The anterior fibres of the levator ani muscle in man.

The anatomy of the anterior portion of the levator ani muscle in studied in 26 adult human cadavers of both sexes. This portion of the muscle is found to consist of three layers of muscle fibres. The three layers are: 1. The pelvic layer. Its fibres (1) are attached to the capsule of the prostate or adventitia of the lateral wall of vagina, (2) intermingle with and supplement the longitudinal muscle layer of the anal canal, and (3) are continuous with the fibres of the opposite side behind the recto-anal junction. 2. The middle layer. The most anterior fibres are twisted on themselves to form the round free border of the muscle that bounds the levator hiatus. The majority of the muscle fibres of this layer proceed backwards to cover and blend with the deep part of the external anal shincter, partly joining the anococcygeal ligament. 3. The perineal layer. These fibres surround the superficial part of the external anal sphincter. A respectable bundle of muscles fibres unites with that of the opposite side in from of the lower part of the anal canal. Remaining fibres terminate in perianal skin or anococcygeal ligament. The role of the anterior portion of the levator ani in fixation and prevention of prolapse of the pelvic viscera is stressed.