CN IV-VI

Question 1

What is the name of CN IV?

Answer 1

Trochlear

Question 2

CN IV trochlear origin and level

Answer 2

Trochlear nucleus
Midbrain at level of inferior colliculus in anterior portion of periaquectal grey

Question 3

CN IV trochlear exit

Answer 3

Two nerves decussate in the superior medullary velum and exit inferior to the inferior colliculi

Question 4

CN IV trochlear function

Answer 4

Extraocular movements (superior oblique muscle)

Question 5

CN IV trochlear exam

Answer 5

Downward and inward eye movements

Question 6

CN IV trochlear lesion

Answer 6

Diplopia when looking down and in, and head tilt to the opposite side

Question 7

CN IV trochlear exits the skull via…

Answer 7

the superior orbital fissure

Question 8

What is the name of CN V?

Answer 8

Trigeminal

Question 9

Origins and levels (4) of CN V trigeminal?

Answer 9

1. Nucleus of the spinal tract of trigeminal (P&T) at midpons-C5
2. chief sensory nucleus (touch) at midpons
3. mesencephalic nucleus (proprioception) at midpons-midbrain
4. motor nucleus (muscles of mastication) at midpons

Question 10

Where does CN V trigeminal exit?

Answer 10

Midpons

Question 11

What are the peripheral branches of CN V trigeminal?

Answer 11

V1 ophthalmic (sensory)
V2 maxillary (sensory)
V3 mandibular (mixed)

Question 12

peripheral branches of CN V trigeminal

Where does V1 ophthalmic branch exit the skull?

Answer 12

Superior orbital fissure

Question 13

peripheral branches of CN V trigeminal

Where does V2 maxillary branch exit the skull?

Answer 13

Foramen rotundum

Question 14

peripheral branches of CN V trigeminal

Where does V3 mandibular branch exit the skull?

Answer 14

Foramen ovale

Question 15

peripheral branches of CN V trigeminal

The meningeal branch of V3 re-enters the skull with the middle meningeal artery through…

Answer 15

the foramen spinosum

Question 16

peripheral branches of CN V trigeminal

The maxillary division (V2) goes through foramen rotundum and enters…

Answer 16

the pterygopalatine fossa

Question 17

peripheral branches of CN V trigeminal

In the pterygopalatine fossa, V2 receives… from…

Answer 17

…receives postganglionic parasympathetic fibers from the pterygopalatine ganglion

Question 18

peripheral branches of CN V trigeminal

Describe where and how V2 sends postganglionic fibers

Answer 18

V2 sends postganglionic fibers via its zygomaticotemporal branch, to the lacrimal branch of VI, and from there, to the lacrimal gland

Question 19

peripheral branches of CN V trigeminal

Where does the maxillary nerve ultimately exit the skull?

Answer 19

The infraorbital foramen

Question 20

Sensory function of CN V trigeminal

Answer 20

Sensory to: face, scalp, teeth, most of tongue, oral and nasal mucosa, dura mater, and cerebral blood vessels

Question 21

Sensory fibers coming in from all three divisions of CN V are what type of cells? Where are their cell bodies?

Answer 21

Pseudounipolar cells with cell bodies in the trigeminal (semilunar ganglion) or the mesencephalic nucleus (in proprioception)

Question 22

Motor function of CN V trigeminal

Answer 22

Motor to: muscles of mastication (masseter, temporalis, medial and lateral pterygoid muscles), the tensor tympani and tensor veli palatini muscles, the mylohyoid, and the anterior belly of the digastric muscles

Question 23

CN V trigeminal examination

Answer 23

Touch by cotton swab, pain by pinprick, temperature, corneal reflex, jaw reflex, masticatory movements

Question 24

CN V trigeminal lesion

Answer 24

Trigeminal neuralgia, facial anesthesia or numbness, inability or difficulty to bite down

Question 25

Name CN VI

Answer 25

Abducent

Question 26

Origin and level of CN VI abducent

Answer 26

Abducent nucleus at lower pons at level of the facial colliculus

Question 27

CN VI abducent exit

Answer 27

Pontomedullary junction between basilar pons and pyramid

Question 28

CN VI abducent function

Answer 28

Extraocular movements (lateral rectus muscle)

Question 29

CN VI abducent exam

Answer 29

Lateral eye movements

Question 30

CN VI abducent lesion

Answer 30

Diplopia, medial strabismus

Question 31

CN VI abducent exits skull via…

Answer 31

superior orbital fissure