Introduction:
Sphenoid sinus is a midline single paranasal sinus. Its development is variable with consequent anatomical variations. For sinus surgeons and endoscopes, it is very important to consider the anatomical variations of the sinus and its relation with optic nerve and other structures to avoid mishaps and hazardous serious complications.
Materials and methods:
The study was conducted on 100 patients and 25 dried skulls. CT scan was conducted to all patients to evaluate pneumatization, septation of the sinus, presence of Onodi cells and optic nerve relation to it. all results were statistically analyzed.
Results:
With CT scanning, the commonest type of pneumatization was the sellar (64%), followed by the pre-sellar (22%), the post-sellar (11%) and the least common was the conchal pneumatization (3%). The findings matched with those of dried skulls examination except that the conchal type wasn't shown. Examination of CT images of the patients showed absence of inter- sphenoid sinus septum in 3% with Inter-sphenoid sinus septation found in 97%. Out of them, (39%) had single inter-sphenoid sinus septum (main septum) with no accessory septa. Accessory septa were either vertical or horizontal and ranges from 1 to 4. Studying the relations between optic nerve and sphenoid sinus, the optic nerve was bilaterally symmetrical in 92.8% and asymmetrical in 7.2%.

Conclusion:
Anatomy of sphenoid sinus is very variable and as compared with previous literature it showed some variations with gender then it should be considered during surgery and endoscopy and well pre-assessed before any intervention.