Cranial Nerves Flashcards
What are the Cranial Nerves
- Olfactory
- optic
- oculumotor
- trochlear
- trigeminal
- Abducens
- fascial
- Vestibulocochlear
- Glossalpharyngeal
- vagus
- accessory
- hypoglosssa
What nerves are sensory and what nerves are motor?
- Olfactory - S
- optic - S
- oculumotor -M
- trochlear-M
- trigeminal-B
- Abducens -M
- fascial-B
- Vestibulocochlear - S
- Glossalpharyngeal - B
- vagus -B
- accessory - M
- hypoglosssa - M
Olfactory Nerve
- sensory only
- olfaction/smell
- only sensory input that can reach cortex without synapses in cortex
- olfactory bulb => medial temporal lobe of cerebrum and olfactory cortex in insule => amygdala and parahippocampal gyrus
Optic nerve
- sensory only
- vision
oculomotor
- motor
- serves muscles of the eye
trochlear
Motor
serves superior oblique eye muscle
trigeminal
- Motor and sensory
- sensory from face and mouth
- motor to muscles of mastication
- function in chewing, fascial sensation, sensation from TMJ and teeth, afferent limb of corneal reflex
Abducens
- motor
- serves the lateral rectus eye muscle
CN6
fascial
- motor and sensory
- serves the muscles of fascial expression, lacrimal glands and salivary glands
Vestibulocochlear
- Sensory
- equilibrium and hearing
Glossopharyngeal
- motor and sensory
- serves the pharynx for swallowing
- posterior third of tongue, parotid salivary gland
vagus
- motor and sensory
- sensation from visceral (internal organs)
- parasympathetic motor regulation of visceral organs
accessory
- motor
- serves muscles the move head, neck and shoudle
hypoglosssa
- motor
- serves muscles of the tongue
What occurs with damage to Olfactory and how to test it
- loss of sense of smell = Aanosmia
- test = pungent smells such as coffee, vanila
- close one nostril to test each nerve
What are the three divisions of the trigeminal nerve
V1 = opthalmic branch
V2 = maxillary branch
V3 = mandibular branch
What are the motor connections of the trigeminal nerve
- trigeminal motor nucleus is in pons
- receives bilateral connections from corticobrainstem tract (upper)
- innervates muscles for mastication
- motor axons travel in mandibular branch
- also innervate: tensor tympani, mylohyoid, tensor palatini, diagastric ms
What are the three trigeminal sensory nuclei
Primary/main sensory:
- first order neurons synapse here, light touch and pressure
Mesencephalic nucleus (midbrain)
- proprioceptive info from mm’s of mastication
- transmitted ipsilaterally by axons of CN-V to here
- reticular formation in midbrain
Spinal trigeminal nucleus
- neurons for pain and temperature synapse here (pons/medullar)
How to test the trigeminal nerve
- light tough and pressure for face and head, forehead, cheeks, chin as well as pain and temp
- to test muscular innervation, palpate the temporal/masseter muscles
- have patient clench teeth while observing for jaw deviation or symmetry in muscle contration
Testing trigeminal nerve: masseter reflex
- proprioceptive sensory information from mesencephalic nucleus neurons
- synapse with trigeminal motor nucleus
- normal mandible jerks slightly upward with an UMN lesion this will be exaggerated
testing trigeminal nerve: corneal reflex
- pain information from cornea travels via spinal trigeminal tract to spinal trigeminal nucleus
- internuerons synapse on bilateral fascial nerve nuclei
- motor neurons in fasical nerve innervate obicularis oculi which closes eyelids
What will be seen clinically with deficits with trigeminal nerve lesions
Ipsilateral:
- loss of sensation, paresthesia or numbness of face
- trigeminal neuralgia/tic douloureux
- flaccid paralysis of muscles of mastication
- loss of corneal reflex
- deviation of jaw to ipsilateral side
what might accompany damage to the trigeminal nerve
- ataxia (middle cerebellar peduncle)
- nystagmus (cerebellum)
- vertigo
- tinnitus
- fascial palsy
Trigeminal neuralgia
- severe sharp stabbing pain in area of distribution
- begins and ends abruptly
- primary cause is pressure of blood vessel compressing the nerve
Corticobrainstem tract damage vs trigeminal nerve damage
- due to Bilateral connection, UMN lesions does not usually produce weakness in upper fasical muscles
- but if you damage the trigeminal nerve then there will be ipsilateral muscle weakness on the full 1/2 of face
Fasical motor functions
- fasical nucleus: located in the caudal pons
- muscles of the fascial expression, close the eye, move the lips
- involved in motor portion of corneal reflex (with CN V)
- dampens vibration of stapes