Atlantoccipital joint

Atlantoccipital joint , articulatio atlanto-occipitalis, paired. It is formed by the articular surface of the occipital condyles, condyli occipitales, and the upper articular fossa of the atlas, fovea arlcularis superior. The longitudinal axes of articular surfaces of the occipital bone and the atlas somewhat converge anteriorly. The dorsal surfaces of the occipital bone are shorter than the articular surfaces of the atlas. The joint capsule is attached to the edge of the articular cartilage. According to the shape of articular surfaces, this joint belongs to a group of ellipsoidal, or condylar, joints.

In both, the right and left joints, which have separate joint capsules, the movements are performed simultaneously, i.e. They form one combined joint; Possible kivatelnye (bending forward and back) and minor lateral movements of the head.

In this connection, there are:

1. Anterior atlantocostylar membrane, membrana atlanto-occipitalis anterior. Stretches over the entire gap between the anterior edge of the large occipital foramen and the upper edge of the anterior arch of the atlas; Fuses with the upper end of the lig. Longitudinale anterius. Behind it is located anterior atlantocapital ligament, lig. Atlanto-occipitalis anterior, stretched between the occipital bone and the middle part of the anterior arch of the atlas.

2. The posterior atlantocostylar membrane, membrana atlanto-occipitalis posterior. It is located between the posterior edge of the large occipital opening and the upper edge of the posterior arch of the atlas. In the anterior section there is an opening through which the vessels and nerves come. This membrane is a modified yellow ligament. The lateral sections of the membrane are lateral atlanto-occluding ligaments, ligg. Atlantooccipitaiis lateralia. When articulating the atlas and the axial vertebra, three joints are formed - two pairs and one unpaired.

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