Trigeminal and Facial Nerve Pathways - Michaels

Question 1

3 sensory trigeminal nuclei:

Answer 1

mesencephalic
principal sensory (fine touch, vibration)
Spinal trigeminal ( pain and temp)

Question 2

Damage to trigeminal motor nucleus would cause?

Answer 2

Atrophy of masseter on side of lesion

Jaw will deviate toward lesioned side

Question 3

Describe divisions of the VPM, medial to lateral

Answer 3

Taste area, intraoral cavity, face

Question 4

What is the mesecephalic trigemina nucelus involved with?

Answer 4

Jaw Jerk Reflex (For chewing with skillz)

Proprioceptors in the peridontium recieve input from stretch receptors and muscles of mastications

Info then projects to the trigeminal motor nucleus

Question 5

Describe the different parts of facial nerve 7 that makes it a mixed nerve

Answer 5

Branchial motor - supplies ipsilateral facial expression muscles and stapedius
(stapedius is reason nerve damage causes sensitivity to loud sounds)

Visceral motor - Parasympathetic to lacrimal, submandibular, and sublingual glands
(Why you get dry eyes and mouth with facial nerve damage)

Somatic sensory - outer ear, nasal cavity and palate sense

Special Sense - Ipsilateral, taste for anterior 2/3 of tongue

Question 6

Why do yo ualmost always damage the facial nerve when you damage the abducent nucleus?

Answer 6

The facial nerve wraps around the abducent nucleus

Question 7

What is involved in the corneal blink reflex?

Answer 7

Cranial nerves 5 and 7

Cornea sensory travels in V1 to trigeminal ganglion and then the spinal trigmeinal nucleus

Spinal trigmenial nucleus provides direct output to bilateral motor nuclei of facial nerve

Efferents then go to orbicularis oculi to do bilateral blink

Question 8

Descending corticobulbar pathway is the upper motor neuron pathway innervating cranial nerves 5, 7, 9, 10 , and 12. It innervates these cranial nerve nuclei bilaterally except for what?

Answer 8

The lower part of the facial nerve nucleus are only distributed contralaterally, not bilaterally.

Therefore unilateral damage to corticobulbar pathway will cause contralateral weakness of lower face.

Dr Michaels didnt explain this well. Ask me if ya got questions