displacement of part of the rubbery centre, or nucleus, of a cartilaginous disk from between the vertebrae so that it presses against the spinal cord. Pain occurs in the arms if the protrusion occurs at the level of the neck (between the fifth and sixth or sixth and seventh cervical vertebrae) or in the lower back and legs if the protrusion occurs low in the backbone (usually between the fourth and fifth lumbar vertebrae or between the fifth lumbar and first sacral vertebrae). Treatment, depending on the severity of the condition, may include bed rest, analgesic medication (e.g., aspirin), traction, orthopedic support, and physical therapy or surgical removal of the protruded portion of the disk and fusion of the spinal vertebrae at the point affected.