Cranial nerves 2 Flashcards
what muscles does the mandibular nerve supply
MUSCLES THAT ORIGNIATE FROM TEH 1ST PHARYNGEAL ARCH- supplied by special visceral efferent fibers.
muscles of mastication
tensor tympani
tensor veli palatini
mylohyoid
anterior belly of digastric
what are the muscles of mastication
lateral pterygoid
medial pterygoid
temporalis
masseter
what is the jaw jerk test used for
and how does it differ from the corneal reflex
to test the trigeminal nerve and nuclei
afferent and efferent limbs are trigeminal
corneal reflex–
afferent is trigeminal
efferent is facial
where is the oculomotor nucleus found
in midbrain
it is a singular nucleus
what is the route of the oculomotor nerve
pass between posterior cerebral and superior cerebellar arteries
lies close to posterior communicating artery
runs anteriorly on the lateral wall of the cavernous sinus
passes through superior orbital fissure and enters the orbit
divides into superior and inferior divisions
both divisions pass through common tendinous ring of Zinn
does the oculomotor nerve have divisions
yes
superior and inferior divisions
it divides after entering the orbit
what does the superior branch of the oculomotor nerve supply
- levator palpebrae superioris (elevate upper lid)
- superior rectus
what does the inferior branch of the oculomotor nerve supply
- medial rectus
- inferior rectus
- inferior oblique muscles
- plus carries parasympathetic fibres to the ciliary ganglion
is oculomotor nerve motor or sensory
motor
has both visceral and somatic fibres
which nuclei are in midbrain
3 and 4
why is levator palpebrae superioris a special muscle
contains both striated and smooth muscle fibres
smooth muscles supplied by sympathetics, which belong to spinal cord (which reach this muscle by the superior branch of the oculomotor nerve)
hence why when scared eyes are wide open
what muscle does the trochlear nerve supply
superior oblique muscle- allow us to move our eyeball
what is unique about the trochlear nerve
it exits from the posterior surface of the brainstem unlike the other cranial nerves
(all exit brain/stem from antero or anterolateral surface)
also very thin
what is the route of the trochlear nerve
-exits brainstem posteriorly
-runs anteriorly around cerebral peduncle
-enters cavernous sinus
-passes through superior orbital fissure
-supplies superior oblique muscle
what happens if there is injury to eht etrochlear nerve
patient cant look medially and inferiorly
they experience DIPLOPIA (walking downstairs/reading)
where is the nucleus of the abducent nerve found
in the pons
what does the abducent nerve supply
lateral rectus muscle
what is the route of the abducent nerve
exits brainstem medially between pons and medulla- in groove called pontobulbar groove
enters cavernous sinus (only cranial nerve found WITHIN- all others are on the lateral wall)
enters orbit through the superior orbital fissure
supplies lateral rectus
what happens if there is an injury to the right abducent nerve
DIPLOPIA WHEN LOOKING RIGHT
right eye would not abduct fully
where are the nucleuses of the cranial nerves found
1st 4- above pons (midbrain or brain)
middle 4- pons
last 4- medulla
what is special about the abducent nerve
it enters the cavernous sinus
all other cranial nerves are on the lateral side of the sinus
what fibres does the facial nerve
motor fibres
parasympathetics fibres
sensory
what is unique about the motor nucleus of the facial nerve
it has two divisions
superior division- controls upper facial muscles
- connected to IPSILATERAL and CONTRALATERAL motor cortices
inferior division- controls lower facial muscles
- connected to CONTRALATERAL cortex ONLY
almost always cortex controls other side- except for the superior division (has a backup)
what is the route of the facial nerve
enter from the anterolateral surface of the brainstem
motor root emerges in the angle between lower pons and cerebellum - CEREBELLOPONTINE ANGLE
enters the temporal bone at the internal acoustic meatus, with VIII and labyrinthine artery (branch of the basilar artery)
why is the cerebellopontine angle important
facial nerve exits brainstem
vestibulacohlear nerve enters brainstem here
what is found within the internal acoustic meatus
7, 8, labyrinthine artery
what happens to the facial nerve after the internal acoustic meatus
enters the facial canal within the temporal bone (bony canal)
this canal has two bands
1. geniculate ganglion (cell bodies for taste fibres are found here- sensory)
2. stapedius branch- supplying stapedius muscle
receives chorda tympani
leave temporal bone through stylomastoid foramen
why is the facial nerve at risk during birth
mastoid process not developed in newborns
facial nerve at risk if baby delivered by foreceps
as no protection
mastoid process develops when they hold their head
what happens to facial nerve after going through stylomastoid foramen
goes into infratemporal fossa
gives branches to occipitalis and auricular muscles
rest enters parotid gland and divides to form a plexus within (5 branches)
they remain connections therefore surgery is complex
they supply muscles of facial expression
what are the branches of the facial nerve and how to remember
Two
Zebras
Befriended
My
Cat
temporal- superior facial muscles (test by raising eyebrows)
zygomatic- (test by lifting lips)
buccal- (blow cheek)
marginal mandibular
cervical
