The spine is made up of individual bones called vertebrae, which serve as the structural building blocks of the spinal column. At each vertebral level, spinal nerves exit the spine and travel to various parts of the body to supply muscles and skin. The lumbar vertebrae (located in the lower back) give rise to nerves that supply the lower limbs. If these nerves become compressed or irritated, pain may be referred to the lower legs. Common causes include arthritis, trauma, spinal stenosis, and disc prolapse. Less common but more serious causes include infection and malignancy.