Every child knows that our ears are responsible for hearing; but also balance and sense of space are other important tasks of the inner ear. We explain how middle ear and inner ear are built, what functions they have and what diseases can occur.
What exactly belongs to middle and inner ear, where exactly are they?
The inside of the ear begins after 3 to 4 centimeters of ear canal with the eardrum, which separates the outside world from the inside of the ear. This connective tissue membrane measures one centimeter in diameter - behind it lies the air-filled area of the middle ear: the tympanic cavity.
The middle ear
The lenticular tympanic cavity can be thought of as a very small cube with an edge length of about 9.3 millimeters - one "side surface" is the eardrum, a smaller one lies opposite and consists of an oval and a round window, behind which the inner ear hides. Between the eardrum and the oval window, a chain of ossicles is stretched, namely hammer, anvil and stirrup. Three further side surfaces consist of bone covered with mucous membrane. The last page is the opening of the Eustachian tube, the
Tuba auditiva. It is a 3.5-centimeter-long, lined with mucous membrane and connects the middle ear and nasopharynx. This compound opens only when swallowing, yawning or mouth open wide - which is important to produce the same air pressure between middle ear and outside air. Otherwise, the eardrum bulges painfully inward or outward. As the name middle ear suggests, this is located between the outer and inner ear.
The inner ear
The inner ear is located in the middle of the petrous bone, a thick skull bone, and consists of specially shaped bony cavities, the bulbous vestibule, the cochlea and the three circular semicircular ducts into which the cells and structures of the inner ear are embedded.
The cochlea and semicircular canals have a common starting point, the atrium of the inner ear. From there it goes straight on to the cochlea, above the forecourt are the three semicircular canals, which show in all three directions of space, as well as the sensory cells of Sacculus and Utriculus.
The bony cochlea is pea-sized, about 3 inches long and has two and a half turns. It is filled with fluid and contains a tubular cell structure (Corti organ), which converts the sound waves into nerve signals. In the forecourt are Sacculus and Utriculus. They register as our bodies move up and down or back and forth. In the three semicircular canals, on the other hand, every rotational movement is perceived and reported to the brain.