Atlanto-occipital joint

The atlanto-occipital joint is a bone joint between the occipital part of the skull and the apex of the atlas, through which the axis of connection of the head with the body passes (the atlanto-occipital joint). The joint is formed by the articular surface of the upper edge of the foramen magnum and the condyles of the atlas. Only minor angular movements are possible around this joint. The articular surfaces are connected to each other by cross-shaped grooves and spines; in the front and rear parts they are flat, in the lateral parts they are concave. Lateral head movements are limited by the posterior border of the atlas condyle (the fixed part of the skull). The atlanto-occipital joint, together with other organs, perceives the static load of the head and partly the dynamic force that occurs when the head moves. The precise location and strength of attachment of the muscles and ligaments of the skull limits side-to-side and vertical movement of the head. These restrictions are not enough to ensure that movement is not limited when turning the neck, which the atlanto-occipital joints carry out when passively holding the head with the hands of a corpse. Normally, head movements are very small, even when tilted forward by 40% in the sagittal plane. Restriction of movement is observed in all directions. Neck muscle tone imparts additional rigidity and lateral flexion is severely limited. The mobility of the head in the cervical spine corresponds to minor angular movements of this section. An increase in loads beyond this mobility, occurring in childhood, leads to the development of kyphoscoliosis with a decrease in anatomical curves and rickets. Dynamic physical activity during training using weights significantly increases the capabilities of the joint system of the neck.