zygapophysial

Zygapophysial refers to the zygapophysis, the articular processes of a vertebra that form the zygapophysial joints with adjacent vertebrae. Each vertebra bears superior and inferior articular processes; the superior process articulates with the inferior process of the vertebra above, and the inferior process articulates with the superior process of the vertebra below. The contact surfaces, or facets, are covered with hyaline cartilage and the joints are synovial, enclosed by a fibrous capsule and supported by surrounding ligaments.

Orientation of the zygapophysial joints varies by region. In the cervical spine, facets are oriented obliquely, allowing a greater range of rotation. In the thoracic spine, facets are more coronally oriented, limiting flexion and extension and guiding rib movements. In the lumbar spine, facets are oriented mainly sagittally, permitting forward bending and backward bending while limiting rotation. Together, these joints stabilize the spine and guide movement.

Clinical relevance includes degenerative changes known as facet arthropathy, which can cause localized neck or back pain. Imaging may reveal facet joint changes, and management can include physical therapy, analgesics, and procedures such as facet joint injections or neuroablation when appropriate. The zygapophysial joints thus play a central role in spinal stability, load transmission, and coordinated motion while contributing to proprioceptive feedback.