C2 (Axis) - 2nd Cervical Vertebra

The C2 vertebra, known as the axis vertebra or the epistropheus, is the second-uppermost of the vertebrae making up the backbone and of the seven (7) cervical vertebrae at the top of the spine. Its nickname, the axis vertebra, derives from its role in allowing the head to rotate from its support atop the C1 vertebra where the skull attaches to the neck. As with the C1, the C2 vertebra is different from the other true vertebrae or moveable vertebrae below them. The ventral body or centrum of...

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Full C2 (Axis) - 2nd Cervical Vertebra Description

[Continued from above] . . . the C2 is actually contiguous with the C1 vertebra, which lacks a separate ventral body; but it is this fusion in part that gives the C1-C2 joint a wide range of lateral motion (providing most of the lateral motion of the head and neck). This fusion gives the C2 vertebra a third name, the vertebra dentata, for the tooth-like odontoid process or dens-a protuberance that rises from the back of the centrum and fuses with the odontoid peg of the atlas vertebra. The vertebral foramen of the axis vertebra is large enough to protect the last of the brain stem yet slightly smaller than that of the C1, but two oblique transverse foramen likewise allow the passage of nerves, the vertebral artery, and the vertebral vein from the spinal cord out to the body.