Lecture: Ascending Sensory Pathways II

Question 1

in which cranial nerves is general sensation from the head carried?

Answer 1

V
VII
IX
X

Question 2

where do sensory fibres from the cranial nerves carrying sensation from the head run?

Answer 2

Trigeminal Sensory Nucleus

part of the Trigeminal Sensory Pathway

Question 3

What are the major divisions of the Trigeminal Sensory Nucleus

Answer 3

From rostral to caudal:
Mesencephalic nucleus
Pontine/Chief sensory nucleus
Spinal Nucleus

Question 4

To which part of the TSN does pain and temperature information travel?

Answer 4

The most caudal part of the spinal nucleus

the caudal end

Question 5

To which part of the TSN does touch and pressure information travel?

Answer 5

To the most rostral part of the spinal nucleus

the caudal end

Question 6

Where are the primary neuron cell bodies for pain, temperature, touch, pressure and discriminatory touch pathways?

Answer 6

In the trigeminal ganglion

situated prior to entry to the brainstem and the TSN

Question 7

What type of fibres carry information regarding pain, temperature, touch and pressure?

Answer 7

Thin, slow fibres

Question 8

What would be the consequences of a lesion on the right of the medulla

Answer 8

loss of sensation from RIGHT side of face

loss of sensation from the LEFT side of body

Question 9

What is different about Propriocetion fibres travelling to the mesencephalic nucleus?

Answer 9

First order neuron cell body not located in the peripheral ganglia, but actually within the TSN itself, in mesencephalic nucleus

Question 10

Where do fibres carrying information about discriminatory touch travel?

Answer 10

Travel to Pontine (chief sensory) nucleus

large one in the middle of TSN

Question 11

What type of fibres carry information about discriminatory touch?

Answer 11

Large diameter
myelinated
fast conduction fibres

Question 12

How do secondary fibres ascend to the thalamus?

Answer 12

In the Trigeminothalamic tract

to the ventroposteromedial thalamus (VPM)

Question 13

How do fibres in the proprioception pathway synapse?

Answer 13

Unlike the other pathways, does not synapse in the TSN but alongside it, next to the mesencephalic nucleus
+ gives off a motor branch which synapses in trigeminal motor nucleus - sends a branch back to msucles of face, e.g mastication (jaw jerk reflex)