Figure 1.

The five components of the glymphatic system. The fluid transport pathway is divided into five distinct segments: (1) cerebrospinal fluid (CSF) is produced by the choroid plexus and likely by extrachoroidal sources (capillary influx and metabolic water production); (2) arterial wall pulsatility drives CSF deep into brain along perivascular spaces; (3) CSF enters the brain parenchyma supported by aquaporin-4 (AQP4) water channels and disperses within the neuropil; interstitial fluid (ISF) mixes with CSF, (4) accumulates in the perivenous space, and drains out of the brain via (5) meningeal and cervical lymphatic vessels, as well as along cranial and spinal nerves Fluids from both the brain and the cribriform plate drain into the cervical lymphatic vessels, which then empty into the venous system at the level of the subclavian veins. The olfactory/cervical lymphatic drainage route is the primary bulk flow pathway.