Infections of the ear can affect one or more of the various parts of the ear. There are three main parts to the ear: inner ear, middle ear and outer ear. The outer ear collects sounds, and consists of the ear and ear canal up to the eardrum.
The middle ear is the space beneath the ear drum and is about the size of a pencil eraser. The middle ear is an air-filled space that is separated from the outer ear by a very thin eardrum.
Attached to the eardrum are three bones. Sound waves hit the eardrum and make it vibrate. The eardrum vibrations make the attached bones transmit the vibrations to the inner ear.
The inner ear converts the vibrations to electrical signals and sends these signals to the brain. The inner ear also helps maintain your physical balance.
The Eustachian tube connects the middle ear space to the nasopharynx in the back of the nasal cavity. This tube helps equalize ear pressure.