Human atlas C1 vertebra

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In anatomy, the C1 vertebra stands as the first and most superior cervical vertebra of the spine. Named after the Atlas figure from Greek mythology, it supports the skull, which serves as the globe of the head. The topmost vertebra is responsible for forming a joint with the axis that connects the skull to the spine. The atlas and axis are specially designed to provide a greater range of motion than typical vertebrae. They facilitate both nodding and rotation movements of the head by enabling it to tilt up and down on the vertebral column and rotate side to side, respectively. The atlanto-occipital joint enables the skull to move smoothly in an upward or downward direction along the vertebral column, while the dens acts as a pivot that allows for rotational movement. This unique design permits smooth rotation of the atlas and attached head around the axis, allowing it to turn from one side to the other. One notable feature of the atlas is its distinctive structure. Unlike regular vertebrae with bodies, the atlas has no body; instead, it consists of a ring-like shape formed by an anterior arch, posterior arch, and two lateral masses. The significance of the atlas and axis extends beyond anatomy to the realm of neurology. The brain stem extends down to the axis, underscoring their importance in facilitating communication between different parts of the body.