Those nearer the middle detect lower-pitched sounds, such as a large dog barking. Hair cells near the base of the cochlea detect higher-pitched sounds, such as a cell phone ringing. Certain chemicals then rush in, creating an electrical signal that is carried by the auditory nerve to the brain. The bristly structures of the hair cells then bump up against an overlying membrane, which causes the bristles to tilt to one side and open pore-like channels. Hair cells that sit on top of the membrane “ride” this wave and move up and down with it. Incoming sound vibrations cause the fluid inside the cochlea to ripple, and a traveling wave forms along the basilar membrane. The upper and lower parts of the cochlea are separated by an elastic, “basilar” membrane that serves as the base, or ground floor, upon which key hearing structures sit. The middle-ear bones amplify the sound vibrations and send them to the cochlea, a fluid-filled structure shaped like a snail, in the inner ear. The arrow shaped structures at the top of the photo. Under great magnification, hair cells can be seen as The incoming sound waves make the eardrum vibrate, and the vibrations travel to three tiny bones in the middle ear called the malleus, incus, and stapes-the Latin names for hammer, anvil, and stirrup. The auditory nerve then carries these signals to the brain.įirst, sound waves enter the outer ear and travel through a narrow passageway called the ear canal, which leads to the eardrum.
#Hammer anvil and stirrup series
Healthy hearing relies on a series of events that change sound waves in the air into electrochemical signals within the ear. White, middle-aged women are most at risk. Many cases of otosclerosis are thought to be inherited. Otosclerosis affects more than three million Americans. In otosclerosis, abnormal remodeling disrupts the ability of sound to travel from the middle ear to the inner ear. Bone remodeling is a lifelong process in which bone tissue renews itself by replacing old tissue with new.
Otosclerosis is a term derived from oto, meaning “of the ear,” and sclerosis, meaning “abnormal hardening of body tissue.” The condition is caused by abnormal bone remodeling in the middle ear. Congressional Testimony and the NIDCD Budget.Research Training in NIDCD Laboratories (Intramural).Types of Research Training Funding Opportunities.About NIDCD's Research Training Program.Scientific Workshop and Meeting Reports.Building a Diverse Scientific Workforce.
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