scala tympani

noun

scala tym·​pa·​ni -ˈtim-pə-ˌnī  -ˌnē 

plural scalae tympanorum -ˌtim-pə-ˈnōr-əm, -ˈnȯr-əm 

: the lymph-filled spirally arranged canal in the bony canal of the cochlea that is separated from the cochlear duct by the basilar membrane, communicates at its upper end with the scala vestibuli, and abuts at its lower end upon the membrane that separates the round window from the middle ear