| Articulatio atlantooccipitalis|
The atlanto-occipital joint (articulation between the atlas and the occipital bone) consists of a pair of condyloid joints. The atlanto-occipital joint is a synovial joint.
Atlanto-occipital joint Wikipedia
The ligaments connecting the bones are:Two articular capsules
Posterior atlanto-occipital membrane
Anterior atlanto-occipital membrane
The movements permitted in this joint are:(a) flexion and extension around the mediolateral axis, which give rise to the ordinary forward and backward nodding of the head.
(b) slight lateral motion, lateroflexion, to one or other side around the anteroposterior axis.
Flexion is produced mainly by the action of the longi capitis and recti capitis anteriores; extension by the recti capitis posteriores major and minor, the obliquus capitis superior, the semispinalis capitis, splenius capitis, sternocleidomastoideus, and upper fibers of the trapezius.
The recti laterales are concerned in the lateral movement, assisted by the trapezius, splenius capitis, semispinalis capitis, and the sternocleidomastoideus of the same side, all acting together.