Trunk (thorax, abdomen, back)

Zygapophysial (Facet) Joints

Articulationes zygapophysiales (Facetgewrichten)

Origin

Inferior articular process of superior vertebra

Insertion

Superior articular process of inferior vertebra, enclosed by fibrous capsule with synovial meniscoids

Function

Guides and restricts spinal segmental motion planes; bears 15-20% of axial load (up to 40% in hyperextension)

Innervation

Medial branch of the dorsal ramus of spinal nerves (dual innervation from corresponding and superior levels)

Movement & chain

Gliding translation: gapping during flexion, compression and imbrication during extension and ipsilateral side-bending

Palpation

Deep palpation 1.5–2 cm lateral to spinous processes eliciting local segmental tenderness

Clinical

Facet arthropathy / facet joint syndrome with referred non-dermatomal pain to buttock/thigh; treated by medial branch block / radiofrequency ablation (RFA).

Segmental innervation

C1–S1 via medial branches

In clinical practice

Manual joint mobilization, core stabilization, and diagnostic fluoroscopic joint injections

Region in the model

Trunk (thorax, abdomen, back)