On presentation of the human cerebral sulci from inside of the cerebrum.

The human cerebral cortex is highly convoluted forming patterns of gyri separated by sulci. The cerebral sulci and gyri are fundamental in cortical anatomy as well as neuroimage processing and analysis. Narrow and deep cerebral sulci are not fully discernible either on the cortical or white matter surface. To cope with this limitation, I propose a new sulci presentation method that employs the inner cortical surface for sulci examination from the inside of the cerebrum. The method has four steps, construct the cortical surface, segment and label the sulci, dissect (open) the cortical surface, and explore the fully exposed sulci from the inside. The inside sulcal maps are created for the left and right lateral, left and right medial, and basal hemispheric surfaces with the sulci parcellated by color and labeled. These three-dimensional sulcal maps presented here are probably the first of this kind created. The proposed method demonstrates the full course and depths of sulci, including narrow, deep, and/or convoluted sulci, which has an educational value and facilitates their quantification. In particular, it provides a straightforward identification of sulcal pits which are valuable markers in studying neurologic disorders. It enhances the visibility of sulci variations by exposing branches, segments, and inter-sulcal continuity. The inside view also clearly demonstrates the sulcal wall skewness along with its variability and enables its assessment. Lastly, this method exposes the sulcal 3-hinges introduced here.