Human outer ear: the structure and function of the ear
What is the outer ear and what is its function?
The human ear is a complex sense organ that allows people to catch the smallest changes in the environment through sound and recognize its origin. This process is characterized by the conversion of sound waves into electrical impulses and their subsequent processing by the neurons of the brain. The perception of sound passes through the multi-level system: having curved external auditory canal, it falls into the middle ear and then into the internal.
Hearing plays a significant role in a person’s life. 9% of information about the outside world enters through sound perception. With eyes absorbed 90% of the information and only 1% falls on other senses.In this article discussed in detail the outer ear, its structure and functions.
The device of the external ear
Auditory analyzer fully completes its formation to 12 years, and the peak of the highest severity of the hearing aid at the age from 14 to 19 years. Middle and outer ear carry out a conductive function, internal Department — sound.
The outer element of the auditory system (outer ear) consists of 3 main parts:
- the external auditory meatus;
To determine which side came the sound helps the difference in time of the sound waves right and left ear, which has the only difference in a few fractions of a millisecond. This perception of sound called stereo.
The visible part of the outer ear — the Pinna — mainly consists of cartilage whose thickness is on average equal to 1 mm., the Earlobe does not contain cartilage. Its components — fatty tissue covered by skin.
The auricle has a concave shape, one side is the curl of an ear. From protionamida inside, it is separated by a small depression. The shell cavity is immediately after protionamida to the auditory passage. Another element is the tragus — the cartilaginous projection in front of ear canal.
The ear canal
The second element of the external ear, auditory canal, extends from the auricle to the eardrum. Its basis is the cartilage in the form of a chute. Santoramaa slit, located in the cartilaginous tissue in contact with the parotid gland.
The ear canal consists of cartilage is not completely. In its narrowest part the isthmus — cartilaginous part is connected with the bone at an obtuse angle by dense connective tissue.
Help. The length of the auditory canal is on average 2.5 cm, width 0.9 cm.
Sulfur and sebaceous glands located in the ear canal, produce sulfur. In the process of chewing is its spontaneous deletion due to the fact that the bushing wall begin to shake.
Middle and outer ear are connected through the tympanic membrane — thin membrane, like a translucent plate. The membrane does not pass liquid and air flows, its area is approximately 60 mm2, and the thickness averages 0.1 mm.
The location of the tympanic membrane, a concave inside cavity like a funnel, slightly inclined relative to the auditory passage. Maximum tension is observed in its center.
Eardrum includes layer 3 basics:
- Outer primary layers — the epidermis, the continuation of the skin lining the outer area of the ear canal.
- Fibrous tissue. Endowed with high tensile strength. The fibres are directed in two directions. Due to the one direction are formed circularly located circles, at the expense of another is their connection among themselves.
- An inner layer. It is formed by the mucous membrane.
The structural features of the outer ear of babies
Interestingly, in infants, the device of the external ear has its own characteristics that distinguish it from the structure of the fully formed ear of an adult.
The distinctive features of the external ear of the baby:
- The Pinna is soft enough. Mild curl the ear and earlobe. Their formation occurs only at four.
- The ear canal consists of cartilage, bone part is not formed.
- Ear the ear is not inclined relative to the auditory passage, and horizontally. Size it the same as an adult, although the membrane is much more thick and it covers the mucous membrane.
The functions performed by the outer ear
Anatomy of external ear includes a complicated structure. The function of the outer ear, of course, is not just to conduct sound vibrations, each of its elements carries out the allotted function.
Experts distinguish 3 main functional purpose of the external ear:
- The protection of the internal parts of the auditory organ from the external stimuli of the environment, the penetration of dust particles, bacteria, stains, heat and mechanical impacts on the membrane.
- Maintain constant temperature and pressure in ear membranes, as well as ensuring a sustainable level of humidity.
- Capture and conduct sound waves to the middle division of the organ of hearing. Control of acoustic vibrations — strong muting of audio signals and, conversely, increased quiet. This function is called the natural sound of the resonator. It is intended for the perception of sounds at any volume and frequency and to prevent injury to the ear is too loud beeps.
Thus, the special structure of the outer ear allows not only to capture and transmit sound waves, but also provides protection to the whole organ of hearing from adverse effects.