Hearing

Hearing

• The structures of the ear all work together to collect and transfer sound vibrations to the auditory nerve. The ear uses mechanoreceptors to accomplish this.

• Sound waves are collected by the auricle (outer ear) and are passed through the external auditory canal. The sound waves then travel through the middle ear a set of 3 tiny, jointed bones (ossicles): malleus, incus, and stapes. These are commonly known as the hammer, anvil, and the stirrup. They amplify the sound waves to the inner ear through a membrane called the oval window.

• The inner ear contains the cochlea, a bony snail-shaped structure containing membranes filled with fluid (perilymph). The tiny portion of the cochlea that creates an impulse is called the organ of Corti.

• Sound from the ossicles vibrates the perilymph. The perilymph then vibrates the basilar membrane, which has tiny receptor cells attached to it. The hairs of the receptor cells move against the tectorial membrane, depolarizing the ends of the nerve cells and beginning an action potential. When the action potential is transferred through the auditory nerve, the brain registers these impulses as sounds.

Summary:

• Sound is passed in vibrations through the outer ear and amplified by the tympanic membrane and 3 bones called ossicles. When these vibrations reach the cochlea, perilymph moves the hairs of the receptor cells in the Organ of Corti, causing an impulse to be passed through the auditory nerve to the brain.