Innervation of the levator ani muscles: description of the nerve branches to the pubococcygeus, iliococcygeus, and puborectalis muscles
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We described the innervation of the levator ani muscles (LAM) in human female cadavers. Detailed pelvic dissections of the pubococcygeus (PCM), iliococcygeus (ICM), and puborectalis muscles (PRM) were performed on 17 formaldehyde-fixed cadavers. The pudendal nerve and the sacral nerves entering the pelvis were traced thoroughly, and nerve branches innervating the LAM were documented. Histological analysis of nerve branches entering the LAM confirmed myelinated nerve tissue. LAM were innervated by the pudendal nerve branches, perineal nerve, and inferior rectal nerve (IRN) in 15 (88.2%) and 6 (35.3%) cadavers, respectively, and by the direct sacral nerves S3 and/or S4 in 12 cadavers (70.6%). A variant IRN, independent of the pudendal nerve, was found to innervate the LAM in seven (41.2%) cadavers. The PCM and the PRM were both primarily innervated by the pudendal nerve branches in 13 cadavers (76.5%) each. The ICM was primarily innervated by the direct sacral nerves S3 and/or S4 in 11 cadavers (64.7%).
KeywordsLevator ani muscles Pubococcygeus muscle Iliococcygeus muscle Puborectalis muscle Inferior rectal nerve Pudendal nerve
We are grateful to Radma S. Mahmood, Ph.D., and Rani Sellers, D.V.M., Ph.D., Department of Pathology, at the Albert Einstein College of Medicine, Bronx, New York, for assistance with histological analysis. We thank Tatyana Harris, Graphic Artist at the Albert Einstein College of Medicine, Graphic Arts Center, Bronx, New York, for her illustrations.
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