cranial nerves 1 :) Flashcards
how many pairs of cranial nerves
12
name the nerves
olfactory optic ocular motor trochlear trigeminal abducens facial vestibular glossopharyngeal vagus accessory hypoglossal
what is olfactory nerves for
special sensory for smell
where do the olfactory nerves pass through
cribriform plate of ethmoid bone (through olfactory bulbs)
clinical tests for olfactory nerves
strong smelling substance under each nostril
optic nerves
special sensory vision
where do optic nerves orginiate
retina of the eye
where do the optic nerves psss
through optic canals of sphenoid bone to diecencephlon via optic chiasm
where do temporal field images hit
nasal half of retina
where do nasal visual fields hit
temporal half of retina
where do optic nerves converge
ventral anterior margin of diencephalon at the optic chiasm
what happens to optic nerves at the optic chiasm
temporal visual fields (from nasal half) cross at chiasm and go to opposite side
axons from temporal half of retina remain uncrossed
what happens with damage to optic nerve
blindness in same eye
damage to optic chiams
bitemporal hemianopia (loss of temporal fields as nasal fields cross over which carry temporal)
damage to optic tract
complete visual loss
clinical tests for optic
snellen charts measure visual acuity
test visual fields, 4 quadrants of each eye
damage to ocular nerve
diplopia
laterla strabismus
dilated pupil in affected eye(due to unopposed sympathetic stimulation to dilator pupil)
damage to abducens nerve
diplopia
medial strabismus
what has the longest path in contact with bone out of the cranial nerbes
abducens
may be conreppsied due to intercrainail pressure
damage to trochlear nerve
vertical diplopia
torsional diplopia
clinical test for trochlear
patients to allow end for pen as it is moved across visual fields
clinical test for ocular motor nerve
shine light in eye to check for pupillary light reflex
muscles of the eye
4 rectus (S I L M) 2 oblique (S I)
innervation for the muscles of the eye
3(LR6SO4)
ocular 3
trochlear 4
abducens 6
where does trochlear nerve pass
passes through trochlear (cartilage) attaches to globe to change direction of the muscles fibres
action of superior rectus
medially upwards
action of medial rectus
towards midline
action of superior oblique
down and out
inferior rectus
medially downwards
action of lateral rectus
laterally
action of inferior oblique
upwards and laterally
what are the true cranial nerves olfactory
those that pass through the cribriform plate
where do the olfactory afferents synapse
in olfactory bulb
what does the olfactory bulb contain
cell bodies
what goes to the cerebrum CNI
post synaptic neurones as olfactory tracts (run along side of frontal lobe)
what is the ocular motor involved in
- carrying information to the eye and eye muscles
- reflex activities of the eye
where is the visual cortex
in the occipital bone
where do most of the axons of optic tract synapse and carry on as
lateral geniculate nuclei of the thalamus
- optic radions to visual cortex
how do some axons travel to the ocular motor nuclei
diverge into retinoacetal axons to the midbrain via pretectal nucleus
what are the cranial motor nerves to the extraocular muscles of the globe
ocular motor
trochlear
abducens
where do the CN attach to of the eye
bony wall of the orbit or tendinous ring at back of orbit
where do the motor cranial nerves of the eye pass through of the skull
superior orbital tissues of sphenoid bone
where do the motor eye cranial nerves emerge from of the brain
occularmotor - midbrain
trochlear - midbrain
abducens - pons
what does CN III cary
parasympathetic axons supplying pupillary constrictor muscles and ciliary muscles (reflexes)
what is vertical diplopia
SO not working
eye drifts upwards
what is torsional diplopia
double vision involving rotation towards the midline
- patient often inclines head to opposite side to fuse images
