الفهرس 
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Abstract
Sphenoid sinus is housed within the body of the sphenoid bone enclosed by a thin layer of bone which separates it from the nearby crucial structures like the internal carotid artery, cavernous sinus, optic nerve, optic chiasm and the pituitary gland. Occasionally, it extends into the lesser wings, the greater wings and pterygoid plates of the sphenoid bone, as well as to the clivus posteriorly.
The sphenoid sinus is normally made up of two asymmetrical cavities partitioned by one or more septa that are often asymmetric. It is highly variable in shape, size, and relationship to the Sella and adjacent neurovascular structures.
In Lang’s classification there are four patterns of pneumatization; conchal, presellar, sellar and postsellar. Sphenoid sinus pneumatization can vary from being nonexistent to being substantial, which causes the bone that protects important structures including the internal carotid arteries, the optic nerves, maxillary nerves and the Vidian nerve to be thin or entirely missing.
Protrusion of the optic nerve in majority of studies was defined as a bulging of the optic canal into the sphenoid sinus cavity so as to cause the exposure of more than half the circumference of the nerve, with or without defects in the bony margins.
Delano et al. (50) categorized the various relationships between the optic nerve and posterior PNS into four groups, as follows: type 1 optic nerve, type 2 optic nerve, type 3 optic nerve and type 4 optic nerve.
Onodi cell is the posterior-most ethmoid cell that extends into the sphenoid bone, and it pneumatizes superiorly and laterally into the sphenoid sinus.
The aim of the study was to evaluate the normal variations of the sphenoid sinus and its neurovascular relations by CT scan and to compare the outcomes for the males and females.
The current study was conducted on 200 patients, consisting of 100 males and 100 females, all above 20 years. The patients were recruited from Alexandria university main hospital having undergone PNS CT scan.
In males, there were 2 patients (2%) with conchal type of pneumatization, 13 patients (13%) with pre-sellar type, 70 patients (70%) with sellar type and 15 patients (15%) with post-sellar type. In females, there were 2 patients (2%) with conchal type, 9 patients (9%) with pre-sellar type, 76 patients (76%) with sellar type and 13 patients (13%) with post-sellar type.
In males, 36 patients (36%) were found to have single septum while 62 patients (62%) had multiple septa. In females, 1 patient (1%) with sellar pneumatization had no septum, 31 patients (31%) had single septum while 66 patients (66%) had multiple septa. Regarding septal attachment to carotid CC, in males, 18 patients (18%) had septal attachment to the CC while 80 patients (80%) had no septal attachment to the CC. In females, 18 patients (18%) had septal attachment to the CC while 80 patients (80%) had no septal attachment to the CC.