<unk>  <unk> , Liquor<unk> is, is a clear bodily<unk>  that occupies the subarachnoid space and the ventricular system around and inside the brain. Essentially, the brain "floats" in it.
More specifically the<unk>  occupies the space between the arachnoid mater (the middle layer of the brain cover, meninges) and the pia mater (the layer of the meninges closest to the brain). Moreover it constitutes the content of all intra-cerebral (inside the brain, cerebrum) ventricles, cisterns and sulci (singular sulcus), as well as the central canal of the spinal cord.
It is an approximately isotonic solution and acts as a "cushion" or buffer for the cortex, providing also a basic mechanical and immunological protection to the brain inside the skull.
Cerebrospinal fluid
Serum
Urine
Blood
Intracranial pressure
Subarachnoid space
Tissue 
Head 