The Structure That Forms the "Roof" of the Spiral Organ

Question

The structure that forms the "roof" of the spiral organ is the
A) basilar membrane.
B) tectorial membrane.
C) stapedius.
D) perilymph.
E) endolymph.

Accepted Answer

The tectorial membrane forms the roof of the spiral organ, which is also known as the organ of Corti. This membrane extends over the hair cells and provides a surface against which the cilia of the hair cells can move. The basilar membrane forms the floor of the spiral organ, separating it from the tympanic canal. Stapedius is a small muscle in the middle ear that contracts in response to loud sounds. Perilymph is the fluid that fills the bony labyrinth of the inner ear. Endolymph is the fluid that fills the membranous labyrinth and surrounds the hair cells.