onderrug

The onderrug, or lower back, is the region of the back between the lower thoracic spine and the pelvis. It roughly corresponds to the lumbar spine (L1–L5) and the sacrum. The area contains the lumbar vertebrae, intervertebral discs, muscles and ligaments. It bears much of the body's weight and enables bending, lifting and twisting.

Key structures include the erector spinae and multifidus muscles, the facet joints, the sacroiliac joints and the lumbar discs. Nerve roots from the lumbar and sacral regions provide sensation and movement to the lower limbs; irritation can cause sciatica.

Lower back pain is common. Most acute cases stem from muscle or ligament strain, overuse, or poor posture. Less often, herniated discs, degenerative disc disease, spinal stenosis or inflammatory/infectious conditions are involved. Symptoms range from dull ache and stiffness to sharp pain with movement, sometimes accompanied by numbness or radiating pain.

Diagnosis relies on history and physical examination; imaging is used as needed. Red flags require urgent evaluation, including severe trauma with suspected fracture, fever or unexplained weight loss, progressive weakness or numbness, saddle anesthesia, or loss of bowel or bladder control.

Treatment is usually conservative: short rest followed by gradual activity, physical therapy, and analgesics such as NSAIDs. Persistent or radicular symptoms may require injections or surgery in select cases. Prevention focuses on good posture, core strengthening, safe lifting, maintaining a healthy weight and avoiding smoking.