lumbosacralis

Lumbosacralis is a Latin term used in anatomical and clinical contexts to denote structures and features related to the lumbus (lower back) and the sacrum. In practice, it is often used to describe the lumbosacral region and, more specifically, the lumbosacral junction where the lumbar spine meets the sacrum, as well as associated neural and vascular elements.

Anatomy and boundaries

The lumbosacral region encompasses the lowest lumbar vertebra (typically L5) and the first sacral segment (S1). The lumbosacral junction is marked by the intervertebral disc between L5 and S1, the lumbosacral facet joints, and the articulation with the sacroiliac region. The lumbosacral angle, also referred to as the Ferguson angle, describes the tilt between the lumbar spine and the sacrum and influences spinal loading and posture.

Muscles, ligaments, and joints

Key muscular and soft-tissue components include the psoas major, iliacus, quadratus lumborum, and portions of the erector spinae group, which stabilize and move the lower back. Ligaments such as the iliolumbar and the posterior longitudinal ligament contribute to stability at the L5–S1 level. The lumbosacral region also involves the lumbosacral and sacroiliac joints, which transmit loads between the spine and pelvis.

Nerves and clinical relevance

Nerve roots contributing to the lumbosacral region form the lumbosacral plexus, with fibers from L1 to S4. This plexus gives rise to important nerves including the femoral, obturator, and parts of the sciatic nerve. Clinically, the lumbosacral region is a common site for radiculopathy, disc disease, and strain injuries, such as sciatica or low back pain, often evaluated with imaging and neurologic assessment.

Variations and imaging

Anatomic variations, such as lumbosacral transitional vertebrae at the L5–S1 level, can affect biomechanics and radiologic interpretation. Imaging modalities like MRI and CT are used to assess bone, disc, and neural structures in the lumbosacral region.