Lesson 9: Facial Movements

Question 1

What is the role/roles of the trigeminal nerve?

Answer 1

General sensory of the head and neck, and voluntary motor control of the muscles of mastication

Question 2

What receptors does the trigeminal nerve have?

Answer 2

Encapsulated ends

Question 3

Where does trigeminal sensory input first synapse?

Answer 3

The trigeminal ganglion

Question 4

What are the different branches of the trigeminal nerve?

Answer 4

The opthalmic, maxillary and mandibular branches

Question 5

Where is the secondary order neuron for pain and temperature?

Answer 5

The spinal nucleus of the trigeminal nerve

Question 6

Where is the secondary order neuron for touch and temperature of the face and neck?

Answer 6

The chief sensory nucleus of the trigeminal nerve

Question 7

Where is the first order neuron of proprioception of the jaw? Where does it project to?

Answer 7

The mesencephalic neuron to the ipsilateral cerebellum.

Question 8

What is responsible for the jaw-jerk reflex? How do jaw reflexes and proprioception work?

Answer 8

The mesencephalic nucleus
Info goes to the mesencephalic nucleus, to synapse in the motor nucleus of the trigeminal nerve, and are then sent out, passing through the chief sensory nucleus on their way

Question 9

Where is the motor nucleus of the trigeminal nerve?

Answer 9

In the lateral tegmentum of the pons

Question 10

What symptoms show up with a UMNL to the trigeminal nerve? Compared to LMNL?

Answer 10

Contralateral vs ipsilateral

Question 11

What is trigeminal neuralgia

Answer 11

Pain from irritation along the peripheral trigeminal nerves

Question 12

What are the ganglia of the facial nerve’s sensory info? Where does it receive this special sensory info from?

Answer 12

The geniculate ganglia

The anterior 2/3 of the tongue and nasopharynx

Question 13

What are the three types of roles of the facial nerve?

Answer 13

Special sensory, voluntary motor and involuntary motor

Question 14

Where does the facial nerve motor involuntarily?

Answer 14

Glands of the face, other than the parotid gland
Submandibular, sublingual, lacrimal
Mucosa

Question 15

Where on the brainstem is the facial nerve?

Answer 15

At the pontomedullary junction, near the auditory nerve

Question 16

What happens regarding parasympathetic control of the tongue and glands with a lesion in the facial canal?

Answer 16

The chorda tympani nerve carries parasympathetic fibres to the glands and sensory fibres

Question 17

What happens with a lesion to the facial nerve before the facial canal?

Answer 17

Wallerian degeneration, which could result in incorrect regrowing of the axon

Question 18

What are the symptoms of a LMNL in a facial nerve?

Answer 18

Upper and lower ipsilateral motor control are gone

Question 19

What are the symptoms of an UMNL in a facial nerve? Why?

Answer 19

Only the lower face has weakness. The bilateral input for the upper face to the facial nucleus ensures that there is backup from the contralateral cortex
Still some tone - due to spasticity
Contralateral lower face is paralyzed

Question 20

How is the facial nerve tested?

Answer 20

Squeeze your eyes tightly closed, show me your teeth
Smile - does not distinguish upper & lower
Upper face is involved = peripheral nerve lesion

Question 21

What is the jaw reflex, and what can it show?

Answer 21

Briskly tapping the jaw
Damage to the trigeminal nerve - both afferent and efferent
UMNL: hyperreflexia + absence of voluntary movement
LMNL: no response + voluntary muscle paralysis

Question 22

What does the jaw protrusion test show?

Answer 22

Damage to the peripheral trigeminal nerve

Question 23

What is the corneal reflex and why does it matter?

Answer 23

I touch your cornea. Both eyes blink.

Only reliable reflex for the facial nerve - both afferent and efferent