A straight-leg-raising test this is positive under 30 degrees reveals a large disc protrusion. The nerve root is stretched long before it would normally be. The straight-leg-raising test is most useful for identifying L5-S1 disc lesions because the pressures on the nerve root are highest at this level. During straight leg raising, L4-L5 is not as apt to give as much pain as L5-S1 because the pressure between the disc and the nerve root at L4-L5 is half that at L5-S1. Therefore the L5-S1 disc lesion gives more pain in the lower back and leg than does the L4-L5 disc lesion. No movement on the nerve root occurs until straight leg raising reaches 30 degrees. No movement on L4 occurs during a straight leg raising test. From this, the presence of Turyn’s sign indicates a large disc protrusion at the level of the L5-S1 nerve root.