Question

Cochlear implant given below, identify the marked structure:

• A. Internal magnet
• B. Electrode
• C. Receiver
• D. Antenna

Hint:

Which single component is actually threaded inside the cochlea to deliver current? That coiled intracochlear wire is the answer.

Answer 1

The Correct Option is B

Step 1: Understand the cochlear implant system. A cochlear implant bypasses damaged hair cells and directly stimulates the cochlear (auditory) nerve. It has EXTERNAL parts (microphone, speech processor, transmitting coil/antenna with magnet) and INTERNAL surgically implanted parts (internal receiver-stimulator with an internal magnet, and an electrode array).
Step 2: Trace the signal path. Sound $\rightarrow$ microphone $\rightarrow$ speech processor codes it $\rightarrow$ external transmitting coil sends the signal across the skin by radiofrequency $\rightarrow$ internal receiver-stimulator decodes it $\rightarrow$ current is delivered through the long, thin, coiled electrode array that is threaded into the scala tympani of the cochlea to stimulate the spiral ganglion / cochlear nerve fibres tonotopically.
Step 3: Why option B is correct. In the image, the long thin coiled element entering/lying within the cochlea is the electrode (electrode array) - the only part that actually sits inside the cochlear turns to deliver the stimulating current. The radiograph (right panel) shows this coiled electrode wound inside the cochlea, confirming it.
Step 4: Why the others are wrong. (A) Internal magnet is a small disc-shaped component that holds the external coil in place by magnetic attraction across the skin - it is round, not a coiled wire in the cochlea. (C) Receiver (receiver-stimulator) is the bulky package implanted under the scalp/temporal bone that decodes the signal - it sits OUTSIDE the cochlea. (D) Antenna (transmitting coil) is an EXTERNAL part worn on the skin, not implanted in the cochlea.
Final answer: B. Electrode.