title: Appearance of the levator ani muscle subdivisions in magnetic resonance images.
abstract: OBJECTIVE
  Identify and describe the separate appearance of 5 levator ani muscle subdivisions seen in axial, coronal, and sagittal magnetic resonance imaging (MRI) scan planes.
  
  
  METHODS
  Magnetic resonance scans of 80 nulliparous women with normal pelvic support were evaluated. Characteristic features of each Terminologia Anatomica-listed levator ani component were determined for each scan plane. Muscle component visibility was based on pre-established criteria in axial, coronal, and sagittal scan planes: 1) clear and consistently visible separation or 2) different origin or insertion. Visibility of each of the levator ani subdivisions in each scan plane was assessed in 25 nulliparous women.
  
  
  RESULTS
  In the axial plane, the puborectal muscle can be seen lateral to the pubovisceral muscle and decussating dorsal to the rectum. The course of the puboperineal muscle near the perineal body is visualized in the axial plane. The coronal view is perpendicular to the fiber direction of the puborectal and pubovisceral muscles and shows them as "clusters" of muscle on either side of the vagina. The sagittal plane consistently demonstrates the puborectal muscle passing dorsal to the rectum to form a sling that can consistently be seen as a "bump." This plane is also parallel to the pubovisceral muscle fiber direction and shows the puboperineal muscle.
  
  
  CONCLUSIONS
  The subdivisions of the levator ani muscle are visible in MRI scans, each with distinct morphology and characteristic features.
authors.affiliation: University of Michigan, Ann Arbor, Michigan 48109-0276, USA. rmarguli@med.umich.edu
authors.forename: Rebecca U
authors.initials: RU
authors.lastname: Margulies
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Hsu
authors.forename: Rohna
authors.initials: R
authors.lastname: Kearney
authors.forename: Tamara
authors.initials: T
authors.lastname: Stein
authors.forename: Wolfgang H
authors.initials: WH
authors.lastname: Umek
authors.forename: John O L
authors.initials: JO
authors.lastname: DeLancey
mesh_terms: D000328:Adult; D015992:Body Mass Index; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008953:Models, Anatomic; D017773:Pelvic Floor / Q000033:anatomy & histology*; D012016:Reference Values; D015203:Reproducibility of Results