Levator ani
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| Levator ani | ||
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| Left Levator ani from within. | ||
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| Coronal section through the anal canal. B. Cavity of urinary bladder V.D. Ductus deferens. S.V. Seminal vesicle. R. Second part of rectum. A.C. Anal canal. L.A. Levator ani. I.S. Sphincter ani internus. E.S. Sphinear ani externus. | ||
| Latin | musculus levator ani | |
| Gray's | subject #119 422 | |
| Origin: | ||
| Insertion: | ||
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| Nerve: | ||
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| Dorlands/Elsevier | m_22/12549567 | |
The Levator ani is a broad, thin muscle, situated on the side of the pelvis.
It is attached to the inner surface of the side of the lesser pelvis, and unites with its fellow of the opposite side to form the greater part of the floor of the pelvic cavity.
It supports the viscera in this cavity, and surrounds the various structures which pass through it.
In combination with the Coccygeus muscle, it forms the pelvic diaphragm.
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[edit] Parts
The Levator ani may be divided into three parts:
[edit] Origin and insertion of fibers
The Levator ani arises, in front, from the posterior surface of the superior ramus of the pubis lateral to the symphysis; behind, from the inner surface of the spine of the ischium; and between these two points, from the obturator 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 the coccyx; those placed more anteriorly unite with the muscle of the opposite side, in a median fibrous raphé (anococcygeal raphé), which extends between the coccyx and the margin of the anus.
The middle fibers are inserted into the side of the rectum, blending with the fibers of the Sphincter muscles; lastly, 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 the Sphincter ani externus and Transversus perinei, at the central tendinous point of the perineum.
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 the prostate, which it supports as in a sling, it has been described as a distinct muscle, under the name of Levator prostate.
In the female the anterior fibers of the Levator ani descend upon the side of the vagina.
[edit] Nerve Supply
The Levator ani is supplied by a branch from the fourth sacral nerve and by a branch which is sometimes derived from the perineal, sometimes from the inferior hemorrhoidal division of the pudendal nerve.
[edit] Levator Ani Syndrome
Levator Ani Syndrome is caused by chronic tension of the levator muscle. Proctalgia fugax is caused by rectal muscle spasm. Proctalgia fugax and levator ani syndrome have not been found to be of psychosomatic origin, although stressful events may trigger attacks.
[edit] Diagnosis and clinical features
Levator ani syndrome is characterized by a vague, indefinite rectal discomfort or pain. The pain is felt high in the rectum.
[edit] Additional images
 Right hip bone. Internal surface. |
 Coronal section of pelvis, showing arrangement of fasciæ. Viewed from behind. |
 Muscles of male perineum. |
 The arteries of the pelvis. |
 Sacral plexus of the right side. |
 Iliac colon, sigmoid or pelvic colon, and rectum seen from the front, after removal of pubic bones and bladder. |
 The posterior aspect of the rectum exposed by removing the lower part of the sacrum and the coccyx. |
 Male pelvic organs seen from right side. |
[edit] External links
- GPnotebook -60096433 (Levator ani)
- GPnotebook -53477317 (Pubovaginalis)
- LUC pubv (Pubovaginalis)
- SUNY Figs 41:05-00 - "Muscles of the female superficial perineal pouch."
- SUNY Figs 42:04-00 - "Muscles of the male superficial perineal pouch."
- SUNY Labs 43:16-0102 - "Muscles of the Pelvic Diaphragm"
- SUNY Anatomy Image 9072
- SUNY Anatomy Image 9089
- SUNY Anatomy Image 9871
- Cross section at UV pelvis/pelvis-e12-15
- Norman/Georgetown perineum (analtriangle3)
This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained herein may be outdated. Please edit the article if this is the case, and feel free to remove this notice when it is no longer relevant.
