Article

On the anatomy and histology of the pubovisceral muscle enthesis in women.

Biomechanics Research Laboratory, Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109-2125, USA.
Neurourology and Urodynamics (Impact Factor: 2.67). 05/2011; 30(7):1366-70. DOI: 10.1002/nau.21032
Source: PubMed

ABSTRACT The origin of the pubovisceral muscle (PVM) from the pubic bone is known to be at elevated risk for injury during difficult vaginal births. We examined the anatomy and histology of its enthesial origin to classify its type and see if it differs from appendicular entheses.
Parasagittal sections of the pubic bone, PVM enthesis, myotendinous junction, and muscle proper were harvested from five female cadavers (51-98 years). Histological sections were prepared with hematoxylin and eosin, Masson's trichrome, and Verhoeff-Van Gieson stains. The type of enthesis was identified according to a published enthesial classification scheme. Quantitative imaging analysis was performed in sampling bands 2 mm apart along the enthesis to determine its cross-sectional area and composition.
The PVM enthesis can be classified as a fibrous enthesis. The PVM muscle fibers terminated in collagenous fibers that insert tangentially onto the periosteum of the pubic bone for the most part. Sharpey's fibers were not observed. In a longitudinal cross-section, the area of the connective tissue and muscle becomes equal approximately 8 mm from the pubic bone.
The PVM originates bilaterally from the pubic bone via fibrous entheses whose collagen fibers arise tangentially from the periosteum of the pubic bone.

0 Bookmarks
 · 
148 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: OBJECTIVE: To determine the muscles comprising the minimal levator hiatus. DESIGN: Cross-sectional study. SETTING: The University of Oklahoma Health Sciences Center, USA. POPULATION: Eight female fresh frozen pelves and 80 nulliparouswomen. METHODS: Three-dimensional endovaginal ultrasound was performed in eight fresh frozen female pelves. The structures of the levator hiatus were tagged with needles and the cadavers were dissected to identify the tagged structures. A group of 80 nullipara underwent 3D endovaginal ultrasound, and the minimal levator hiatus area, puborectalis area, and anorectal angle were assessed, and normal values were obtained. MAIN OUTCOME MEASURES: Anatomic borders of minimal levator hiatus and normality in pelvic floor measurements. RESULTS: The pubococcygeus forms the inner lateral border and anterior attachment of the minimal levator hiatus to the pubic bone. The puboanalis fibres are immediately lateral to pubococcygeus attachments. There are variable contributions of the puborectalis fibres lateral to the puboanalis attachment. The posterior border of the minimal levator hiatus is formed by the levator plate. Eighty community-dwelling nulliparous women underwent 3D endovaginal ultrasound. The median age was 47 years (range 22-70 years). The mean of minimal levator hiatus and puborectalis hiatus areas were 13.4 cm(2) (±1.89 cm(2) SD) and 14.8 cm(2) (±2.16 cm(2) SD). The mean anorectal and levator plate descent angles were 156° (±10.04° SD) and 15.9° (±8.28° SD). CONCLUSION: Anterior and lateral borders of the minimal levator hiatus are formed mostly by pubococcygeus. The puborectalis, pubococcygeus, and iliococcygeus form the bulk of the levator plate.
    BJOG An International Journal of Obstetrics & Gynaecology 11/2012; · 3.76 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Childbirth causes overstretching of the Levator ani muscle (LAM) predisposing to avulsion. LAM has not been evaluated early postpartum using Endovaginal Ultrasound (EVUS).The aim was to evaluate the relationship between haematomas and LAM avulsion using EVUS and palpation early and late postpartum. Nullipara were studied prospectively at 36 weeks gestation, within four days and three months postpartum. Palpation and high frequency 3D EVUS (BK-Medical 9-16MHz, 360°probe) were performed. Two independent investigators reviewed the scans. No antenatal LAM avulsions were found (n=269). 114/199 (57.3%) seen early postpartum agreed to examination. 27/114 (24%) had well delineated, hypoechoic areas consistent with haematomas (100% agreement); 26 following vaginal delivery, one following emergency caesarean section. In total, 38 haematomas were found (11 bilateral, 16 unilateral). Haematomas away from the LAM attachment zone to the pubic bone (n=22) resolved. Haematomas at the attachment zone (n=16) manifested as pubococcygeus avulsions three months postpartum. In addition to these 16 avulsions, we found another 20 three months postpartum. 13/20 were not scanned early postpartum and in 7 no haematoma but avulsion was seen early postpartum. Overall, LAM avulsion was found in 23/191 (12.0%) women (13 bilateral, 10 unilateral) three months postpartum. Haematomas were significantly associated with episiotomy, instrumental delivery and increased hiatus measurements. Palpation was unreliable early postpartum as only 7 avulsions were diagnosed. Haematomas at the site of LAM attachment to the pubic bone always result in avulsion diagnosed three months postpartum. However, one third of avulsions are not preceded by a haematoma.
    Ultrasound in Obstetrics and Gynecology 07/2013; · 3.56 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: AimsThe levator ani muscle (LA) injury associated with vaginal birth occurs in a characteristic site of injury on the inner surface of the pubic bone to the pubovisceral portion of the levator ani muscle's origin. This study investigated the gross and microscopic anatomy of the pubic origin of the LA in this region.Methods Pubic origin of the levator ani muscle was examined in situ then harvested from nine female cadavers (35–98 years). A combination of targeted feature sampling and sequential sampling was used where each specimen was cut sequentially in approximately 5 mm thick slices apart in the area of known LA injury. Histological sections were stained with Masson's trichrome.ResultsThe pubovisceral origin is transparent and thin as it attaches tangentially to the pubic periosteum, with its morphology changing from medial to lateral regions. Medially, fibers of the thick muscle belly coalesce toward multiple narrow points of bony attachment for individual fascicles. In the central portion there is an aponeurosis and the distance between muscle and periosteum is wider (∼3 mm) than in the medial region. Laterally, the LA fibers attach to the levator arch where the transition from pubovisceral muscle to the iliococcygeal muscle occurs.Conclusions The morphology of the levator ani origin varies from the medial to lateral margin. The medial origin is a rather direct attachment of the muscle, while lateral origin is made through the levator arch. Neurourol. Urodynam. © 2014 Wiley Periodicals, Inc.
    Neurourology and Urodynamics 08/2014; · 2.67 Impact Factor

Full-text (2 Sources)

Download
46 Downloads
Available from
May 27, 2014