Lesson 9: Facial Movements Flashcards
What is the role/roles of the trigeminal nerve?
General sensory of the head and neck, and voluntary motor control of the muscles of mastication
What receptors does the trigeminal nerve have?
Encapsulated ends
Where does trigeminal sensory input first synapse?
The trigeminal ganglion
What are the different branches of the trigeminal nerve?
The opthalmic, maxillary and mandibular branches
Where is the secondary order neuron for pain and temperature?
The spinal nucleus of the trigeminal nerve
Where is the secondary order neuron for touch and temperature of the face and neck?
The chief sensory nucleus of the trigeminal nerve
Where is the first order neuron of proprioception of the jaw? Where does it project to?
The mesencephalic neuron to the ipsilateral cerebellum.
What is responsible for the jaw-jerk reflex? How do jaw reflexes and proprioception work?
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
Where is the motor nucleus of the trigeminal nerve?
In the lateral tegmentum of the pons
What symptoms show up with a UMNL to the trigeminal nerve? Compared to LMNL?
Contralateral vs ipsilateral
What is trigeminal neuralgia
Pain from irritation along the peripheral trigeminal nerves
What are the ganglia of the facial nerve’s sensory info? Where does it receive this special sensory info from?
The geniculate ganglia
The anterior 2/3 of the tongue and nasopharynx
What are the three types of roles of the facial nerve?
Special sensory, voluntary motor and involuntary motor
Where does the facial nerve motor involuntarily?
Glands of the face, other than the parotid gland
Submandibular, sublingual, lacrimal
Mucosa
Where on the brainstem is the facial nerve?
At the pontomedullary junction, near the auditory nerve
What happens regarding parasympathetic control of the tongue and glands with a lesion in the facial canal?
The chorda tympani nerve carries parasympathetic fibres to the glands and sensory fibres
What happens with a lesion to the facial nerve before the facial canal?
Wallerian degeneration, which could result in incorrect regrowing of the axon
What are the symptoms of a LMNL in a facial nerve?
Upper and lower ipsilateral motor control are gone
What are the symptoms of an UMNL in a facial nerve? Why?
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
How is the facial nerve tested?
Squeeze your eyes tightly closed, show me your teeth
Smile - does not distinguish upper & lower
Upper face is involved = peripheral nerve lesion
What is the jaw reflex, and what can it show?
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
What does the jaw protrusion test show?
Damage to the peripheral trigeminal nerve
What is the corneal reflex and why does it matter?
I touch your cornea. Both eyes blink.
Only reliable reflex for the facial nerve - both afferent and efferent
