Imagine the use of mathematical formulas for brain targeting in neurosurgery. Research results of the 21st century have brought about the beginning of stereotactic anatomy evolution into stereotactic microanatomy, which is primarily based on applied mathematics. The purpose of this book is to present the mathematical principles and applications of stereotactic brain microanatomy in a concise and comprehensive manner. The robust mathematical principles of stereotactic microanatomy of the human brain are explained in detail, as well as its main clinically significant applications to modern stereotactic and functional neurosurgery. Stereotactic space of the human brain is defined in terms of its appropriate mathematical basis, where the principles of analytic geometry are strictly followed. Rigid adherence to these principles can further enable the safe application of mathematical formulas to the processing and use of stereotactic microanatomy data in clinical practice. Additionally, the concept of stereotactically standard brain areas is thoroughly explained, thus opening new horizons for the application of stereotactic microanatomy to highly accurate brain targeting, which is mainly useful for minimally invasive neurosurgical procedures, such as deep brain stimulation. Stereotactic microanatomy aims to guide stereotactic neurosurgical interventions in the best possible way, providing a solid mathematical basis for a safe and respective evolution of stereotactic neurosurgery into stereotactic microneurosurgery.