Short Notes: Anatomy of the Gastrointestinal Tract

Gastro-intestinal tract
1. Stomach
External features

 J shaped muscular bag
 Two orifices
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o Cardiac orifice - Lies behind the left 7 costal cartilage (T11).
 Has a physiological sphincter (not anatomical)
o Pyloric orifice -Lies at the level of transpyloric plane (L1).
Its position is indicated by,
 A circular groove produced by underlying pyloric sphincter
 The prepyloric vein/ vein of Mayo lying in front
 Anatomical, physiological sphincter
 In epigastric, umbilical and left hypochondrial regions
 Widest and most distensible part of GI tract




Fundus-filled with air

Parts of the stomach Cardiac part Body

Pyloric part Pyloric antrum
Pyloric canal


▪Relations –
-Peritoneal,
Ventral mesogastrium (dorsal part) - lesser omentum
Dorsal mesogastrium 1.along the greater curvature- greater omentum
2. near the fundus- gastrosplenic ligament
3. near the cardiac end- gastrophrenic ligament

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, -Visceral,
Anterior – Anterior abdominal wall
Left costal margin
Diaphragm
Left lobe of liver
Posterior (Stomach bed) –
Pancreas
Transverse colon
Left kidney
Left suprarenal gland
Spleen
Splenic artery
▫Are separated from stomach by the lesser sac
Superior – left dome of diaphragm
Inferior – coils of intestine
Functions
 Storage of food
 Mechanical grinding and digestion
 Prevent reflux
 Prevent digestion and damage of its wall
 Controlled release of food at pylorus
 Absorption (H2O, Ethanol)
 Intrinsic factor

Mechanisms to prevent gastroesophageal reflux

 Physiological sphincter at the gastroesophageal junction
o Transverse mucosal folds of gastroesophageal junction
o Sphincteric action of right crus of diaphragm
 Acute angle of entrance of esophagus into the stomach
 The positive intra-abdominal pressure compresses the abdominal part of esophagus.




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