Spinal Sensory Pathways

Question 1

What information is carried in the anterolateral system?

Answer 1

Nociception, temperature, and touch.

Question 2

What are the 3 classes of nociceptors?

Answer 2

1. Mechanical nociceptors: activated by sharp objects that pinch or penetrate the skin
2. Polymodal nociceptors: Respond to high-intensity mechanical, chemical and thermal stimuli
3. Visceral nociceptor: Respond to mechanical stimuli for organs.

Question 3

Discuss sensitization

Answer 3

The enhancement of response when a nociceptor is damaged by strong stimuli. Both Mechanical and Polymodal nociceptors do this.

Question 4

Discuss pain perception

Answer 4

1. Mechanical and Polymodal nociceptors work together to create the sensation of pain.
2. Fast pain is mediated by mechanical nociceptors. Slow pain is mediated by polymodal.

Question 5

Describe the nociception, temp and crude touch pathway

Answer 5

1. Enter spinal cord through lateral part of dorsal root zone.
2. Divide into short ascending and descending branches that run in Lissauer’s tract.
3. Axons terminate on neurons in laminae 1,2 and 5.

Question 6

Describe nociceptive neurotransmitters

Answer 6

Glutamate evokes EPSP in dorsal horn neurons. During high intensity stimulation, polymodal nociceptors use substance P to evoke an EPSP.

Question 7

Describe the direct spinothalamic pathway

Answer 7

Second order neurons located in the dorsal horn project axons across the midline to the CONTRALATERAL anterolateral funiculus where they ascend to the brain

Question 8

Discus Syringomyelia

Answer 8

An enlargement of the spinal canal; Produces bilateral loss of pain and temperature.