Perilymph
The perilymph (lymph from Latin lympha "clear water" with the Greek prefix peri for "near") is a lymph-like fluid between the membranous and bony labyrinth of the inner ear . It surrounds the membranous semicircular canals and the cochlear duct ( ductus cochlearis ).
The perilymph is necessary for the functioning of the hearing . The movements of the ossicles stimulate the perilymph to vibrate, which in turn shakes the wall of the cochlear duct. The latter leads to an excitation of the auditory receptors (hair cells) of the organ of Corti .
The perilymph is believed to be a plasma filtrate across a blood-perilymph barrier . In addition, it is probably the starting product for the endolymph . Ultrafiltration of the blood as well as drainage of the cerebrospinal fluid is assumed to be a possibility of perilymph formation. The perilymphatic space is connected to the subarachnoid space of the brain via the perilymphatic duct ( ductus perilymphaticus or aqueductus cochleae ) . The compositions of perilymph and cerebrospinal fluid are similar but not identical.