[TA] the upper opening of the true pelvis, bounded anteriorly by the pubic symphysis and the pubic crest on either side, laterally by the iliopectineal lines, and posteriorly by the promontory of the sacrum. SYN: apertura pelvis superior [TA], aditus pelvis, first parallel pelvic plane, pelvic brim, pelvic plane of inlet, plane of inlet, superior pelvic aperture.
