<prompt> External anal sphincter is innervated by?S2,S3,S4S2, S3S1,S2L5,Sl  <response>: Ans. isa i.e.,S2, S3, S4Anal Sphincters :Two sphincters, internal and external, surround the anal canal:A. Internal sphincter sphincter ani internus:InvoluntarySympathetic fibers through superior hypogastric plexus aParasympathetic fibers from pelvic splanchnic nerves S2 S3 S4. B. External sphincter sphincter ani externusVoluntarySurrounds the entire length of anal canalInferior rectal nerve S2 S3 S4 and perineal branch 