Ear: The hearing organ. There are three sections of the ear, according to the anatomy textbooks. They are the outer ear (the part we see along the sides of our head behind the temples), the middle ear, and the inner ear. But in terms of function, the ear has four parts: those three and the brain. Hearing thus involves all parts of the ear as well as the auditory cortex of the brain. The external ear helps concentrate the vibrations of air on the ear drum and make it vibrate. These vibrations are transmitted by a chain of little bones in the middle ear to the inner ear. There they stimulate the fibers of the auditory nerve to transmit impulses to the brain.
The outer ear looks complicated but it is the simplest part of the ear. It consists of the pinna or auricle (the visible projecting portion of the ear), the external acoustic meatus (the outside opening to the ear canal), and the external ear canal that leads to the ear drum. In sum, there is the pinna, the meatus and the canal. That’s all. And the external ear has only to concentrate air vibrations on the ear drum and make the drum vibrate.
The middle ear consists of the ear drum (the tympanum or tympanic membrane) and, beyond it, a cavity. This cavity is connected via a canal (the Eustachian tube) to the pharynx (the nasopharynx). The Eustachian tube permits the gas pressure in the middle ear cavity to adjust to external air pressure (so, as you’re descending in a plane, it’s the Eustachian tube that opens when your ears “open”).) The middle ear cavity also contains a chain of 3 little bones (ossicles) that connect the ear drum to the internal ear. The ossicles are named (not the Nina, the Pinta and the Santa Maria but) the malleus, incus, and stapes. In sum, the middle ear communicates with the pharynx, equilibrates with external pressure and transmits the ear drum vibrations to the inner ear.
The internal ear is highly complex. The essential component of the inner ear for hearing is the membranous labyrinth where the fibers of the auditory nerve (the nerve connecting the ear to the brain) end. The membranous labyrinth is a system of communicating sacs and ducts (tubes) filled with fluid (the endolymph). The membranous labyrinth is lodged within a cavity called the bony labyrinth. At some points the membranous labyrinth is attached to the bony labyrinth and at other points the membranous labyrinth is suspended in a fluid (the perilymph) within the bony labyrinth. The bony labyrinth has three parts: a central cavity (the vestibule), semicircular canals (which open into the vestibule) and the cochlea (a snail-shaped spiral tube). The membranous labyrinth also has a vestibule which consists of two sacs (called the utriculus and sacculus) connected by a narrow tube. The utriculus, the larger of the two sacs, is the principal organ of the vestibular system (which informs us about the position and movement of the head). The smaller of the two sacs, the sacculus (literally, the little sac) is connected with a membranous tube in the cochlea containing the organ of Corti. It is in the organ of Corti that are situated the hair cells, the special sensory receptors for hearing.
- Ear bones
Ear bones: Also know as the ossicles, these are the three tiny bones in the middle ear that carry the sound wave from the ear drum into the cochlea.
- Ear canal, self-cleaning
Ear canal, self-cleaning: Most of the time the ear canals are self-cleaning, that is, there is a slow and orderly migration of ear canal skin from the eardrum to the outer opening. Old earwax is constantly being transported from the deeper areas of the ear canal to the opening where it usually dries, flakes, and […]
- Ear cleaning (by a doctor)
Ear cleaning (by a doctor): When ear wax accumulates enough, it may block the ear canal (and hearing). A health care professional may have to wash it out, vacuum it, or remove it with special instruments. Alternatively, your physician may prescribe ear drops that are designed to soften the wax.
- Ear cleaning (yourself)
Ear cleaning (yourself): Wax is not formed in the deep part of the ear canal near the eardrum, but only in the outer part of the canal. Attempts at self-cleaning with cotton swabs, keys, pins, or other objects can impact wax deeper into the canal. This can also impair or damage normal eardrum function. Infection […]
- Ear infection, middle (acute)
a bulging eardrum usually accompanied by pain; or a perforated eardrum, often with drainage of purulent material (pus). Otitis media is the most frequent diagnosis in sick children in the U.S., especially affecting infants and preschoolers. Almost all children have one or more bouts of otitis media before age 6. The eustachian tube is shorter […]