Cranial Nerve Exits

Question 1

CN I

Brain exit

Dural exit

Skull exit

Answer 1

CN I Olfactory

Brain exit: Olfactory bulb

Dural exit: Cribriform plate

Skull exit: Cribriform plate

Question 2

CN II

Brain exit

Dural exit

Skull exit

Answer 2

CN II Optic

Brain exit: Optic chiasma

Dural exit: Posterior pole of the eyeball

Skull exit: Optic canal

Question 3

CN III

Brain exit

Dural exit

Skull exit

Answer 3

CN III Oculomotor

Brain exit: Oculomotor sulcus (interpeduncular fossa)

Dural exit: Cavernous sinus (lateral wall)

Skull exit: Superior orbital fissure

Question 4

CN IV

Brain exit

Dural exit

Skull exit

Answer 4

CN IV Trochlear

Brain exit: Both sides of the frenulum of sup. medullary velum, only one that exits dorsally!

Dural exit: Cavernous sinus (lateral wall)

Skull exit: Superior orbital fissure

Question 5

CN V

Brain exit

Dural exit

Skull exit

Answer 5

CN V Trigeminal

Brain exit: Between pons and brachium pontus anteriorly

Dural exit: Trigeminal/Meckel’s cave, both V1 and V2 through lateral cavernous sinus, but V3 through foramen ovale

Skull exit: V1: superior orbital fissure, V2: foramen rotundum, V3: foramen ovale

Question 6

CN VI

Brain exit

Dural exit

Skull exit

Answer 6

CN VI Abducens

Brain exit: At ponto-medullary junction, on both sides of foramen cecum

Dural exit: Cavernous sinus (freely!) & Dorello’s canal

Skull exit: Superior Orbital Fissure

Question 7

CN VII

Brain exit

Dural exit

Skull exit

Answer 7

CN VII Facial

Brain exit: Cerebello-pontine angle, between pons and brachium pontis

Dural exit: fundus of the internal acoustic meatus

Skull exit: fundus of the internal acoustic meatus

Question 8

CN VIII

Brain exit

Dural exit

Skull exit

Answer 8

CN VIII Vestibulocochlear

Brain exit: Cerebello-pontine angle, between pons and brachium pontis. Lateral to CN VII

Dural exit: fundus of the internal acoustic meatus

Skull exit: fundus of the internal acoustic meatus

Question 9

CN IX

Brain exit

Dural exit

Skull exit

Answer 9

CN IX Glossopharyngeal

Brain exit: Lateral parolivary sulcus (superiorly)

Dural exit: Jugular foramen

Skull exit: Jugular foramen

Question 10

CN X

Brain exit

Dural exit

Skull exit

Answer 10

CN X Vagus

Brain exit: Lateral parolivary sulcus (middle nerve, below CN IX)

Dural exit: Jugular foramen

Skull exit: Jugular foramen

Question 11

CN XI

Brain exit

Dural exit

Skull exit

Answer 11

CN XI Accessory

Brain exit: Lateral parolivary sulcus (inferiorly)

Dural exit: Jugular foramen

Skull exit: Jugular foramen

Question 12

CN XII

Brain exit

Dural exit

Skull exit

Answer 12

CN XII Hypoglossal

Brain exit: Medial Parolivary Sulcus

Dural exit: Hypoglossal canal

Skull exit: Hypoglossal canal