[Morphologic anatomy of the interjugochiasmatic fenestra]

The pituitary body can be surgically approached through the triangular cleft limited by the sphenoidal jugum and the anterior side of the optic chiasma. The mean surface was calculated by measurements on 51 specimens; it reached 65 mm2. The ratio height : width of the cleft attained 1,3-1,4 corresponding to an anterior chiasmatic angle of about 66-70 degrees. With regard to the variations of the intermalar distance, the values of the triangular surface could be classified into 3 types:--to a distance of 100 mm corresponds a surface less than 50 mm2 (narrow or first grade);--to a distance of 115 mm corresponds a surface greater than 80 mm2 (wide or third grade);--Between these values, the surface can be reckoned on a grossly parabolic curve, the top of which amounts to 90 mm when the intermalar distance equals 107 mm.