Cranial Nerves - Lecture 8\ Flashcards
how many cranial nerves arise emerge from the brain
12 pairs
what do the cranial nerves pass through
skull foramina
fissures
canals
what do cranial nerves distribute
their innervation to different structures in the head and neck
which nerves is the “wanderer”
vagus nerve
continuous into the trunk and supplies the thoracic region and abdominal organs
how are cranial nerves numbered
in the order they arise in the brain
rostrally to caudally
cranial nerves can be
sensory
motor
mixed
CN1
olfactory nerve
where does CN1 arise from
olfactory epithelium
where does CN1 run through
cribriform plate of the ethmoid bone
through the olfactory bulb
where does CN1 terminate
primary olfactory cortex
CN1 fxn
carrying afferent impulses for the sense of smell
what is CN1
special visceral afferent
parts of CN1
olfactory bulb
olfactory tract
temporal cortex
with age CN1
olfactory ability decreases with age
anosmia: impaired
CN2
optic nerve
where does CN2 arise from
retina of the eye
what does CN2 pass through
optic canals and converge at the optic chiasm
continue to the thalamus where they synapse
then run to visual cortex
CN2 fxn
carrying afferent impulses for vision
what is CN2
special somatic afferent
how does vision run
retina –> optic nerve –> optic chiasm –> lateral geniculate body –> optic radiations –> visual cortex in occipital lobe
clinically injury to CN2 results in
visual field loss
CN3
oculomotor N
how do fibers of CN3 run
fibers extend from the ventral midbrain
pass through the superior orbital fissure
go to the extrinsic eye muscles
CN3 fxn
raising the eyelid
directing the eyeball
constricting the iris
controlling lens shape
CN3 ptosis
eyelid droop
CN3 ophthalmoplegia
problems in adjusting to light
deviation of eye movements
diplopia
what is diplopia
double vision
CN4
trochlear N
where do fibers of CN4 emerge from
dorsal midbrain
where do CN4 fibers enter
orbits via the superior orbital fissures
what does CN4 innervate
superior oblique muscle
CN4 is a
motor nerve
directs the eyeball
what is CN4
general somatic efferent
what is CN4 the only to do
exit brainstem dorsally
exits contralaterally
Fxn of CN4
anterior oblique muscle for eye movement
clinically CN4
difficulty looing downward and outward when trochlear is injured
eye drifts upward relative to the normal eye
CN5
trigeminal N
3 divisions of CN5
opthalamic (V1)
maxillary (V2)
mandibular (V3)
what does Cn5 convey
sensory impulses from various areas of the face
V1 and V2
supplies motor fibers for mastication (V3)
what is CN5
general somatic afferent
special visceral efferent
what is CN5 principle for
principle sensory nerve for head, face, orbit and oral cavity
what does CN5 mediate
sensations of pain, temperature, proprioception and fine discriminative touch
3 sensory branches of CN5
opthalamic
maxillary
mandibular
CN5 is motor for
mastication muscles for chewing and speaking
reflex for jaw jerk reflex (mandibular)
muscles for chewing and speaking
internal and external pterygoid
temporalis
masseter
mylohyoid
anterior belly of digastric
tensor veli palatini
tensor tympani
CN5 tic doulourex or trigeminal neuralgia
most excruciating pain known
caused by inflammation of nerve
severe cases of tic doulourex or trigeminal neuralgia
nerve is cut
relieves agony but results in loss of sensation on that side of the face
CN6
abducens N
where do CN6 fibers leave
inferior pons