Zygapophyseal Joint
Description
Name
- Zygapophyseal Joint
- Facet Joint
- Apophyseal joints
- Z joint
- Articulatio zygapophysialis
- Intervertebral joint
General
- Small synovial joints located in the spine between the superior/inferior articular processes of adjacent vertebrae
- They concurrently provide stability to the spine and facilitate movement
- Extends from C2 to S1 with regional variability
Joint Description
- Only synovial joints in the spine
- Composed of hyaline cartilage overlying subchondral bone, a synovial membrane and a joint capsule
- Makes up the postero-lateral articulation between Vertebrae
- Contains 1 to 2 ml of synovial fluid contained in a thin, loose fibrous capsule
- Menisci exist within joint space
Cervical Region
- Superior articular facets are superoposteriorly placed
- Corresponding inferior facets are anteroinferiorly oriented
- Joint slopes inferiorly from anterior to posterior, permitting flexion and extension
Thoracic Region
- Superior articular facets largely project posterior
- Inferior facets are mainly anterior
- Joints are restricted in flexion/extension but permit rotational movement
Lumbar Region
- Sagittal oriented with the superior facet posteromedial
- Inferior facet faces anterolaterally
- Articular processes are interlocked, permits limited flexion and extension
Ligaments
- Stabilized by accessory ligaments of the vertebral column
Vascular Supply
- Primarily from the medial branches of the dorsal rami of the spinal nerves
Innervation
- The joint capsule and adjoining structures are richly innervated.
- Each joint receives a dual nerve supply.
- The articular branches arise from the medial branch of the posterior Primary Rami
- E.g. L4/L5 zygapophyseal joint receives supply from the L4 medial branch (corresponding segment) and the L3 medial branch (one level above).