The 10 parts of the ear and the process of sound reception.

The auditory system begins in a curious mechanism of bones and membranes that pick up vibrations.

The auditory system is relatively simple in comparison to those of the other senses; this is because the process by which vibrations are converted into nerve impulses is linear in nature. is linear in nature. Sound is transmitted from the ear to the auditory nerve and from the auditory nerve to the brain by a chain of internal structures.

In this article we will describe the outer, middle and inner ear, the main components of the auditory system, as well as the substructures that are part of the auditory system.and the substructures that make up each of these sections. To complete this description we will explain the process by which vibrations in the air are converted into sounds perceptible to humans.

Parts of the outer ear: from the ear to the eardrum

The outer ear is made up of the ear, the ear canal and the eardrum or tympanic membrane. The function of this segment of the auditory system is to pick up sound vibrations and channel them to the innermost parts of the ear. In this process some of the frequencies picked up are increased and others reduced, so that the sound is modified.

1. The ear or pinna

The ear is the outermost component of the auditory system, and the only one that can be seen from the outside. This structure, also known as the pinna, is composed of cartilage and skin. Its function is to collect auditory energy and redirect it into the middle ear through the ear canal.

2. Ear canal

The ear canal is a cavity that connects the ear to the eardrum. Sound vibrations reach the middle ear through this canal, which is approximately 2.5 to 3 centimeters long and just 7 square millimeters in diameter.

3. Eardrum or tympanic membrane

The eardrum is a membrane that separates the separates the outer ear and the middle earStrictly speaking, it is not part of either of these segments, but it is the structure used to delimit them. It is also known as the "tympanic membrane".

Middle ear: the chain of ossicles

After reaching the eardrum, the sound vibrations are transmitted through the ossicles of the middle ear to the oval window of the cochlea, where they are transduced into nerve impulses.

1. Hammer, anvil and stirrup

The ossicles chain consists of the malleus, incus and stapes.. Amphibians, reptiles and birds have only one bone, the columella, which is morphologically equivalent to the stapes in mammals.

The malleus is attached to the eardrum, while the stapes connects to the cochlea; the transmission of vibrations by the ossicles causes the lymphatic fluid of the inner ear to move, a necessary step for sound transduction.

2. Oval window

The oval window is the membrane that lines the cochlea, so technically it lies between the inner and middle ear. Vibrations in the eardrum are transmitted through the ossicles to the oval window, which consequently also vibrates, stimulating the inner ear.

Inner ear: the cochlea and transduction

The inner ear is a cavity located inside the skull. It is here that the transduction of sound vibrations into nerve impulses takes place, which marks the beginning of the brain's processing of hearing.

The key structure of the inner ear is the cochlea or cochlea, a set of canals that rotate on themselves and amplify sound vibrations into nerve impulses.The key structure of the inner ear is the cochlea, a set of canals that rotate on themselves and amplify the auditory signals they receive. Inside the cochlea is the organ of Corti, which is primarily responsible for hearing.

1. Semicircular canals

The semicircular canals or semicircular canals are an organ of the inner ear made up of two compartments, the saccule and the utricle, which the saccule and the utricle, which enable the sense of balance in association with the ossicles.

2. Vestibular or superior scala

The oval window of the cochlea, which is located on the vestibular scale, connects the stapes with the rest of the inner ear. This structure is filled with perilymphThe cerebrospinal fluid, a substance similar to cerebrospinal fluid that receives the vibrations of the ossicles.

3. Tympanic or lower scale

The sound waves received by the upper scale are transmitted to the lower scale through the perilymph since the two structures are connected by this fluid, while the basilar membrane separates them.

4. Cochlear or middle scale

The cochlear scale is isolated from the vestibular and tympanic scales by Reissner's membrane and the basilar membrane, respectively; however, it also shares endolymph with other parts of the inner ear.

In the middle scale is located the organ of Cortiwhere the transduction of sound vibrations into neural impulses takes place. The hair cells found in this structure enable transduction.

5. Auditory or vestibulocochlear nerve

The vestibulocochlear or auditory nerve, itself composed of the cochlear and vestibular nerves, transmits sound and balance information from the inner ear to the central nervous system. from the inner ear to the central nervous system. The vestibulocochlear nerves constitute the eighth of the twelve cranial nerves.