Anatomy and function of the anal longitudinal muscle.

The longitudinal muscle in the intersphincteric space has received little attention despite an explosion of interest in anorectal physiology in the past decade. Its anatomy is contested and its function unknown. Speculation, however, gives it a role as a skeleton supporting and binding the rest of the internal and external sphincter complex together, as an aid during defaecation by everting the anus, as a support to the haemorrhoidal cushions, and as a determining factor in the ramification of sepsis.