Attachment of the levator ani muscle extends to the superior ramus of the pubic bone through electrophysiological and anatomical examinations

Chih-Wei Peng,Yu-Ting Feng,Hung-Yen Chin,Chih-Hwa Chen,Tsorng-Harn Fong,Ming-Ping Wu

doi:10.1038/s41598-021-89041-6

Abstract

Myofascial pelvic pain (MFPP) of pelvic floor muscles is a common cause of chronic pelvic pain (CPP). The pathological mechanisms and treatments of MFPP are complex and still unclear until now. The levator ani muscle (LAM) is the major pelvic floor muscle. The purpose of this study was to examine the fascia and attachment of LAM through the electromyogram (EMG) and cadaver dissection. Electrophysiological stimulation of the obturator fascia above the arcus tendinous levator ani (ATLA) could trigger contraction and electrophysiological changes in LAM insertion. The LAM of embalmed adult cadavers was examined especially in the area above the ATLA. Some skeletal muscle fibers were found above the ATLA within the obturator fascia and were confirmed by Masson’s trichrome section staining. Our electromyography (EMG) and anatomical data implied that the attachment of LAM aponeurosis extended beyond ATLA to the inferior border of the superior ramus of the pubic bone. The new discovered attachment of LAM could provide a reference position for clinical diagnosis and treatment of MFPP or CPP.

Highlights

Myofascial pelvic pain (MFPP) of pelvic floor muscles is a common cause of chronic pelvic pain (CPP)
The number of spontaneous EMG spikes further increased (Fig. 1B). These results indirectly demonstrated that the obturator fascia may include some muscle fibers instead of consisting of connective tissue only
According to EMG and anatomy data, the levator ani muscle (LAM) aponeurosis may extend beyond arcus tendinous levator ani (ATLA) to the inferior border of the superior ramus of the pubic bone

Summary

Introduction

Myofascial pelvic pain (MFPP) of pelvic floor muscles is a common cause of chronic pelvic pain (CPP). The levator ani muscle (LAM) is the major pelvic floor muscle. Electrophysiological stimulation of the obturator fascia above the arcus tendinous levator ani (ATLA) could trigger contraction and electrophysiological changes in LAM insertion. The new discovered attachment of LAM could provide a reference position for clinical diagnosis and treatment of MFPP or CPP. Myofascial pelvic pain (MFPP), which is a frequent cause of CPP, refers to pain in the pelvic floor muscles, connective tissue, and surrounding fascia[6]. The levator ani muscle (LAM) constitutes the main part of the pelvic floor. It forms from the confluence of three muscles: puborectalis, pubococcygeus, and iliococcygeus muscles. The arcus tendinous of the levator ani (ATLA), known as the second white line, is the origin of iliococcygeus m uscle[14]

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