Lecture 26: Visceral Innervation of the Abdomen Flashcards
three distinct pathways of the SYMPATHETIC NS
- to the body wall
- to the body cavity cranial to the diaphragm
- to the body cavity caudal to the diaphragm
three distinct pathways of the PARASYMPATHETIC NS
- head and neck
- body caudal to neck (thorax, foregut, midgut)
- hindgut and pelvid
visceral pain
damage to visceral structure which follows the sympathetic pathway from the structure to the spinal nerve and then to the DRG
visceral non pain
sensations like fullness, bloating, cramping
follows the parasympathetic pathway to the brain
What structures are included in the foregut
- distal esophagus
- stomach
- proximal duodenum + pancreas
- liver
- gallbladder
What structures are included in the midgut
- distal duodenum + pancreas
- jejunum, ileum, cecum
- appendix
- ascending colon
- proximal 2/3rds of transverse colon
What structures are included in the hindgut
- distal 1/3 of transverse colon
- descending colon
- sigmoid colon
- rectum
- proximal anal canal
What is the general role of sympathetics in the addomen?
sympathetics usually inhibit the function of abdominal organs by decreasing blood flow to them via vasoconstriction
what ways can sympathetic nerve fibers inhibit the contraction of SM in GI tract
- directly
- indirectly through the enteric NS
all preganglionic sympathetic originate in the lateral horn of ____- _____
T1-L4
For the thorax, preganglionic sympathetics originate in ____-_____
T1-L5
CP splanchnic nerves attach to ___ - ____ paravertebral ganglia
C1-T5
For the abdomen, preganglionic sympathetics originate in ____-____ and AP splanchnic nerves attach to ____ - _____
T5-L4 and AP splanchnic from T5-Co (end)
are abdomen preganglionic sympathetics myelinated?
yes b/c preganglionic
AFTER SYNAPSE, postganglionic fibers travel in the ________ along arterial branches to the target organs
periarterial plexus
what part of the GI tract is the transition bw the foregut and midgut
duodenum
where does the hindgut begin
about 2/3 of the way along the transverse colon
what things will parasympathetics stimulate in the abdominal organ
mostly smooth muscle in the walls of the GI tract
also secretory cells in the epithelium
gland cells in the submucosa
a few organ-specific cells (like chief cells of the stomach)
what is the location of preganglionic parasympathetic cell body
brain
the preganglionic parasympathetic axons travels to the body via the ____
vagus nerve (CN X)
where do preganglionic axons synapse
in small ganglia in the wall of the organ to be innervated
preganglionic parasympathetic cell bodies destined for the hindgut and pelvic organs are located in the spinal cord ventral horn at what levels
S2,3,4 (Craniosacral)
preganglionic parasympathetics pass through the _____and the _____ to enter the ventral ramus
ventral root and spinal nerve
Hindgut pain follows what pathway back to the CNS
parasympathetic
referred pain from hindgut…where does mix up occur
dorsal horn
For the foregut and midgut, non-pain follows what nerve to the brainstem
vagus
for the hindgut, non-pain follows what nerve
pelvic splanchnics
what cell bodies live in the dorsal root ganglion of S2,S3,S4
pain, nonpain, somatic sensory
role of parasympathetics in the enteric NS
stimulate smooth muscle contraction directly and through the ENS directly
stimulates glandular secretions
role of sympathetics in the ENS
inhibit smooth muscle contraction directly and indirectly through ENS
- vasoconstriction
What is Hirschprung’s diease (congenital megacolon)
failure of the neural crest to migrate and form the ENS
- distal colon cannot generate peristalsis, fecal matter accumulates in the proximal colon, causing it to enlarge
