Innervation of the GI Tract

Question 1

Are thoracic splanchnic nerves pre or postganglionic? Where do they originate?

Answer 1

Pre

Sympathetic chain ganglia T5-T12

Question 2

Where do we find greater splanchnic nerve? Where does it send postgang fibers?

Answer 2

T5-9, descends in posterior mediastinum and synapses in coeliac ganglion

postgang fibers distributed in branches of celiac trunk to esophagus, stomach, spleen, pancreas, liver, biliary system, duodenum, and greater omentum

Question 3

Where do we find lesser splanchnic nerve? Where does it send postgang fibers?

Answer 3

T10-11, descends in abdomen to synapse in superior mesenteric ganglion

post gang fibers distributed with branches of sup mesenteric artery to jeju, ileum, cecum, ascending colon, and transverse colon

Question 4

Where do we find least splanchnic nerve? Where does it send postgang fibers?

Answer 4

T12, descends in abdomen to synapse in aorticorenal ganglion

postgang fibers distributed with renal arteries to kidneys

Pregang fibers distributed to suprarenal medulla

Question 5

Are lumbar splanchnic nerves pre or postgang? Where do they originate?

Answer 5

Pre

Sympathetic chain ganglia L1-5

Question 6

Where do the 1st and 2nd lumbar splanchnic nerves come from? Where are their postgang fibers distributed?

Answer 6

splanchnic from L1 and L2 sympathetic ganglia, terminate in intermesenteric plexus on anterior surface of abdominal aorta, between SMA and IMA

distributed with IMA and got to descending colon, sigmoid, and proximal rectum

Question 7

Where do the 3rd and 4th lumbar splanchnic nerves come from? Where are their fibers distributed?

Answer 7

3rd from L1 and 4th from L4 and 5
enter superior hypogastric plexus on anterior surface of distal abdominal aorta

postgang fibers from superior hypogastric plexus go to ureter
post gang fiber from inferior plexus distributed with branches of internal iliac artery to organs of pelvic cavity and perineum

Question 8

Where does the sacral splanchnic nerves originate? Where are the postgang fibers distributed?

Answer 8

pregang sympathetic originating from S1-5 in inferior hypogastric plexus

distributed with pudendal nerve and branches of internal iliac to organs of pelvic cavity and perineum

Question 9

Where does the pelvic splanchnic nerves originate? Where are the postgang fibers distributed?

Answer 9

pregang parasympathetic fibers form sacral spinal cord (S2-4)

synapse in intrinsic/enteric plexuses located in walls of individual organs including descending colon sigmoid colon, rectum, anal canal, urogenital organs of pelvic cavity, and structures in urogenital triangle of perineum

Question 10

What is the enteric nervous system responsible for? What are its 2 components?

Answer 10

regulating physiologic activity in distal esophagus, stomach, intestines, pancreas, and biliary system

Myenteric and submucosal plexus

Question 11

What is the myenteric plexus in charge of?

Answer 11

Regulates motility, vasomotion of muscle layers, secretion of gastric glands

Question 12

What is the submucosal plexus in charge of?

Answer 12

Prominent in SI, exocrine and endocrine secretion, vasomotion (blood flow regulate water and electrolyte movement), micro motility, and immune