Cranial Nerves

Question 1

What are the 12 cranial nerves in order?

Answer 1

Olfactory (I), Optic (II), Oculomotor (III), Trochlear (IV), Trigeminal (V), Abducens (VI), Facial (VII), Vestibulocochlear (VIII), Glossopharyngeal (IX), Vagus (X), Accessory (XI), Hypoglossal (XII).

Question 2

What is the function of the olfactory nerve (CN I)?

Answer 2

The olfactory nerve is responsible for the sense of smell.

Question 3

What is the function of the optic nerve (CN II)?

Answer 3

The optic nerve transmits visual information from the retina to the brain.

Question 4

What is the function of the oculomotor nerve (CN III)?

Answer 4

Controls most of the eye movements, pupillary constriction, and eyelid elevation.

Question 5

What is the function of the trochlear nerve (CN IV)?

Answer 5

Innervates the superior oblique muscle, which moves the eye downward and inward.

Question 6

What is the function of the trigeminal nerve (CN V)?

Answer 6

Provides sensory innervation to the face and motor control to the muscles of mastication.

Question 7

What are the three branches of the trigeminal nerve?

Answer 7

Ophthalmic (V1), Maxillary (V2), Mandibular (V3).

Question 8

What is the function of the abducens nerve (CN VI)?

Answer 8

Innervates the lateral rectus muscle, which abducts the eye.

Question 9

What is the function of the facial nerve (CN VII)?

Answer 9

Controls muscles of facial expression, taste (anterior 2/3 of the tongue), salivation, and lacrimation.

Question 10

What is the function of the vestibulocochlear nerve (CN VIII)?

Answer 10

Responsible for hearing and balance.

Question 11

What is the function of the glossopharyngeal nerve (CN IX)?

Answer 11

Taste (posterior 1/3 of the tongue), swallowing, salivation, and monitoring carotid body/sinus.

Question 12

What is the function of the vagus nerve (CN X)?

Answer 12

Autonomic control of the heart, lungs, digestion, and motor function in speech and swallowing.

Question 13

What is the function of the accessory nerve (CN XI)?

Answer 13

Controls the sternocleidomastoid and trapezius muscles for head and shoulder movements.

Question 14

What is the function of the hypoglossal nerve (CN XII)?

Answer 14

Controls tongue movements.

Question 15

What is anosmia?

Answer 15

Loss of smell, which can result from CN I dysfunction.

Question 16

What conditions can cause optic nerve (CN II) damage?

Answer 16

Stroke, demyelination (multiple sclerosis), tumors, and optic neuritis.

Question 17

What is ptosis and which cranial nerve is responsible?

Answer 17

Drooping of the eyelid due to CN III dysfunction.

Question 18

What is the clinical presentation of trochlear nerve (CN IV) palsy?

Answer 18

Vertical diplopia and head tilt away from the affected side.

Question 19

What is trigeminal neuralgia?

Answer 19

Severe, recurrent facial pain along the trigeminal nerve distribution.

Question 20

What is the corneal reflex and which cranial nerves are involved?

Answer 20

A protective reflex where touching the cornea causes blinking; CN V (afferent) and CN VII (efferent) are involved.

Question 21

What is Bell’s palsy?

Answer 21

Idiopathic facial nerve (CN VII) paralysis causing unilateral facial drooping.

Question 22

What is the Rinne test?

Answer 22

A test to differentiate conductive vs. sensorineural hearing loss using a tuning fork.

Question 23

What is the Weber test?

Answer 23

A test where a tuning fork is placed on the forehead to assess hearing loss laterality.

Question 24

What happens in a CN IX lesion?

Answer 24

Loss of gag reflex, impaired swallowing, and taste loss in the posterior 1/3 of the tongue.

Question 25

What is uvula deviation in CN X lesion?

Answer 25

The uvula deviates away from the side of the lesion.

Question 26

What is the role of the vagus nerve in the autonomic nervous system?

Answer 26

Regulates parasympathetic functions, including heart rate and digestion.

Question 27

What is the effect of CN XI palsy?

Answer 27

Weakness in turning the head (sternocleidomastoid) and shoulder shrugging (trapezius).

Question 28

What is tongue deviation in CN XII lesion?

Answer 28

The tongue deviates toward the side of the lesion when protruded.

Question 29

Which cranial nerves are purely sensory?

Answer 29

CN I (Olfactory), CN II (Optic), CN VIII (Vestibulocochlear).

Question 30

Which cranial nerves are purely motor?

Answer 30

CN III (Oculomotor), CN IV (Trochlear), CN VI (Abducens), CN XI (Accessory), CN XII (Hypoglossal).

Question 31

Which cranial nerves are mixed (sensory and motor)?

Answer 31

CN V (Trigeminal), CN VII (Facial), CN IX (Glossopharyngeal), CN X (Vagus).

Question 32

What are the autonomic functions of the cranial nerves?

Answer 32

CN III (pupillary constriction), CN VII (lacrimation and salivation), CN IX (salivation), CN X (parasympathetic control of heart and gut).

Question 33

What is nystagmus and which cranial nerve is involved?

Answer 33

Involuntary eye movements, involving CN VIII.

Question 34

What is diplopia?

Answer 34

Double vision, often due to dysfunction of CN III, IV, or VI.

Question 35

What is Horner’s syndrome?

Answer 35

Ptosis, miosis, and anhidrosis due to sympathetic pathway disruption.

Question 36

What is the function of the superior oblique muscle and which cranial nerve innervates it?

Answer 36

Depresses and abducts the eye, innervated by CN IV.

Question 37

What is the function of the lateral rectus muscle and which cranial nerve innervates it?

Answer 37

Abducts the eye, innervated by CN VI.

Question 38

What happens in an optic chiasm lesion?

Answer 38

Bitemporal hemianopia due to compression of crossing nasal retinal fibers.

Question 39

What is the main blood supply to the cranial nerves?

Answer 39

Branches of the vertebrobasilar system and internal carotid arteries.

Question 40

What is the function of the pupillary light reflex and which nerves are involved?

Answer 40

Constricts the pupil in response to light; CN II (afferent) and CN III (efferent).

Question 41

What is dysarthria and which cranial nerves are involved?

Answer 41

Slurred speech due to CN V, VII, IX, X, or XII dysfunction.

Question 42

Which cranial nerve is responsible for taste in the anterior 2/3 of the tongue?

Answer 42

CN VII (Facial nerve).

Question 43

Which cranial nerve is responsible for taste in the posterior 1/3 of the tongue?

Answer 43

CN IX (Glossopharyngeal nerve).

Question 44

Which cranial nerve innervates the parotid gland?

Answer 44

CN IX (Glossopharyngeal nerve).

Question 45

What is trigeminal autonomic cephalalgia?

Answer 45

A group of severe unilateral headache disorders involving CN V.

Question 46

What is the function of the spinal trigeminal nucleus?

Answer 46

Processes pain and temperature sensation from the face (CN V).

Question 47

What is the function of the nucleus ambiguus?

Answer 47

Motor control of CN IX and CN X for swallowing and phonation.

Question 48

What is the consequence of a lesion in the nucleus solitarius?

Answer 48

Loss of taste and autonomic dysfunction.

Question 49

What is the function of the Edinger-Westphal nucleus?

Answer 49

Parasympathetic control of the pupil via CN III.