[Contribution of anal external sphincter and puborectal muscle to anal pressure (author's transl)]

During anesthesia and relaxation the separated M. sphincter ani ext. and the M. puborectalis have a constant pressure of 30 mm Hg. Therefore, these muscles also have the ability to make tonic contractions and not only phasic contractions. This means that these muscles are also responsible for the anal tonic basal pressure.