Supine Myelography and the Septum Posticum

The septum posticum, a midline meningeal structure which may be improperly diagnosed as an abnormality due to its appearance as a filling defect on supine myelograms, is discussed. An anatomical dissection analysis of 43 spinal cords was carried out to determine the findings that may be expected from the septum posticum on supine myelograms. Other anatomical and myelographic features of the posterior spinal subarachnoid space are also discussed with particular emphasis on the avoidance of false positive readings.