Cranial nerves

Question 1

What nerve innervates the muscles of mastication?

Answer 1

Trigeminal nerve (V3)

Question 2

What are the muscles of mastication?

Answer 2

3 close the jaw:

• -masseter
• -temporalis
• -medial pterygoid

1 opens the jaw: lateral pterygoid

Question 3

Result of facial nerve (CN VII) lesion

Answer 3

• -ipsilateral facial paralysis (paralysis of muscles of facial expression)
• -inability to close eye (orbicularis oculi)
• -loss of corneal reflex (efferent limb)

if the lesion is to the proximal facial nerve:

• -loss of taste sensation to anterior 2/3 of the tongue
• -hyperacusis (increased sensitivity to sound because of paralysis of stapedius muscle)
• -disturbed lacrimation and salivation

Question 4

What is facial nerve palsy?

Answer 4

complete destruction of the facial nerve nucleus itself, or its effert fibers (the facial nerve)

Question 5

With regard to facial lesions, where would an upper motor neuron lesion be, and what would be the result?

Answer 5

Lesion of the motor cortex or connection between the cortex and the facial nucleus.

Results in contralateral paralysis of lower face.
**The forehead is spared due to bilateral UMN innervation

Question 6

What would be the result of a lower motor neuron (LMN) lesion to the facial pathway

Answer 6

ipsilateral paralysis of the upper and lower face.

Question 7

What diseases is facial nerve palsy associated with?

Answer 7

• -Lyme disease
• -herpes simplex
• -herpes zoster (less common)
• -sarcoidosis
• -tumors
• -diabetes

Question 8

Treatment of facial nerve palsy

Answer 8

corticosteroids

Question 9

An inability to chew would result from a lesion to what nerve?

Answer 9

Trigeminal (V3)

a lesion of this nerve would cause the jaw to deviate to the side of the lesion (side of muscle weakness) due to unopposed force from opposite pterygoid muscle

Question 10

Physical exam manifestation of a CN X lesion

Answer 10

uvula deviates away from the side of the lesion

Question 11

Physical exam manifestation of CN XII lesion

Answer 11

Tongue deviates toward the side of the lesion due to weakened tongue muscles on affected side.

(genioglossus, hypoglossus, styloglossus)

Question 12

Physical exam manifestation of CN XI lesion

Answer 12

Weakness turning head to contralateral side of lesion (Right sternocleidomastoid contracts to turn head to the left)

Shoulder droop/weakness in attempt to shrug shoulder on the side of the lesion (trapezius)

Question 13

Impairment of facial sensation would result from a lesion to what nerve?

Answer 13

Trigeminal

Question 14

The three cranial nerves that supply taste

Answer 14

7, 9, 10

Question 15

What nerve is required to say “mi”?

Answer 15

CN 7 is needed to move the lips while saying “mi”

Question 16

What nerve is needed to say “kuh”?

Answer 16

CN X is needed to raise the palate while saying “kuh”

Question 17

What nerve carries general somatic sensation from the posterior part of the upper pharynx?

Answer 17

CN IX

Question 18

gag relfex afferent, efferent?

Answer 18

CN 9, 10