The earliest human known to have the capability of walking erect on two legs is Sahelanphropus, who lived 6 million years ago. The ability to stand erect led to required extensive changes in the human skeleton, including significant changes in the cervical spine. In modern humans, the cervical spine holds the head upright and gives it great mobility. The combination of great mobility in this spinal segment combined with the requirement that it carry significant weight makes the cervical spine susceptible to a wide variety of pathologies. The cervical spine not only supports the head upright, but acts as a channel for the full set of neural elements connecting the brain with all near and distant parts of the body; thus, pathologies involving the spinal column in this segment directly affect the cervical spinal cord and exiting nerve roots. Today, excellence in spine surgery requires a thorough understanding of spinal anatomy, relevant neurology, and biomechanics, as well as skilled use of a variety of surgical techniques. The surgeon must master the ability to effectively select from a wide and constantly changing variety of alternative instrumentations and surgical approaches. In addition, the trend towards reducing the invasiveness of surgical procedures has led to the use of smaller and smaller tools and smaller surgical incisions with more limited views of the relevant anatomy. As a result of the rapid pace of change, the choice of an optimal technique in any given situation is increasingly complex. In this book, we begin with a basic review of anatomy, neurology, neurophysiology, and biomechanics. We also discuss clinical and radiological assessment required for a differential diagnosis, and present a thorough discussion of the importance of sagittal alignment of the spine and the utility of gait analysis. We proceed with a thorough discussion of nontraumatic pathologies causing cervical myelopathy, beginning with the craniocervical junction down through the subaxial spine, in pediatric and adult populations. This discussion includes steps in the differential diagnosis for specific pathologies, surgical techniques and nuances, radiation-based treatment alternatives, and special topics ranging from the use of stem cells to robotics and endoscopic surgery. We have attempted to provide both fundamental and state-of-the-art knowledge and to share the rich experience of some of the leading spine surgeons worldwide, with the aim of enabling surgeons at all levels to advance their own capabilities for performing safe and successful procedures in this area of complex anatomy.