- Ear Anatomy chapter 11

Outer Ear

Collects sound waves and transmits them to the middle and inner ear.

Pinna

Part of the outer ear that collects sound.

External Auditory Canal

The canal that leads into the middle and inner ear, measuring approximately 2.5 cm.

Ceruminous Glands

Modified sweat glands that produce ear wax (cerumen).

Tympanic Membrane

Also known as the ear drum; it vibrates in response to sound waves.

Middle Ear

Contains three ossicles that conduct sound waves to the inner ear.

Malleus

The hammer-shaped bone in the middle ear that is attached to the tympanic membrane.

Incus

The anvil-shaped bone in the middle ear that is connected to the malleus.

Stapes

The stirrup-shaped bone in the middle ear that touches the bony labyrinth.

Bony Labyrinth

The rigid, bony structure that houses the membranous labyrinth within the inner ear. Outer shell of inner ear

Vestibule

The area of the inner ear that contains equilibrium receptors.

Auditory (Eustachian) Tube

The canal that connects the middle ear to the nasopharynx and helps control ear pressure.

Conductive Hearing Loss

Loss of hearing due to blockages or issues of sounwaves with the tympanic membrane or ossicles.

Utricle

Part of the inner ear that responds to horizontal acceleration in forward direction.

Otoconia Crystals + gel membrane

made of Calcium carbonate crystals that influence hair cells' in opposite direction of motion in the inner ear.

Gateways on stereocilia that depolarize to create an action potential signal.

What is the function of ion channels on stereocilia?

Cranial nerve VIII responsible for hearing and balance

Vestibulocochlear Nerve

Saccule

Senses vertical movement, such as tilting the head up or down.

Otolithic Membrane

Membrane that pushes stereocilia on hair cells when looking down.

Semicircular Canals

Part of the bony labyrinth vestibular apparatus that senses rotational movement.

Ampullae

Regions in semicircular canals that house hair cells + cilia extending out to gelatinous culpa

Crista Ampullaris

Sensory organ in semi-circular canals containing hair cells.

When spinning, endolymph fluid flows in the opposite direction of rotation and pushes the cupula and cilia, leading to afferent depolarization.

How does endolymph movement affect cupula and cilia during rotation?

Lateral Canal

Semicircular canal that senses left and right head rotation.

Posterior Canal

Semicircular canal that senses rotation for right ear to touch right shoulder.

Anterior Canal

Semicircular canal that senses up and down movement.

Organ of Corti

Structure that transduces mechanical sound waves into nerve impulses.

Sound waves from stapes enter the oval window of the cochlea (a part of the bony labyrinth) to the perilymph.

How do sound waves transmit from the stapes?

Fluid within the cochlea that causes the basilar membrane to move.

Perilymph fluid

Basilar Membrane

becomes more stiff with more force based on different pitch making tectorial membrane to move back and forth Membrane

Tectorial Membrane

Membrane that moves back and forth in response to vibrations of the basilar membrane.