Sensory Pathway

Question 1

Is sensory pathway afferent or efferent?

Answer 1

Afferent

Question 2

What does the somatosensory pathway detect?

Answer 2

Pain, touch, pressure, temperature, proprioception, vibration

Question 3

What does the lateral spinothalamic tract detect?

Answer 3

Pain, temperature and coarse touch

Question 4

What does the dorsal column tract detect?

Answer 4

Proprioception, vibration, pressure, fine touch

Question 5

What is a soma?

Answer 5

Cell body

Question 6

What’s the common relay station?

Answer 6

Thalamus

Question 7

Characteristics of lateral spinothalamic tract

Answer 7

Decussates at second order neuron in spinal cord, travels to thalamus

3rd order neuron goes to relevant cortex

Question 8

Characteristics of dorsal columns tract

Answer 8

Detects proprioception, vibration and fine touch
Impulse activates terminals of 1st order neuron
Enters via dorsal root and ascends on same side - ipsilateral
At the medulla, the 2nd order neuron decussates and travels to projections - the thalamus
Establishes synapse with 3rd order neuron which induces response

Question 9

Symptoms of unilateral damage to the cord (hemisection)

Answer 9

Brown-Sequard syndrome: a lesion in the spinal cord which results in weakness or paralysis (hemiparaplegia) on one side of the body and a loss of sensation (hemianesthesia) on the opposite side. May be caused by a spinal cord tumour, trauma, ischemia or infectious/inflammatory diseases (TB or MS)

Fine touch is lost in the ipsilateral side below the cord lesion

Question 10

Symptoms of anterior spinal cord damage

Answer 10

Anterior spinal artery syndrome: most common cause of spinal cord infarction, caused by ischemia of the anterior spinal artery. Results in loss of function on most anterior 2/3 of spinal cord, characterised by loss of pain and temperature sensation
Bilateral loss of pain
Anterior lesion only affects lateral spinothalamic tract - no pain/temperature/coarse touch

Question 11

What will be affected first in an expanding spinal cord lesion?

Answer 11

Syringomyelia: development of a fluid filled cyst within the spinal cord. The cyst expands, causing damage (e.g. loss of sensitivity to pain and temperature). Can be caused by tumours, injuries and inflammation
Temperature

First affected is lateral STT

Question 12

What are the consequences of irritating the trigemino-thalamic tract?

Answer 12

Trigeminal neuralgia: excruciating pain, can occur spontaneously, can be caused by tumours or irritation of sensory fibres of trigeminal nerve
Projects to thalamus by trigemic tract
Contralateral face pain
Second order neurons have synaptic connections with third order neurons in cortex

Somatosensory in head and neck - trigeminal nerve

Question 13

Trigemino-thalamic tract

Answer 13

Supplies head and neck, decussates in medulla

Question 14

What will be the consequences of irritating the trigemini-thalaic tract?

Answer 14

Contralateral face pain

Question 15

Trigeminal neuralgia

Answer 15

Excruciating pain
Spontaneous
Irritation of sensory fibres