QS Study

The stomach is a reservoir of food particles, where digestion begins. It is the internal organ in which the major part of the digestion of food occurs, being (in humans and many mammals) a pear-shaped enlargement of the alimentary canal linking the esophagus to the small intestine. It is a muscular J-shaped pouch like hollow organ that hangs inferior to the diaphragm in the upper left portion of the abdominal cavity.

Nerve supply of stomach

The stomach is supplied by sympathetic and parasympathetic nerves.

(A) Sympathetic nerves

Derived from: The coeliac plexus.

The nerves are:

(i) Chief pathway for pain sensation.

(ii) Motor to pyloric sphincter.

(B) Parasympathetic nerves

Derived front: Right and left vagus nerves –

Anterior vagal trunk: Formed from the left vagus nerve.

Supplies –

a) The anterior surface of the stomach.

b) Pylorus.

Posterior vagal trunk: Formed from the right vagus nerve.

Supplies – Posterior surface of the stomach.

These nerves are –

(i) Motor to the muscular wall of the stomach.

(ii) Secretomotor to gastric glands.

(iii) Inhibitory to pyloric sphincter.

Development

  • The stomach appears as a fusiform dilatation of foregut.
  • Lining epithelium and gland – Develop from endoderm.
  • Musculature and connective tissue – Develop from mesoderm.