Which cervical vertebra forms a ring around the odontoid process and supports the skull?

Which cervical vertebra forms a ring around the odontoid process and supports the skull?

• A. Atlas (C1)
• B. Axis (C2)
• C. Occipital bone
• D. Sacrum

Answer: (A)

Atlas forms a ring around the odontoid process and supports the skull. Its ring-like structure, made up of the anterior arch, posterior arch, and lateral masses, encircles the dens that projects upward from the axis (the second cervical vertebra). The dens serves as a pivot, stabilized by the transverse ligament of the atlas, allowing the atlas and skull to rotate relative to the axis. The skull rests on the atlas at the atlanto-occipital joints, enabling head nodding and movement. The axis provides the dens itself but does not form the ring; the occipital bone is part of the skull, and the sacrum is a distant pelvic bone.

Atlas forms a ring around the odontoid process and supports the skull. Its ring-like structure, made up of the anterior arch, posterior arch, and lateral masses, encircles the dens that projects upward from the axis (the second cervical vertebra). The dens serves as a pivot, stabilized by the transverse ligament of the atlas, allowing the atlas and skull to rotate relative to the axis. The skull rests on the atlas at the atlanto-occipital joints, enabling head nodding and movement. The axis provides the dens itself but does not form the ring; the occipital bone is part of the skull, and the sacrum is a distant pelvic bone.