Exits of cranial nerves (from brain, dura and skull) and their subarachnoid pathway

Question 1

I olfactory nerve

Answer 1

B: olfactory bulb
dural exit: cribriform plate
skull: cribriform plate
—

Question 2

II optic nerve

Answer 2

brain: optic chiasma
dural: posterior pole of eyeball!!
skull: optic canal
cistern: chiasmatic cistern

Question 3

III occulomotor nerve

Answer 3

brain: occulomotor sulcus(=medial sulcus of crus cerebri) in the interpeduncular fossa; b/w post cerebral A and sup. cerebellar A

Dural: Cavernous sinus (lateral wall) enters b/w ant. and post. petroclinoidal folds

skull: sup. orbital fissure
cistern: interpeduncular fossa

**III occulomotor, IV (trochlear nerve), VI abducent nerve** all pass through cavernous sinus and sup. orbital fissure!!!!!!!

Question 4

IV trochlear nerve

Answer 4

brain: below inferior colliculi; both sides of the frenulum of sup. medullary velum
NOTE: IV n is not the only nerve that exits on the DORSAL aspect of the brain!

dural: cavernous sinus (enters within the ant. petroclinoidal fold)
skull: sup orbital fissure

cistern:
1. quadrigeminal (initial part)
2. ambiens cistern (encircling the brainstem)

Question 5

V trigeminal nerve

Answer 5

brain: b/w pons and brachium pontis, anteriorly- larger sensory root inferiorly, motor root superiorly
dural: (meckel’s cave)

V/I: cavernous sinus (lateral wall)—->sup. orbital fissure
V/2: cavernous sinus lateral wall)—->foramen rotundum
V/3: foramen ovale—>for. ovale

cisterns: lateral pontine cisterns (pontocerebellar cistern)

Question 6

VI abducens nerve

Answer 6

at the pontomedullary junction, on both sides of foramen cecum

dural: cavernous sinus (freely!)
ascends in the cloves in the drool’s canal; enters the cavernous sinus far below the posterior petroclinoidal fold

skull: sup orbital fissure
cistern: median pontine cistern (pontomedullary cistern)

Question 7

VII facial Nerve

Answer 7

b/w pons and brachium posteriorly- in the cerebellopontine angle

dural: fundus of IAM
cistern: lateral pontine cistern (pontocerebellar cistern)

***VIII vestibulocochlear nerve (b/w pons and brachium pontis, posteriorly in the cerebellopontine angle; laterally from the n VII

Question 8

VIII vestibulocochlear nerve

Answer 8

brain: (b/w pons and brachium pontis, posteriorly in the cerebellopontine angle; laterally from the n VII
dural: fundus of IAM
cistern: lateral pontine cistern (pontocerebellar cistern)

Question 9

IX glossopharyngeal N

Answer 9

Brain: in the lateral paraolivary sulcus (superiorly)

skull: Jugular foramen (anterior part, pars nervosa)
cistern: –

***jugular foramen:
IX, X, XI

Question 10

X vagus nerve

Answer 10

in the lateral paraolivary sulcus (below IX n)
skull: Jugular foramen (anterior part, pars nervosa)

cistern: –

Question 11

XI accessory n

Answer 11

in the lateral paraolivary sulcus Iinferiorly)- the CN roots of XI
from spinal segments c1-6 or spinal roots of n XI

Question 12

XII hypoglossal n

Answer 12

brain: in the medial paraolivary sulcus
dural: hypoglossal canal

Question 13

facial nerve VII

Answer 13

nervus intermedius enters b/w VII and VIII but BELONGS TO VII (PARASYMPATHETIX AND TASTE FIBERS)

Question 14

REAL CRANIAL NERVES

Answer 14

CN III-XII
originate from brainstem =midbrain, pons and medulla

CN I and II not real because they are extensions of the brain (CNS)