Referred Pain 7

Question 0

What pathway do the visceral afferent fibers take?

Answer 0

They go from the effector organ thru the prevertebral ganglion thru the splanchnic nerve thru the PARAvertebral ganglion thru the white ramus to the dorsal root ganglion where their cell bodies are located and to the dorsal horn.

Question 1

What specific fibers are responsible for relaying pain from the viscera?

Answer 1

Visceral afferent

Question 2

Along what structure is this visceral pain referred and where is it felt?

Answer 2

The pain is referred out along the ventral ramus. The fiber briefly travels in and is felt in the dermatome supplied by this ventral ramus.

Question 3

Explain proximal-distal pain. Give example

Answer 3

Injury is primal and pain is felt distally.
A herniated disc between L4 and L5 causes compression of dorsal and central roots of L5. Pain is felt along the dermatome for L5 which travels down the leg and into the foot.

Question 4

Explain visceral/embryological referred pain and give example.

Answer 4

Pain is referred to a dermatome distant from the site of injury due to the migration of the structure during embryological development.

The diaphragm arises embryologically in the cervical (neck) region and as such is innervated by the phrenic n. (C3,4,5). During development, the diaphragm descends to the region dividing the thorax from the abdomen. Injury/stimulation to the pleura over the diaphragm can result in pain being referred to the skin over the neck/ear.

Question 5

Explain visceral/somatic referred pain and give example

Answer 5

Pain from the viscera is referred to a body dermatome distant from the site of the pain.

Cardiac infarction: pain originates in the myocardium, passes back through the cervical nn (splanchnic nn.) to the sympathetic trunk, back into the white ramus communicans and into the ventral ramus of T1-4. The pain is referred out along the dermatomes of T1-4 (the skin of the thorax and down the medial side of the left upper limb.

Question 6

Why is pain from myocardial infarction relayed down the medial side of the left arm?

Answer 6

Because embryological let the left side of the heart is innervated by the left side of the nervous system.

Question 7

The area around the umbilicus is supplied with sensory innervation by which vertebral level?

Answer 7

T10