ABDOMINAL INNERVATION

Question 1

The nerves for sympathetic innervation of the GI are located in spinal levels ____ to ____. The ___ level innervates the head, the ____ levels for the thorax and the ____ levels for the lumbar GI.

Answer 1

T5-L2 spinal nerves provide SNS innervation to GI. T1 supplies the head, T2-T4 goes to the thorax and T5-T9 supplies the lumbar GI.

Question 2

The autonomic nervous system innervates the GI both parasympathetically and sympathetically. If the PSNS acts, that serves to increase ________ and ______. The SNS acts to _______ and _______.

Answer 2

PSNS - increase motility and secretion;

SNS - vasoconstrict GI vessels and reduce motility.

Question 3

The pre-ganglionic cell body locations of the PSNS for the gut are located in the _______ and _______. The PSNS post-ganglionics synapse on the __________.

Answer 3

Brain stem via the Vagus nerve or Sacral spinal cord (S2-4) via the Pelvic Splanchnics nerve;
Terminal ganglia directly on the Organ wall

Question 4

The pre-ganglionic cell bodies for the SNS of the gut lie in the ______ ____ of the spinal cord through the spinal nerves ____ to ___. The post-ganglionics of the gut SNS are located in the _______ _____ near the spinal cord.

Answer 4

Lateral horn, T5-L2;

Prevertebral “pre-aortic” ganglia

Question 5

Describe the location and roles of the myenteric plexus, within the enteric nervous system.

Answer 5

Myenteric Plexus is located between smooth muscle walls of the enteric nervous system. Through PSNS innervation, it modulates the gut wall, increases motility and peristalsis. If innervated by SNS, it increases muscular and vascular tone.

Question 6

Describe the location and roles of the submucosal plexus, in the enteric nervous system.

Answer 6

Submucosal plexus is located in the submucosal layer, DEEPER to the circular layer of smooth muscle. Through SNS innervation, it modulates fluid transport; but through PSNS it acts as a secretomotor.

Question 7

The SNS fibers in the enteric nervous system are already ____-_______. Yet the PSNS fibers in the enteric nervous system synapses on ________.

Answer 7

Post-ganglionic fibers;

Wall of the gut.

Question 8

Define peristalsis in the intestinal tract.

Answer 8

Plexuses in the enteric SM wall stimulate relaxations and contractions. The outer longitudinal layer contracts in FRONT of the bolus, whereas the inner circular layer contracts BEHIND the bolus.

Question 9

Describe the cause of Hirschsprung’s Disease.

Answer 9

Aganglionic Megacolon is caused by a defect in neural crest cell migration from the mutated RET proto-oncogene. This leads to the constriction of the aganglionic distal segment and a dilated proximal segment.

Question 10

Describe the pathophysiology and treatment of Hirschsprung’s Disease.

Answer 10

Absent enteric ganglions cause an overriding SNS and PSNS innervation. The SNS dominates smooth muscle tone that causes constriction at the aganglionic segment. This causes UNCOORDINATED peristalsis at the proximal end with ganglions. The Pull-through operation takes out the aganglionic segment and leaves the proximal end.

Question 11

What is the function of splanchnic nerves?

Answer 11

Splanchnic nerves are preganglionic fibers that connect the sympathetic chain to pre-vertebral ganglion. They innervate abdominal viscera.

Question 12

Pre-vertebral sympathetics have the same name as ________. If sympathetics come from a certain spinal cord level, then the afferents will ____ ______ to the same level.

Answer 12

Arteries;

Go back

Question 13

What splanchnic nerve supplies sympathetic innervation to the the foregut and where are its pre-ganglionic cell bodies? Where are its pre-vertebral ganglia located?

Answer 13

Greater Thoracic spinal nerves, (T5-T9 level);

Synapse on Celiac ganglia

Question 14

What splanchnic nerve supplies sympathetic innervation to the the midgut and where are its pre-ganglionic cell bodies? Where are its pre-aortic ganglia located?

