Ear Anatomy

The ear is made up of three parts: the outer, middle, and inner ear. All three parts of the ear are important for detecting sound by working together to move sound from the outer part through the middle and into the inner part of the ear. Ears also help to maintain balance.

Outer Ear

The outer ear includes:

  • auricle (cartilage covered by skin placed on opposite sides of the head)

  • auditory canal (also called the ear canal)

  • eardrum outer layer (also called the tympanic membrane)

 

Middle Ear

The middle ear includes:

  • eardrum

  • cavity (also called the tympanic cavity)

  • ossicles (3 tiny bones that are attached)

    • malleus (or hammer) – long handle attached to the eardrum

    • incus (or anvil) – the bridge bone between the malleus and the stapes

    • stapes (or stirrup) – the footplate; the smallest bone in the body

Inner Ear

The Inner ear includes:

  • oval window – connects the middle ear with the inner ear

  • semicircular ducts – filled with fluid; attached to cochlea and nerves; send information on balance and head position to the brain

  • cochlea – spiral-shaped organ of hearing; transforms sound into signals that get sent to the brain

    • auditory tube – drains fluid from the middle ear into the throat behind the nose

The outer part of the ear collects sound. Sound travels through the auricle and the auditory canal, a short tube that ends at the eardrum.

Sound entering the outer ear travels through the middle ear and causes the eardrum and ossicles in the middle ear to vibrate. As it travels, it amplifies (becomes louder) and changes from air to liquid

When the stapes moves, it pushes the oval window, which then moves the cochlea. The cochlea takes the fluid vibration of sounds from the surrounding semicircular ducts and translates them into signals that are sent to the brain by nerves like the vestibular nerve and cochlear nerve.