The cochlea has the shape of a snail shell that rotates around a bony axis which is the modiolus . From the modiolus starts the lamina spiralis ossea which at the top forms a created hammulus. The lamina divides the space of the cochlea into 2 levels (scala): vestibular and tympani Both of these are filled with perilymph. The membranous cochlea (ductus cochlearis) is formed by 2 elastic membranes. The basilar membrane is also the lamina spiralis ossea, while Reisner's membrane starts at a narrow angle with the basilar membrane and both form the ductus cochlearis. The third wall of the ductus cochlearis is formed by the stria vascularis, which has Na/K ATP-s pumps that maintain the concentration of electrolytes between the scales of the cochlea. Organ of the Court It is responsible for listening. The Cortical Organ consists of a row of internal hearing cells (5600).Both the inner and outer cells have cilia at the top. These cells are responsible for converting kinetic energy into electrochemical energy that is interpreted as sound.