A scythe in the medical sense of the term designates a membrane forming a partition separating two entities which is the case in the brain and the cerebellum. The falx cerebri is part of the brain and is located vertically between the two cerebral hemispheres.
It has the shape of a scythe hence the name, its upper part being attached to the skull and its lower part forming a semi-circle. This membrane is one of the three partitions of the brain formed by the dura mater which protects and covers the central nervous system. The dura mater corresponds to the outermost layer of the three layers (with the arachnoid and the pia mater) forming the meninges whose role is to protect the structures of the nervous system.