Greater splanchnic nerve

Greater splanchnic nerve

• Preganglionic fibers :

  Arise from Lateral Horn Cells (L.H.Cs) of lower six thoracic segments.

• Relay :

  In coeliac and superior mesentric collateral ganglia.
  - Nerve fibers to adrenal medulla relay in adrenal medulla itself.

• Postganglionic fibers :

  Fibers pass along blood vessels to reach abdominal viscera.

• Functions :

  1. Splanchnic vessels : vasoconstrictor and vasodilator to the blood vessels of stomach, liver, pancreas, kidney, small intestine and proximal colon. (Vasoconstriction is more powerful )
  2. GIT : inhibitory to their walls and motor to their sphincters. Also , inhibitory to gastric and intestinal secretions and motility.
  3. Liver : stimulates glycogenolysis > increased blood glucose level
  4. Spleen : motor to splenic capsule > squeeze of blood rich in RBCs.
  5. Kidney : vasoconstriction > decreased renal blood flow and urine output. Also, stimulate renin secretion.
  6. Pancreas : inhibits insulin hormone and pancreatic juice secretion.
  7. Gall bladder : inhibitory to the wall and motor to the sphincter of oddi.
  8. Adrenal medulla : secretion of adrenaline 80% and nor-adrenalin 20% .