Ear

Question 1

What is human hearing range?

Answer 1

20hz-20,000hz

Question 2

What is the function of the outer ear?

Answer 2

Collects sound

Question 3

What is the function of the middle ear?

Answer 3

Transmits sound

Question 4

What is the function of the inner ear?

Answer 4

Converts sound into neural impulses.

Question 5

Give the components of the outer ear.

Answer 5

Auricle, external auditory canal, tympanic membrane

Question 6

Give the components of the middle ear.

Answer 6

Hammer, anvil, stirrup

Question 7

Give the components of the inner ear.

Answer 7

Semicircular canals, oval window, cochlea

Question 8

Where is the middle ear?

Answer 8

Temporal bone of the skull

Question 9

Which nerve innervates the middle ear?

Answer 9

CN IX : Glossopharyngeal

Question 10

What connects the middle ear to the pharynx?

Answer 10

Eustachian tube. This exposes the middle ear to atmospheric pressure.

Question 11

What causes a difference in pressure between the middle and outer ear?

Answer 11

Changes in altitude

Question 12

Vibrations of the tympanic membrane transmit to the inner ear via which bones?

Answer 12

Ossicles (smallest bones in body) which have synovial joints:
Malleus
Incus
Stapes

Question 13

Is the cochlear air or fluid filled?

Answer 13

Fluid filled

Question 14

What membrane lies between the middle and inner ear?

Answer 14

Oval window

Question 15

Which muscles in the middle ear control the amount of energy transmitted to the inner ear?

Answer 15

Tensor tympani

Stapedius

Question 16

Which nerve innervates tensor tympani?

Answer 16

CN V, V3

Mandibular branch of trigeminal nerve

Question 17

Which nerve innervates stapedius?

Answer 17

CN VII

Facial nerve

Question 18

Which bone does tensor tympani attach to?

Answer 18

Malleus

Question 19

Which bone does stapedius attach to?

Answer 19

Stapes

Question 20

Which membranous tube divides the cochlear lengthwise?

Answer 20

Cochlear duct

Contains sensory receptors

Question 21

What fluid does the cochlea duct contain?

Answer 21

Endolymph: high K+, low Na+

Question 22

What structures lie above and below the cochlear duct?

Answer 22

Above: Scala vestibuli
Below: Scala tympani

Question 23

Briefly outline the path of sound transmission in the ear.

Answer 23

External acoustic meatus > Tympanic membrane > Ossicles > Oval window >
Scala vestibuli > Cochlear duct > Organ of Corti

Question 24

What are the receptor cells on the Organ of Corti called?

Answer 24

Hair cells. They are mechanoreceptors that have stereo-cilia. There are inner and outer hair cells.

Question 25

What is the function of inner hair cells?

Answer 25

Stereo-cilia extend into the endolymph. They convert pressure waves caused by movement of cochlear fluid into receptor potentials.

Question 26

What is the function of outer hair cells?

Answer 26

Stereo-cilia are embedded in overlying tectorial membrane. They mechanically alter its movement to sharpen frequency tuning.

Question 27

What are the spiral ganglion and where do they lie?

Answer 27

These are the cell bodies of cochlear nerve fibres. They lie within the cochlea.

Question 28

Briefly outline the pathway of neural transmission in hearing.

Answer 28

Cochlear nerve > Second order neurones in pons > Superior olivary nucleus > Inferior colliculus of midbrain > Inferior branchium nerve fibre > Medial geniculate body of thalamus > Internal capsule > Primary auditory cortex of temporal lobe

Question 29

What region of the temporal lobe surrounds the primary auditory cortex?

Answer 29

Wernicke's area

Question 30

What happens if Wernicke's area is damaged?

Answer 30

Wernicke's area processes language in the brain. If damaged, the patient will not be able to understand speech and their speech will be incomprehensible.

Question 31

What nerve is the cochlear nerve a branch of?

Answer 31

CN VIII | Vestibulocochlear nerve

Question 32

What does I'M Auditory stand for?

Answer 32

Inferior colliculus, Medial geniculate body, for Auditory information

Question 33

What is Bell's palsy?

Answer 33

Acute unilateral inflammation of facial nerve. Results in pain behind the ear, paralysis of facial muscles and failure to close eye.

Question 34

What is the vestibular apparatus?

Answer 34

Found in the inner ear. A series of endolymph-filled membranous tubes.

Question 35

What are the two sac swellings in the vestibular apparatus?

Answer 35

Utricle and saccule.

Question 36

How many semicircular canals does the vestibular apparatus contain?

Answer 36

Three

Question 37

What is the function of the semicircular canals?

Answer 37

They detect angular acceleration during rotation of the head.

Question 38

How is glutamate linked to the direction of stereo-cilia movement?

Answer 38

Each hair cell receptor has one direction of maximum glutamate release. When bent in one direction, the receptor cell depolarises. When bent in the opposite direction, the receptor cell hyperpolarises.

Question 39

What is nystagmus?

Answer 39

Rapid jerky movement of the eyes. Caused by damage to semicircular canals on one side.

Question 40

What is the function of the utricle and saccule?

Answer 40

They provide information about linear acceleration of the head and changes in head position in relation to gravity.

Question 41

How do the hair cells in the utricle stand?

Answer 41

They point straight up when the body is standing. They respond when the head is tipped away from the horizontal plane.

Question 42

How do the hair cells in the saccule stand?

Answer 42

They project at right angles to those of the utricle. They respond when you move from lying down to a standing position.

Question 43

What are otoliths?

Answer 43

Calcium carbonate crystals in a gelatinous substance that cover stereo-cilia.

Question 44

Briefly outline the usage of vestibular information.

Answer 44

1. Control of eye movement. In spite of head movement, eyes can remain fixed on the same point. 2. Reflex mechanisms of maintaining upright posture and balance 3. Conscious awareness of the position and acceleration of the body i.e. proprioception.