The sellar face and floor have been drilled out. The bone that covers the anterior wall of the cavernous sinus has also been removed exposing the transition between the paraclinoidal and cavernous segments of the ICA. Here we can clearly see that the paraclinoidal ICA is located not within but at the roof of the cavernous sinus. The middle clinoid is a non-constant bony prominence that indents the most medial portion of the roof of the cavernous sinus, marking the transition between paraclinoidal and cavernous ICA. A small right middle clinoid has been removed, but a larger left middle clinoid remains in place. The left middle clinoid has been disconnected from the tubercullum sella and the bone covering the anterior wall of the cavernous sinus. (Image courtesy of JC Fernandez-Miranda)