Answer 14

Lesser and Least Throracic Nerves, (T10-T12);
Superior mesenteric ganglia (for proximal midgut),
Aortico-renal ganglia (for distal midgut)

Question 15

What splanchnic nerve supplies sympathetic innervation to the the hindgut and where are its pre-ganglionic cell bodies? Where are its pre-aortic ganglia located?

Answer 15

Lumbar Spinal nerves, (L1-L2);

Inferior Mesenteric ganglia

Question 16

PSNS pre-ganglionic fibers coming from the brain stem travel through _____ nerves and synapse on the organ walls of the _____ and ______.

Answer 16

Vagus nerve/Vagal trunks;

Foregut and midgut

Question 17

PSNS pre-ganglionic fibers coming from the sacral region (S2-S4) travel through the _____ _____ nerves to synapse on the enteric plexus of the ______.

Answer 17

Pelvic Splanchnic nerves;

Hindgut

Question 18

The Posterior vagal trunk travels through the ____ plexus to provide PSNS innervation to the _____. It’s preganglionic fibers run along the branches of the celiac ______ to synapse on the organ wall.

Answer 18

Celiac plexus,
Foregut;
Celiac arteries

Question 19

Pre-ganglionic vagal trunks pass through the _____ ____ ganglia where it’s fibers travel along the SMA branches. These provide PSNS innervation to the organs of the _____.

Answer 19

Superior mesenteric ganglia;

Midgut

Question 20

The hindgut is innervated by pre-ganglionics of the ____ ____ nerves. These nerves are distributed on arteries within the ________ of the rectum and colon and synapse on the cell bodies of the ____ ____.

Answer 20

Pelvic Splanchnic nerves;
Mesentery of the rectum and colon;
Enteric plexus

Question 21

Referred pain of the visceral abdominal organs travels exclusively through fibers of the __________ pathway.

Answer 21

Sympathetic pathway

Question 22

Trace the afferents nerve pathway of a distended stomach after a large meal. Be specific in labeling the nerves.

Answer 22

Distended stomach > Afferent fiber > Celiac Ganglion > Greater Thoracic Splanchnic Nerve > Para-vertebral ganglion (T5-T9, foregut) > White Ramus Communicans > Ventral ramus > DRG > Dorsal Root > Dorsal Horn > CNS

Question 23

Trace the nerve pathway for a distended duodenum.

Answer 23

Distended foregut duodenum > info transmitted to proper level in spinal cord (T5-T9) > level responds back with REFLEX.
This is not perceived as pain!

Question 24

This type of abdominal pain is poorly localized, dull and occurs at the ________. It occurs in very general regions.

Answer 24

Visceral pain;

Midline

Question 25

This type of referred pain is INTENSE, and precise. A hallmark of this pain is “rebound tenderness” where the rebound after a palpated region is more painful than the palpation itself. It occurs after prolonged contact with what structure?

Answer 25

Parietal pain;

Parietal peritoneum

Question 26

This type of abdominal pain is lateralized to a region or _______. The feeling is noxious and associated with more nerve fibers to one side when stimulated.

Answer 26

Referred pain;

quadrant

Question 27

Information present in parietal pain is travels back a reverse efferent pathway on what type of nerves? What is the significance of this?

Answer 27

Somatic sensory nerves.

This is similar to the pain that one feels when someone pinches skin (somatic sensation).

Question 28

Visceral pain in the foregut is present as ______ pain. If present in the midgut, it presents as ______ pain; yet in the hindgut it presents as _____ pain.

Answer 28

Epigastric (T5/6);
Umbilical (T10);
Suprapubic (T12-L1)

Question 29

Pain of the foregut is relayed via _______ afferent pathways of the ____ nerve. Pain here would be felt as ________.

Answer 29

Parasympathetic of vagus nerve that innervates foregut and midgut. Visceral Pain is felt as distension