Head and neck cranial nerves pt 2

Question 1

What are the 3 branches of CN V?

Answer 1

ophthalmic - V1
maxillary - V2
mandibular - V3

Question 2

where does the ophthalmic nerve exit?

Answer 2

superior orbital fissure

Question 3

where does the maxillary nerve exit?

Answer 3

foramen rotunda

Question 4

where does the mandibular nerve exit?

Answer 4

foramen ovale

Question 5

what is it called when one branch of the trigeminal nerve becomes hypersensitive to pain? what is it often caused by?

Answer 5

trigeminal neuralgia
blood vessel pushing against affected nerve

Question 6

Which branch is the only one that contains both sensory and motor axons?

Answer 6

mandibular nerve
for mastication

Question 7

If the mandibular nerve was damaged, what are some observable signs?

Answer 7

demonstrable loss of bite strength
jaw deviating toward the lesioned side when mouth is actively open

Question 8

What are some important functions of the facial nerve? (CN VII)

Answer 8

1) Six branches innervate muscles of facial expression
2) Sensory to some of the ear
3) Taste sensation to anterior tongue
3) Innervation to lacrimal, submandibular, and sublingual glands

Question 9

If there was a lesion on one of the branches of the facial nerve, what could it de-innervate?

Answer 9

-temporal
-zygomatic
-buccal
-mandibular
-cervical
-posterior auricular

Question 10

Paralysis or weakness to one side of the face is called ______

Answer 10

Bell’s Palsy
Peripheral CN VII

Question 11

What would happen if there was a lesion centrally located within the cortex/brainstem?

Answer 11

Similar signs to Bell’s palsy but will have the ability to generate wrinkles to entire forehead, not partial

Question 12

What muscle does the facial nerve innervate in the middle ear?

Answer 12

stapedius

Question 13

The result of de-innervation of the stapedius muscle would result in _______: sounds are abnormally and painfully loud

Answer 13

hyperacusis

Question 14

What are the 2 parasympathetic nerves of the facial nerve that innervate glands?

Answer 14

Greater petrosal nerve –> lacrimal nerve
Chorda tympani –> submandibular & sublingual glands

Question 15

Besides loss of facial expression, what else can lesions to the facial nerve lead to? (hint: eyes, mouth)

Answer 15

De-innervation of:
lacrimal gland = dry eyes
submandibular & sublingual = dry mouth, altered taste sensations

Question 16

What does vestibulocochlear (CN VIII) innervate?

Answer 16

organs of balance and hearing encased within temporal bone

Question 17

What lesion or impingements can lead to altered equilibrium and hearing?

Answer 17

Very proximal facial nerve lesion
acoustic neuronma/schwannoma - both facial and vestibulocochlear nerve enter the skull through internal acoustic meatus

Question 18

What are the 2 subdivisions of the vestibulocochlear called?

Answer 18

vestibular nerve (balance and equilibrium)
cochlear nerve (hearing)

Question 19

What is the auricle (external ear) made out of?

Answer 19

hyaline cartilage

Question 20

What is the auricle innervated by?

Answer 20

CN V3, VII, and upper cervical spinal nerves

Question 21

What are the 3 ossicles of the middle ear?

Answer 21

malleus
incus
stapes

Question 22

Describe the process of how we hear

Answer 22

1) sound waves push the tympanic membrane, moving the three ossicles of the middle ear
2) stapes pushes into the oval window of the inner ear
3) vibrations of the oval window stimulates the cochlea. The fluid inside moves which causes the basilar membrane to vibrate
4) The hair cells in the organ of corti of the cochlea responds to the movement of the basilar membrane, converting the waves into electrical signals

Question 23

What are the semicircular canals filled of?

Answer 23

endolymph

Question 24

How does the ear play a role in balance and equilibrium?

Answer 24

1) the inner ear senses head movement by the semicircular canals and otolith organs (utricle and saccule)
2) The ampulla of the semicircular canals detects rotational head movement. Inside is the cupula. As fluid moves, cupula deforms and stimulates sensory cilia to create nerve impulses sending to the brain via vestibular nerve
3) The otoliths move and shift the membrane, causing the hair cells to bend
4) bending of the hair cells create electrical signals which sends to the brain via vestibular nerve