Hearing organ: anatomical structure and functions of major departments

The organs of hearing allow us to perceive the variety of sounds of the outside world, to recognize their nature and location. Thanks to the ability to hear, a person gains the ability to speak. The organ of hearing is the most complicated, finely tuned system of three departments, consistently connected among themselves.

Outer ear

The first section is an auricle - a complex form of cartilaginous plate, on both sides covered with skin, and an external auditory canal.

The main function of the auricle is the acceptance of acoustic air vibrations. From the hole in the auricle begins the external auditory meatus - a tube 27 - 35 mm in length, which extends deep into the temporal bone of the skull. In the skin lining the ear canal, there are sulfur glands, the secret of which prevents the penetration of infection into the organ of hearing. The tympanic membrane is a thin but strong membrane separating the outer ear from the second part of the ear organ, the middle ear.

Middle ear

In the deepening of the temporal bone is the tympanum, which forms the main part of the middle ear. The auditory (eustachian) tube is the connecting link between the middle ear and the nasopharynx. With swallowing movements of the Eustachian tube opens and allows air to penetrate into the middle ear, which balances the pressure in the tympanum and the external auditory canal.

In the middle ear there are movably connected miniature auditory ossicles - a complex mechanism for transferring acoustic vibrations coming from the external auditory canal to the auditory cells of the inner ear. The first bone is a hammer with a long end attached to the eardrum. The second is an anvil connected to the third miniature bone, stapes. The staple adjoins to the oval window, from which the inner ear begins. Bones, which includes the organ of hearing, are very small. For example, the weight of stapes is only 2.5 mg.

The inner ear

The third department of the hearing organ is represented by the antechamber (miniature bone chamber), semicircular canals and a special formation - a thin-walled bone tube twisted into a spiral.

This part of the auditory analyzer, resembling a grape snail in shape, is called - the auditory snail.

The organ of hearing has important anatomical formations, allowing to maintain balance and evaluate the position of the body in space. This is the vestibule and semicircular canals, filled with liquid and lined from the inside by very sensitive cells. When a person changes the position of the body, the fluid moves in the channels. Receptors fix the displacement of the fluid and send a signal about this event to the brain. So the organ of hearing and balance allows the brain to learn about the movements of our body.

The membrane inside the cochlea consists of about 25 thousand of the finest fibers of various lengths, each of which responds to the sounds of a certain frequency and excites the endings of the auditory nerve. Nervous excitation is first transmitted to the medulla oblongata, then reaches the cerebral cortex. In the auditory centers of the brain, irritations are analyzed and systematized, as a result of which we hear the sounds filling the world.