zygapophysis

Paired processes at the cephalic and caudal ends of the neural arch. They function as interlocking structures between adjacent vertebrae, and limit dorsoventral flexion and lateral movement of the column in the trunk region[AAO]. The articular processes or zygapophyses of a vertebra, in human anatomy contain two superior and two inferior, spring from the junctions of the pedicles and laminae. 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. The articular surfaces are coated with hyaline cartilage.