Ear is important not just for hearing, but also as an organ for a balance. Each ear consists of three parts: the outer ear, the middle ear and the inner ear.
The outer ear consists of a visible part of the ear, skin and cartilage, which is called auricla, and of outer auditory corridor, about 20 mm long, leading from the auricla to the eardrum. The shallow part of the outer auditory corridor is made of cartilage covered with skin cells that create cerumen and hair; the deeper part of that corridor has a thin lining surrounded by the bone. The outer ear is separated from the middle ear by eardrum, which extends through the end of the outer auditory corridor.
The middle ear is a small cavity between the eardrum and the inner ear, bridged with three aditory ossicles: the malleus, the incus, and the stapes. The malleus is attached to the inner lining of the eardrum, and the stapes on the membrane covering the opening, the so-called an oval window, that leads to the inner ear. From the middle ear there are various connecting corridors: some lead to the pneumatic cells, some lead to the inner ear, and one, known as Eustachian (or auditory) tube, leads to the upper part of the pharynx.
The Eustachian tube channels the air from the nose into the middle ear chamber so that the air pressure in the middle ear (on the eardrum) is equal to atmospheric pressure. The tube is blocked sometimes, e.g. when you are having a common cold, so you can easily tell when the tube is cleaned because the sudden pressure equalization causes the ”cracking” in the ear.
The inner ear consists of a series of chambers, filled with liquid. It is generally divided into cochlea and labyrinth. The labyrinth is made up of three semicircular tubes, called channels. They are located at right angles so that each channel is in its horizontal or vertical plane. The inner ear manages the balance, even though it is, as well as other ear parts, essential for the main function of the ear – hearing.
How do we hear?
Movements of the objects cause air motion, thus creating sound waves. The visible part of the ear accumulates those waves that then travel through the outer auditory hallway and ”strike” the eardrum, so that it vibrates. The vibrations pass through the malleus, incus, stapes and oval window to the liquid in the cochlea. The hairs in the cochlea convert these vibrations into the nerve impulses that are transmitted to the brain by the auditory nerve. This, the main form of hearing, is supplemented by conducting vibration through the skull bones to the inner ear.
How do we keep a balance?
The brain continually monitors the positions and movements of the head and body to maintain balance. In the inner ear, there is a form called a labyrinth, which monitors the position and movement of the head with three semicircular canals. Each channel is at right angles to the other two so if you move, tilt, nod or move your head in any other way, one or more semicircular channels monitors that movement and transfers the information to the brain. The brain matches this information with informations recieved with eye, and muscles in the body and limb, and evaluates the position and movements which are required to maintain balance.
Deafness and dizziness
Unlike general thinking, deafness and dizziness are not actually disturbances, but symptoms of some disorder.
There are two types of deafness: conductive and perceptive.
In conductive deafness, the sound does not reach the inner ear, which is, for example, the consequence of clogging in the outer ear. In perceptive deafness, the sound reaches the inner ear, but is not transmitted to the brain, usually due to the cranial or auditory nerve damage, such as in some forms of professional deafness.
Dizziness is a fake feeling, during which you think that your head is spinning or that your surroundings are spinning. Dizziness often causes loss of balance. This is a common symptom of the inner ear disorder, in which the balance organs are located.
This type of deafness is the result of a mechanical deficiency in the middle ear that prevents the sound into the inner ear.
Damage to the inner ear can lead to perceptive deafness. The sound received does not reach the brain.