Angle ∠BAC might refer to any of four angles: the clockwise angle from B to C, the anticlockwise angle from B to C, the clockwise angle from C to B, or the anticlockwise angle from C to B, where the direction in which the angle is measured determines its sign (see Positive and negative angles). However, in many geometrical situations it is obvious from context that the positive angle less than or equal to 180 degrees is meant, and no ambiguity arises. Otherwise, a convention may be adopted so that ∠BAC always refers to the anticlockwise (positive) angle from B to
Straight leg raise more specific, the ankle can be dorsiflexed and the cervical spine flexed. This increases the stretching of the nerve root and dura. If the patient experiences sciatic pain when the straight leg is at an angle of between 30 and 70 degrees, then the test is positive and a herniated disk is a possible cause of the pain. A negative test suggests a likely different cause for back pain. A meta-analysis reported the accuracy as: If raising the opposite leg causes pain (cross or contralateral straight leg raising): Lasègue's sign was named after Charles Lasègue (1816-1883). In 1864 Lasègue described