19.9 NS: Functional organisation of the spinal cord

Question 1

Where do sensory fibres (e.g. from mechanoreceptors) travel in white matter?

What about nociceptors?

Answer 1

Sensory: travel longitudinally

Nociceptors: travel up anterior tracts

Question 2

Ascending tracts are…..

Descending tracts are….

Answer 2

Sensory

Motor

Question 3

Motoneurons located medially send axons out to ….. muscles

Answer 3

proximal muiscles

Question 4

What is a motor pool?

What is a motor unit?

Answer 4

All motor neurons that innervate e.g. biceps

One neuron innervating a collection of fibres

Question 5

How do muscle spindles lie in relation to each other?

Spindles sense muscle…

Answer 5

In parallel

Stretch

Question 6

When e.g. triceps get longer, the spindles get shorter. What is reduced (excitatory/inhibitory)?

Answer 6

Excitement of interneurons is reduced, so more biceps activity

Question 7

The short propriosinal neurons are where? Are they bi/ipsilateral?

Long propriospinal neurons?

Answer 7

Short: lateral, ipsilateral

Long: medial, bilateral