The Sensory System Flashcards Preview

Neurology > The Sensory System > Flashcards

Flashcards in The Sensory System Deck (17):
1

What fibers carry pain?

thinly myelinated A-delta fibers

2

What fibers carry temperature?

unmyelinated C fibers

3

What tract carries pain and temp signals?

spinothalamic

4

Where do the pain and temp signal decusate?

anterior white commisure, so ascend contralaterally

5

What fibers carry proprioception, vibration and light touch?

heavily myelinated A-alpha and A-beta fibers

6

What tract carries proprioception, vibration and light touch?

dorsal columns

7

Where do the dorsal columns decussate?

in the medulla (nuclei gracilis and cuneatus) (so ascend ipsilaterally)

after they decussate they ascend further in the medial lemniscus

8

Describe the somatotopic arrangement of fibers in the spinothalamic tract.

sacral segments are located laterally and cervical segments medially (so your feet stick out)

9

Describe the somatotopic arrangement of fibers in the dorsal columns.

opposite of the spinothalamic because they don't decussate until higher up, so sacral segments are medial and cervical (arm) segments are lateral

then after they decusate and continue on as the medial lemniscus, it's the same as the STT so that the feet are lateral and the arms are medial

10

Where does the STT terminate?

in the ventroposterolateral (VPL) lobe of the thalamus

11

Where does the trigeminal tract terminate?

in the ventroposteromedial (VPM) of the thalamus

12

What is a paresthesia?

a paresthesia is an abnormal sensation described as tingling, prickling, pins and needs, etc.

13

What is a dysesthesia?


a dysesthesia is an unpleasant sensation triggered by painful stimuli

14

What is hyperesthesia?

an increased sensitivity to sensory stimuli (but you still feel it as the appropriate sensation - pain is just more painful)

15

What is allodynia?

this is pain provoked by a normally innocuous stimuli

16

What does "dissociated sensory loss" mean?

when you lose the sensation of a single tract (e.g., losing pain/temp, but keeping vibration etc.)

17

What are three examples of dissociated sensory loss syndromes?

syringomyelia (lost of pain and temp)
anterior spinal artery stroke (loss of pain and temp)
subacute combined degeneration (loss of proprioception and vibration and touch)