Spinal Cord Tracts

Question 1

Spinothalamic
a) Function
b) Course

Answer 1

a) Pain, Temp, Crude Touch, Pressure
b) 1st order neuron enters dorsal horn and synapses onto 2nd order neuron. nerve fibres from 2nd order neuron decussate and rise up the anterior and antero-lateral part of th white matter of the spinal cord, travel to cerebrum. synapse onto 3rd order neuron in thalamus, which then brings it to the sensory cortex

Question 2

Explain what modalities are gone in anterior spinal syndrome?

Answer 2

light touch, pinprick and temp sensation at areas below the spinal cord lesion - bilaterally

Question 3

Dorsal Column Medial Lemniscus
a) Function
b) Pathway

Answer 3

a) fine touch, vibration, pressure, proprioception
b) 1st order neuron enter dorsal aspect (not enter grey matter) and rises up the spinal cord ipsilaterally. synapses at medulla oblongata (part of brainstem) for 2nd order neuron, then decussate. from medial aspect of medulla oblongata, travels upwards to the thalamus to synapse with 3rd order neuron. 3rd order neuron brings impulses to sensory cortex

Question 4

Explain the modalities gone in hemisection of the spinal cord?

Answer 4

• fine touch, vibration, proprioception all gone on the affected side (DCML travels up the spinal cord ipsilaterally and decussates in the medulla oblongata)
• fine touch, vibration, proprioception remains fine on the unaffected side
• sensory loss on contralateral side (spinothalamic fibres decussate upon entering spinal cord, and travel up the contralateral half of the spinal cord)
• sensory function maintained on ipisilateral side

Question 5

Explain the modalities gone in a bilateral posterior column loss?

Answer 5

fine touch, vibration, proprioception all gone

light touch, pinprick, temp, pain all ok