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The tympanic duct or scala tympani is one of the perilymph-filled cavities in the inner ear of humans. It is separated from the cochlear duct by the basilar membrane , and it extends from the round window to the helicotrema , where it continues as vestibular duct .
The helicotrema (from Greek: ἕλιξ [helix] meaning coil and τρη̂μα [trēma] meaning hole) is the part of the cochlear labyrinth where the scala tympani and the scala vestibuli meet. It is the main component of the cochlear apex. The hair cells near this area best detect low frequency sounds.
The first half of the duct is now referred to as the scala vestibuli, while the second half, which includes the basilar membrane, is called the scala tympani. As a result of this increase in length, the basilar membrane and papilla are both extended, with the latter developing into the organ of Corti , while the lagena is now called the ...
In detail, the pinna of the outer ear helps to focus a sound, which impacts on the eardrum. The malleus rests on the membrane, and receives the vibration. This vibration is transmitted along the incus and stapes to the oval window. Two small muscles, the tensor tympani and stapedius, also help modulate noise.
It is found within the scala tympani and scala vestibuli of the cochlea. The ionic composition of perilymph is comparable to that of plasma and cerebrospinal fluid. The major cation in perilymph is sodium, with the values of sodium and potassium concentration in the perilymph being 138 mM and 6.9 mM, respectively. [1]
A cross section of the cochlea will reveal an anatomical structure with three main chambers (scala vestibuli, scala media, and scala tympani). [5] At the apical end of the cochlea, at an opening known as the helicotrema, the scala vestibuli merges with the scala tympani.
The Atticus is the part of the tegmentum tympani where the stapes and incus are attached. The floor of the cavity (also called the jugular wall) is narrow, and consists of a thin plate of bone (fundus tympani) which separates the tympanic cavity from the jugular fossa. It presents, near the labyrinthic wall, a small aperture for the passage of ...
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 . [ 8 ] Because those stereocilia are in the midst of a high concentration of potassium, once their cation channels are pulled open, potassium ions as well as calcium ions flow into the top of the hair ...