Lecture 4 - Abdominal Pain

Question 1

Sympathetics

• function
• location of preganglionic cell bodies
• location of postganglionic cell bodies

Answer 1

• vasoconstriction and decreased motility
• preganglionic cell bodies are located in the lateral horn of T5-L2
• postganglionic cell bodies are located in the prevertebral ganglia

Question 2

what two plexuses make up the enteric nervous system?

Answer 2

Myenteric plexus - cells located between muscle layers that regulate peristalsis
Submucosal plexus - cells located in submucosal layer

Question 3

What role do the sympathetics and parasympathetics play in both the Myenteric Plexus and Submucosal Plexus?

Answer 3

MP - S: Maintains muscle tone and vascular tone. It keeps the the bowels constricted.
MP - PS: modulate gut wall motility and increases peristalsis
SP - S: Modulates fluid transport
SP - PS: secretomotor

Question 4

Sympathetic distribution to the gut

Answer 4

Everything is exactly the same as we’ve seen previously but now, the nerves run straight through the sympathetic trunk onto splanchnic nerves to the prevertebral ganglion.

Question 5

Which spinal cord levels get which splanchnic nerves and which gprevertebral ganglion?

Answer 5

T5-T9 - Greater splanchnic nerve and Celiac ganglion - Foregut
T10-T11 - Lesser Splanchnic nerve and superior mesenteric ganglion - midgut
T12 - Least Thoracic Splanchnic nerve and Aorticorenal/superior mesenteric ganglion - midgut
L1-L2 - Lumbar Splanchnic nerve and Inferior mesenteric ganglion - hindgut

Question 6

Foregut parasympathetic innervation

Answer 6

Preganglionics run in anterior and posterior vagal trunks. They synapse on postganglionic neurons in enteric ganglia.
- Some run through celiac plexus and distribute onto blood vessels of the celiac trunk.

Question 7

Midgut parasympathetic innervation

Answer 7

Preganglionics run in vagal trunks. They pass through superior mesenteric ganglia and are distributed onto branches of the superior mesenteric artery. Synapse on cell bodies in enteric plexus.

Question 8

Hindgut parasympathetic Innervation

Answer 8

Preganglionics travel in the pelvic splanchnic nerves to be distributed onto arteries in the mesentery of the rectum and colon. They then synapse on cell bodies in the enteric plexus.

Question 9

Afferents: function and pathway for PS, S, Entric

Answer 9

S - visceral pain info. Travels in the reverse efferent pathway except goes up dorsal root instead of ventral root.
PS - Reflex afferents that carry info about the physiological state of the organ. Carried in vagus or pelvic splanchnic nerves.
Enteric - Reflex afferents that carry info about the physiological state of the organ. Pathway is local and back to the CNS

Question 10

Visceral Pain

Answer 10

Follows sympathetic path. Pain is usually pretty dull. It is generally localied towards the midline and will be associated with the dermatome segment that is associated with that organ. For instance if it is something in the foregut you will feel it in the T5-T9 region of the epigastric region in the midline.

Question 11

Referred pain

Answer 11

usually occurs when the pain intensifies. Usually well-localized and lateralized. Felt in areas remote to the affected organ.

Question 12

Parietal Peritoneum

Answer 12

Happens when noxious stimulus makes contact with the peritoneum. More localized and intense. Fibers travel with peripheral somatic sensory nerves corresponding to the cutaneous dermatomes corresponding to T6-L1.

Question 13

Parasyympathetics

• function
• location of preganglionic cell bodies
• location of postganglionic cell bodies

Answer 13

• increased motility and secreation
• For foregut and midgut the preganglionics run in the vagus nerve so the cell bodies are in the brainstem.
• For hindgut the preganglionics run in the pelvic splanchnic nerves, so their cell bodies are found in the spinal cord at levels S2-S4.
• The postganglionic cell bodies are studded in ganglia throughout the GI tract.