LU M B A R S P I N E R O M BY ANTHONY LETT
This week’s focus is on the lumbar spine and its ranges of flexion and extension.
Although movements between individual vertebra are relatively small and include only gliding and cartilaginous joints, (in this kind of joint the cartilage directly unites one bony structure to another: bone – cartilage – bone) the summation of all of these small movements produces a considerable range of movement of the whole spine, more comparable to that seen in a triaxial/multiaxial joint. (Multiaxial joints are more commonly known as ball & socket joints. All movement is possible in this type of joint. Examples include the Hip and Shoulder joints.) Movements of the lumbar spine include flexion-extension in the sagittal plane, right/left lateral flexion primarily in the frontal plane and right/left rotation primarily in the transverse plane. Movements of the lumbar spine can be described as relative to the spine as a whole or relative to a given motion segment (segmental motion.) A motion segment is composed of two adjacent vertebra and their related soft tissue, including the disks. Segmental movement varies markedly throughout the spine but in general, movements of the vertebral column are freer in the cervical and lumbar region. In contrast, they are more limited (except for rotation) in the thoracic region due to their connection to the relatively rigid rib cage.