Taken from Hoppenfeld's Exam of the Spine and Extremities(minus the figures and the typos of course): "this test is designed to reproduce back and leg pain so that its cause can be determined. Instruct the patient to lie supine on an examination table. Lift his leg upward by supporting his foot around the calcaneus. the knee should remain straight. To insure that it does, place your free hand on the anterior aspect of the knee to prevent it from bending.The xtent to which the leg can be raised without discomfort or pain varies, but normally the angle between the leg and the table measures approximately 80 degrees. If straiught leg raising is painful, you must determine whether the pathology is due to problems in the sciatic nerve or to hamstring tightness. hamstring pain involves only the posterior thigh, whereas sciatic pain can extend all the way down the leg. The patient may also complain of low back pain, and on occasion, pain in the opposite leg (positive cross leg straight leg raising test). At eh point where the patient experiencespain, lower the leg slightly and then dorsiflex the foot to stretch the sciatic nerve and produce sciatic pain. if the paatient does not experiencepain when you dorsiflex his foot, the pain induced by straight leg raising is probably due to tight hamstrings. If there is a positive reaction to the straight leg raising test and the dorsiflexion manuever, ask the patient to locatre as nearly as possible, the source of the pain. it may be either in the lumbar spine or anywhre along the course of the sciatic nerve." hope this helps Ed Catibog, M.D.