The cerebellar medullary pool, as the name implies, is a cavity in the brain filled with cerebrospinal fluid, located behind the medulla oblongata, below the cerebellum, above the foramen magnum of the occipital bone, and actually in the posterior portion of the skull base, behind the brain stem. Because the brain is immersed in cerebrospinal fluid and surrounded by the skull, the cerebrospinal fluid is a protection for the brain. And at the base of the skull, because of the presence of the cerebellar medullary pool, there may be more protection for the cerebellum and brainstem. Its main clinical significance lies in the puncture of the cerebellar medullary pool. When intracranial infection or demyelinating disease or tumor, the clinical need to collect cerebrospinal fluid, the more common puncture site in the lumbar spine, mainly for the lumbar 4, lumbar 5 of the interspace, but some patients, such as in the lumbar spine on the skin of the break or vertebral deformity or trauma and can not be lumbar puncture, or lumbar puncture failure, repeated puncture did not collect the cerebrospinal fluid, will be taken to cerebellar medulla oblongata pool puncture in the cerebellar medullary pool, in the cerebellar medulla oblongata pool,. Normal people have a relatively large cavity, puncture correctly can be more easily collected cerebrospinal fluid, usually does not damage the brain tissue.