The Quadratus Lumborum (QL) is a deep-seated muscle located in the lower back. It plays a significant role in torso stability and movement, supporting the spine and pelvis.
Precisely Locating the Quadratus Lumborum
The quadratus lumborum is a paired, quadrilateral-shaped muscle found deep within the lower back, positioned on either side of the lumbar spine. It lies beneath larger, more superficial back muscles, making it a deep abdominal muscle. Its unique position connects the torso’s upper and lower skeletal structures, making it an important link in the body’s core.
The muscle originates from the iliac crest (the top rim of the hip bone) and the iliolumbar ligament. Its fibers extend upwards and medially from these points. It then inserts onto the medial half of the lower border of the 12th rib and the transverse processes of the first through fourth lumbar vertebrae (L1-L4). This arrangement allows the muscle to span across the pelvis, spine, and lower rib cage.
Key Roles of the Quadratus Lumborum
The quadratus lumborum is a multi-functional muscle that contributes to trunk mechanics. Its primary role involves stabilizing the lumbar spine and pelvis. It helps maintain an upright posture and provides support during movements, keeping the spine neutral and sturdy.
Beyond stabilization, the QL facilitates specific trunk movements. When only one side of the QL contracts, it causes lateral flexion, bending the trunk sideways towards that contracting side. When both quadratus lumborum muscles contract simultaneously, they contribute to the extension of the lumbar spine, assisting in movements where the lower back bends backward. The QL also plays a part in respiration by helping to fix the 12th rib during forced exhalation, providing a stable base for the diaphragm.
Understanding Quadratus Lumborum Discomfort
Discomfort associated with the quadratus lumborum muscle is a common source of lower back pain. This pain typically manifests as a deep ache or tightness in the lower back region, which can occur on one or both sides of the spine. The severity and type of pain can vary, sometimes feeling sharp, especially during movements.
Pain originating from the QL can worsen with various activities, including walking, standing, sitting for prolonged periods, or rolling over in bed. Everyday actions like sneezing or coughing can also aggravate the discomfort due to the muscle’s connection to the lower ribs and its role in respiration. This muscle’s issues can also lead to referred pain, meaning discomfort may be felt in other areas such as the hips, buttocks, or groin. These symptoms can significantly interfere with daily activities, highlighting the QL’s influence on overall comfort and mobility.