Asymmetry of the planum parietale.

Using in vivo magnetic resonance morphometry we measured the posterior wall of the left and right posterior ascending portion of the Sylvian fissure, an inferior parietal area of the brain that we have termed the planum parietale. Among 106 right-handers (53 women and 53 men) and 35 left-handers (18 women and 17 men), handedness and gender exerted an interactive influence on planum parietale asymmetry; right-handed men and left-handed women showed particularly strong rightward asymmetry. There was no correlation between asymmetry of the planum parietale and that of the anatomically adjacent planum temporale, suggesting an independency of these two structural markers of brain laterality.