Acoustic organ

Acoustic organ. General information

The acoustic organ at the person is the pair body intended for perception of sound signals that, in turn, influences quality of orientation in the environment.

Sound signals are perceived by means of the sound analyzer which main unit of a structure are phonoreceptors. Carries out information in the form of signals the acoustical nerve which is a part of an eighth cranial nerve. A terminal point of reception of signals and the place of their processing – the cortical department of the acoustic analyzer located in bark of big hemispheres in its temporal share. More detailed information on a structure of an acoustic organ is given below.

Acoustic organ structure

Acoustic organ at the person – an ear in which allocate three departments:

• The outside ear presented by an auricle, outside acoustical pass and a tympanic membrane. The auricle consists of the elastic cartilage covered with skin and has irregular shape. In most cases it is not mobile, its functions are minimum (in comparison with animals). Length of outside acoustical pass makes from 27 to 35 mm, diameter – about 6-8 mm. Its main objective – to carry out sound vibrations to a tympanic membrane. At last, the tympanic membrane formed by connecting fabric is an outside wall of a drum cavity and separates a middle ear from outside;
• The middle ear is placed in a drum cavity – deepening in a temporal bone. In a drum cavity three acoustical stones known as a hammer, an anvil, a stirrup are located. Besides, on average to fish soup there is an Eustachian tube connecting a tympanic cavity to a nasopharynx. Interacting with each other, acoustical stones direct sound vibrations to an inner ear;
• Internally the ear represents the webby labyrinth located in a temporal bone. Internally the ear is divided into a threshold, three semicircular channels, a snail. Directly only the snail while two other elements of an inner ear – a part of an organ of equilibrium treats an acoustic organ. The snail has an appearance of the thin cone twirled in the form of a spiral. On all length it by means of two membranes is divided into three channels – a threshold ladder (upper), cochlear channel (average) and a drum ladder (lower). At the same time the lower and upper channels are filled with special liquid – a perilympha, and the cochlear channel is filled with an endolymph. The main membrane of a snail supports кортиев body – the device which perceives sounds;
• Kortiyev body is presented by several rows of the voloskovy cells performing functions of receptors. Except receptor cells кортиев the body contains the cover membrane hanging over voloskovy cells. In kortiyevy body there is a transformation of fluctuations of the liquids filling an ear to nervous impulse. Schematically this process looks as follows: sound vibrations are transferred from liquid, the filling snail, to a stirrup thanks to what the membrane with the voloskovy cells located on it begins to fluctuate. During fluctuations they concern a cover membrane that brings them to an excitement state, and it, in turn, involves formation of nervous impulse. Each voloskovy cell is connected to sensitive neuron which set forms an acoustical nerve.

Diseases of acoustic organs

Protection of acoustic organs and prevention of diseases has to have regular character as some diseases are capable to cause not only disorder of hearing and, as a result, orientation in space, but also to affect sense of equilibrium. Besides, rather complex structure of an acoustic organ, some isolation of a number of its departments quite often complicate diagnosis of diseases and their treatment.

The most widespread diseases of an acoustic organ can be divided into four conditional categories: the inflammatory, noninflammatory, resulted injuries and caused by a fungal invasion:

• Inflammatory diseases of an acoustic organ among which are often meeting otitis, labyrinthitis, otosclerosis arise after the postponed viral or infectious diseases. Carry suppurations, pain and an itch around acoustical pass to displays of otitis of an outside ear. Sometimes a symptom is deterioration in hearing. In the absence of timely treatment otitis quite often passes into a form chronic, or gives complications. The inflammation of a middle ear is followed by the temperature increase expressed by deterioration in hearing, the sharp shooting ear pain. Emergence of purulent discharges is a sign of purulent otitis. At overdue treatment of this disease of an acoustic organ the probability of emergence of injuries of a tympanic membrane is high. At last, otitis of an inner ear causes dizziness, rapid falling of quality of hearing, inability to focus a look. The labyrinthitis, meningitis, brain abscess, blood poisoning can be complications of this disease;
• Noninflammatory diseases of an acoustic organ. Carry to those, in particular, an otosclerosis – the hereditary damage of a bone of the ear capsule causing decrease in hearing. At other disease of an ear – Menyer's disease – the amount of liquid in a cavity of an inner ear which puts pressure upon a vestibular mechanism increases. Symptoms of a disease are vomiting, nausea, a sonitus, the progressing decrease in hearing. One more kind of noninflammatory diseases is eighth cranial nerve neuritis. It can provoke relative deafness emergence. Most often surgical methods are applied to treatment of noninflammatory diseases of an ear, because timely and careful protection of acoustic organs is important that it will allow to prevent deterioration in a course of diseases;
• Fungus diseases of an acoustic organ, as a rule, are caused by opportunistic mushrooms. The course of such diseases complicated quite often leads to sepsis. In certain cases otomycoses develop in the postoperative period, at traumatic injuries of skin, etc. At fungus diseases complaints to allocations from an ear, a constant itch and a sonitus become frequent complaints of patients. Treatment of diseases long, but existence of a fungus in an ear not always provokes development of a disease. Due prevention and care of acoustic organs will not allow a disease to develop.