Question

Scala tympani is connected to scala vestibuli by means of
a. Stapes
b. Helicotrema
c. Basilar membrane
d. Tectorial membrane

Answer 1

Hint: The cochlea is the sensory organ of hearing. The cochlea is a spiral tube that is coiled two and one-half turn around a hollow central pillar, the modiolus. The hollow center contains the cochlear artery and vein, and the cochlear nerve. Cochlear nerve is a division of the very short vestibulocochlear nerve.

Complete answer:
At the round window end, Scala tympani is present, which faces the middle ear. At the helicotrema, scala vestibuli merges with scala tympani that is located at the apex or upper end of the cochlea. Pressure introduced into scala vestibuli is transmitted up the cochlear duct, through the helicotrema, and down the duct via scala tympani.

The spiral ganglion cells of the cochlear nerve are found in a bony spiral canal winding around the central core. The osseous spiral lamina is a thin bony shelf it projects halfway across the cochlear canal, partly dividing it into two compartments. An upper chamber, the scala vestibuli, and a lower chamber called the scala tympani. The scala vestibuli and scala tympani, are filled with perilymph, communicate with each other through, called the helicotrema.

- Stapes are the third bone of the three ossicles of the middle ear, it transmits vibrations from the incus to the inner ear.
- Basilar membrane is present within the cochlea of the inner ear and separates scala media and scala tympani.
- Tectorial membrane is present in the acellular membrane in the cochlea of the inner ear.

Hence, the correct answer is option (B).

Additional information:
At the basal end, near the middle ear, the scala vestibuli opens into the vestibule. The basal end of the scala tympani ends just below the round window. Nearby there is an opening of the narrow cochlear aqueduct, through which passes the perilymphatic duct. In the inner ear, vibrations are converted into nerve impulses. The cochlea maintains two distinct fluid compartments, the scala vestibuli/tympani, and the scala media.

The Sound pressure is transmitted into scala vestibuli by the stapes, which fits into the oval window. The organ of Corti sits on the basilar membrane and contains receptors and supporting cells.

Note: Scala vestibuli is the lymph-filled and spirally arranged canal in the bony canal of the cochlea. It is separated from the cochlear duct below by the vestibular membrane and is connected with the oval window, and receives vibrations from the stapes. Scala vestibuli merges with scala tympani at the helicotrema which is located at the apex. The function is to transduce the movement of air that causes the tympanic membrane and the ossicles to vibrate, to the movement of liquid and the basilar membrane.