Unit 3 Auditory Anatomy Terms

Ear

The ear is a transducer. It converts electric acoustic energy (sound waves) into electrochemical energy that is transmitted to the auditory nerve brain.

Outer Ear

What you can see, the passageway into the inner ear. Energy is acoustic.

Middle Ear

Contains the ossicles, the energy is mechanical vibrations.

Inner Ear

Vestibular System and cochlea, energy is hydrodynamic wave motion.

Pinna/Auricle

In the outer ear, cartilaginous sound collector, collects sound from the environment. Whole outer ear, the part you see.

Helix

In the pinna, curved part around the outside.

Antihelix

Fold anterior to the helix, curved part on the inside next to helix, bifurcates by splitting into 2.

Tragus

Flap covering the entrance to the ear canal, cartilage is covered by epithelium.

Ear Lobe

Non-cartilaginous skin flap.

External Auditory Meatus (EAM)

Ear canal, diameter: ~7mm, length: ~25mm, concha>eardrum. Lateral 1/3 is cartilage, medial 2/3 is bone. Angle is ~55 degrees at the EAM and tympanic membrane (eardrum). Ciliated epithelium gets the gunk out, cue-tips push the gunk back in. Could cause the eardrum to stop moving.

Tympanic Membrane

Boundary between the outer and middle ear, functions like a drum, vibrates. If the membrane can't move, it can't transmit sounds, slightly concave when viewed from EAM.

Ossicles

In the middle ear, transmit energy from TM to inner ear, very tiny bones and all 3 fit on a dime. Malleus, Incus, Stapes.

Malleus

Hammer, contains manubrium (long part on the bottom), head (roundish part on top), and neck (separates manubrium and head is connected here). Malleus joins the TM along length of manubrium. Head articulates with the incus, largest of the ossicles.

Incus

Contains long process (parallel with the manubrium of malleus), body (articulates with malleus at the articular facet) and lenticular process (end of long process, articulates with stapes).

Stapes

Contains head (at the top, articulates with incus), neck (below head), footplate (articulates/joins oval window at bottom). Smallest of ossicles.

Oval Window

Part of the middle ear, fenestra vestibuli, connects with the stapes.

Round Window

Part of middle ear, fenestra cochlea, leads to scale tympani in inner ear.

Eustachian Tube

Runs from middle ear to the pharynx, drains middle ear, vestibular function is to keep air pressure equalized. This is happening when your ears pop.

Middle Ear Muscles

Reduce transmissions of high intensity sounds, part of auditory reflex.

Stapedius Muscle

Middle ear muscle that keeps high intensity sounds from entering the cochlea. More effective against high intensity, low frequency sounds.

Tensor Tympani

Middle ear muscle, when it contracts, it pulls the malleus which tightens the TM. Connected to the ossicles by a tendon and also protects cochlea from sounds. More effective against high intensity, low frequency sounds.

Bony Labyrinth

Bone and membrane.

Membraneous Labyrinth

Bone and membrane that is generally in the osseous labyrinth.

Semicircular Canals

Inner ear, sense balance, movement of the body in space.

Cochlea

Inner ear, helps with hearing.

Vestibule

Inner ear, in between the semicircular canals and cochlea. The entry to the inner ear space.

Anterior/Superior Semicircular Canals

On top, sense when the head moves to the shoulder.

Posterior/Vertical Semicircular Canals

Sense when your head moves up and down, nodding yes.

Horizontal/Lateral Semicircular Canals

In the middle, sense shaking no, side to side.

Ampulla

Wider part of the canal that contains fluid, fluid senses the movement.

Modiolus

Core, finely perforated bone at the core. Where fibers of the 8th vestibulocochlear nerve pass through.

Osseous Spiral Lamina

Bony shelves that extend from modulus, divide the cochlear labyrinth into 2 chambers: scala tympani and scala vestibuli.

Perilymph

Fluid that fills in the scala vestibuli and tympani.

Endolymph

Fluid that fills the scala media

Basilar Membrane

Floor of the scala media, organ of hearing is located along the basilar membrane, structures that arise from BM are inner ear hair cells.

Organ of Corti (spiral organ)

Includes auditory receptors

Outer Hair Cells (OHC)

Contains 3 rows.

Inner Hair Cells (IHC)

Contains 1 row near modulus, don't come in contact with tectorial membrane.

Tectorial Membrane

Has some functionality to the way we hear sound, related to proximity of outer hair cells.

Stereocilia

Sensory hairs on the surface of cells.

Cilia

Cilia are linked if stereo cilia move on one cell, bump into others making them move as well.