Organ of Corti - Wikipedia
cochlea with a snapshot of its basilar membrane displaced in response to a .. backbone, probably actin, having a pitch of about 75” with the long axis. Adjacent to their direct tectorial connection, can efficiently deliver forces via their cilia. Describe the relationship of amplitude and frequency of a sound wave to attributes of sound; Trace . Above the basilar membrane is the tectorial membrane. . Cochlear neurons send descending projections to the spinal cord and ascending. Gregory D. Cramer, in Clinical Anatomy of the Spine, Spinal Cord, and Ans (Third The tectorial membrane is the superior extension of the posterior longitudinal rim of the foramen magnum (specifically the upper region of the basilar part of the . of individual stereocilia, (ii) the cross-linkage between adjacent stereocilia.
The hair cells have projections at their top called stereocilia. When the stereocilia are moved, mechanically gated ion channels open, the hair cells are depolarized and as a result glutamate is released as a neurotransmitter.
The glutamate then causes depolarization of the next neurons, which have axons that form the vestibulocochlear nerve. But why are the stereocilia moved when the hair cells move up and down?
This is because of the tectorial membrane, which lies over the stereocilia. The stereocilia are tweaked because the tectorial membrane does not move up and down when the basilar membrane moves up and down.
Otosclerosis In otosclerosis, there is excess formation of bone about the oval window, leading to reduced mobility of the stapes. The progressive hearing loss tends to become apparent either in teenage years or early adulthood. There is a strong genetic component.
Tectorial membrane of the spine | Radiology Reference Article | dubaiairporthotel.info
The treatment is either a hearing aid or surgery, which is usually successful. Otitis Media See your lab notes for discussion of otitis media. Inflammation of the middle ear is usually the result of an upper respiratory tract infection, which moves up the Eustachian tubes.
- Cochlea and Vestibular System
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- Organ of Corti
This is more likely in children with their short Eustachian tubes. Deafness See your lab notes for distinguishing conduction deafness and sensory deafness. As a result, the attached oval window moves and causes movement of the round windowwhich leads to displacement of the cochlear fluid.
The latter is referred to as Bone Conduction or BC hearing, as complementary to the first one described, which is instead called Air Conduction or AC hearing. The basilar membrane on the tympanic duct presses against the hair cells of the organ as perilymphatic pressure waves pass.
The stereocilia atop the IHCs move with this fluid displacement and in response their cationor positive ion selective, channels are pulled open by cadherin structures called tip links that connect adjacent stereocilia. The organ of Corti, surrounded in potassium rich fluid endolymphlies on the basilar membrane at the base of the scala media.
Under the organ of Corti is the scala tympani and above it, the scala vestibuli. Both structures exist in a low potassium fluid called perilymph. So, the bending of the stereocilia is how hair cells sense sounds. Outer hair cells have a special function within the cochlea. They are shaped cylindrically, like a can, and have stereocilia at the top of the cell, and a nucleus at the bottom.
When the stereocilia are bent in response to a sound wave, an electromotile response occurs. This means the cell changes in length. So, with every sound wave, the cell shortens and then elongates. This pushes against the tectoral membrane, selectively amplifying the vibration of the basilar membrane.039 The Function of the Organ of Corti
This allows us to hear very quiet sounds. The electromotile response of an outer hair cell is shown in the movie: Click here to see Quicktime Movie KB When you are exposed to loud music or noise, it is your hair cells which are damaged.
Hearing loss occurs because loud sounds are really just large pressure waves like when you stand next to a subwoofer and can "feel" the bass. These large pressure waves bend the stereocilia too far, sometimes to the point where they are damaged.
This kills the hair cell.