”A big river with wide waves, the wind blowing rice blossoms scent both sides of the river.” These are the two lines from the song “My Motherland”. It sings the praise of the long origin of the mother river and depicts the beautiful scenery on both sides of the big river. Nature is magnificent and colorful, in fact, there is also a curved and undulating “heavenly river” deep in the human brain, which is like a trickle of water, moistening things silently, bypassing thousands of mountains and ravines, nourishing nerve cells. It is not a mountain spring that flows day and night, but the cerebrospinal fluid, which is rich in many functions and contains many substances. The cerebrospinal fluid is like water, not water, but like water. The “rivers” that flow from the cerebrospinal fluid, the “lakes” and “gullies” that it fills, are called the cerebrospinal fluid circulation system in medical anatomy and physiology. It is called the cerebrospinal fluid circulation system. This long river in our brain, like the Yangtze River, has a source. This source is in the choroid plexus in the two lateral ventricles of the brain in the middle of the longitudinal zone. It secretes clear and crystal clear cerebrospinal fluid every second, like a small mountain spring, quietly percolating out, accumulating in the two lateral ventricles, which becomes the largest “inland lake” in the brain that never dries up. The cerebrospinal fluid from the lateral ventricles flows through the interventricular foramen into a third ventricle as narrow as an adzuki bean, watering the “mountainous peaks” here. Then it rushes down non-stop and flows into the dangerous and slender 2 cm long “three gorges” section – the midbrain aqueduct, which is really “Shujiang River spring water patting mountain flow”. This dangerous section is a disaster-prone bottleneck. Its biggest danger is that this narrow pipe is often blocked due to inflammation, trauma, bleeding, and adjacent tumors, causing the upstream flooding and water accumulation. This is where the medical diagnosis of “obstructive hydrocephalus” comes from. Obstructive hydrocephalus is one of the most common types of hydrocephalus, often occurring in infants and young children. The most typical symptoms and signs of hydrocephalus are enlargement of the head, difficulty in closing fontanel, poor development, and mental retardation; enlargement of the lateral ventricle and the third ventricle can be seen on CT films. At this point, the only way to alleviate the upstream disaster is to use the method of Dayu’s water treatment and take a diversion to divert the flow. The most effective surgery today is to open an artificial river to transfer the “brain and water ventrally”, allowing the accumulated water to flow into the “ventral sea” through a tube. This is medically known as a ventriculo-abdominal shunt. There are also cases where the blocked septum is poked through under the guidance of a brain endoscope to allow the “river” to flow again, or a “short channel” is created to divert the flow in a different way. This is an immediate solution for cerebrospinal fluid. After the cerebrospinal fluid has passed through the “three gorges”, it is as if “a light boat has passed over ten thousand mountains”, and then it comes to the “third lake” in the brain, which is open and clear. -The fourth ventricle of the brain and the adjacent occipital pool. This room is shaped like a curved moon and has three outlets. After all the cerebrospinal fluid is injected into this area, it quickly flows to the vertebral canal and the vast subarachnoid space of the brain, overflowing into pools, chambers, ditches and streams throughout the brain, forming a “water network” that intersects and communicates with each other, nourishing millions of nerve cells in the brain. Finally, relying on countless arachnoid granules, drops of “water droplets” are reabsorbed into the microvasculature of the brain, and after processing, fresh cerebrospinal fluid is again secreted from the choroid plexus, which contains various chemical components, such as sodium, glucose, and protein. This creates a virtuous cycle of cerebrospinal fluid flow that never rests, perfectly maintaining the “ecological balance” of the brain, nourishing this magical fertile ground, and ensuring the endless vitality of the brain. The circulation of cerebrospinal fluid is also called the third cycle. The human body secretes about 500 ml of cerebrospinal fluid every day, and about 150 ml of it accumulates in the ventricles, brain pools and spinal canal. This accumulated cerebrospinal fluid is not a pool of stagnant water, but is replaced 3 to 4 times a day, spitting out the old and bringing in the new. Therefore, for many brain disorders, such as epidemic meningitis and tuberculous meningitis, the doctor will take cerebrospinal fluid from the patient at different times and perform tests such as manometry, routine, biochemical and bacterial culture for diagnosis, differential diagnosis and observation of changes in the condition. This is similar to water conservators collecting river water from different sections and periods for testing to determine the degree of water clarity and pollution and to develop treatment plans. Therefore, when a patient is suspected of having intracerebral inflammation, trauma, hemorrhage, edema, etc., it is necessary and safe for the doctor to choose to do a ventriculocentesis or lumbar puncture to take cerebrospinal fluid for examination, and the patient and family need not worry about it. Moreover, extracting 2 to 3 ml of cerebrospinal fluid is like scooping a bucket of water in a big river, which is irrelevant to the big picture. This large river deep in the brain also has a unique role as a vehicle for treating certain brain diseases. For example, when encephalitis ventriculitis is present, doctors can inject sensitive antibacterial drugs directly into the ventricles of the brain through lumbar puncture and ventriculocentesis, and with the help of flowing cerebrospinal fluid the more concentrated drugs are rapidly diffused throughout the brain, evading the blockage of the blood-brain barrier. In cases of trauma or vascular rupture resulting in subarachnoid hemorrhage or ventricular hemorrhage, ventricular drainage and perfusion can also be performed. By using the circulatory pathway of cerebrospinal fluid, the harmful “blood” or contaminated “water” can be drained and flushed out of the brain, and this treatment can often achieve twice the effect with half the effort. Therefore, this river deep in the brain, although its appearance, no shocking waves, lack of surging, but it has been like a trickle, quietly dedicated. Although it is not a huge river, but in a sense, it is also the indispensable mother river of the human body. We should take good care of the mother river in our own brain.