Human Anatomy Part 1 - K. A. Diubenko, A. K. Kolomiitsev, Iu. B. Chaikovsky 2002

Special Part
Arthrology, artrologia [the study of bone joints] — Classification of joints and their general characteristics
Articulations between the first and second cervical vertebrae, and between the first vertebra and the skull

The connections between the First and Second cervical vertebrae, as well as between the first vertebra and the Skull, are particularly complex. The Articulation of the occipital condyles with the articular surfaces of the atlas forms a combined, ellipsoid atlanto-occipital joint, art. atlanto-occipitalis. Movements possible in this joint include rotation around the sagittal axis (lateral HEAD tilt) and the frontal axis (flexion and extension). The connection between the atlas and the second cervical vertebra forms three joints: a paired, combined planar lateral atlanto-axial joint, art. atlanto-axialis lateralis, located between the inferior articular surfaces of the atlas and the superior articular surfaces of the axis, and an unpaired, cylindrical median atlanto-axial joint, art. atlanto-axialis mediana, situated between the dens of the axis and the articular facet of the atlas (Fig. 78 C).

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Fig. 78. Connections of THE Vertebral Column with the skull:

A - ligaments and JOINTS OF THE cervical vertebrae and Occipital bone; B - ligaments of the median atlanto-axial joint; C - connection of the atlas with the dens of the axis

The joints are reinforced by strong ligaments. Stretched between the anterior and posterior arches of the atlas and the margin of the foramen magnum are the anterior and posterior atlanto-occipital membranes, membrana atlantooccipitalis anterior et posterior. The transverse ligament of the atlas, lig. transversum atlantis, spans between the lateral masses of the atlas.

A fibrous band extends from the upper free margin of the transverse ligament to the anterior semi-circumference of the foramen magnum. From the lower margin of the same ligament, a fibrous bundle also descends to the body of the second vertebra. The upper and lower fiber bundles, together with the transverse ligament, form the cruciate ligament of the atlas, ligg. cruciforme atlantis (Fig. 78A). From the upper part of the lateral surfaces of the dens, two alar ligaments, ligg. alaria (Fig. 78B), extend to the occipital condyles.