Nerves of the GI tract Flashcards
Parasympathetic division that innervates the GI tract?
Originates in central nervous system
- Brainstem - CN III, VII, IX, X
- spinal cord - S2-S4 pelvic splanchnic nerves
- functions - maintain the status quo (homeostasis)
what is the characteristic of the greater splanchnic nerve and what it supplies?
Originates from the spinal cord T5-T9 and synapses in the celiac ganglion which surrounds the celiac trunk
Postganglionic fibers distributed with branches of the celiac trunk to:
- stomach
- spleen
- pnacreas
- liver
- biliary system
- duodenum
- greater omentum
all of this is sympathetic nerves
what is the characteristic of the lesser splanchnic nerve and what it supplies?
Originates from the spinal cord T10-T11
-synapses in the superior mesenteric ganglion that surrounds the origin of the superior mesenteric artery (SMA)
Distributed with the branches of the SMA to the midgut:
- jejunum
- ileum
- cecum
- ascending colon
- transverse colon
what is the characteristic of the least splanchnic nerve and what it supplies?
Originates from the spinal cord (T12)
-synapses in the aorticorenal ganglion
Distributed with the renal arteries to:
- kidneys (postganglionic sympathetic fibers)
- medulla of suprarenal glands (preganglionic sympathetic fibers)
what do the first 2 lumbar splanchnic nerves associate with, where do they synapse, and what are they distributed to?
First and second lumbar splanchnic nerves are associated with the spinal nerves L1 and L2
synapse in the intermesenteric plexus on the anterior aorta between the SMA and the IMA
distributed to
- descending colon
- sigmoid colon
- proximal rectum
what do the 3rd and 4th lumbar splanchnic nerves associate with and what do they synapse on and are distributed to?
3rd and 4th lumbar splanchnic nerve originates from the spinal cord
3rd nerve is associated with spinal nerve L3
fourth nerve is associated with spinal nerves L4 and L5
Travel to the superior hypogastric plexus on the distal aorta
- some neurons synapse here and travel to the ureter
- most neurons synapse in the inferior hypogastric plexus on the anterior sacrum
postganglionic neurons travel with branches of the internal iliac artery to the pelvic viscera and perineum
where do the sacral splanchnic nerves originate from, where do they travel to and what do they synapse on
Sacral splanchnic nerves originate from the spinal cord and are associated with spinal nerves S1-S5
synapse on the inferior hypogastric plexus
Neurons distributed with branches of the internal iliac artery to the pelvic viscera and perineum
Characteristics of the vagus nerve, how it travels, and where it is distributed to?
Vagus nerve originates from the dorsal motor nucleus in the medulla oblongata
- supply the thoracic viscera
- form the esophageal plexus in the thorax
Anterior vagal trunk:
- synapses the stomach (enteric plexus)
- postganglionic neurons distributed to glands and SM
Posterior vagal trunk:
- pancreas
- liver
- biliary system
- small intestine
- proximal large intestine (including transverse colon ending at the left colic flexure)
characteristics of the pelvic splanchnic nerves and where they synapse to?
Parasympathetic preganglionic nerurons originate from the spinal cord S2-S4
Neruons synapse in the:
- Descending colon
- sigmoid colon
- rectum
- anal canal
- urogenital organs
- organs in perineum
what are the types of abdominal pain
Somatic pain: results from irritation of the parietal peritoneum; diseased organ rubs to irritate the peritoneum lining of the abdominal cavity
- severe pain detected at anatomical location
- pain travels to somatic afferent fibers in abdominal wall to the spinal cord and finally to the brain
- sensitive to stretching and rebound tenderness
Visceral pain:
- organic pain varies from dull to severe; this pain is poorly localized
- it radiates to the dermatome level which receives visceral afferent fibers from the organ concerned
- pain travels in the splanchnic nerve
