Visceral Innervation of the Abdomen

Question 1

what are the 3 distinct pathways of the sympathetic NS

Answer 1

1) to the body wall (ie: hind paws)
2) body cavity cranial to diaphragm
3) body cavity caudal to diaphragm

Question 2

what are the 3 distinct pathways of the parasympathetic NS

Answer 2

1) head and neck
2) body caudal to the neck: thorax, foregut, midgut
3) hindgut and pelvis

Question 3

describe pain

Answer 3

damage to visceral structure which follows the sympathetic pathway backward then heads dorsally

Question 4

describe non pain

Answer 4

sensations such as fullness, bloating and cramping

follows parasympathetic pathway backward

Question 5

what system is the thoracolumbar system?

Answer 5

sympathetic

Question 6

what system is the craniosacral system?

Answer 6

parasympathetic

Question 7

what is the role of the sympathetics in the abdomen?

Answer 7

will inhibit the function of abdominal organs, typically by decreasing blood flow to organs through vasoconstriction

Question 8

where do thorax sympathetics originate?

Answer 8

T1-T5 –> CP splanchnic nerves attach to C1-T5 paravertebral ganglia

Question 9

what do abdomen sympathetics originate?

Answer 9

T5-L4 –> AP splanchnic nerves attach to T5 -Coccygeal level paravertebral ganglia

Question 10

what levels are the body wall found on?

Answer 10

ALL LEVELS

Question 11

what happens after synapse for postganglionic fibers?

Answer 11

travel in periarterial plexuses along arterial branches to the target organs

Question 12

what sympathetics supply the celiac trunk?

Answer 12

celiac ganglion

Question 13

what sympathetics supply the cranial mesenteric artery?

Answer 13

cranial mesenteric ganglion

Question 14

what sympathetics supply the caudal mesenteric artery?

Answer 14

caudal mesenteric ganglion

Question 15

where does hindgut begin?

Answer 15

about 2/3 of the way along the transverse colon

Question 16

what is the role of parasympathetics in the abdomen?

Answer 16

usually will stimulate the abdominal organs (smooth muscle in the walls of the GI tract) and secretory cells in the epithelium, gland cells in the submucosa, and a few organ-specific cells

Question 17

describe the parasympathetic pathways in the foregut and hindgut

Answer 17

same pathway that has been learned

Question 18

where are preganglionic parasympathetic cell bodies destined for hindgut and pelvic organs located?

Answer 18

spinal cord anterior horn at levels S2, S3, S4

Question 19

the sacral splanchnic nerves (sympathetic AP nerves) are branches of:

Answer 19

branches of the sympathetic chain

Question 20

the pelvic splanchnic nerves (parasympathetic) are branches of:

Answer 20

branches of ventral rami

Question 21

where might the mix up occur for referred pain for foregut and midgut?

Answer 21

likely dorsal horn (same as thorax)

Question 22

how does pain travel in the hindgut?

Answer 22

follows the parasympathetic pathway back to the CNS

Question 23

where does referred pain from hindgut get mixed up?

Answer 23

still occurs in the dorsal horn

Question 24

how does nonpain travel for the foregut and midgut?

Answer 24

follows the vagus nerve to the brainstem

Question 25

how does nonpain travel for the hindgut

Answer 25

follows the pelvic splanchnics

Question 26

what cell bodies live in the dorsal root ganglion of S2, 3 and 4?

Answer 26

pain, nonpain, somatic sensory

Question 27

what is the enteric nervous system?

Answer 27

-classified as a separate component of the ANS for regulating the GI tract
-acts as a local reflex response with afferent and efferent neurons acting through an array of excitatory and inhibitory interneurons

Question 28

where is the myenteric (auerbach’s) plexus located in the GI tract

Answer 28

between circular and longitudinal layers of smooth muscle

Question 29

where is the submucosal (meissner’s) plexus located in the GI tract

Answer 29

submucosa

Question 30

what does the parasympathetic do in the enteric nervous system

Answer 30

stimulates smooth muscle contraction directly and through the ENS indirectly

stimulates glandular secretions

Question 31

what does the sympathetic do in the enteric nervous system?

Answer 31

-inhibits smooth muscle contraction directly and through the ENS indirectly
-vasoconstriction
-isolation of the GI tract from autonomics does not greatly diminish ENS function

Question 32

how does movement in the GI tract work?

Answer 32

1) sensory neurons perceive the distension by the caused by the bolus
2) stimulate interneurons distal to it to relax, proximal to it to contract
3) continuous contraction proximal to the bolus pushes the bolus along the GI tract

Question 33

what is hirschprung’s disease (congenital megacolon)

Answer 33

-failure of neural crest to migrate and form teh ENS
-distal colon can not generate peristalsis, fecal matter accumulates in proximal colon and proximal colon enlarges