Anatomy

The levator ani muscle

Anatomy and Overview of Levator ani

The levator ani is an extended, slender muscle group, located on either side of the pelvis bone. The muscle can be divided into three parts. They are

  1. Pubococcygeus
  2. Iliococcygeus
  3. Ischiococcygeus

Its function is very important because it helps to stabilize the abdominal and pelvic organs. It prevents the organs from the pelvis and abdomen.

The Levator Ani

Pubococcygeus part

The medial part of the pelvic surface of the body of the pubis gives rise to the anterior fibers. These fibres closely surround the prostate and constitute the levator prostate in the male.

In case of females, the vagina is surrounded by these fibres and form the sphincter vaginae.

In both cases the anterior fibres are inserted into the perineal body.

The middle fibres constitute the puborectalis. From the body of pubis i.e the lateral part of the pelvic surface these fibers arise. Around the anorectal junction, they partly form a loop or sling and are partly continuous with the longitudinal muscle coat of the rectum. In females the anterior portion if ouborectalis is thinner and shorter.

The anterior half of the white line on the obturator fascia gives rise to the posterior fibers of the pubococcygeus. These get attached to the anococcygeal ligament and tip of the coccyx.

Illiococcygeus part

The fibres that forms illicoccygeus part arise from:

  1. On the obturator fascia, there is the presence of the white line and its posterior half only.
  2. The pelvic surface of the ischial spine. They are inserted into the anococcygeal ligament and into the side of the last two pieces of the coccyx.

Coccygeus part

This muscle represents the posterior or iliococcygeus part of the pelvic diaphragm. It is triangular in shape. It is partly muscular and partly tendinous.

Its fibres arise from:

  1. The ischial spine present on the pelvic surface.
  2. The ligament called sacrospinous ligament. It is inserted into the side of the coccyx, and into the fifth sacral vertebra.

Also read about : Anatomy of Abdomen

Nerve supply of Levator Ani

The levator ani is supplied by:

  1. The  fourth sacral nerve’s branch.
  2. The  inferior rectal nerve’s branch .
  3. The branch which is derived from sacral nerves which is fourth and fifth supplies the coccygeus.

Actions of levators Ani and coccygeus

  1. The pelvic outlet’s posterior part is closed by the levator ani and coccygeus muscles.
  2. The pelvic viscera is supported by levator ani  as well it fixes the perineal body.
  3. The levators ani and coccygei counteract or resist increases intra-abdominal pressure during the coughing, sneezing, lifting and other muscular efforts, and the continence of the bladder and the rectum is maintained by it.
  4. A particular pelvic outlet is opened during micturition, defaecation, and parturition, but the contraction of fibers around other openings resists increases intra-abdominal pressure and prevents any prolapsed through the pelvic floor
  5. In coughing and sneezing there is a momentary increase in the intra abdominal pressure but it is more prolonged in yawning, micturition, defaecation, and lifting heavy weights. Incase of the second stage of labour it is most prolonged and intense .
  6. The coccygeus pulls forwards and support the coccyx, after it has been pressed backwards during defaecation, parturition or childbirth.

Relations of the levator Ani

  1. The superior or pelvic surface is covered with pelvic fascia which separates it from the bladder, prostate, rectum, and peritoneum.
  2. Anal fascia covers the inferior or perineal surface and forms the medial boundary of the ischioanal fossa.
  3. The anterior borders of the two muscles are separated by a triangular space for the passage of the urethra and the vagina.
  4. The posterior border is free and lies against the anterior margin of the coccygeus.

Functions of levator ani:

There are various functions of it some important functions are given below:

  1. Levator Ani helps to stabilize the abdominal and pelvic organs with the aid of its tonic activity.
  2. It controls the opening and closing of the levator hiatus.

The urethra and the rectum are mechanically closed at the levator hiatus in a quiescent state. At the beginning of urination and defecation, the muscle relaxes. The preservation of urinary and bowel continence is done by levator ani muscle as it has an important role.

Takeaway:

The levator ani is an extended, slender muscle group, located on either side of the pelvis bone. It is divided into three parts. Levator ani helps to stabilize the abdominal and pelvic organs with the aid of its tonic activity. It controls the opening and closing of the levator hiatus

Rashmi Shrestha

Namastey!! I am Rashmi Shrestha. I am an enthusiast writer and reader. I have completed my degree Bsc. Human biology from Kathmandu University. I love to read poetry and write some too. I am looking forward to working with WOMS

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