Kernig's sign is a clinical sign which is present in meningitis. The subject lies down on his or her back and a thigh is flexed to form a right angle with the trunk (i.e. perpendicular to the plane the subject is lying). The examiner then attempts to extend the leg. A positive Kernig's sign is present if complete extension of the leg is not possible because of limitation by pain.
Selected Kernig's sign links: