<prompt> Pudendal nerve supplying motor pa to external sphincter is derived from?L5-S1 roots51-S2 rootsL2-L3 rootsS2-S3 roots  <response>: S2-S3 roots. There are two sphincters of the urethra a. Internal urethral sphincter also ka sphincter vesicae - it is involuntary in nature - made up of smooth muscle - supplied by sympathetic nerves, from lower thoracic upper lumbar segments of spinal cord b. External urethral sphincter also ka sphincter vesicae - it is voluntary in nature - made up of striated muscle fibres - supplied by the perineal branch of the pudendal nerve derived from spinal nerves S2,S3 S4 - it controls the membranous urethra and is responsible for the voluntary holding of urine. 