Anatomy of the pubovisceral muscle origin: Macroscopic and microscopic findings within the injury zone

Kim, Jin–Yong; Betschart, Cornelia; Ramanah, R.; Ashton‐Miller, James A.; DeLancey, John O.L.

doi:10.1002/nau.22649

Cited by 33 publications

(43 citation statements)

References 20 publications

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“…The PVm and puborectal muscle (PRm) originate from the fibrous enthesis on the dorsal surface of the pubic bone [16, 17]. This section of the muscle is translationally and rotationally fixed.…”

Section: Methodsmentioning

confidence: 99%

Finite element model focused on stress distribution in the levator ani muscle during vaginal delivery

et al. 2016

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Introduction and hypothesisDuring vaginal delivery, the levator ani muscle (LAM) undergoes severe deformation. This stress can lead to stretch-related LAM injuries. The objective of this study was to develop a sophisticated MRI-based model to simulate changes in the LAM during vaginal delivery.MethodsA 3D finite element model of the female pelvic floor and fetal head was developed. The model geometry was based on MRI data from a nulliparous woman and 1-day-old neonate. Material parameters were estimated using uniaxial test data from the literature and by least-square minimization method. The boundary conditions reflected all anatomical constraints and supports. A simulation of vaginal delivery with regard to the cardinal movements of labor was then performed.ResultsThe mean stress values in the iliococcygeus portion of the LAM during fetal head extension were 4.91–7.93 MPa. The highest stress values were induced in the pubovisceral and puborectal LAM portions (mean 27.46 MPa) at the outset of fetal head extension. The last LAM subdivision engaged in the changes in stress was the posteromedial section of the puborectal muscle. The mean stress values were 16.89 MPa at the end of fetal head extension. The LAM was elongated by nearly 2.5 times from its initial resting position.ConclusionsThe cardinal movements of labor significantly affect the subsequent heterogeneous stress distribution in the LAM. The absolute stress values were highest in portions of the muscle that arise from the pubic bone. These areas are at the highest risk for muscle injuries with long-term complications.

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Section: Methodsmentioning

confidence: 99%

Finite element model focused on stress distribution in the levator ani muscle during vaginal delivery

et al. 2016

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“…23,24 The pubovisceral muscle’s attachment to the pubic bone is a thin and transparent aponeurosis that arises tangentially to the pubic periosteum. 25 The thin nature of the attachment of the aponeurosis makes it subject to injury when the forces in the fiber direction exceed the strength of the muscle origin.…”

Section: Levator Ani Musclementioning

confidence: 99%

What's new in the functional anatomy of pelvic organ prolapse?

DeLancey¹

2016

Current Opinion in Obstetrics &Amp; Gynecology

105

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Purpose of Review Provide an evidence-based review of pelvic floor functional anatomy related to pelvic organ prolapse. Recent Findings Pelvic organ support depends on interactions between the levator ani muscle and pelvic connective tissues. Muscle failure exposes the vaginal wall a pressure differential producing abnormal tension on the attachments of the pelvic organs to the pelvic side-wall. Birth-induced injury to the pubococcygeal portion of the levator ani muscle is seen in 55% of women with prolapse and 16% of women with normal support. Failure of the connective tissue attachments between the uterus and vagina to the pelvic wall (cardinal, uterosacral, paravaginal) are strongly related with prolapse (effect sizes ~2.5) and are also highly correlated with one another (r ~0.85). Small differences exist with prolapse in factors involving the vaginal wall length and width (effect sizes ~1). The primary difference in ligament properties between women with and without prolapse is found in ligament length. Only minor differences in ligament stiffness are seen. Summary Pelvic organ prolapse occurs due to injury to the levator ani muscles and failure of the connections between the pelvic organs to the pelvic sidewall. Abnormalities of the vaginal wall fascial tissues may play a minor role.

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Section: Introductionmentioning

confidence: 99%

“…The pubovisceral (PV) muscle, also known as pubococcygeus, is the portion of the levator ani muscle most vulnerable to sustaining a tear from the pubic bone during vaginal birth. [1][2][3] The PV muscle is at high risk for stretch-related tear, 4 likely due to a multitude of interacting factors. Variations in maternal pelvic shape, fetal head shape, the degree of molding during delivery, symphyseal diastasis, and presentation may all affect the maximum muscle stretch ratios, increasing the risk of muscle tear.…”

Section: Introductionmentioning

confidence: 99%

Association of index finger palpatory assessment of pubovisceral muscle body integrity with MRI‐documented tear

Sheng

Low

et al. 2019

Neurourology and Urodynamics

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Aims Pubovisceral (PV) muscle tears are associated with pelvic floor disorders. The goal of this study was to determine whether index finger palpatory assessment of PV muscle body integrity through the lateral vaginal wall is a reliable indicator of PV muscle tear severity diagnosed by magnetic resonance imaging (MRI). Methods We studied 85 women, 7 weeks after vaginal birth. All had at least one risk factor for obstetric‐related PV muscle tear. The ordinal outcome measure of MRI‐documented PV muscle tear was defined as: none, less than 50% unilateral tear, 50% or greater unilateral tear or less than 50% bilateral tear, and 50% or greater bilateral tear. PV muscle body integrity by palpatory assessment was scored on a matrix, with each side scored independently and classified as PV muscle body “present” (assuredly felt), “equivocal” (not sure if felt), or “absent” (assuredly not felt). Proportional odds models were constructed to estimate the relationship between PV muscle body integrity palpatory assessment and MRI‐documented PV muscle tears. Results Thirty‐five percent of study participants exhibited varying degrees of MRI‐documented PV muscle tears. Using palpatory assessment, we identified “PV muscle body present bilaterally” in 20%, “equivocal unilaterally or present contralaterally” in 8%, “equivocal or absent unilaterally” or “equivocal bilaterally” in 62%, and “absent bilaterally” in 9%. The odds ratio for estimating MRI results from palpatory assessment was 3.62 (95% confidence interval = 1.70‐7.73, P = 0.001). Conclusions A rapid and inexpensive palpatory assessment in the clinic was highly associated with the risk of MRI‐documented PV muscle tear and is a useful component of a clinical assessment.

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Anatomy of the pubovisceral muscle origin: Macroscopic and microscopic findings within the injury zone

Cited by 33 publications

References 20 publications

Finite element model focused on stress distribution in the levator ani muscle during vaginal delivery

Finite element model focused on stress distribution in the levator ani muscle during vaginal delivery

What's new in the functional anatomy of pelvic organ prolapse?

Association of index finger palpatory assessment of pubovisceral muscle body integrity with MRI‐documented tear

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