Friday, 4-22-Trigeminal Pathways (Stephens)

Question 1

In the SLOW PAIN conscious sensory pathway from the head:

What is the primary neuron and what is it conveyed by?

What is the secondary neuron and what is it conveyed by?

Answer 1

Primary neuron=trigeminal ganglion and conveyed by Descending tract of V

Secondary neuron=Subnucleus caudalis and conveyed by Trigemino-Reticular fibers

This is the Trigemino-reticulo-thalamic pathway–> This diffuse, multi-neuronal pathway will eventually reach the centromedian and reticular nuclei of the thalamus

Question 2

In the CRUDE TACTILE conscious sensory pathway from the head:

What is the primary neuron and what is it conveyed by?

What is the secondary neuron and what is it conveyed by?

What is the tertiary neuron and where does it project?

Answer 2

Primary neuron=Trigeminal ganglion and conveyed by ascending and descending tracts of V

Secondary neuron=Subnuclei rostralis and interpolaris and conveyed by TL (decussate); Some secondary axons ascend in DCTT

Tertiary neuron=VPM and projects to primary somesthetic cortex

Question 3

In the PRECISE/2-PT TACTILE conscious sensory pathway from the head:

What is the primary neuron and what is it conveyed by?

What is the secondary neuron and what is it conveyed by?

What is the tertiary neuron and where does it project?

Answer 3

Primary neuron=trigeminal ganglion and conveyed by ascending tract of V

Secondary neuron=Main sensory nucleus of V and conveyed by DCTT; some may decussate and ascend in TL

Tertiary neuron=VPM and projects to primary somesthetic cortex

Question 4

In the PROPRIOCEPTION conscious sensory pathway from the head:

What is the primary neuron and what is it conveyed by?

What is the secondary neuron and what is it conveyed by?

What is the tertiary neuron and where does it project?

Answer 4

Primary neuron=Mesencephalic nucleus of V and conveyed by mesencephalic tract of V

Secondary neuron=Main sensory nucleus and conveyed by DCTT

Tertiary neuron=VPM and projects to primary somesthetic cortex

Question 5

List the possible outcomes from a unilateral lesion of the trigeminal nerve:

Answer 5

• anesthesia and loss of general sensations in the V dermatomes
• loss of jaw jerk reflex
• atrophy of the muscles of mastication
• loss of ipsilateral and consensual corneal reflex

Question 6

A brainstem lesion in the upper medulla involving the primary fibers in the __ and the secondary fibers in the __ will result in patients demonstrating ipsilateral hemianalgesia of the face and contralateral hemianalgesia of the bodyq

Answer 6

Primary fibers in the DESCENDING TRACT OF V

Secondary fibers in the SL

Question 7

___ is a result of a unilateral destruction of the CN V and corticospinal tract in the pons resulting in ipsilateral trigeminal anesthesia & paralysis, and contralateral spastic hemiplegia

Answer 7

Alternating trigeminal hemiplegia

Question 8

What are the 4 central nuclei of the trigeminal nerve?

Answer 8

• Main sensory nucleus
• Descending (spinal) nucleus of V
• Mesencephalic nucleus of V
• Trigeminal motor nucleus

Question 9

This nucleus receives precise tactile, crude tactile, and proprioceptive information from the face. It is analagous to the nuclei gracilis and cuneatus

Answer 9

Main sensory nucleus

Question 10

This nucleus is continuous with and directly analagous to the dorsolateral fasciculus of Lissauer in the SC. All pain and temp sensations as well as general tactile information from the face terminate in 1 or more of its 3 subnuclei.

Answer 10

Descending (Spinal) nucleus of V

Question 11

What are the 3 subnuclei of the descending nucleus of V?

Answer 11

• Subnucleus Rostralis
• Subnucleus Interpolaris
• Subnucleus caudalis

Question 12

This subnucleus of the descending (spinal) nucleus of V receives tactile information from the CENTRAL REGION of the face:

Answer 12

Subnucleus rostralis

Question 13

This subnucleus of the descending (spinal) nucleus of V receives information from the PERIPHERAL REGION of the face

Answer 13

Subnucleus interpolaris

Question 14

This subnucleus of the descending (spinal) nucleus of V receives pain and temperature information from anterior 1/2 of the head

Answer 14

Subnucleus caudalis

Question 15

This nucleus is the only nucleus in the CNS comprised of pseudounipolar neurons and conveys proprioceptive and pressure information from muscles of the head and oral region

Answer 15

Mesencephalic nucleus of V

Question 16

This nucleus innervates muscles derived from mesenchymal cells in the 1st branchial arch.

Answer 16

Trigeminal motor nucleus

Question 17

In the FAST PAIN/TEMP conscious sensory pathway from the head:

What are the primary neurons and what are they conveyed by?

What are the secondary neurons and what are they conveyed by?

What are the tertiary neurons and where do they project?

Answer 17

Primary neuron=trigeminal ganglion and conveyed by Descending Tract of V

Secondary neuron=Subnucleus caudalis and conveyed by TL (decussation)

Tertiary neuron=VPM nucleus and projects to primary somesthetic cortex