In a patient with sensorineural hearing loss receiving a cochlear implant, which structure is directly stimulated by the device?

The cochlear implant is designed to restore hearing by directly stimulating the auditory system. In this case, the correct structure that is stimulated by the cochlear implant is the auditory nerve endings in the cochlea.

Cochlear implants bypass damaged hair cells within the inner ear, which are responsible for converting sound vibrations into electrical signals. Instead, the device transmits electrical impulses directly to the auditory nerve endings situated in the cochlea. This direct stimulation allows auditory signals to be sent to the brain, resulting in the perception of sound, even in cases where the inner hair cells may be dysfunctional or absent.

The inner hair cells of the cochlea play a crucial role in normal hearing by detecting sound vibrations. However, in patients requiring cochlear implants, these hair cells are typically damaged or non-functional, which is why the device does not stimulate them directly. Instead, it targets the corresponding auditory nerve endings, effectively circumventing the damaged structures.

The cochlear nerve itself is a continuation of the auditory nerve and transmits signals to the brainstem (where it enters the pons), but the implant does not stimulate this nerve at that level; it stimulates the nerve endings directly within the cochlea. Olivocochlear efferent axons are involved in