Cranial Nerves

Question 1

What are the cranial nerves?

Answer 1

1. olfactory (smell)
2. optic (vision)
3. oculomotor (eye movement [most extraocular movements], elevation of upper eyelid, pupillary constriction)
4. trochlear (eye movement [down and in])
5. trigeminal (Motor: mm of mastication; Sensory: face, tongue [not taste])
6. abducens (eye movement [lateral deviation])
7. facial (sensory: taste [ant 2/3 tongue]; motor: facial mm)
8. accoustic (balance/equilibrium: vestibular division; hearing: cochlear division)
9. glossopharyngeal (motor: pharynx; sensory: pharynx and posterior tongue, including taste)
10. vagus (motor: palate, pharynx and larynx; sensory: pharynx and larynx, PaNS)
11. accessory (controls trapezius and SCM)
12. hypoglossal (tongue)

Question 2

Which cranial nerves originate in the brainstem?

Answer 2

CN 3-12

Question 3

Cranial nerves are numbered according to what sequence?

Answer 3

order in which they leave the brain (from sup. to inf.)

Question 4

The olfactory nerve is a collection of sensory nerve rootlets that pass through the many openings of the:

Answer 4

cribiform plate of the ethmoid

Question 5

Hair cells in the nose have ___ on one side and an ___ on the other side in order to transduce chemical activity into APs.

Answer 5

cilia; axon

Question 6

About how many olfactory receptors are in humans? In german sheppards?

Answer 6

40 million; 2 billion

Question 7

People with no sense of smell have a disorder called:

Answer 7

anosmia

Question 8

An olfactory hallucination is called:

Answer 8

phantosmia

Question 9

A condition in which a smell that’s present in the environment is distorted:

Answer 9

parosmia

Question 10

What’s the aka for the blind spot in the eye?

Answer 10

scotoma

Question 11

The clinical term for near-sightedness.

Answer 11

myopia (means you can see better close up than far away

Question 12

The clinical term for far-sightedness.

Answer 12

hyperopia (mean you can see better far away than close up)

Question 13

Myopia and hyperopia are due to:

Answer 13

a misshapen cornea, the transparent part of the eye that covers the iris and pupil

Question 14

With ___ a person has difficulty focusing on an object that is close up.

Answer 14

presbyopia

Question 15

A ___ is a clouding of the lens most commonly due to aging.

Answer 15

cataract

Question 16

The central portion of the retina is called the:

Answer 16

macula

Question 17

___ is a term for a group of disorders that result in optic nerve damage, often associated with increased fluid intraocular pressure.

Answer 17

glaucoma

Question 18

What does the oculomotor (CN 3) supply?

Answer 18

• most of the extrinsic muscles of the eye, except the lateral rectus and superior oblique
• also supplies levator palpebrae superioris which lifts the upper eyelid
• supplies the ciliary muscle which adjusts the lens of the eye
• also supplies the sphincter pupillae which constricts the pupil

Question 19

What does the trochlear nerve (CN 4) do?

Answer 19

motor to the superior oblique muscle; turns eye downward

Question 20

What does the abducens (CN VI) do?

Answer 20

motor to lateral rectus muscle; abducts eye

Question 21

The largest and most complex of the cranial nerves, what does the trigeminal nerve (CN V) supply?

Answer 21

• supplies sensations to the face, mucous membranes and other structures of the head
• motor nerve for muscles of mastication and contains proprioceptive fibres

Question 22

What are the divisions of the trigeminal nerve (CN V)?

Answer 22

• ophthalmic division (CN Vi)
• maxillary division (CN Vii)
• mandibular division (CN Viii)

Question 23

What’s the sensory function of the trigeminal nerve (CN V)?

Answer 23

carry somatic sensory info (touch, pain, thermal) from the skin of the face, mucous membranes of the nasal and oral cavities including sinuses

Question 24

What’s the motor function of CN Viii?

Answer 24

muscles of mastication

Question 25

This condition, dealing with CN V, is considered to be one of the most painful afflictions known

Answer 25

trigeminal neuralgia

Question 26

What does the facial nerve (CN VII) supply and detect?

