Autonomic Of The Abdomen 1

Question 1

What senses are detected by somatic sensory?

Answer 1

• pain
• pressure
• touch
• temperature
• proprioception

Question 2

What are the sensory of visceral afferents?

Answer 2

• distension
• inflammation
• ischemia
• psychological changes
• abnormal muscle spasm

Question 3

What are the main sympathetic ganglia?

Answer 3

Paravertebral or chain ganglia

• three in cervical region
• one associated with each ventral ramus in
other regions

Preaortic/prevertebral ganglia

• at roots of major arteries branching from abdominal aorta
• Celiac
• Superior mesenteric •Inferior mesenteric
• Renal

Question 4

Discuss postganglionic parasympathetic

Answer 4

• found scattered near or in the walls of target organs
• discrete parasympathetic ganglia are only found in the head associated with the parasympathetic cranial nerves
• In the GI: synapse on the neurons of the submucosal (Meissner) and myenteric (Auerbach) plexus (Enteric system)

Question 5

What are the functions of ANS in the GI?

Answer 5

Sympathetic:
• Vasoconstriction
• Constriction of sphincters

Parasympathetic:
• Increase GI motility
• Increase GI secretion

Enteric:
• Intrinsic neuronal circuit consisting of motor and sensory neurons organized in two interconnected plexuses (myenteric and Meissner’s)
• Generally independent, but receives input from both the parasympathetic and sympathetic systems

Question 6

What are the derivatives of the foregut?

Answer 6

Pharynx and its derivatives,
Lower respiratory tract,
Esophagus, Stomach

Duodenum up to the major duodenal papilla Liver, Biliary apparatus and Pancreas

Question 7

What are the derivatives of thd midguts?

Answer 7

Duodenum distal to the major duodenal papilla, Jejunum & Ileum; Cecum & Appendix, Ascending colon & right 2/3 of transverse colon

Question 8

What are the derivatives of the hindgut?

Answer 8

Left 1/3 of Transverse colon,
Descending colon, Sigmoid colon & rectum Anal canal up to the pectinate line
Urinary bladder & most of Urethra

Question 9

Describe the sympathetics to the gastrointestinal system

Answer 9

• Preganglionic fiber enters chain via WRC
• Passes on through ganglion WITHOUT synapsing
• Still preganglionic fiber then leaves the medial aspect of the ganglion and travels to a sympathetic ganglion on the abdominal aorta- PREAORTIC GANGLION
• Postganglionic fibers then travel along plexuses on the arteries to the GI tract

Question 10

What are the sympathetic splachnics (preganglionic) to GI?

Answer 10

• Greater Splanchnic(T5-T9) synapses in the celiac ganglion.
• Lesser Splanchnic(T10-11) synapses in the aortico-renal ganglion.
• Least Splanchnic (T12) synapses in the renal plexus.
• Lumbar Splanchnic (L1-L2) synapses in the intermesenteric and/or superior hypogastric plexus

Question 11

Describe the sympathetic postganglionic to the GI

Answer 11

• Postganglionic sympathetic fibers travel on peri-arterial plexuses to get to their target organs.

• Arterial supplied based on embryonic origin:
– Foregut- Celiac artery
– Midgut- Superior mesenteric artery
– Hindgut- Inferior mesenteric artery

Question 12

Why are the greater, lesser, least and lumbar splachn8cs special?

Answer 12

Also provide preganglionic to the kidneys, ureters and pelvic organs

Question 13

What are the main parasympathetics to the GI system?

Answer 13

Vagus nerve
• Foregut and midgut

Pelvic splanchnic S2-S4
• Hindgut

Question 14

What is the significance of visceral fibers?

Answer 14

• Visceral afferents fibers that mediate pain sensation (e.g. respond to ischemia, inflammation and distention) travel with sympathetic fibers until the midpoint of the sigmoid colon where they then follow parasympathetics.
• Therefore by knowing the preganglionic sympathetic supply to a particular organ, you will be able to determine where in the body pain from those organs will refer to

Question 15

Where do visceral sensory fibers hitchhike?

Answer 15

Visceral sensory fibers hitchhike on sympathetic fibers. (until the midpoint of sigmoid
colon, after which they follow parasympathetics. Why - the pelvic pain line)

Question 16

What is a refferred pain ?

Answer 16

• Sensory information enters the spinal cord from one location, but is interpreted by the CNS as coming from another location
• For example, the gut (visceral) have low sensory output and these sensory afferents converge on the same spinal cord level that receive sensory afferents from high output areas such as the body wall (somatic)
• As a result the low sensory output is interpreted as coming from the area of high sensory output
• Pain can also be referred from one somatic region to another

Question 17

Describe reffered pain in the GI

Answer 17

Visceral afferents follow the autonomic supply “backwards” to the spinal cord

Generally, referred pain from→ Foregut Structures: perceived
as epigastric/upper quadrant pain (sympathetics T5-9)

Midgut Structures: perceived as periumbilical pain (sympathetics T10-12)

Hindgut Structures (up to the midpoint of sigmoid colon): perceived as lower quadrant/ flank/ groin/ lower limb (sympathetics L1-2)

Hindgut Structures (after the midpoint of sigmoid colon): perceived as perineal pain (parasympathetics S2-S4)