The physiology of hearing involves the complex process of sound waves entering the ear, being transformed into electrical signals, and being transmitted to the brain for interpretation. The process can be broken down into three main stages: the outer ear, the middle ear, and the inner ear.
Outer Ear: The outer ear is made up of the pinna, which is the visible part of the ear, and the ear canal.Sound waves enter the ear canal and are funneled towards the eardrum. The pinna helps to amplify and direct the sound waves towards the eardrum.
Middle Ear: The middle ear is located behind the eardrum and contains three small bones, called ossicles, which are the malleus, incus, and stapes. These bones are connected to each other and to the eardrum. When the eardrum vibrates in response to sound waves, the ossicles also vibrate and amplify the sound. The stapes is attached to the oval window, which is the entrance to the inner ear.
Inner Ear: The inner ear is composed of the cochlea and the vestibular system. The cochlea is a snail-shaped structure that contains thousands of hair cells, which are the sensory receptors for hearing. The hair cells are arranged along the basilar membrane, which runs the length of the cochlea. When the stapes vibrates against the oval window, it creates waves in the fluid-filled cochlea, which cause the basilar membrane to vibrate. The hair cells are sensitive to the movement of the basilar membrane and bend in response to the vibrations. This bending causes ion channels to open and trigger an electrical signal that is sent to the auditory nerve, which carries the signal to the brain for processing.
In summary, the physiology of hearing involves the transformation of sound waves into electrical signals that are sent to the brain for interpretation. The process involves the outer ear, the middle ear, and the inner ear, and is dependent on the coordinated function of several structures and mechanisms.
