Cranial Nerves- Exit from Skull, Foramen, Fissures

Question 1

Olfactory nerve - CN I- Location of exit from the skull

Answer 1

the cribriform foramina (ethmoid bone)

Question 2

Optic nerve- CN II - exit from the skull

Answer 2

optic canal (two- one for each eye)

Question 3

Oculomotor nerve- CN III- exit from the skull

Answer 3

superior orbital fissure (both parasympathetic and motor axons go through)

Question 4

trochlear - CN IV- exit from the skull

Answer 4

superior orbital fissure

Question 5

Exit from the skull - trigeminal, ophthalmic, CN V1

Answer 5

superior orbital fissure

Question 6

trigeminal, maxillary n.- CN V2- initial exit from the skull

Answer 6

foramen rotundum

Question 7

What foramen, canals, and fissures do the branches of CN V2- maxillary n. go through?

Answer 7

foramen rotundum- initial exit from skull

palatovaginal canal- pharyngeal n.

lesser palatine foramen- lesser palatine n.

greater palatine foramen- greater palatine n.

incisive fossa- nasopalatine n.

sphenopalatine foramen- nasopalatine nn/ posterior superior lateral and posterior superior medial nasal nn’s.

pterygomaxillary fissures- posterior superior alveolar n.

inferior orbital fissure- transmits CN V2 (maxillary), infraorbital vessels, and postganglionic parasympathetic axons from pterygopalatine ganglion to eye

infraorbital groove, canal, and foramen

• ** OPENING ON FACE: infraorbital nerve exits through the infraorbital foramen
• infraorbital groove and canal: transmits infraorbital n., a., v

Question 8

CN V3- Trigeminal, mandibular n. - initial exit from the skull

Answer 8

foramen ovale

Question 9

What foramen and fissures do the branches of the trigeminal nerve, mandibular division - CN V3- go through

Answer 9

foramen spinosum- CN V3 goes through and then becomes meningeal nerve

foramen ovale- CN V3 goes through and then branches off —>

• deep temporal n.
• masseteric n.
• lateral pterygoid n.
• medial pterygoid n.
• buccal n.
• lingual n.
• CN V3–> nerve to mylohyoid

mandibular foramen- inferior alveolar n. goes through

mental foramen- inferior alveolar n. goes through and then becomes mental n. at the chin

** inferior alveolar nerve does not pass through anything as it becomes the nerve to mylohyoid.

auriculo-temporal nerve- goes around the middle meningeal artery along with the postganglionic parasympathetic axons from CN IX and otic ganglion

Question 10

What vessel do the auriculo-temporal nerve and postganglionic parasympathetic fibers of CN IX go around?

Answer 10

the middle meningeal artery

Question 11

CN VI- abducens- exit from the skull-

Answer 11

superior orbital fissure

Question 12

CN VII- Facial nerve- primary exit from the skull for all 5 axon functions?

Answer 12

internal auditory meatus

internal auditory meatus/stylomastoid foramen for branchial motor axons

Question 13

What foramina/ fissures do the sensory and taste axons of the facial nerve pass through before innervating their target structures?

Answer 13

sensory axons- stylomastoid foramen–> becomes posterior auricular n.

taste axons

• -petrotympanic fissure –> run with chorda tympani preganglionic parasympathetic axons
• • (greater petrosal nerve): hiatus of greater petrosal n.
• -(n. of pterygoid canal): pterygoid canal –> then goes through the pterygopalatine fossa (preganglionic parasympathetic enter and exit and taste axons enter and exit)

Question 14

CN IX- glossopharyngeal- primary exit from the skull

Answer 14

jugular foramen

Question 15

What channel does the tympanic nerve go through after exiting the superior and inferior ganglion and what primary cranial nerve is this associated with/what do the sensory axons go on to innervate after exiting from this channel?

Answer 15

(CN IX- glossopharyngeal nerve)

tympanic canaliculus

–> sensory axons enter the tympanic canaliculus and exit to provide sensory innervation to inner ear
CLINICAL: injury of the tympanic nerve (associated with glossopharyngeal n.) can cause an ear ache

Question 16

What opening in the temporal bone does the lesser petrosal nerve go through to enter the middle cranial fossa/what cranial nerve is this pathway associated with?

Answer 16

hiatus for the lesser petrosal nerve

Question 17

What opening does the lesser petrosal nerve go through before its preganglionic parasympathetic fibers synapse on the otic ganglion?

Answer 17

foramen ovale

Question 18

CN X- vagus n. - primary exit from the skull

Answer 18

jugular foramen

Question 19

What vascular structure does the thoracic cardiac branch of the vagus nerve innervate?

Answer 19

** located in mediastinum

the aortic arch (to help regulate blood pressure)

Question 20

What opening does the spinal accessory pass through before going through the jugular foramen?

Answer 20

foramen magnum

(the nerves moves superiorly through the foramen magnum and inferiorly through the jugular foramen)

NERVE GOES INTO THE SKULL THROUGH FORAMEN MAGNUM AND THEN COMES OUT THROUGH JUGULAR FORAMEN

Question 21

CN XI- accessory n. - primary exit from the skull:

Answer 21

jugular foramen

Question 22

CN XII- hypoglossal n.- exit from the skull

Answer 22

hypoglossal canal