CN I-III

Question 1

Name of CN I

Answer 1

Olfactory

Question 2

Where are the cells of origin of CN I olfactory?

Answer 2

In olfactory mucosa of upper portion of nasal cavity

Question 3

CN I olfactory processes transverse the ___ and end in the ___.

Answer 3

…transverse the cribriform plate and end in the olfactory bulb.

Question 4

The olfactory bulb projects through lateral olfactory stria directly to the…

Answer 4

Primary olfactory cortex

Question 5

Medial olfactory stria sends fibers via ___ to the ___.

Answer 5

Medial olfactory stria sends fibers via anterior commissure to the contralateral olfactory bulb.

Question 6

Olfaction is the only sense that…

Answer 6

reaches its cortex directly, not via the thalamus

Question 7

How is CN I olfactory examined?

Answer 7

Odorants are applied to each nostril with eyes closed

Question 8

Lesion of CN I olfactory leads to…

Answer 8

Anosmia (loss of smell)

Question 9

What is the name of CN II?

Answer 9

Optic

Question 10

Where are CN II optic cells of origin?

Answer 10

In ganglion cells of the retina

Question 11

Fibers in optic nerves partially cross in ___,
proceed in ___,
and synapse in ___.

Answer 11

Fibers in optic nerves partially cross in optic chiasma,
proceed in optic tract,
and synapse in lateral geniculate body.

Question 12

Fibers from optic tract also form superior brachium. What will the superior brachium do?

Answer 12

Send light reflex information to the superior colliculus

Question 13

From the lateral geniculate nucleus, optic fibers reach…

Answer 13

The primary visual cortex via optic radiation

Question 14

Where is the primary visual cortex?

Answer 14

Cuneus and lingual gyri

Question 15

Left halves of both eyes visual fields ultimately end in the…

Answer 15

right visual cortex (and vice versa)

Question 16

Function of CN II optic

Answer 16

Vision

Question 17

How do we examine CN II optic?

Answer 17

Test visual acuity, field mapping, and reflexes

Question 18

Lesion of CN II optic leads to…

Answer 18

Anopsia (loss of vision)

Question 19

Where does CN II optic exit the skull?

Answer 19

Optic canal

Question 20

What is the name of CN III?

Answer 20

Oculomotor

Question 21

What is the origin of CN III oculomotor?

Answer 21

Oculomotor nucleus (motor)
Edinger-Westphal nucleus (parasympathetic)

Question 22

What is the level of the nuclei of CN III oculomotor?

Answer 22

Midbrain at level of superior colliculus, anterior portion of periaqueductal grey

Question 23

Where does CN III oculomotor exit?

Answer 23

At interpeduncular fossa

Question 24

What are the motor functions of CN III oculomotor?

Answer 24

Extraocular muscles (superior, medial, inferior rectus, inferior oblique, levator palpebrae superioris)

Question 25

What are the parasympathetic functions of CN III oculomotor?

Answer 25

Pupillary constriction in response to light and accommodation for near vision (sphincter pupillae muscle) and thickening of lens during accommodation (ciliaris muscle)

Question 26

CN III oculomotor parasympathetic fibers synapse with…

Answer 26

Ciliary ganglion

Question 27

CN III oculomotor postganglionic parasympathetic fibers ride in short ciliary nerves to…

Answer 27

Sphincter pupillae and ciliaris muscles

Question 28

Postganglionic sympathetic fibers from internal carotid plexus (from cervical sympathetic ganglia) use short ciliary nerves to the…

Answer 28

Dilator pupillae

Question 29

How do we examine CN III oculomotor?

Answer 29

Light and accommodation reflexes, vertical and medial eye movements, eyelid movement

Question 30

Lesion of CN III oculomotor leads to…

Answer 30

Diplopia, ptosis, lateral strabismus, mydriasis, cycloplegia

Question 31

Where does CN III oculomotor exit the skull?

Answer 31

Superior orbital fissure