IT IS CERTAINLY true that sphenoiditis frequently brings to mind that "out of sight, out of mind." The literature is filled with reports of treatment and management of maxillary, frontal, and ethmoid sinus infections. The average rhinological examination can very well evaluate the status of these structures, but all too frequently the sphenoid sinus is somewhat overlooked in its proper evaluation.* And yet, there are no fewer than 13 vital structures that are intimately concerned with the average sphenoid sinus: the dura mater, the pituitary body, the optic nerve and chiasm, the cavernous sinus, the internal carotid artery, the abducens nerve, the oculomotor nerve, the trochlear nerve, the ophthalmic nerve, the maxillary nerve, the sphenopalatine ganglion, the sphenopalatine artery, and the pterygoid canal and its nerve. Certainly herniation of the mucosa through dehiscences in the bone has been known to occur. This may well extend the sphenoid sinus well beyond