Tympanic duct

Tympanic duct (also known as scala tympani) is a perilymph-filled cavity located within the cochlea of the inner ear. It extends from the round window, one of the two openings in the bone that encloses the cochlea, to the helicotrema, where it connects with the scala vestibuli.

Etymology

The term "tympanic duct" is derived from the Greek word "tympanon", meaning drum. This is in reference to its location near the tympanic membrane, or eardrum. The term "scala" is Latin for staircase, referring to the spiral structure of the cochlea.

Structure

The tympanic duct is one of three fluid-filled spaces within the cochlea. It is separated from the scala media (the middle chamber) by the basilar membrane, and from the scala vestibuli (the upper chamber) by the helicotrema. The duct is filled with perilymph, a fluid that is high in sodium ions and low in potassium ions.

Function

The primary function of the tympanic duct is to transmit sound vibrations from the cochlea to the brain. When sound waves enter the ear, they cause the eardrum to vibrate. These vibrations are then transmitted to the cochlea via the ossicles, a group of three small bones in the middle ear. Within the cochlea, the vibrations cause the perilymph in the tympanic duct to move, which in turn causes the basilar membrane to move. This movement stimulates the hair cells in the organ of Corti, which send electrical signals to the brain via the auditory nerve.

Related Terms

• Cochlea: The spiral-shaped, fluid-filled inner ear structure that is responsible for converting sound vibrations into electrical signals that can be interpreted by the brain.
• Perilymph: The fluid that fills the scala tympani and scala vestibuli in the cochlea.
• Basilar membrane: A membrane in the cochlea that separates the scala media from the scala tympani and scala vestibuli.
• Scala vestibuli: The upper chamber of the cochlea, which is filled with perilymph and connects to the scala media at the helicotrema.
• Scala media: The middle chamber of the cochlea, which is filled with endolymph and contains the organ of Corti.
• Organ of Corti: The sensory organ in the cochlea that converts sound vibrations into electrical signals.

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