an obsolete concept of a trilaminar, triangular sheet of muscle and fascia spanning the ischiopubic rami; composed of the sphincter urethrae and the deep transverse perineal muscles (which were said to be flat muscles forming a continuous sheet), plus the perineal membrane below and a superior fascia of the diaphragm above. Evidence of the latter is lacking. The muscle-containing space between the fascial structures was formerly referred to as the deep perineal space. The terms urogenital diaphragm and deep perineal space are not recognized by Terminologia Anatomica due to more accurate understanding of the morphology, especially of the sphincter urethrae. SYN: diaphragma urogenitale.