Cranial nerves 2

Question 1

what muscles does the mandibular nerve supply

Answer 1

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

Question 2

what are the muscles of mastication

Answer 2

lateral pterygoid
medial pterygoid
temporalis
masseter

Question 3

what is the jaw jerk test used for
and how does it differ from the corneal reflex

Answer 3

to test the trigeminal nerve and nuclei
afferent and efferent limbs are trigeminal

corneal reflex–
afferent is trigeminal
efferent is facial

Question 4

where is the oculomotor nucleus found

Answer 4

in midbrain
it is a singular nucleus

Question 5

what is the route of the oculomotor nerve

Answer 5

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

Question 6

does the oculomotor nerve have divisions

Answer 6

yes
superior and inferior divisions
it divides after entering the orbit

Question 7

what does the superior branch of the oculomotor nerve supply

Answer 7

1. levator palpebrae superioris (elevate upper lid)
2. superior rectus

Question 8

what does the inferior branch of the oculomotor nerve supply

Answer 8

1. medial rectus
2. inferior rectus
3. inferior oblique muscles
4. plus carries parasympathetic fibres to the ciliary ganglion

Question 9

is oculomotor nerve motor or sensory

Answer 9

motor
has both visceral and somatic fibres

Question 10

which nuclei are in midbrain

Answer 10

3 and 4

Question 11

why is levator palpebrae superioris a special muscle

Answer 11

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

Question 12

what muscle does the trochlear nerve supply

Answer 12

superior oblique muscle- allow us to move our eyeball

Question 13

what is unique about the trochlear nerve

Answer 13

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

Question 14

what is the route of the trochlear nerve

Answer 14

-exits brainstem posteriorly
-runs anteriorly around cerebral peduncle
-enters cavernous sinus
-passes through superior orbital fissure
-supplies superior oblique muscle

Question 15

what happens if there is injury to eht etrochlear nerve

Answer 15

patient cant look medially and inferiorly
they experience DIPLOPIA (walking downstairs/reading)

Question 16

where is the nucleus of the abducent nerve found

Answer 16

in the pons

Question 17

what does the abducent nerve supply

Answer 17

lateral rectus muscle

Question 18

what is the route of the abducent nerve

Answer 18

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

Question 19

what happens if there is an injury to the right abducent nerve

Answer 19

DIPLOPIA WHEN LOOKING RIGHT
right eye would not abduct fully

Question 20

where are the nucleuses of the cranial nerves found

Answer 20

1st 4- above pons (midbrain or brain)
middle 4- pons
last 4- medulla

Question 21

what is special about the abducent nerve

Answer 21

it enters the cavernous sinus
all other cranial nerves are on the lateral side of the sinus

Question 22

what fibres does the facial nerve

Answer 22

motor fibres
parasympathetics fibres
sensory

Question 23

what is unique about the motor nucleus of the facial nerve

Answer 23

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)

Question 24

what is the route of the facial nerve

Answer 24

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)

Question 25

why is the cerebellopontine angle important

Answer 25

facial nerve exits brainstem
vestibulacohlear nerve enters brainstem here

Question 26

what is found within the internal acoustic meatus

Answer 26

7, 8, labyrinthine artery

Question 27

what happens to the facial nerve after the internal acoustic meatus

Answer 27

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

Question 28

why is the facial nerve at risk during birth

Answer 28

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

Question 29

what happens to facial nerve after going through stylomastoid foramen

Answer 29

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

Question 30

what are the branches of the facial nerve and how to remember

Answer 30

Two
Zebras
Befriended
My
Cat

temporal- superior facial muscles (test by raising eyebrows)
zygomatic- (test by lifting lips)
buccal- (blow cheek)
marginal mandibular
cervical