Cranial Nerves 1

how many CN are there

- 12 pairs

how can CNs be classified by

- primarily sensory

- primarily motor

- mixed sensory and motor

cranial nerves exit the _____ via the _______/fissures

- CNS

- foramina

cranial nerves are numbered from _____ to ______

- top

- bottom

rule of 4s

- 4 CNs above pons

- 4 CNs in pons

- 4 CNs in medulla

name CN I and the kind of nerve

- olfactory nerve

- sensory

function of CN I (olfactoary)

- sense of smell

damage of CN I (olfactoary) results in...

- anosmia (decreased sense of smell)

disorders associated with damage of CN I (olfactoary)

- PD

- alzheimer's

- TBI

explain the path of CN I (olfactoary)

1. olfactory sensory receptors stimulated (we breathe in)

2. triggers action potential (AP)

3. olfactory bulb that turns AP into electrical signals

4. olfactory tract

5. cortical olfactory area (part of sensory cortex that processes sense of smell

CN I (olfactoary) exception

- only CN that does NOT go through the thalamus

- CN goes directly to cortex

name CN II and the kind of nerve

- optic nerve

- sensory nerve / spatial sensory

function of CN II (optic)

- carries sensory messages from the retina all the way to cortical area (occipital lobe b/c in charge of seeing)

optic chiasm

- when some optic nerve fibers cross over

explain the path of CN II (optic)

- optic chiasm

- optic tract

- occipital lobe via THALAMUS

damage of CN II (optic) results in...

- visual field loss

list CNs associated with eyes

- 2,3,4,6

name CN III and the kind of nerve

- oculomotor nerve

- motor; originates from midbrain, above pons

function of CN III (oculomotor)

- eyeball movement

- controls eyelids

- parasympathetic: pupil constrictor

damage of CN III (oculomotor) results in...

- ptosis (drooping of the eyelid)

- loss of pupillary light reflex

name CN IV and the kind of nerve

- trochlear nerve

- motor; originates from midbrain

function of CN IV (trochlear)

- carries motor fibers for eyeball

- ex. when you ask for someone to follow your finger at PCP, you're testing this nerve

damage of CN IV (trochlear) results in...

- diplopia (double vision) when looking down

diplopia

- double vision

ptosis

- drooping of the eyelid

anosmia

- decreased sense of smell

name CN V and the kind of nerve

- trigeminal Nerve

- mixed; sensory AND motor; originates in pons

3 divisions of CN V (trigeminal) and if they are sensory or motor

- ophthalmic (sensory)

- maxillary (sensory)

- mandibular (sensory and motor)

sensory function of CN V (trigeminal)

- touch, pain, temp and vibration for face and mouth

- feeling on your face in general

- anterior 2/3 of tongue (taste)

motor function of CN V (trigeminal)

- innervates muscles of mastication

- chewing muscles

damage of CN V (trigeminal) results in...

- difficulty chewing

- loss of sensation on the face (ex. can't feel wind on your face)

name CN VI and the kind of nerve

- abducens nerve

- motor; originates in pons

function of CN VI (abducens)

- motor fibers controls eye movement

name CN VII and the kind of nerve

- facial nerve

- mixed; motor and sensory; exits from pons

sensory function of CN VII (facial)

- sensation near ears

- special sensory: anterior 2/3 of tongue

parasympathetic function of CN VII (facial)

- salivary glands

motor function of CN VII (facial)

- muscles of the face

- making facial expressions

upper part of face is controlled by ______

- both hemispheres of the brain

- receives bilateral innervation

lower part of face is controlled by ________

- the contralateral side of the brain

- just one side

bell's palsy

- facial nerve (CN VII) dysfunction

- not permanent

LMN syndrome

- sudden onset of paralysis of ipsilateral upper and lower facial muscles

LMN lesion vs. UPM lesion in terms of CN VII

- LMN: bell's palsy, will go away on its own like a virus

- UMN: different type of facial muscle paralysis, probably will not go away