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| Levator ani | |
|---|---|
 Left levator ani seen from within. | |
 Coronal section through the male anal canal. B. Cavity ofurinary bladder V.D.Vas deferens. S.V.Seminal vesicle. R. Second part ofrectum. A.C.Anal canal. L.A. Levator ani. I.S.Internal anal sphincter. E.SExternal anal sphincter. | |
| Details | |
| Origin | Inner surface of the side of thelesser pelvis |
| Insertion | Inner surface ofcoccyx, levator ani of opposite side, and into structures that penetrate it. |
| Artery | Inferior gluteal artery |
| Nerve | Pubococcygeus andiliococcygeus: |
| Actions | Supports theviscera inpelvic cavity |
| Identifiers | |
| Latin | musculus levator ani |
| TA98 | A04.5.04.002 |
| TA2 | 2403 |
| FMA | 19087 |
| Anatomical terms of muscle | |
Thelevator ani is a broad, thinmuscle group, situated on either side of thepelvis. It is formed from three muscle components: the pubococcygeus, the iliococcygeus, and the puborectalis.[3]
It is attached to the inner surface of each side of thelesser pelvis, and these unite to form the greater part of thepelvic floor. Thecoccygeus muscle completes the pelvic floor, which is also called thepelvic diaphragm.
It supports theviscera in thepelvic cavity, and surrounds the various structures that pass through it.
The levator ani is the mainpelvic floor muscle and contracts rhythmically during femaleorgasm, and painfully duringvaginismus.[4]
The levator ani is made up of 3 parts:
The iliococcygeus arises from the inner side of theischium (the lower and back part of thehip bone) and from the posterior part of thetendinous arch of theobturator fascia, and is attached to thecoccyx andanococcygeal body; it is usually thin, and may be absent, or be largely replaced by fibrous tissue. An accessoryslip at its posterior part is sometimes named theiliosacralis.
The pubococcygeus muscle has medial fibres forming thepubovaginalis in the female, and thepuboprostaticus in the male.
The levator ani arises, in front, from the posterior surface of thesuperior pubic ramus lateral to thesymphysis; behind, from the inner surface of the spine of theischium; and between these two points, from theobturator fascia.
Posteriorly, this fascial origin corresponds, more or less closely, with the tendinous arch of the pelvic fascia, but in front, the muscle arises from the fascia at a varying distance above the arch, in some cases reaching nearly as high as the canal for the obturator vessels and nerve.
The fibers pass downward and backward to the middle line of the floor of the pelvis; the most posterior are inserted into the side of the last two segments of thecoccyx; those placed more anteriorly unite with the muscle of the opposite side, in a median fibrous ridge called theanococcygeal body or raphe, which extends between the coccyx and the margin of theanus.
The middle fibers are inserted into the side of therectum, blending with the fibers of thesphincter muscles; lastly in the male, the anterior fibers descend upon the side of the prostate to unite beneath it with the muscle of the opposite side, joining with the fibers of theexternal anal sphincter andtransverse perineal muscles, at the central tendinous point of theperineum.
The anterior portion is occasionally separated from the rest of the muscle by connective tissue.
From this circumstance, as well as from its peculiar relation with theprostate, which it supports as in a sling, it has been described as a distinct muscle, under the name oflevator prostatæ.
In the female, the anterior fibers of the levator ani descend upon the side of thevagina.
The levator ani muscles are mostly innervated by thepudendal nerve,perineal nerve and acting together.[5]
In addition,sacral spinal nerves (S3,S4) innervate the muscles directly as well (in ~70%[5] of people). Sometimes (in ~40%[5] of people) the inferior rectal nerve innervates the levator ani muscles independently of the pudendal nerve.
| Pubococcygeus muscle | |
|---|---|
| Details | |
| Origin | back of the pubis and from the anterior part of theobturator fascia |
| Insertion | coccyx andsacrum |
| Nerve | S3, S4 |
| Actions | controls urine flow and contracts during orgasm |
| Identifiers | |
| Latin | musculus pubococcygeus |
| TA98 | A04.5.04.002 |
| TA2 | 2403 |
| FMA | 19087 |
| Anatomical terms of muscle | |
Thepubococcygeus muscle orPC muscle is a hammock-like muscle, found in both sexes, that stretches from thepubic bone to thecoccyx (tail bone) forming thefloor of thepelvic cavity and supporting the pelvic organs.
The pubococcygeus arises from the back of the pubis and from the anterior part of theobturator fascia, and is directed backward almost horizontally along the side of theanal canal toward thecoccyx andsacrum, to which it finds attachment.
Between the termination of the vertebral column and the anus, the two pubococcygeus muscles come together and form a thick, fibromuscular layer lying on the raphe (ridge) or (anococcygeal body) formed by the iliococcygei.
The greater part of this muscle is inserted into the coccyx and into the last one or two pieces of the sacrum.
This insertion into the vertebral column is, however, not accepted by all observers.
The pubococcygeus muscle controls urine flow and contracts duringorgasm as well as assisting in maleejaculation.[6] It also aids inchildbirth as well as core stability.[7]
A strong pubococcygeus muscle has also been linked to a reduction inurinary incontinence and proper positioning of the baby's head during childbirth.
TheKegel exercises are a series of voluntary contractions of all theperineal muscles. Such movement is done in an effort to strengthen all the striated muscles in the perineum's area. They are often referred to simply as "kegels", named after their founder, Dr.Arnold Kegel.[8] These exercises also serve to contract, among others, theischiocavernosus,bulbospongiosus, andcremaster muscle in men, as voluntary contraction of the pubococcygeus muscle also engages thecremasteric reflex, which lifts the testicles up, although this does not occur in all men. Kegel exercises have been prescribed to ameliorateerectile dysfunction due tovenous leakage and to help men controlpremature ejaculation[9] and to treat urinary incontinence in both sexes.[10][needs update][11]
| Puborectalis muscle | |
|---|---|
 The posterior aspect of the rectum exposed by removing the lower part of the sacrum and the coccyx. (Puborectalis not labeled but levator ani labeled at bottom right and external anal sphincter labeled at bottom center.) | |
| Details | |
| Origin | lower part of thepubic symphysis,superior fascia of the urogenital diaphragm |
| Nerve | S3, S4. levator ani nerve[12] |
| Actions | inhibitdefecation |
| Identifiers | |
| Latin | musculus puborectalis |
| TA98 | A04.5.04.002 |
| TA2 | 2403 |
| FMA | 19087 |
| Anatomical terms of muscle | |
The fibers that form asling looping around therectum are namedpuborectalis (puboanalis). They arise from the lower part of thepubic symphysis, and from thesuperior fascia of the urogenital diaphragm. The origin of the puborectalis fibers is at the posterior surface of thepubis while their insertion is at the midline sling posterior to the rectum. The muscle band is innervated by perineal branches of the S3 and S4 nerve roots.
They meet with the corresponding fibers of the opposite side around the lower part of the rectum, and form for it a strong sling. Relaxation increases the angle between rectum and anus, allowing defecation in conjunction with relaxation of theinternal andexternal anal sphincters. Levator ani relaxation and rectal emptying is facilitated by anorectal straightening during squatting.[13]
The levator ani muscles are responsible for "wagging" the tail intailedquadrupeds. These muscles are not as strong in the human, as tail-wagging is more demanding than the support function that the muscles serve in humans.[14]
Levator ani syndrome is episodicrectal pain caused by spasm of the levator ani muscle.[15][16][17]
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This article incorporates text in thepublic domain frompage 422 of the 20th edition ofGray's Anatomy(1918)
