10+11 Ascending sensory pathways

Question 1

Which somaesthetic modalities are carried by the spinothalamic pathway?
Fibre type?

Answer 1

Pain, temperature, touch, pressure.

Thin and poorly myelinated.

Question 2

Which somaesthetic modalities are carried by the dorsal column pathway?
Fibre type?

Answer 2

2 point discriminative touch, vibration and proprioception.

Large, heavily myelinated.

Question 3

How many cells do sensory pathways contain?

Where do the cell bodies lie?

Answer 3

Three.

1st: dorsal root ganglia.
2nd: CNS ipsilateral grey matter.
3rd: thalamus.

Question 4

What is the route taken by the spinothalamic pathway?

Answer 4

1 via zone of Lissauer to dorsal grey horn. 2 cross midline. CONTRALATERAL. After medulla: spinal lemniscus. 2 from VPL thalamus to cortex.

Question 5

What is the route taken by the dorsal column pathway?

Answer 5

1 ascends in IPSILATERAL dorsal column (cuneate/gracile). Synapse with 2 in closed medulla, cross as internal arcuate fibres, ascend via medial lemniscus to thalamus. 3 from VPL to cortex.

Question 6

Which cranial nerves run in the trigeminal nucleus?

Answer 6

Trigeminal.
Facial.
Glossopharyngeal.
Vagus.

Question 7

The spinal portion of the trigeminal nucleus is split - what is the distribution of the sensory modalities?

Answer 7

Pain and temperature - bottom (caudal).

Touch and pressure - top (rostral).

Question 8

What is the route taken by information running in the trigeminothalamic tract?

Answer 8

1o cell body in trigeminal ganglion, descend in spinal tract. Synapse in trigeminal nucleus. 2 crosses midline, runs CONTRALATERALLY in trigeminothalamic tract to VPM of thalamus.
Exception: proprioception - 1 cell body in mesencephalic part. 2 body is just lateral.

Question 9

What types of information do the pontine and mesencephalic parts of the trigeminal nucleus receive?

Answer 9

Pontine: discriminative touch.
Mesencephalic: proprioception (fibres may contact trigeminal motor nucleus).