Which arthokinematic action describes the occipital condyles acting on the atlas during atlanto-occipital extension?

The correct choice describes the arthrokinematic movement that occurs at the atlanto-occipital joint during extension of the head. When the occipital condyles articulate with the atlas – the first cervical vertebra – the primary movement during extension is a posterior roll of the condyles.

As the head extends backward, the occipital condyles roll posteriorly on the articular surfaces of the atlas. Simultaneously, there is an anterior glide that occurs. This means that as the posterior roll happens, the anterior aspect of the occipital condyles moves slightly forward over the atlas. This combination of movements allows for proper alignment and function of this joint, which facilitates the extension and flexion range of motion of the head.

Understanding these arthrokinematic actions is crucial for clinical applications, especially when analyzing neck movement or addressing potential dysfunctions in this area. The other choices suggest different rolling and gliding movements that do not accurately represent the mechanics of the atlanto-occipital joint during extension.