ANATOMY

Detailed explanation-1: -The organ of Corti is formed when ridges of epithelial cells from the cochlear duct produce rows of mechanosensory hair cells that are covered by the tectorial membrane. The spiral ganglion forms when ganglion cells derived from the vestibulocochlear nerve (CN VIII) migrate along the spirals of the membranous cochlea.

Detailed explanation-2: -The cochlear duct develops from the ventral otic vesicle (otocyst). It grows slightly flattened between the middle and outside of the body. This development may be regulated by the genes EYA1, SIX1, GATA3, and TBX1. The organ of Corti develops inside the cochlear duct.

Detailed explanation-3: -The cochlear duct starts at the saccule and ends blindly at the apex of the cochlea. The cochlear duct subdivides the bony labyrinth into two perilymph chambers, namely the scala vestibuli anteriorly (opens into the vestibule) and the scala tympani posteriorly (ends at the round window) 1.

Detailed explanation-4: -The cochlear tube is formed by three membranous and fluid-filled canals, which are the scala vestibuli (SV most superior and connected with the vestibule), scala media (SM), and scala tympani (ST most inferior and ends at the secondary tympanic membrane and the round window) forming a two-and-a-half spiral structure.

Detailed explanation-5: -Two membranes separate the cochlear duct proper, which is also known as the scala media, from the scala tympani and scala vestibule. The basilar membrane demarcates the scala media from the scala tympani, while the vestibular membrane separates the scala media from the scala vestibule.