Motor innervation

Question 1

what is affected in a CN 3 nucleus lesion

Answer 1

• ipsilateral MR, IR, IO
• ipsilateral sphincter (dilated pupil),
• cb muscle (lack of acc),
• contra/ipsi SR
• bilateral ptosis

Question 2

what happens if lesion when follows of the superior+ posterior cerebral arteries around the cerebral peduncles

Answer 2

contralateral body weakness if lesion is close to the cerebral peduncles

Question 3

what does cn4 follow

Answer 3

superior cerebellar and posterior cerebral arteries around the cerebral peduncle

Question 4

inferior branch of cn3

Answer 4

io, ir, mr, parasympathetic, pupils-sphincter

Question 5

lagopthalmos

Answer 5

obicularis cannot close eye properly –> dryness of cornea –> blindness usually with a cn 7 palsy

Question 6

external ophthalmoplegia affected muscles

Answer 6

any or all eoms can be affected

Question 7

cn6 fascicle location

Answer 7

within pons–> corticospinal tract (contra-weakness)

Question 8

cn6 in cav sin

Answer 8

• within the cav sin near ica
• sympathetic fibers leave the ica + travel with the cn6 before splitting to cn3 or cn4
• first nerve involved with ica aneurysm
• horner’s usually occurs in the cav sin due to all the signs

Question 9

where does the cn4 travel through (last step)

Answer 9

travels through the superior orbital fissure above the CTR outside the muscle cone

Question 10

what is the CN3 most frequently affected by

Answer 10

posterior communicating artery aneurysm

Question 11

what does the SR nuclei innervate

Answer 11

contralateral superior rectus

Question 12

what does cn6 nucleus contain and what do they do

Answer 12

internuclear neurons that travel in the MLF to the contralateral MR nucleus

Question 13

cn4 fascicle location

Answer 13

posterior

below the inferior colliculus

Question 14

why are you relatively extorted in primary gaze

Answer 14

• head tilt will force intorsion
• head turn will force the bad eye to abduct so the rectus muscles control up and down movements
• head is tilted downwards is the objects are more in line with the hyper eye

Question 15

CN3 fascicle pathway

Answer 15

• passes through ipsilateral superior cerebellar peduncle (ipsi ataxia)
• through red nucleus (contra tremor)
• through cerebral peduncle (CST- contra weakness)
• passes through posterior cerebral artery + superior cerebellar artery
• follows the posterior communicating artery

Question 16

what curves around the cn6 nucleus

Answer 16

facial nucleus

Question 17

CN3 fascicle pathway innervention

Answer 17

• ipsilateral involvement of everything (MR, IR, IO, SR, levator, sphincter, CB)
• contra eye is normal

Question 18

procerus

Answer 18

(pulls eyebrows down + medially)

Question 19

cn 6 clinical correlate- sharp bend over the petrous ridge

Answer 19

susceptible to compression and stretching injuries, particularly with increased ICP

Question 20

superior branch of cn3

Answer 20

sr, levator

Question 21

if lesion above sof and ctr

Answer 21

so palsy

numbness of forehead (cn5)

Question 22

trochlear nerve nucleus location

Answer 22

midbrain at the level of the inferior colliculus

• anterior to cerebral aqueduct
• dorsal to MLF
• caudal to cn3 nucleus

Question 23

orbicularis

Answer 23

closes eyelids

Question 24

what cranial nerves are involved in sensory for EOMS

Answer 24

2,5

Question 25

cn6 lesion

Answer 25

gaze palsy innervation to LR to contralateral MR

Question 26

what does the edinger westphal nucleus innervate

Answer 26

iris, sphincter (miosis), cb (acc, cb contracts, parasympathetic)

Question 27

where wall does the cn4 enter

Answer 27

wall of cav sin

Question 28

cn 6 palsy - what deviation from primary position

Answer 28

esotropic deviation- greater at distance

Question 29

levator innervates

Answer 29

bilaterally

Question 30

the parasympathetic fibers are spared in

Answer 30

spared in ischemic lesion due to vasculature surrounding the nerve first thing to go involved in compressive lesions, including an aneurysm or tumor

