Given below is a diagrammatic cross section of a single loop of human cochlea. [Figure] Which one of the following options correctly represents the names of three different parts?
- B : Tectorial membrane, C : Perilymph, D : Secretory cells
- A : Perilymph, B : Tectorial membrane, C : Endolymph
- C : Endolymph, D : Sensory hair cells, A : Serum
- D : Sensory hair cells, A : Endolymph, B : Tectorial membrane
Answer
(2) A : Perilymph, B : Tectorial membrane, C : Endolymph
Solution
In a cross section of the cochlea, the upper (scala vestibuli) and lower (scala tympani) chambers marked A are filled with perilymph.
The middle chamber (scala media), marked C, is filled with endolymph.
B is the elastic membrane lying over the hair cells ⇒ tectorial membrane.
D, on the basilar membrane, is the organ of Corti with its sensory hair cells.
As per NCERT, the scala vestibuli and scala tympani contain perilymph, the scala media is filled with endolymph, and the tectorial membrane overlies the rows of hair cells of the organ of Corti.
∴ A : Perilymph, B : Tectorial membrane, C : Endolymph.
Answer: (2)