Figure 1

The surgical procedure of approaching to the depths of the brain [[3]]. (a) A layered structure from the skull bone to the brain. In order to expose a lesion area located in the brain, it is required to path through those layers. (b) Opening the skull. After dissection of soft tissues (skins and muscles), the skull bone layer is exposed. Some drill holes are made so that high-speed drill can cut the skull in curvilinear fashion. (c) Opening the dura matter. The arcuate opening can be made in the dura matter layer. (d) Cutting the arachoid matter. The arachoid matter and trabeculae fix brain and internal structures (nerves and veins), so those connective tissues should be removed to retract the brain. (e) Exposing the lesion area. Due to spatula pressure, Retraction the brain has potential dangers to injure to adjacent brain regions.