The perilymphatic duct is where the perlyphatic space (i.e., the vestibule of the inner ear) is connected to the subarachnoid space. This works as a type of shunt

Shunt

Shunt may refer to:* Shunt - a hole or passage allowing fluid to move from one part of the body to another* Shunt - a device allowing electrical current to pass around a point in a circuit...

 to eliminate excess perilymph

Perilymph

Perilymph is an extracellular fluid located within the cochlea in two of its three compartments: the scala tympani and scala vestibuli. The ionic composition of perilymph is comparable to that of plasma and cerebrospinal fluid...

 fluid from the perlymphatic space around the cochlea

Cochlea

The cochlea is the auditory portion of the inner ear. It is a spiral-shaped cavity in the bony labyrinth, making 2.5 turns around its axis, the modiolus....

 of the ear

Ear

The ear is the organ that detects sound. It not only receives sound, but also aids in balance and body position. The ear is part of the auditory system....

. Perilymph is continuous with cerebrospinal fluid

Cerebrospinal fluid

Cerebrospinal fluid , Liquor cerebrospinalis, is a clear, colorless, bodily fluid, that occupies the subarachnoid space and the ventricular system around and inside the brain and spinal cord...

 (CSF) in the subarachnoid space. CSF pressure abnormalities do not generally have clinical impact on the inner ear which is explained physically by the bore diameter of the perilymphatic duct and its length. This duct goes through the skull

Human skull

The human skull is a bony structure, skeleton, that is in the human head and which supports the structures of the face and forms a cavity for the brain.In humans, the adult skull is normally made up of 22 bones...

 and is parallel with but not directly associated with the endolyphatic duct. The duct is lined by an epithelium.