Question

Which is not a part of the cochlear duct?
A. Reissners’s membrane
B. Scala media
C. Macula of the utricle
D. Tectorial membrane

Answer 1

Hint:The ear is the organ of hearing and balance. The organs of hearing and equilibrium convert mechanical energy to receptor(action) potential. Therefore they are called mechanoreceptors. The ears are located on the sides of the head. The ears show three parts: external, middle, and internal.

Complete answer:The cochlear duct is a 35mm, long spirally coiled tube of about two and a half turns resembling a snail shell. Part of the bony labyrinth that encloses a cochlear duct is called the cochlear canal.
The cochlear duct and the cochlear canal are together referred to as cochlea.
The Wall of the cochlear duct is fused with that of the cochlear canal on the sides but is free above and below. As a result, the cochlea has three longitudinal chambers called scale, inside it, upper, middle, and lower.
These chambers are separated from one another by thin membranes and become progressively narrower from the base to the apex.
The middle chamber is called scale media. It is actually a cochlear duct and is an outgrowth from the saccule. Therefore it is filled with endolymph, which is secreted by its epithelium lining. The floor of the scala media is called the basilar membrane, and its roof, the Reissner’s membrane.
The upper and lower chambers of the cochlea are termed the scala vestibuli and scala tympani respectively. They contain perilymph and both communicate with each other at the distal end of the cochlea by a narrow passage called helicotrema.
At the proximal end, the scala vestibuli and scala tympani communicate with the oval and round window respectively.

So the correct answer is option is B. macula of the utricle.

Additional information:
The parts of the ear include:
1. External ear – the external ear has two regions: pinna, auricle of the ear lobe, and external auditory canal or meatus.
2. Internal ear- it is a delicate, irregular organ called a membranous labyrinth. It is surrounded by an almost similarly shaped bony labyrinth.
3. Middle chamber: it is called scala media. It is actually the cochlear duct and is an outgrowth from the saccule. The floor of scala media is called the basilar membrane.

Note:The macula is the projecting ridge of the saccule and utricle are otolith organs present in the inner ear.
The basilar membrane on it’s an organ of hearing called the organ of Corti. The latter consists of receptor cells and supporting cells. The receptor cells also called hair cells bear hair at the surface and have synaptic contact with the dendrites of neurons at the bases.