Hearing and Balance Mechanoreceptors

What is the difference between Optic and Otic

Optic refers to eye and Otic refers to ear

What are the 3 section of ear?

Outer (external) ear, Middle (ossicles) ear for hearing and inner (labyrinth) ear for hearing and equilibrium

What are the 7 main parts of ear?

Tympanic Membrane, Malleus (Hammer), Incus (Anvil), Stapes (stirrup), Oval Window, Cochlea and Semicircular Canals.

What is the function of 3 small bones (Malleus, Incus and Stapes)

Tympanic membrane vibrates in response to sound waves
Malleus vibrates due to change in Tympanic Membrane
Incus vibrates due to change in Malleus
Stapes vibrates due to change in incus

What is the function of Oval Window?

Oval Window moves fluid within cochlea in response to vibrations from stapes

What in the function of Cochlea?

Contains receptors that react to changes in sound waves

What is of Semicircular Canals and its function in ear?

Fluid-filled structures that respond to changes in body position.

What happens after sound waves enter oval window

Vibrations cause disturbance in:
- perilymph → endolymph → basilar membrane → tectorial membrane → hair cells

_____ frequency is detected close to oval window

Highest

_____ frequency is detected further from oval window

Lowest

What are mosquito ring tones?

High pitched ring tones

Fire alarms use _____ frequency tones so that older people can hear them

low

Volume is associated with ______ and pitched is associated with ______

Volume is for Amplitude
Pitch is for frequency

Movement of fluid surrounding the receptors causes ______ to move and triggers an action potential in ear

Sterocilia

What are ossciles

3 small bones on our body: Malleus (hammer), Incus (anvil) and Stapes (stirrup)

What are the First 3 steps sound transmission?

1. Sound in the external acoustic meatus hits the tympanic membrane (eardrum), causing it to vibrate.

2. Pressure is equalized by the pharyngotympanic tube (aka eustachian or auditory tube), which is about 45 mm long

3. The TM (aka eardrum) causes the ossicles in the air-filled middle ear to move.

What are the last 4 steps in sound transmission?

4. The ossicles articulate to form a lever system that amplifies and transmits the vibratory motion of the TM to fluids of the inner ear cochlea via oval window

5. Vibration of the stirrup (stapes) at the oval window causes waves to start traveling in the fluid filled cochlea

6. Sensory hair cells (stereocilia) are stimulated

7. The stereocilia send impulses to the cochlear nerve, a division of Nerve VIII (vestibulocochlear nerve)

What does information go from cochlear nerve?

Cochlear Nerve -> Medulla -> Pons -> Midbrain -> Thalamus -> primary auditory cortex (temporal lobe)

What are the 3 parts of the middle ear and their fuctions?

1. Cochlea: hearing
2. Vestibule: equilibrium
3. Semicircular canals: equilibrium

What is the difference between semicircular canal and vestibule?

Semicircular canal: Determines kinetic (rotational) equilibrium

Vestibule (ortholitic organs of utricle & saccule): Determine static equilibrium

What are the 3 parts of Semicircular canal and functions?

- Transverse - right/left movement
- Coronal - tilting
- Sagittal - forward / backward

What are the 2 parts of the Vestibule?

Utricle - manages body position due to horizontal gravity
Saccule - manages body position due to vertical gravity

How does vestibule and semicircular canal assist in signal transmission to brain?

1. When your head moves, fluid inside of the vestibule and semicircular canals moves.

2. The movement of the fluid causes the hair cells to move

3. The movement of the hair cells sends an electrical impulse to the vestibular nerve

4. The vestibular nerve (via the vestibulocochlear never) transmits the signal to the cerebellum, brain stem, and spinal cord.

What are the 2 types of vestibular disorders?

Vertigo and Nystagmus

What is Vertigo?

a sensation of spinning.

What causes vertigo?

Vertigo is often caused by inner ear problem (build up of fluid, clumping of calcium particles or an infection)

What is Nystagmus?

"dancing eyes."
Eyes move uncontrollably up and down, side to side, or in a circle.

What causes Nystagmus?

Cataracts, strokes, head injuries, inner ear problems, or certain medications.