Lecture 20

Question 1

Define the following modality that describes a CN.

SSS

Answer 1

SSS (special somatic sensory): special senses derived from the ectoderm (sight, sound, balance)

Question 2

Define the following modality that describes a CN.

SVS

Answer 2

SVS (special visceral sensory): special sense derived from endoderm (taste)

Question 3

Define the following modality that describes a CN.

SVM

Answer 3

SVM (special visceral motor): Muscles derived from pharyngeal arches

Question 4

Define the following modality that describes a CN.

GVS

Answer 4

GVS (general visceral sensory): General sensation from viscera

Question 5

Define the following modality that describes a CN.

GVM

Answer 5

GVM (general visceral motor): autonomic motor nerves to the smooth muscles of the gut tract

Question 6

Define the following modality that describes a CN.

GSS

Answer 6

GSS (general somatic sensory): general senses from the ectoderm (skin)

Question 7

Define the following modality that describes a CN.

GSM

Answer 7

GSM (general somatic motor): Skeletal muscles

Question 8

For CN I List the following
Name: 
Modality/modalities): 
Function/functions): 
Sensory areas and/or muscles innervated: 
Foramen through which it passes:

Answer 8

CNI
Name: Olfactory Nerve

Modality/modalities): SVS

Function/functions): smell

Sensory areas and/or muscles innervated: axons of CN I synapse in the olfactory bulb (form synapse with mitral cells called “glomeruli”)

Foramen through which it passes: passes through the cribriform plate of the ethmoid bone

Question 9

For CN II List the following
Name: 
Modality/modalities): 
Function/functions): 
Sensory areas and/or muscles innervated: 
Foramen through which it passes:

Answer 9

CN II
Name: Optic nerve

Modality/modalities): SSS

Function/functions): Sight

Sensory areas and/or
muscles innervated: optic disc

Foramen through which it passes: exits orbit through optic canal

Question 10

For CN III List the following
Name: 
Modality/modalities): 
Function/functions): 
Sensory areas and/or muscles innervated: 
Foramen through which it passes:

Answer 10

CN III
Name: Oculomotor nerve

Modality/modalities): GSM and GVM

Function/functions): eye movement and opening eyelids

Sensory areas and/or muscles innervated: supplies 4 of the 6 extrinsic muscles of the eye

Foramen through which it
passes: superior orbital fissure

Question 11

For CN IV List the following
Name: 
Modality/modalities): 
Function/functions): 
Sensory areas and/or muscles innervated: 
Foramen through which it passes:

Answer 11

CN IV
Name: Trochlear nerve

Modality/modalities): GSM

Function/functions): eye movement

Sensory areas and/or muscles innervated: innervates the superior oblique muscle of the eye

Foramen through which it passes: Enters orbit through the superior orbital fissure

Question 12

For CN VI List the following
Name: 
Modality/modalities): 
Function/functions): 
Sensory areas and/or muscles innervated: 
Foramen through which it passes:

Answer 12

CNVI
Name: Abducens nerve

Modality/modalities): GSM

Function/functions): eye movement

Sensory areas and/or muscles innervated: innervates the lateral rectus muscle of the eye

Foramen through which it passes: Enters orbit through superior orbital fissure

Question 13

For CN VIII List the following
Name: 
Modality/modalities): 
Function/functions): 
Sensory areas and/or muscles innervated: 
Foramen through which it passes:

Answer 13

CN VIII
Name: Vestibulocochlear nerve

Modality/modalities): SSS

Function/functions):
Auditory component: hearing
Vestibular component: Balance

Sensory areas and/or muscles innervated:
Auditory component: Cell bodies in the spiral ganglion of the cochlea
Vestibular component: to the Cell bodies in the vestibular ganglion from the receptors for balance and equilibrium

Foramen through which it passes: Internal acoustic meatus

Question 14

For CN XI List the following
Name: 
Modality/modalities): 
Function/functions): 
Sensory areas and/or muscles innervated: 
Foramen through which it passes:

Answer 14

CN XI
Name: Spinal Accessory Nerve

Modality/modalities): SVM

Function/functions): motor innervation to the neck

Sensory areas and/or muscles innervated: Motor innervation to the Sternocleidomastoid and Trapezius muscles

Foramen through which it passes: Single trunk enters the cranial cavity via the Foramen Magnum
Spinal accessory trunk exits the cranial cavity via the Jugular Foramen

Question 15

For CN XII List the following
Name: 
Modality/modalities): 
Function/functions): 
Sensory areas and/or muscles innervated: 
Foramen through which it passes:

Answer 15

CN XII
Name: Hypoglossal nerve

Modality/modalities): GSM

Function/functions): Supplies the extrinsic and intrinsic muscles of the tongue (Genioglossus, Hyoglossus, and Styloglossus)

Sensory areas and/or muscles innervated: Genioglossus, Hyoglossus, and Styloglossus muscles of the tongue

Foramen through which it passes: exits cranial cavity via the hypoglossal foramen

Question 16

Which CN begins in the ganglionic layer of the retina (not rods and cones)? where does 50% decussation of this CN occur?

Answer 16

CN II (optic)

50% decussation in the optic chiasma

Question 17

Which 2 CN’s are “crossed”? which of these is the only CN to emerge dorsally?

Answer 17

CN IV (trochlear) and CN II (optic)

CN IV (trochlear) is the only nerve to emerge dorsally

Question 18

Describe the origin and the path of CN VI.

Answer 18

CN VI (abducens) originates from the abducens nucleus

It lies on the medial aspect of the lateral rectus muscle

Question 19

Which nerve arises from the C1-3(4) lateral rootlets? what makes this unique?

Answer 19

CN XI (spinal accessory nerve)

It is a combination of dorsal and ventral roots of cervical nerves (uncommon)

Question 20

The cranial roots of the spinal accessory nerve leave with the____ nerve, and the rest of the fibers reach the 2 muscles reffered to as the spinal accessory muscles. Name these 2 muscles.

Answer 20

Vagus

The Sternocleidomastoid and Trapezius muscles are considered the “spinal accessory muscles” (innervated by CN XI)

Question 21

The path of CN XII runs from the ______nucleus to the floor of the ____ ventricle and exits via the hypoglossal foramen.

Answer 21

hypoglossal

4th

Question 22

What 2 structures does CN XII split during it’s path through the neck?

Answer 22

The internal and external jugular veins

Question 23

What type of cell tissue composes the olfactory epithelium? Name the 1 cell type it does not feature that the 2 cell types it does feature.

Answer 23

pseudostratified columnar epithelium

Does NOT have goblet cells

Has Sustentacular cells (support cells with pigment granules)
Has Basal cells (supply the stem cells that replace olfactory epithelium cells when they age)

Question 24

Olfactory cells are____neurons whose apical end feature ____ _____ that extend into the nasal cavity and whose basal end extends as a ______axon through the cribriform plate.

Answer 24

bipolar

non-motile cilia

unmyelinated

Question 25

Where does the basal end of olfactory cell neurons synapse?

Answer 25

in the mitral cells in the olfactory bulb

Question 26

What secretes odorant binding protein that binds to odorant molecules in the nasal cavity?

Answer 26

Olfactory glands of bowman

Question 27

What is considered to be a “slender extension of the forebrain”?

Answer 27

Olfactory Tracts: slender extension of the forebrain