The articular processes or zygapophyses (Greek ζυγον = "yoke" (because it links two vertebrae) + απο = "away" + φυσις = "process") of a vertebra, two superior and two inferior, spring from the junctions of the pedicles and laminæ. These stick out of an end of a vertebra to lock with a zygapophysis on the next vertebra, to make the backbone more stable.
The superior processes project upward from a lower vertebra, and their articular surfaces are directed more or less backward.
The inferior processes project downward from a higher vertebra, and their articular surfaces are directed more or less forward and outward.
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