Relevant anatomy of the craniovertebral junction

Objectives. Anatomy of the craniovertebral junction (CVJ) includes the foramen magnum located in the occipital bone, atlas (C1), and axis (C2) united by ligaments and muscles, the lower cranial and upper spinal nerves, the caudal brainstem and rostral spinal cord, the vertebral arteries and their branches, the venous drainages through the jugular vein, and the vertebral plexus. The objective of this chapter is to provide a 360° description of the relevant microsurgical and endoscopic anatomy of the CVJ. Materials and Methods. Cadaveric dissections were performed, and anatomical observations were made with the aid of a surgical microscope and of a 0- and 30-degree rod-lens endoscopes. Three-dimensional (3D) models were reconstructed, using dedicated software, from the anatomical images of the head of The National Library of Medicine’s Visible Human Project. Results. The relevant anatomy of the CVJ was explored through (1) a posteromedial perspective directed at the squamosal part of the occipital bone and the middle part of the posterior arch of C1; (2) a posterolateral perspective focused on the condylar part of the occipital bone, lateral mass of C1 and C2; (3) an anterolateral perspective directed to the jugular foramen, transverse process of C1 and C2; (4) an anteromedial perspective that provides exposure of the clival portion of occipital bone, anterior arch of C1, and odontoid process. Conclusions. Description of the relevant anatomy of the CVJ with a 360° anatomical perspective upgraded with 3D models may provide anatomical information more readily applicable to the operative setting.