This chapter comprehensively describes the intricate biomechanics of the atlanto-axial joint, a complex structure located at the crucial cranio-cervical junction. It introduces the primary ligaments of the atlanto-axial joint—the transverse ligament of the atlas, apical ligament, alar ligament, cruciform ligament, and accessory atlanto-axial ligament—and highlights their anatomical attributes and physiological significance in providing stability and facilitating cervical spine movement. The discussion extends to the clinical ramifications of these ligaments and highlights their indispensable role in preventing excessive movements that could compromise the spinal cord. It addresses the critical contribution to ligament health of the vascular network based on the vertebral, occipital, and deep cervical arteries. It also explores the impact of developmental malformations such as those associated with FBN1 mutations on the integrity and function of these ligaments, leading to potential neurological symptoms and spinal cord compression. Diagnostic approaches are outlined with a focus on imaging methods such as radiography, CT, and MRI, which are vital for visualizing bony structures and soft tissues in order to identify malformations, instability, and neural tissue compression. The chapter concludes with an exploration of surgical interventions for atlanto-axial ligamentous developmental anomalies, emphasizing the complexities and risks associated with such procedures, and the importance of meticulous preoperative planning and postoperative care.