Review of the functional anatomy of the spinal ligaments and the lumbar erector spinae muscles

A reassessment is presented of the functional anatomy of the spine and associated musculature. Recent detailed anatomical studies of the erector spinae muscle group have shown a complex organization which is not well explained by traditional models of the mechanical behavior of the spine. In an arch‐like model for the spine this complexity is required to control the curvature and the compressive thrust along the spine to ensure mechanical stability. This model also assigns a biomechanical function to the erector spinae muscles that is consistent with their anatomical description, unlike previous lever models. Implications are that posture, the many‐curved configuration of the spine adopted during maneuvers, is important when assessing spinal function and that the spine forms a dynamic structure in which all the muscles, ligaments, discs, and vertebrae must be considered synergistically. © 1992 Wiley‐Liss, Inc.