Question 31

cn 7 facial nucleus

Answer 31

loops around cn6 nucleus in pons

Question 32

what branches does the facial nerve divide int

Answer 32

temporal and zygomatic supplies the frontalis , procerus, corrugator, orbicularis

Question 33

what happens in a complete cn3 palsy

Answer 33

- ptosis - the eye is positioned down and out due to the unopposed actions of the SO and LR - they cannot adduct (MR) - in the abducted position, cannot move up or down (SR, IR) - in the adducted position, they cannot move the eye up (IO) - pupil dilation - decreased acc

Question 34

what is the so palsy compensation

Answer 34

head tilt to the opposite shoulder - chin down - head turn towards - in lateral movements -abducts- turns head away from eye involved bc to abduct eye (rectus muscles to go up and down)-minimizes diplopia

Question 35

cn6 nerve pathway

Answer 35

1. fascicle 2. exit the groove between the pons and medulla 3. runs along the occipital bone and posterior slope of the petrous portion of the temporal bone - -makes a sharp bend over the petrous ridge 4. enters the cav sin 5. enters the orbit through the superior orbital fissure within the ctr

Question 36

what does cn 6 (abducens) innervate

Answer 36

LR

Question 37

CN 4 pathway

Answer 37

1. fascicle -below of inferior colliculus 2. decussates 3. follows the superior cerebellar and posterior cerebral arteries around the cerebral peduncle 4. enters wall of cav sin 5. travels through the SOF above the CTR

Question 38

cn6 palsy restriction

Answer 38

cannot abduct eye

Question 39

CN6 nucleus location

Answer 39

- within in the pons | - contains the abducens motor neurons

Question 40

what does the trochlear nerve innervate

Answer 40

cn4

Question 41

cn 7 pathway

Answer 41

1. fascicle travels around the abducens nucleus 2. emerges from the brainstem at the lower border of the pons 3. enters the internal acoustic foramen (w/ cn 8) 4. exits the skull through the stylomastoid foramen 5. divide into several branches

Question 42

what fibers are superficial on the cn3 nerve

Answer 42

parasympathetic

Question 43

when cn3 fascicle goes through ipsi superior cerebellar peduncle

Answer 43

ipsi ataxia

Question 44

what is an incomplete cn3 palsy

Answer 44

external ophthalmoplegia

Question 45

where is the oculomotor nerve located

Answer 45

midbrain @ superior colliculus - ventral to cerebral aquaduct - dorsal to MLF

Question 46

when cn3 fascicle goes through cerebral peduncle what happens

Answer 46

contra weakness

Question 47

what is within the lateral wall of the cav sin

Answer 47

cn 3,4,6 | sympathetic fibers join after leaving the ICA (join to go to eyelids)

Question 48

what is spared in an external ophthalmoplegia

Answer 48

internal muscles (pupil, acc)

Question 49

what cranial nerves are involved in motor for EOMS

Answer 49

3,4,6 | 7-eyelids

Question 50

corrugator

Answer 50

(pulls eyebrowns medially)

Question 51

cn4 lesion

Answer 51

contralateral so palsy

Question 52

what is the first nerve the cav sin affected in ica aneurysm

Answer 52

cn 6

Question 53

cn 4 palsy | eye deviation in primary position

Answer 53

hyper deviation (bc SO normally pulls eye down)

Question 54

where is the oculomotor nerve subnuclei located

Answer 54

IR, IO, MR nuclei | -innervate ipsilateral eye

Question 55

when cn3 fascicle goes through red nucleus

Answer 55

contralateral tremor

Question 56

what does the oculomotor nerve innervate

Answer 56

IO, MR, SR, IR, Levator, pupils (sphincter), mullers

Question 57

cn 6 palsy compensation

Answer 57

turn head towards action of muscle to compensate (towards paralyzed side)

Question 58

cn4 restrictions

Answer 58

when adducted, eye won't depress

Question 59

what is spared in internal ophthalmoplegia

Answer 59

eoms

Question 60

frontalis

Answer 60

(raises eyebrows)

Question 61

cn 7 functions

Answer 61

- motor root --> facial muscles - sensory root --> taste - parasympathetic --> glands of face, lacrimal gland