Hearing System
The anatomy of the hearing system can be divided into four components. These division are the:
The Outer Ear
The outer ear is made up of the pinna or auricle, which is the “ear” we see on the side of our head, and the external auditory canal, or ear canal. The pinna collects and funnels sound down to the ear canal and towards the ear drum. The ear canal is actually curved and is about 1 inch long in adults. Each individuals ear canal is unique and must be considered when examining the function of the canal. The external auditory canal has hairs and glands that produce wax called cerumen. Cerumen helps to lubricate the skin and keeps the ear canal functioning normally.
Anatomy of the Ear
The Middle Ear
The eardrum (tympanic membrane) is a thin skin-lined membrane at the most inner end of the ear canal and separates the ear canal from the middle ear. On the inner side of the tympanic membrane, behind the eardrum, lies an air-filled space called the middle ear cavity. The vibrations of the tympanic membrane caused by sound are transmitted to the inner ear through the middle ear cavity. The three tiny bones, or ossicles, that transmit the sound to the inner ear are the malleus (hammer), incus (anvil), and stapes (stirrup). The stapes bone transmits the vibrations into the inner ear.
The Inner Ear
The inner ear has two divisions—hearing and balance functions are carried out in the inner ear. The hearing division of the inner ear consists of the cochlea and nerve of hearing. The cochlea is a snail-shaped, bony structure that contains the sensory organ of hearing called the organ of Corti. The organ of Corti releases chemical messengers when the vibrations from the stapes activate its tiny hair cells. These chemicals then excited the nerves of hearing which carry sound to the brain.
Central Auditory Pathways
The central auditory system is an incredibly complex network of neural pathways in the brain that are response for sound localizations, speech understanding, and perception of music.