From the Idea to Its Realization: The Evolution of Minimally Invasive Techniques in Neurosurgery

Figure 3

By analogy with a terrestrial globe the superficial coordinates on the head are defined by polar coordinate system by degrees of longitude and latitude. The poles correspond to the nose anterior and to the protuberantia occipitalis posterior, respectively. The (blue) zero meridian is running in the midline from anterior to posterior, dividing the head into a right and a left hemisphere, and the (red) equator divides the head into an anterior and posterior half and is running near the central region.