sensory systems including physiology of pain

Question 1

What type of primary afferent fibre mediates touch, pressure and vibration

Answer 1

A beta - large and myelinated

Question 2

What type of primary afferent fibre mediates cold , fast pain and pressure

Answer 2

A delt - small myelinated

Question 3

What type of primary afferent fibre mediates warmth, slow pain

Answer 3

C - unmyelinated and therefore slow

Question 4

What senses proprioception of muscles

Answer 4

Muscle spindles

Question 5

Describe path of a mechanoreceptor fibre A alpha or A beta

Answer 5

They come in through the dorsal root and enter the dorsal horn then travel straight up the dorsal column - they then synapse and the 2nd order fibres decussatee

Question 5

Describe brown-Sequard syndrome

Answer 5

Hemisection of the spinal cord:
- Loss of vibration, motor function, deep touch and proprioception on the ipsilateral side below the lesion due to to the fibres deccusating above in the brain
- Loss of pain and thermoreception on the contralateral side due to the fibres decussating at the level of the spinal cord

Question 5

Describe the pathway for noiciceptive and thermoreceptive information

Answer 5

Information comes to the dorsal horn via the dorsal root and then immediately synapses and the 2nd order neuron decussates and travels up the other side of the spinal cord in the lateral spinothalamic tract

Question 6

Describe location of a lesion and whether the symptoms are ipsilateral or contralateral

Answer 6

If the lesion is above the decussation of the motor fibres, there will be contralateral symptoms but if it is below the decussation, it will be ipsilateral

Question 7

What is lateral inhibition

Answer 7

Activation of one sensory input causes synaptic inhibition of its neighbours - gives better definition of boundaries