CH14: Cranial nerves 2

Question 1

Which reflexes involve the optic and oculomotor nerves?

Answer 1

• pupillary
• consensual
• accommodation

Question 2

What is the pupillary reflex?

Answer 2

Pupil constricts when light is shined in the eye

Question 3

What is the consensual reflex?

Answer 3

Pupil of eye constricts when light shined into opposite eye

Question 4

What is the accommodation reflex?

Answer 4

• Lens adjusts to focus light on the retina
• Pupil constricts
• Pupils move medially
  (when viewing object at close range)

Question 5

What is the stimulus for the pupillary and consensual reflexes?

Answer 5

light shined in the eye

Question 6

How are the eyes innervated by the ANS?

Answer 6

• parasympathetic (CN III, constricts pupil)

- sympathetic (dilates pupil)

Question 7

3 branches of the trigeminal nerve

Answer 7

• ophthalmic (somatosensory)
• maxillary (somatosensory)
• mandibular (somatosensory/motor)

Question 8

trigeminal nerve sensory nerve fibers transmit info from

Answer 8

• face

- TMJ

Question 9

trigeminal nerve motor fibers transmit info to

Answer 9

muscles of mastication

Question 10

Which reflexes are mediated by the trigeminal nerve?

Answer 10

• masseter

- corneal

Question 11

What is the masseter reflex?

Answer 11

Masseter contracts when tapped with reflex hammer

Question 12

masseter reflex

• afferents
• efferents

Answer 12

trigeminal (both)

Question 13

What is the corneal reflex?

Answer 13

• “blink”

- Eyelids close when cornea is touched

Question 14

corneal reflex

• afferents
• efferents

Answer 14

• trigeminal

- facial

Question 15

Which muscles are innervated by the facial nerve?

Answer 15

• muscles of facial expression
• most glands in the head (salivary, nasal, lacrimal)
• eye closure
• lip movements

Question 16

Aside from facial expression and glandular info, what other sensory info does the facial nerve convey?

Answer 16

• info from posterior ear canal
• taste from anterior tongue (to solitary nucleus)
• touch, pain, and pressure info from the tongue, pharynx, and skin near the ear canal to the trigeminal spinal nucleus

Question 17

Where are signals to and from CN VII processed?

Answer 17

• pons
• medulla
• upper spinal cord

Question 18

What are the branches of the vestibulocochlear nerve?

Answer 18

• vestibular branch

- cochlear branch

Question 19

function of vestibular branch of CN VIII

Answer 19

Transmits information about head position and head movement

Question 20

function of cochlear branch of CN VIII

Answer 20

transmits info related to hearing

Question 21

Where are peripheral receptors for CN VIII functions?

Answer 21

in the inner ear (labyrinth)

Question 22

labyrinth consists of

Answer 22

• vestibular apparatus

- cochlea

Question 23

What does auditory information do in the CNS?

Answer 23

• orients head and eyes toward sounds
• increases activity level throughout the CNS
• provides conscious awareness and recognition of sounds

Question 24

cochlea

Answer 24

Snail shell–shaped organ formed by a spiraling, fluid-filled tube.

Question 25

What divides the cochlea into upper and lower chambers?

Answer 25

basilar membrane

Question 26

What is the basilar membrane?

Answer 26

consists of fibers oriented across the width of the cochlea

Question 27

Scala vestibuli is divided by a membrane that separates

Answer 27

• cochlear duct

- remainder of upper chamber

Question 28

vestibulocochlear signals are first processed by this

Answer 28

cochlear nuclei

Question 29

From the cochlear nuclei, signals are transmitted to these 3 structures

Answer 29

• reticular formation
• inferior colliculus
• medial geniculate body

Question 30

connections to the reticular formation account for

Answer 30

activating effect on CNS (loud sound wakes you up)

Question 31

What happens in the inferior colliculus?

Answer 31

directly and via the superior olive, auditory info is integrated from both ears to DETECT LOCATION OF SOUNDS

Question 32

function of medial geniculate body

Answer 32

Serves as a thalamic relay station for auditory information to the primary auditory cortex

(where sounds reach conscious awareness)

Question 33

What are the designated cortical areas for processing auditory information?

Answer 33

• primary auditory cortex
• auditory association cortex
• Wernicke’s area

Question 34

primary auditory cortex

Answer 34

site of conscious awareness of the intensity of sounds

Question 35

auditory association cortex

Answer 35

compares sounds with memories of other sounds, then categorizes the sounds as language, music, or noise

Question 36

Wernicke’s area

Answer 36

where comprehension of spoken language occurs

Question 37

sound waves » cochlea

Answer 37

• strike eardrum (tympanic membrane)
• ossicles move, causing vibration of membrane at opening of upper chamber
• fluid in upper chamber moves
• basilar membrane and attached hair cells vibrate
• hair cells bend and depolarize
• cochlear nerve endings activated

Question 38

Why do hair cells bend?

Answer 38

embedded in immobile tectorial membrane