Ear Anatomy and Physiology

External Ear

• The external auditory canal, also known as the ear canal, is a tube that connects the outer ear to the eardrum.
• It is lined with cartilage and contains hairs that help to filter out dust and other debris.

Middle Ear

• Located in the temporal bone, the middle ear contains three small bones called ossicles: the malleus, incus, and stapes.
• These bones are responsible for transmitting sound vibrations from the eardrum to the inner ear.
• The eardrum, also known as the tympanic membrane, separates the middle ear from the outer ear.
• The middle ear also contains a tube called the Eustachian tube, which connects to the back of the throat and helps to regulate air pressure.

Inner Ear

• The inner ear contains the labyrinth, a complex structure filled with fluid that is responsible for hearing and balance.
• The labyrinth has three parts: the cochlea, vestibule, and semicircular canals.
• The cochlea is responsible for hearing, while the vestibule and semicircular canals are responsible for balance and equilibrium.
• The inner ear also contains the auditory nerve, which carries sound signals to the brain.

Hearing and Balance

• Hearing and balance are both affected by the movement of fluid in the labyrinth.
• When sound waves reach the eardrum, they cause the fluid in the cochlea to vibrate, which stimulates the auditory nerve.
• The vestibule and semicircular canals are filled with a gel-like substance that moves in response to changes in head position, which helps to maintain balance and equilibrium.
• Any damage to the inner ear or the auditory nerve can lead to hearing loss or balance disorders.