The collections of the Museum in the Department of Anatomy, Faculty of Medicine, J. E. Purkynĕ University in Brno, include a skull of about 25 to 30-year-old individual with extreme microcephaly that has been so far described rarely in the morphological literature. The skull capacity is 355 cm3, which is only 26.1% of the skull capacity in a "normal" individual. While the facial skeleton is reduced only by 10-15% if compared with the norm, the cerebral part is striking by its extraordinarily small dimensions (smaller by 30-40% in comparison with the norm), particularly in the area of the frontal bone squama. The size of the skull is characterized best by the values of the basic metric measurements: maximal length of the skull 122 mm (norm: 172 mm), maximal breadth of the skull 94 mm (norm: 140 mm), height of the skull 96 mm (norm: 130 mm), circumference of the skull through the glabella 351 mm (norm: 510 mm). Foramen occipitale magnum is shifted strikingly to the dorsal direction. The cause of the microcephaly described cannot be explained explicitly just on the basis of the findings in the skull. For finding the actual cause a number of other data should be known. Authors' hypothesis that the problem is primary microcephaly has been supported even by roentgenological finding.

Department of Anatomy Medical Faculty J E Purkynĕ University Brno Czechoslovakia