Spinal Pathways

Question 1

What are the 3 white matter sensory tracts aka ascending tracts?

Answer 1

• Dorsal column pathway (c)
• Spinocerebellar pathway (c)
• Spinothalamic pathway (i)

Question 2

What type of sensory information is the dorsal column pathway responsible for?

Answer 2

Discriminative touch, proprioception, vibration, and pressure

Question 3

Describe the dorsal column pathway

Answer 3

1st order neuron from input enters the spinal cord via the dorsal side. If the sensory information is coming from T6 or above it enters the fasciculus cuneatus if it is from below T6 it enters the fasciculus gracilis and then ascends ipsilaterally to the medulla. Here the1st order neuron synapses with 2nd order neuron in the caudal medulla, before decussating and ascending the brainstem contralaterally to the 1st order neuron. Once in the thalamus the 2nd order neuron synapses with the 3rd order neuron which extends into appropriate region of cerebrum.

Question 4

How many neurons are in the dorsal column pathway?

Answer 4

3

Question 5

What is the medial lemniscus?

Answer 5

A continuation of the dorsal column, this pathway starts within the brainstem, after the decussation of internal arcuate fibers (second-order neurons). Beginning in the caudal medulla to the rostral medulla to the middle of pons to the rostral midbrain and into the thalamus.

Question 6

Where are the cell bodies of 1st, and 3rd order neurons contained in the dorsal column pathway?

Answer 6

1st order = dorsal root ganglia (DRG)
3rd order = Ventral posterolateral nucleus (VPL) in thalamus

Question 7

Where are the axons of the 3rd order neurons in the dorsal column pathway located?

Answer 7

In the internal capsule (located laterally to the thymus) comprised of three sections:
- Anterior limb
- Genu
- Posterior limb