Gastric Veins and Left Gastroepiploic Veins: drain into the splenic vein.
• Right Gastroepiploic Vein: drains into superior mesenteric vein.

Lymphatic Drainage of the Stomach

• Anterior & posterior surface drain into gastric and gastro-omental lymph nodes (LNs).
• Efferent vessels drain into pancreaticosplenic, pyloric, and pancreaticoduodenal LNs.
• All lymph drains into celiac LNs.

Nerve Supply of the Stomach

• Parasympathetic:
  • Anterior vagal trunk (from left vagus nerve) supplies anterior surface.
  • Posterior vagal trunk (from right vagus nerve) supplies posterior surface.
• Sympathetic: from greater splanchnic nerves (T6-T9) via celiac plexus to pyloric sphincter and pain fibers.

Anatomy of the Duodenum

• The duodenum is the first part of the small intestine.
• It's the shortest, most fixed, and dilated part of the small intestine
• It's shaped like a "C" and runs around the head of the pancreas.

Position of the Small Intestine

• Small intestine is the longest part of the GIT
• Occupies central and lower part of the abdomen.
• Surrounded by large intestine and covered anteriorly by greater omentum.
• Extends from pyloroduodenal junction to ileocecal junction.
• Divided into 3 parts: duodenum, jejunum, ileum.

Parts of the Duodenum

• 25 cm long with 4 parts:
  • 1st (superior) part: 5 cm long, opposite L1 vertebra.
  • 2nd (descending) part: 7-10 cm, from L2-L3 vertebrae.
  • 3rd (horizontal) part: 6-8 cm, at L3 vertebra.
  • 4th (ascending) part: 5 cm, from L3 to L2 vertebrae.

Peritoneal Coverings of the Duodenum

• Mostly retroperitoneal, except:
  • First 2 cm is suspended by lesser and greater omentum.
  • Distal end is attached to the right crus of the diaphragm by suspensory ligament of Treitz (surgical landmark).

Relations of the First Part of the Duodenum

• Anteriorly:
  • Quadrate lobe of the liver.
  • Gall bladder.
• Posteriorly:
  • Bile duct.
  • Gastroduodenal artery.
  • Portal vein.

Relations of the Second Part of the Duodenum

• Anteriorly:
  • Right lobe of the liver.
  • Transverse colon.
  • Loops of jejunum.
• Posteriorly:
  • Right kidney.
  • Right renal vessels.
  • Right ureteric pelvis.
  • Right psoas major muscle.

Relations of the Third Part of the Duodenum

• Anteriorly:
  • Root of the mesentery.
  • Superior mesenteric vessels.
• Posteriorly:
  • Right ureter.
  • Right psoas major muscle.
  • Right gonadal vessels.
  • Inferior vena cava.
  • Abdominal aorta and origin of inferior mesenteric artery.

Relations of the Fourth Part of the Duodenum

• Anteriorly:
  • Coils of jejunum.
• Posteriorly:
  • Left psoas major muscle.
  • Left sympathetic trunk.
  • Left renal vessels.
  • Left gonadal vessels.
  • Inferior mesenteric vein.

Structures Opening in the 2nd Part of the Duodenum

• Bile duct: joins with the main pancreatic duct to form the hepatopancreatic ampulla (ampulla of Vater) surrounded by the sphincter of Oddi.
• Accessory pancreatic duct: opens 1" above the major duodenal papilla, in the minor duodenal papilla.

Blood Supply of the Duodenum

• Arterial Supply:
  • Upper 1/2: supraduodenal and superior pancreaticoduodenal arteries from gastroduodenal.
• Lower 1/2: inferior pancreaticoduodenal artery from superior mesenteric.
• Venous Drainage:
  • Superior pancreaticoduodenal vein drains into portal vein.
• Inferior pancreaticoduodenal vein drains into superior mesenteric.

Lymphatic Drainage of the Duodenum

• Drains to pancreatico-duodenal lymph nodes, then drains into celiac and superior mesenteric LNs, some drain to pyloric and hepatic LNs.

Nerve Supply of the Duodenum

• Sympathetic (greater and lesser splanchnic nerves), and parasympathetic (vagus nerve) nerves supplying from celiac superior mesenteric plexuses.