The craniovertebral junction is the most complex of the axial skeleton, residing between the skull and the upper cervical spine. Congenital, developmental, and acquired bony abnormalities result in compression and distortion of the neural structures, the vertebrobasilar vascular system, and the cerebrospinal fluid channels. The clinical significance of this has only been recently recognized, and mistaken diagnoses have led to a delayed treatment and at times adverse results. A review of the anatomy, the embryology, and the mechanics of this region is essential to the understanding of the pathophysiology encountered.