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Levator Ani Muscle Anatomy Evaluated by Origin-Insertion Pairs

Kearney, Rohna MRCOG, MD; Sawhney, Raja MFA; DeLancey, John O. L. MD

doi: 10.1097/01.AOG.0000128906.61529.6b
Reviews

OBJECTIVE: To examine the published literature and suggest a resolution to the confusion that exists in levator ani muscle descriptions and terminology.

DATA SOURCES: A MEDLINE search was performed using the keyword “levator ani,” limited to human studies in women. References found in these articles were reviewed to identify research reported before 1966 and articles not included in the search.

STUDY SELECTION: Studies were accepted if they contained direct observations of female specimens. Only those that contained specific descriptions or illustrations of the muscle origins and insertions in more than 5 female specimens were included. Review of 265 human studies yielded 9 qualifying articles, and reference tracing disclosed 3 additional reports.

TABULATION, INTEGRATION, AND RESULTS: The literature review identified 5 origin-insertion pairs consistently described in studies directly examining the levator ani muscle in women, but 16 terms were used by authors for these 5 components of the muscle. Labeled illustrations often provided more precise information than was provided in the text. Terms were reviewed for inconsistencies of usage and appropriateness of term choice. The terms puboperineal, pubovaginal, and puboanal (for components of the pubovisceral [“pubococcygeal”] muscle), along with puborectal and iliococcygeal, are sufficient to describe the divisions of the levator ani muscle.

CONCLUSION: Although there was great diversity and conflict in terms chosen among the original articles, the number of origin and insertion pairs was relatively consistent among authors and confusion can be avoided by standardizing terminology.

LEVEL OF EVIDENCE: III

The confusion about levator ani anatomy arising from bewildering terminology can be cleared by naming muscle parts based on origin-insertion pairs.

From the Department of Obstetrics and Gynecology, University of Michigan Medical School, Ann Arbor, Michigan.

Received November 13, 2003. Received in revised form January 28, 2004. Accepted March 18, 2004.

Supported by National Institutes of Health grants R01 HD 38665 and R01 DK 51405.

Address reprint requests to: John O. L. DeLancey, MD, University of Michigan, Department of Obstetrics and Gynecology, 1500 East Medical Center Drive, Ann Arbor, MI 8109–0276; e-mail: delancey@umich.edu.

© 2004 The American College of Obstetricians and Gynecologists