any structural anomaly of the butterfly-shaped depression which is centrally located in the cranial floor, narrow in the middle and wider laterally, and houses the temporal lobes of the cerebrum and the pituitary gland; it is separated from the posterior fossa by the clivus and the petrous crest; it is bounded: in front, by the posterior margins of the lesser wings of the sphenoid bone, the anterior clinoid processes, and the ridge forming the anterior margin of the chiasmatic groove; behind, by the superior angles of the petrous portions of the temporal bones and the dorsum sellae; laterally, by the temporal squamae, sphenoidal angles of the parietals, and greater wings of the sphenoid; it is traversed by the squamosal, sphenoparietal, sphenosquamosal, and sphenopetrosal sutures