Case 2 - pain

Question 1

what cells become the ENS

Answer 1

neural crest cells

Question 2

what is visceral pain

Answer 2

comes from the abdominal viscera which are innervated by autonomic fibres and respond mainly to the sensations of distension and muscular contraction

Question 3

what does visceral pain feel like

Answer 3

typically vague, dull and nauseating

Question 4

is visceral pain localised

Answer 4

very poorly, and tends to be referred to areas corresponding to the embryonic origin of the affected structure

Question 5

what structures cause upper abdominal pain

Answer 5

stomach, duodenum and liver

Question 6

where is somatic pain from

Answer 6

the parietal peritoneum, which is innervated by somatic nerves, which respond to irritation from infectious, chemical or other inflammatory processes.

somatic pain is sharp and well localised

Question 7

what is referred pain

Answer 7

pain perceived distal from its source and results from convergence of nerve fibres at the spinal cord

Question 8

features of referred pain

Answer 8

pain perceived at a location other than the site of the painful stimulus
it is the result of a network of interconnecting sensory nerves, that supply many different tissues
When there is an injury at one site in the network it is possible that when the signal is interpreted in the brain signals are experienced in the surrounding nervous tissue
Several neuroanatomic and physiologic theories state that nociceptive dorsal horn and brainstem neurones receive convergent inputs from various tissues
As a result, higher centres cannot correctly identify the actual input source.

Question 9

what is the convergence projection theory

Answer 9

states that pain is not or hardly felt in the area of actual nociception due to a low density of nociceptive afferent innervation

Question 10

features of the convergence projection theory

Answer 10

These are usually deep, axial or proximal tissues like ligaments, joint capsules, tendons and muscle tissue
Pain is projected into a more distal area with a high density of nociceptive afferent innervation, that converges on the same second order neurone in the dorsal horn as the tissue of actual nociception
The nociceptive input is then transported to the somatosensory cortex via the spinothalamic tracts and the thalamus
The somatosensory cortex is then confronted with the task of localising the origin of nociceptive unout
It then makes a a projection error and decides to project the pain into the more dismal tissue with the higher density of nociceptive afferent innervation that is represented to a greater extent in the somatosensory cortex