Hearing consists of the psychophysiological processes that provide living beings with the ability to hear.. Humans are not the only ones with this sense and, in fact, it is worth noting that our hearing ability is very limited. While our species can hear an auditory frequency of 20 kHz (20,000 Hertz), a moth can perceive sound waves of 300 kHz, many magnitudes ahead.
To put it quickly and simply, the pinna concentrates the waves coming from the environment, which travel through all the auditory structures and cause the waves to be transformed into information that travels to the brain. This key step is carried out by hair cells, located in the organ of Corti. These bodies are permanent and cannot be repaired if damaged, which is why special care is taken not to subject our ears to excessively high sound levels.
The sense of hearing is really interesting, not only in humans. Many mammals, for example, can use their cranial musculature to orient the pinna and receive information more quickly and accurately. In evolutionary terms, hearing a sound one second earlier can mean the difference between life and death. Based on these premises and many others, Here we tell you all about the 9 parts and bones of the human ear..
What is the morphology of the ear?
The human ear is divided into three distinct sections: outer, middle and inner. In addition to its physiological importance, this classification is essential in the clinical field, since an external ear infection has nothing to do with a broken bone in the inner ear. Here are the 9 parts and bones of the human ear according to their location. Do not miss them.
1. Outer ear
This is the outermost part of the ear, as its name suggests. It contains the pinna and the external auditory canal.
It is the only visible part of the ear and acts as a “bell” to capture sound waves.. Interestingly, some scientists argue that certain sections of these structures can be considered vestigial. Although we may have musculature that could direct the pinna (as in the case of foxes, for example) towards the sound source, this musculature is atrophied and does not seem to be of any clear use.
1.2 External auditory canal
A canal about 2.5 centimeters long and 0.7 square millimeters wide, extending from the pinna to the ear. extends from the pinna to the eardrum.. The outer wall of this canal is directly associated with the temporomandibular joint. For this reason, seemingly simple tasks such as chewing or yawning are made difficult during otitis.
2. Middle ear
An air-filled, almost square-shaped cavity located in the petrous portion of the temporal bone. Anatomically, the middle ear is located at the top of the cerebellum, between the brain masses and the eardrum. We tell you about each of its parts.
The eardrum is a semitransparent membrane.The tympanic membrane, elastic and cone-shaped, communicates the middle ear ear canal with the outer ear, sealing the first cavity. The vibration of the tympanic membrane is the first step in the conversion of sound waves into nerve signals that the brain can interpret.
2.2 Tympanic cavity
A cavity located behind the eardrum that communicates with the nostrils.. It is divided into several walls: roof, floor, posterior section and anterior section, which includes the entrance of the Eustachian tube. It is lined by mucosa and a simple flat epithelial sheet in its posterior part, while the anterior part is lined by a ciliated stratified cylindrical epithelium.
2.3 Ossicles of the ear
Perhaps the most important parts of the entire auditory section. These short, irregular bones form a chain located in the tympanic cavity of the middle ear, whose function is to transmit the vibrations emitted by the tympanic membrane to the inner ear, through the oval window (membrane covering the entrance of the cochlea).through the oval window (membrane that covers the entrance of the cochlea). We can mention the following generalities of these three bony structures:
- HammerHammer: it is formed by a head, a neck, a manubrium and two apophyses. Through the incudomalleolar joint, it transmits the vibrations of the tympanum to the incus.
- AnvilAnvil : with a body and two branches, this irregular bone is connected to the malleus by the incudomalleolar joint and to the stapes by the incudo-stapedial joint.
- StapesStirrup: has a head, a neck, two crosses (one anterior and one posterior) and a base. It connects with the incus and the oval window, and its dysfunctionality causes otosclerosis.
In summary, these complex structures are responsible for transmitting tympanic vibrations to the Eustachian tube, the next step in the middle ear.
2.4 Eustachian tube
The Eustachian tube is the connecting highway between the middle ear, the back of the nose and the nasopharynx (throat). Its main function is to maintaining and equalizing the air pressure inside the middle ear with that outside the middle ear.. When the tube does not open during swallowing or yawning, pressure differences are generated and various pathologies appear at the otic and auditory levels.
3. Inner ear
The inner ear is the final part of the auditory system. It is divided into an anterior and a posterior labyrinth. We tell you about its parts.
Formerly called the snail, the cochlea refers to a structure in the form of a spirally coiled tube located in the anterior coiled spiral tube located in the anterior portion of the inner ear.. It is divided into three different sections: the tympanic ramp, the vestibular ramp and the cochlear duct. However, the most important thing about this structure is that it contains the organ of Corti, which is in charge of hearing itself.
Inside this organ are about 3,500 outer hair cells and 12,000 outer hair cells. These cells contain apical stereocilia that move with sound vibrations, which generates an electrical potential in the cellular environment. This transduction mechanism allows the transformation of the sound wave into electrical impulses that can be analyzed by the brain.
The vestibule is the region of the inner ear that is responsible for the perception of body movement.It is therefore historically (and medically) associated with the maintenance of balance in mammals. The vestibule contains hair cells, but in this case its function is to detect linear accelerations or decelerations occurring in any of the three planes of space. The otoliths (crystals) in this section, depending on their physiological position, can inform the hair cells of the position of the head and the movements that the living being is making in space.
3.3 Semicircular ducts
A complex structure made up of three very small tubes, whose purpose is also to help maintain balance. They are oriented in the three axes of space and are responsible for detecting any movement of angular acceleration in any of the physical planes.
When the vestibule or semicircular canals fail, the patient experiences a series of very marked balance problems. These manifest themselves in the form of dizziness, vertigo, unsteadiness, falls, vision changes and disorientation. For all these reasons, inner ear failures are very evident from a clinical point of view.
This time we have introduced you to the 9 parts of the ear, starting with the pinna and the reception of sound and ending with the human balance. If we want to keep you with a general idea, this is the following: waves are received by the ear, the eardrum resonates and transmits the relevant vibrations through all the bone chains and ultimately the hair cells of the organ of Corti transform this movement into electrical nerve signals.
In addition to hearing itself, the auditory structures are also essential in other processes, such as the maintenance of balance and certain mechanical movements in the head (such as chewing). Without a doubt, this biological system is a true work of art from an evolutionary point of view.