Innervation of the Stomach:

The stomach receives both autonomic (sympathetic and parasympathetic) and sensory innervation to regulate its motor activity, secretion, and sensations such as pain and fullness.

1. Parasympathetic Innervation:

• Source: Vagus nerve (cranial nerve X)

• Role: Stimulates peristalsis, gastric secretion (like hydrochloric acid), and relaxes the pyloric sphincter.

• Path:

  • The right vagus nerve becomes the posterior vagal trunk.

  • The left vagus nerve becomes the anterior vagal trunk.

• Both trunks branch further to innervate the stomach, contributing to the celiac plexus and intramural ganglia within the stomach wall.

2. Sympathetic Innervation:

• Source: Thoracic splanchnic nerves (T5–T9 segments).

• Path:

  • Preganglionic fibers pass through the greater splanchnic nerve.

  • Synapse occurs in the celiac ganglion.

  • Postganglionic fibers then follow the celiac plexus to innervate the stomach.

• Role: Inhibits gastric motility and secretion, contracts the pyloric sphincter, and conveys visceral pain signals (e.g., distension, inflammation).

3. Sensory (Afferent) Innervation:

• The vagus nerve carries non-painful sensations (such as fullness).

• Sympathetic fibers convey painful stimuli, such as distension, via the thoracic spinal cord segments.

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