The ischiorectal fossae of one fresh and 47 preserved cadaver specimens were dissected to elucidate its fascial boundaries, neurovascular relationships, spatial orientation, and possible functions. Based upon measurements of approximately half of the dissected specimens, a three-dimensional model of the ischiorectal fossa was developed to clarify visually its fascial relationships and orientation within the perineum. Seven fetal specimens were also dissected for comparative purposes. A distinct fascial septum, the lamina terminalis, connecting the medial and lateral walls of the fossa to form its anterior boundary, was consistently found as a dense fibrous component attaching inferiorly to the posterior aspect of the urogenital diaphragm. The functional significance of the ischiorectal fossa in supporting the urogenital diaphragm, in anal activities, and in sparing the compression of the neurovascular supply to the perineum is discussed.