Answer 26

* all muscles of facial expression including orbicularis oculi but NOT levator palpebrae superioris (that's CN 3) * CN 7 closes the eye, CN 3 opens the eye * taste * lacrimal glands * sublingual and submandibular glands (salivvary glands) * muscous glands of the nose

Question 27

This form of flaccid paralysis or weakening develops suddenly. It's associated with damage to CN 7 due to viral infections, trauma, pressure from a tumor. Can strike any age but disproportionately attacks pregnant women and people with diabetes. 85% of people start recovering in three week, even without treatment.

Answer 27

bell's palsy

Question 28

Flaccid paralysis is weakness or loss of muscle tone resulting from injury or disease of \_\_\_; spastic paralysis is cause by injury or disease affecting \_\_\_

Answer 28

PNS (LMNs); CNS (UMNs)

Question 29

What are the akas for the vestibulocochlear nerve (CN 8)?

Answer 29

acoustic nerve, auditory nerve

Question 30

What are the two separate components that travel together from the inner ear as CN 8?

Answer 30

* vestibular nerve carries impulses for equilibrium (balance) * cochlear nerve carries impulses for hearing

Question 31

Sound waves converge through the ___ (part of the ear that's outside the head) and outer ear canal to strike the tympanic membrane

Answer 31

auricle (aka pinna)

Question 32

The vibrations of the tympanic membrane are transmitted by way of 3 ___ to the \_\_\_

Answer 32

ossicles (malleus, incus, stapes); cochlea ("snail-like")

Question 33

The ___ contains hair cells whose mechanical distortions are transduced into APs

Answer 33

cochlea

Question 34

What are the sensory functions of the vagus nerve (CN 10)?

Answer 34

viscera and glands of the neck (larynx, trachea, esophagus), thoracic viscera, abdominal viscera, proximal colon

Question 35

What are the motor functions of the vagus nerve (CN 10)?

Answer 35

organs and glands of the neck, thorax and abdomen up to the proximal colon

Question 36

what does the vagus nerve innervate?

Answer 36

* levator veli palantini (elevates the soft palate to help prevent food from entering the nasopharynx) * pharyngeal constrictors * muscles of the larynx (speech) * regulate heart rate, gastrointestinal peristalsis and sweating * afferent vagus nerve fibres innervating the pharynx are responsible for the gag reflex * regulates the chemical levels in the digestive system so that the intestines can process food and keep track of what types of nutrients are being gained from the food that is taken in

Question 37

Which nerves control eye movement?

Answer 37

3. oculomotor (eye movement [most extraocular movements], elevation of upper eyelid, pupillary constriction) 4. trochlear (eye movement [down and in]) 6. abducens (eye movement [lateral deviation])

Question 38

Which nerves sense taste?

Answer 38

* CN VII facial * sensory: taste (ant 2/3 tongue) * motor: facial mm * CN IX glossopharyngeal * motor: pharynx * sensory: pharynx and posterior tongue, including taste

Question 39

What does the accessory nerve (CN 11) innervate?

Answer 39

motor to SCM and trapezius

Question 40

Patients with ___ \_\_\_ present with the head twisted to the affected side and chin pointed toward the opposite shoulder.

Answer 40

acquired torticollies

Question 41

What does the hypoglossal nerve (CN12) innervate?

Answer 41

* all intrinsic tongue mm * most extrinsic tongue mm (ex genioglossus)

Question 42

What's the translation of malleus, incus and stapes?

Answer 42

hammer, anvil, stirrup

Question 43

What are some things that can happen as a result of an underactive vagus nerve?

Answer 43

* can lead to gastroparesis, a frequent and severe complication of diabetes * sufferers may experience: * stomach pain * nausea * heartburn * stomach spasms * weight loss * therapy can include vagus nerve stimulation via a device, similar to a pacemaker, attached to the nerve

Question 44

What are some things that can happen as a result of an overactive vagus nerve?

Answer 44

* over activation of the vagus nerve during emotional stress is a parasympathetic overcompensation of a strong sympathetic nervous system response associated with stress, can cause: * vasovagal syncope * can also lead to temporary loss of bladder control under moments of extreme fear * can cause vasovagal syncope (fainting) due to a sudden drop in cardiac output. triggers include: * prolonged standing, especially when combined with warm temperatures, confined spaces, and/or crowding * emotional situations especially those of sudden onset * pain * fasting * fatigue/lack of sleep * menstruation * illness with fever * standing quickly