Orientation and moment arms of some trunk muscles.

The orientations and moment arms of nine trunk muscles: latissimus dorsi, iliocostalis, longissimus dorsi, obliquii, rectus and transversalis abdominis, quadratus lumborum, and iliopsoas were obtained on embalmed specimens. Each muscle was considered as one or several, linear or curvilinear, lines of action. Origins, insertions, and points along the length of main bundles were digitized for each muscle using a three-dimensional digitizer. The results obtained from seven male specimens are presented and will permit more refined biomechanical models.