Abdomen - Nervous System 2

The Vagus Nerve: Foregut and Midgut innervation

• In the thorax, the right vagus runs posterior to the esophagus, and the left vagus runs anterior to it.
• Around the esophageal hiatus (T10), the two vagus nerves mix, and then they separate again, to form the right and left vagal trunks.
• Left (Anterior) Vagal Trunk: Gives off Hepatic Branch and Principle Anterior Gastric Branch.
• Right (Posterior) Trunk: Forms the Celiac Plexus ------> Superior Mesenteric Plexus.
• These nerves are perivascular -- they follow the course of the arteries.
  

Pelvic Splanchnic Nerves: Hindgut innervation

• The Pelvic Splanchnic Nerves are parasympathetic Sacral spinal nerves S2-S4.
• They form Pelvic Plexuses ------> Inferior Hypogastric Plexus ------> Pelvic viscera, and separately, the hindgut.
• These nerves are Non-Perivascular. They do not follow the arteries, but instead crisscross the arteries. The nerves are still located in mesentery.
• The lower anus (below pectinate line) is innervated by somatic nerves -- the pudendal nerve -- not parasympathetic pelvic splanchnic.
  

• Greater Thoracic Splanchnics: T6-T9, Sympathetic spinal nerves supplying the foregut and midgut.
• Lesser Thoracic Splanchnic: T10-T11, Sympathetic spinal nerves supplying the hindgut, generally.
• Least Thoracic Splanchnic: T12. It supplies the Renal Plexus.

Category: Anatomy Notes