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Levator ani muscle: want to learn more about it?

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Levator ani muscle

Levator ani muscle (Musculus levator ani)

The levator ani is a broad muscular sheet located in the pelvis. Together with the coccygeus muscle and their associated fascias it forms the pelvic diaphragm. The levator ani is collection of three muscles: puborectalis, pubococcygeus, and iliococcygeus.

The function of the entire levator ani muscle is crucial, in that it stabilizes the abdominal and pelvic organs. It literally stops your organs from falling straight out of your pelvis and abdomen!

Key facts about the levator ani muscle
Origins

Puborectalis: Posterior surface of bodies of pubic bones

Pubococcygeus: Posterior surface of bodies of pubic bones (lateral to puborectalis)

Iliococcygeus: Tendinous arch of interal obturator fascia, Ischial spine

Insertions

Puborectalis: None (forms 'puborectal sling' posterior to rectum)

Pubococcygeus: Anococcygeal ligament, Coccyx, Perineal body and musculature of prostate/ vagina

Iliococcygeus: Anococcygeal ligament, Coccyx

Innervation Nerve to levator ani (S4); Pubococcygeus also receives branches via inferior rectal/ perineal branches of Pudendal nerve (S2- S4)
Blood supply Inferior gluteal, inferior vesical and pudendal arteries
Function Stability and support of the abdominal and pelvic organs, resistance against increased intra-abdominal pressure, opening and closing of the levator hiatus

This article will describe the anatomy function of the three muscles forming the levator ani.

Origins and insertions

The levator ani is formed of the following three muscles:

  • Puborectalis muscle: originates lateral from the symphysis on both sides and encircles the rectum (anorectal junction) which causes a ventral bend between the rectum and anal canal. Partly it is interwoven with the external anal sphincter.
  • Pubococcygeus muscle: runs from the pubic bone (lateral of the origin of the puborectalis muscle) to the tendinous center of the perineum, anococcygeal body and tailbone. In men, medial muscle fibers are partly connected to the prostate.
  • Iliococcygeus muscle: extends more laterally from the fascia of obturator internus muscle to the tailbone. As a whole the levator ani builds a V-shaped structure. Both levator arms limit a triangle opening (levator hiatus) which is divided by prerectal fibers into the urogenital hiatus (ventral) and anal hiatus (dorsal). The urogenital hiatus is the pathway for the urethra and, in women, the vagina. The rectum runs through the anal hiatus.

Feeling puzzled? Learn the origins, insertions, innervations and functions of the levator ani 10x faster with our trunk wall muscle anatomy chart. 

Innervation

It is primarily supplied by nerve to levator ani (S4). To a small degree the pudendal nerve (S2-S4) contributes to its innervation as well.

Blood supply

Blood supply to levator ani comes from the branches of the inferior gluteal, inferior vesical and pudendal arteries.

Function

Through its tonic activity, the levator ani stabilizes the abdominal and pelvic organs on the one hand and controls the opening and closing of the levator hiatus on the other hand.

While in quiescent state, the urethra and the rectum are mechanically closed at the levator hiatus. The muscle relaxes at the beginning of urination and defecation. By this means the levator ani muscle plays a crucial role in the preservation of urinary and bowel continence.

Clinical aspects

The levator hiatus is a potential weak spot of the pelvic floor musculature, especially in women. Through increased intra-abdominal pressure (e.g. pregnancy, obesity or even chronic cough) the pelvic floor can be impaired and damaged in the long term. This may cause a descent of the perineum (descending perineum syndrome, DPS) up to a complete prolaps of the vagina or rectum. Consequences are urinary and bowel incontinence.

Approximately 6% of the population suffer under intermittent painful muscle spasms of the levator ani (levator ani syndrome). These can occur at any time and are often accompanied by a feeling of pressure and tension in the anorectal region. To this day the etiology remains unclear. Both neuralgia of the pudendal nerve and psychosomatic components are in discussion.

Levator ani muscle: want to learn more about it?

Our engaging videos, interactive quizzes, in-depth articles and HD atlas are here to get you top results faster.

What do you prefer to learn with?

“I would honestly say that Kenhub cut my study time in half.” – Read more. Kim Bengochea Kim Bengochea, Regis University, Denver

Show references

References:

  • D. Drenckhahn/J. Waschke: Taschenbuch Anatomie, 1.Auflage, Urban & Fischer Verlag/Elsevier (2008), S.299-300
  • M. Schünke/E. Schulte/U. Schumacher: Prometheus – LernAtlas der Anatomie – Allgemeine Anatomie und Bewegungssystem, 2.Auflage, Thieme Verlag (2007), S.160-161, 178-187
  • J. Kirsch et. al.: Taschenlehrbuch Anatomie, 1.Auflage, Thieme Verlag (2010), S.434-436
  • R.Tunn/E. Hanzal/ D. Perucchini: Urogynäkologie in Praxis und Klinik, 2.Auflage, De Gruyter (2009), S.29-36
  • H. Rohde: Lehratlas der Proktologie, 1.Auflage, Thieme Verlag (2006), S.183-184

Illustrators:

  • Levator ani muscle (Musculus levator ani) - Liene Znotina
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