Corpus: Levator ani muscle

The levator ani muscle is a staggered, almost transverse muscle plate which, together with the coccygeus muscle, forms the pelvic diaphragm and is used for defecation.

Origin[Bearbeiten]

The levator ani muscle consists of 3 fibre tracts that have different origins:

• The puborectalis muscle has its origin at the pelvic symphysis.
• The pubococcygeus muscle originates from the pubic bone.
• The iliococcygeus muscle originates from the fascia of the internal obturator muscle, also known as the arcus tendineus musculi levatoris ani.

Attachment[Bearbeiten]

The attachments of the various parts of the muscle are the anococcygeal ligament, the perineal tendon centre and the coccygeal bone directly.

All parts of the levator ani muscle are innervated either directly by motor branches (rami musculares) of the sacral plexus or by a branch of the pudendal nerve.

Corresponding to the gender-specific differences in the bony pelvic ring, the levator ani muscle has gender-specific differences. In women, it is more strongly interspersed with connective tissue, while in men the muscle is more strongly developed overall, particularly in favour of the puborectalis muscle.

Some fibres of the pubococcygeus muscle form the pubovaginalis muscle in women and the levator prostatae muscle in men.

The levator ani muscle lifts the anus during defecation and assumes a steep, funnel-shaped position. Through its basal muscle tone (primarily through the puborectalis muscle), it forms the flexura perinealis of the rectum and thus supports faecal continence. The levator ani muscle also stabilises the position of the pelvic organs.

Paralysis of the levator ani muscle can lead to prolapse of the rectum as well as the uterus and vagina at the urogenital hiatus.

During labour, the levator ani muscle may also tear, resulting in damage to the pelvic diaphragm. In women who have had several vaginal births, pelvic floor dysfunction or insufficiency can occur in old age, resulting in urinary bladder and rectal obstructions and thus causing urinary and faecal incontinence. In men, this can occur after a prostate resection. Surgical therapies for pelvic floor insufficiency aim to fix the affected pelvic organs and restore continence; the puborectalis muscle is of particular importance here.

Pelvic floor hernias can occur in muscle-weak areas of the pelvic floor, e.g. between the various muscle parts of the levator ani muscle.

In the deceased, the levator ani muscle becomes flaccid due to a lack of tone in the pelvic organs and takes on a funnel shape.