Prezygapophyses

Prezygapophyses are paired anterior articular processes on the neural arch of a vertebra. Along with the postzygapophyses on the opposite side, they form the zygapophysial joints that connect adjacent vertebrae. The articular surfaces of the prezygapophyses contact the postzygapophyses of the neighboring vertebra, creating a bilateral series of joints that stabilizes the spine while allowing controlled movement.

Structure and variation: Prezygapophyses originate on the neural arch, projecting toward the direction of the adjacent vertebra. Their size, orientation, and degree of overlap vary among vertebrate groups, reflecting different locomotor demands and lifestyles. In many reptiles and birds, the zygapophyses are well developed and arranged to resist excessive bending, whereas in some mammals the pattern is adapted by changes in the relative orientation of the articular surfaces across different regions of the spine (cervical, thoracic, lumbar).

Function: The prezygapophyses, together with the postzygapophyses, limit certain movements of the spine, particularly excessive lateral flexion and torsion, contributing to overall axial stability. The arrangement of these joints helps maintain alignment of the vertebral column during locomotion and supports posture.

Taxonomic and paleontological relevance: The presence, shape, and orientation of prezygapophyses are used in comparative anatomy and vertebrate paleontology to infer vertebral position, relationships among taxa, and aspects of locomotor style. They are part of the broader system of zygapophyses that characterize vertebral articulation across many vertebrate groups.