Clinically Relevant Anatomy of Cranial Nerves

Question 1

Intracranial course of olfactory nerve (CN I) and connection to brain.

Answer 1

Olfactory nerves synapse in the olfactory bulb then travel to cortical areas in the olfactory tract.

Question 2

Intracranial course of optic nerve (CN II) and connection to brain

Answer 2

Travels around the pituitary stalk to the optic chasm, forming the optic tract. Diencephalon

Question 3

Intracranial course of oculomotor nerve (CN III) and connection to brain

Answer 3

Travels to the orbit in the lateral wall of the cavernous sinus. Mesencephalon

Question 4

Intracranial course of trochlear nerve (CN IV) and connection to brain.

Answer 4

Travels towards the orbit in the lateral wall of the cavernous sinus. Mesencephalon

Question 5

Intracranial course of Abducent nerve (CN VI) and connection to brain.

Answer 5

Travels towards the orbit WITHIN the cavernous sinus. Pontomedullary junction.

Question 6

Intracranial course of Vestibulochochlear (CN VIII) and connection to brain.

Answer 6

Travels posteromedially from the internal acoustic meatus to the pontomedullary junction.

Question 7

Intracranial course of accessory nerve (CN XI) and connection to brain.

Answer 7

Ascends through foramen magnum then travels towards the jugular foramen in the posterior cranial fossa. Cervical spinal cord.

Question 8

Intracranial course of hypoglossal nerve (CN XII) and connection to brain.

Answer 8

Passes anteriorly to hypoglossal canal. Rootlets to lateral pyramids of medulla.

Question 9

Upon exiting the cranium, what structure does CN XII descend with?

Answer 9

Carotid sheath.

Question 10

Intracranial course of trigeminal nerve (CN V) and connection to the brain.

Answer 10

travels inferior to the edge of the tentorium cerebella between the posterior and middle cranial fosse. Pons, laterally.

Question 11

What are the 3 divisions of the trigeminal nerve and what modality are they?

Answer 11

Ophthalmic (CNV1) - sensory
Maxillary (CNV2) - sensory
Mandibular (CNV3) - sensory and motor

Question 12

Intracranial course of the facial nerve (CN VII) and connection to brain.

Answer 12

Travels directly into acoustic meatus in posterior cranial fossa. Pontomedulalry junction, anterolaterally.

Question 13

Intracranial course of the glossopharyngeal nerve (CN IX) and connection to brain.

Answer 13

Travels directly towards jugular foramen in the posterior cranial fossa. Lateral aspect of superior medulla oblongata

Question 14

Intracranial course of the vagus nerve (CN X) and connection to the brain.

Answer 14

Travels directlytowards jugular foramen in the posterior cranial fossa. Lateral aspect of medulla oblongata (inferior to CN IX).

Question 15

What structure does the vagus nerve descend in?

Answer 15

Carotid sheath.

Question 16

How do you test the optic nerve (CN II)?

Answer 16

Light reflexes, visual field testing, snellen chart

Question 17

How do you test the oculomotor nerve (CN III)?

Answer 17

Extra ocular eye movements (H test).

Question 18

How do you test the trochlear nerve (CN IV)?

Answer 18

Extra ocular eye movements (in and down).

Question 19

How do you test the trigeminal nerve (CN V)?

Answer 19

Facial sensation, power of muscles of mastication.

Question 20

How do you test the abducent nerve (CN VI)?

Answer 20

Extra ocular eye movements (lateral gaze)

Question 21

How do you test the facial nerve (CN VII)?

Answer 21

Power of muscles of facial expression

Question 22

How do you test the vestibulochochlear nerve (CN VIII)?

Answer 22

Rinne & Weber tests

Question 23

How do you test the vagus nerve (CN X)?

Answer 23

Elevation of the soft palate, assess for normal swallowing and speech

Question 24

How do you test the spinal accessory nerve (CN XI)?

Answer 24

Turning of head & shrugging shoulders

Question 25

How do you test the hypoglossal nerve (CN XII)?

Answer 25

Protrusion of the tongue