Our ears help us process our surrounding environment by allowing us to hear a wide variety of sounds. They are also critical for our sense of balance, position and equilibrium (as anyone who has ever been sea sick can attest). The ear is a very complex organ, and actually would be more accurately described as three unique organs which work together to process the sounds in our environment and transfer that information to the brain. In this article, you’ll learn about the anatomy of the human ear and how it relates to the ear’s multiple functions.
Anatomy of the human ear
The three major organs or sections of the human ear are the outer ear, middle ear and inner ear. Sound waves which enter the outer ear travel through various structures in the middle and inner ear before being converted into sensory impulses that are sent from the ears to the brain via nerves.
The outer ear includes all parts of the ear that you can see on the outside of your head, including the auricle or pinna (the cartilage that sticks out and helps collect and amplify sound waves) and earlobe, as well as some parts that you can’t always see, like the auditory canal (ear canal) and the outer layer of the eardrum, which is called the tympanic membrane.
The middle ear begins with the rest of the eardrum, the three tiny bones that are attached to it (malleus, incus and stapes), and the tympanic cavity in which they are all located.
Finally, the inner ear includes structures which translate the sound vibrations from the middle ear into nerve impulses to send to the brain. These structures include the oval window, semicircular canals, cochlea (which resembles a small snail shell), vestibule and auditory tube.
Functions of the ear
The first function of the ear, which is hearing, requires all three parts of the ear to work in concert and is done through the following process: the auricle collects and amplifies sound waves, which then travel through the auditory canal and reach the tympanic membrane, causing the eardrum to vibrate. Vibrations of the eardrum are transferred to the malleus, incus, and stapes bones. The stapes pushes against the oval window and cochlea as it vibrates, which converts the air vibrations of the outer and middle ear into liquid vibrations for the fluid-filled inner ear. The semicircular canals, also filled with fluid, vibrate as a result, and the cochlea converts these vibrations into nerve impulses carrying information about the sound to the brain via the cochlear nerve.
The second function of the ear, balance and equilibrium, takes place mostly within the inner ear. The same semicircular canals responsible for sending sound vibration information to the cochlea also send information about the position of the head and balance. The cochlea is once again responsible for translating this into electrical impulses to send to the brain, this time via the vestibular nerve.
The auditory tube is responsible for draining fluid out from the middle ear into the throat right behind the nose. Although they have very different functions, these three parts of the body are closely related, so much so that there is an entire specialized field of medicine devoted to ear, nose and throat (ENT doctors).