Nerves of the Abdomen Flashcards
In general, what type of nerves supply the body wall, diaphragm and parietal peritoneum?
somatic nerves
In general, what type of nerves supply the visceral part of the abdomen?
autonomic nerves with both motor and sensroy componetns
THe sympathetic autonomic fibers are assotiated with what spinal cord segments?
T1-L2
Parasympathetic autnomic fibers are associated with what spinal cord segments?
brain stem cranial nerves and spinal cord segments S2-S4
What are the general functions of the sympathetic nervous system in the GI system?
inhibit peristalsis
vasoconstriction to divert blood away
What are the general functions of the parasympathetic nervous system in the GI tract?
stimualtes peristalsis, relaxes sphincters and stimulates glandular secretion
What two sets of splanchnics have sympathetic nerves?
thoracic splanchnics
lumbar splanchnics
What are the three thoracic splanchnics?
greater splanchnic
lesser splanchnic
least splanchnic
Are the fibers in the thoracic splanchnics preganglionic or postganglionic?
preganglionic - from T5-T12
they pass through the sympathetic trunk WITHOUT synapsing to travel to the prevertebral ganglia/plexuses
How many lumbar splanchnics ar ethere?
4 pairs, so 8
The preganglionic sympathetic branches of the lumbar splanchnics leave the sympathetic trunk at what levels?
L1-L4
The symapthetic outflow ends at what level?
L2 spinal chord level
So the lumbar sympathetics that exit from L3 and L4 are actually from what?
L1-L2 levels
What two plexuses do most of the lumbar splanchnic nerves join?
intermesenteric and inferior mesenteric plexuses
just some go to the superior hypogastric plexus as well
What are the parasympathetic nerves of the GI system?
the vagus and the pelvic splanchnic nerves
What levels do the pelvic splanchnics come off?
S2-S4
THe preganglionic parasympathetic fibers exit from S2-4 and then ascend into the abdomen via what plexuses?
the hypogastric plexuses
Where do the preganglionic parasympathetics from the hypogastric plexuses synapse? Aka…what part of the GI system gets parasympathetics from the pelvic splanchnics instead of the vagus?
onto postganglionic parasymapthetic fibers in the walls of organs DISTAL to the left colic flexure
so basically the hindgut
True or false: most preganglionic parasympathetic fibers do not synapse in the prevertebral ganglia an dinstead pass thorugh the plexuses to follow arteries to the wall of the gut.
true
What part of the GI system gets its parasymapthetics from the vagus?
anything proximal to the left colic flexure - so foregut and midgut
The posterior vagal trunk has a large branch that brings preganglionic parasympathetic fibers to the celiac and superior mesneteric plexuses. What’s it called?
the celiac branch
As mentioned before, the visceral afferent sensory fibers are in the sympathetic nerves. THey travel in the splanchnic nerves to dorsal root ganglia at what levels of the spinal cord?
T1-L2
this is why visceral sensation is dull and vague compared to somatic pain - the info is received by too many levels for accurate localization
Describe how referred pain works in the abdomen?
spinal cord segments receive both somatic AND visceral sensory input that converge on a relatively limited number of second order neurons
thus, visceral pain is often referred to the somatic tissue supplied by the same cord segment
THe visceral sensory nerves going in the parasympathetic fibers PROXIMAL to the L colic flexur will course to what sensory ganlion?
the nodose or sensory ganglion of the vagus
because the vagus supplies proximal to the left colic flexure
