It is bounded approximately by the intraparietal sulcus, the inferior postcentral sulcus, the posterior subcentral sulcus and the lateral sulcus. