part of part of Homo sapiens lumbar vertebra 4 zone of bone organ superior articular facet of fourth lumbar vertebra 2026-03-19T00:00:00Z A zone of bone organ comprising the concave, medially facing articular surface on the superior articular process of the fourth lumbar vertebra, oriented in the sagittal plane. It articulates with the inferior articular facet of the third lumbar vertebra, contributing to the L3–L4 zygapophyseal joint, which bears significant compressive and shear loads in the lower lumbar spine. David Osumi-Sutherland