Anatomy of the Ear

Parakeet Chirping in Ea

The anatomy of the ear can be divided into 3 parts:

The outer ear includes the external part of the ear and the ear canal.

The middle ear is separated from the outer ear by the ear drum and contains three tiny bones called ossicles.

The inner ear serves two functions - the cochlea for hearing and the semicircular canals for balance.


How do we hear?

Parts of the outer, middle and outer ear
  1. Sound waves that produce sound are collected by the pinna, the external part of the ear, that is made of ridged cartilage, covered with skin. It has a concave shape so it can funnel sound waves into the ear canal.
  2. These sound waves are directed down the ear canal where they reach the eardrum (tympanic membrane).
  3. The ear drum vibrates with these sound waves, causing the ossicles, referred to as the hammer, anvil, and stirrup, to vibrate.
  4. The ossicles carry the vibration to the cochlea, a fluid filled snail shaped structure in the inner ear.
  5. The cochlea is filled with thousands of tiny hairs called cilia, which are attached to nerve cells.
  6. As the liquid in the cochlea vibrates, it moves the cilia which stimulate the nerve cells to send different signals to the brain via the auditory nerve.
  7. The brain receives the signals,distinguishes them, and translates them into the sound we hear.


effects of aging on the ear

What happens to our ears as we age:

  • The eardrum thickens
  • The tiny bones in the middle ear stiffen
  • Loss and breakage of hairs(cilia) in the inner ear
  • Nerve function decreases
  • The brain's ability to translate sound signals slows down

As a result hearing may decline. This gradual decline in hearing over time, due to aging is called Presbycusis , said to be the most common causes of hearing loss in men and women over 50.

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