The external anal sphincter (or sphincter ani externus) is a flat plane of muscular fibers, elliptical in shape and intimately adherent to the skin surrounding the margin of the anus. Apr 25, · Other articles where External anal sphincter is discussed: The external sphincter is a layer of voluntary (striated) muscle encircling the outside wall of the anal canal and anal opening. The internal anal sphincter, IAS, (or sphincter ani internus) is a muscular ring that surrounds about – cm of the anal canal; its inferior border is in contact with, but quite separate from, the external anal sphincter. External anal sphincter. External anal sphincter (EAS) is a striated muscle under voluntary control which is supplied by the inferior rectal nerve, a . Apr 27, · The internal sphincter is part of the inner surface of the canal; it is composed of concentric layers of circular muscle tissue and is not under voluntary control. The external sphincter is a layer of voluntary (striated) muscle encircling the outside wall of the anal canal Thus, the internal.
Apr 27, · Chapter The rectum and anal canal External anal sphincter The rectum and anal canal are supplied by the superior rectal artery. Anal stenosis means that the anal opening is too small or does not relax or open properly. The external anal sphincter is a thick, red voluntary muscle. External anal sphincter - Musculus sphincter ani externus Anatomical Parts. Illustrated anatomical parts with images from e-Anatomy and descriptions of anatomical structures.