Inner Ear

This cross section through the cochlea of the inner ear shows the structures important for the transduction of sound from a vibration to a neural signal. Begin by identifying the bony portion of the cochlea, located in the petrous portion of the temporal bone. The inner ear contains two fluid-filled canals that spiral makes 2.75 turns around a central bony axis known as the modiolus. The scala vestibuli and scala tympani contain perilymph whereas the scala media contains endolymph. The scala vestibuli and scala tympani are continuous with sound waves travelling up the vestibuli and returning through the tympani. The scala vestibuli and scala media are separated by the vestibular membrane, and the scala media and scala tympani are separated by the basilar membrane. The organ of Corti is located on the basilar membrane and contains the hair cells that can be observed more closely in subsequent slides. The bony portion of the cochlea also contains the spiral ganglion, which contains cell bodies of cranial nerve VIII. What are the relative ionic contents of perilymph and endolymph?