|
Learn About Your Hearing System
1. What are the structures that participate in the human auditory sensitivity?
The structures of the human auditory sensitivity are the ears (external, middle and internal), the vestibulocochlear nerves and the auditory areas of the brain (located in the temporal lobes of both hemispheres).
2. What are the main parts of the human ear?
The human ear is divided into three mains parts: the external ear, the middle ear and the internal ear.
Hearing Review - Image Diversity: human ear
3. What are the structures that form the external ear? What is its function?
The internal ear comprises the pinna, or auricle, and the auditory canal. Its function is to conduct the sound waves to the tympanum.
4. What are the elements that form the middle ear? What are the names of the three middle ear ossicles that participate in the phonosensitivity?
The middle ear is formed by the tympanum, the ossicular chain and the oval window. The functional ossicles of the middle ear are the hammer (malleus), the incus and the stapes.
Hearing Review - Image Diversity: middle ear ossicles
5. What is the tympanum? In which part of the ear is it located and what is its function?
The tympanum (or ear drum) is a membrane located in the middle ear just after the auditory canal and so it separates the middle ear from the external ear. The function of the tympanum is to vibrate with the same frequency of the sound waves that reach it.
6. How is the sound vibration captured by the tympanum transmitted through the ossicular chain of the middle ear?
The acoustic transmission from the external to the middle ear (and to the internal ear too) is entirely mechanical. The vibration of the tympanic membrane triggers the vibration of the hammer that then causes the incus to vibrate. The incus then causes the stapes to vibrate.
7. What are the elements that constitute the internal ear? What are the functions of those structures?
In the internal ear there are the cochlea and the semicircular canals. The fluid that fills the cochlea receives vibration from the ossicular chain of the middle ear and transmits the pressure to the semicircular canals. Within the semicircular canals the pressure variation of the filling fluid moves cilia of the hair cells of these structures. The hair cells then generate action potentials that are transmitted to the brain through the auditory nerves.
Hearing Review - Image Diversity: internal ear auditory pathway
8. Why is there a sense of pressure change inside the ear when someone goes down a mountain?
The pressure inside the middle ear is maintained equal to the external ear (so to the exterior too) due to a communicating duct between the middle ear and the pharynx called the auditory tube, or Eustachian tube. When someone goes down a mountain the air pressure upon the middle ear increases and it is necessary to do some exercises like fake swallowing to force the opening of the pharyngeal orifice of the auditory tube to equalize the pressure again.
9. What is the vestibular system? How does it operate?
The vestibular system is the part of the ear that participates in the control and regulation of the equilibrium of the body (balance).
The semicircular canals of the inner (internal) ear are perpendicularly placed and detect changes in the gravitational position of the head (this is another sensorial function of the inner ear, besides auditory perception). When the head rotates the pressure of the fluid within the canals upon the cilia of specific receptor cells varies and these cells generate action potentials transmitted by the vestibulocochlear nerve. The neural impulse is then interpreted by the brain as information about the gravitational position of the head.
Hearing Review - Image Diversity: vestibular system
|
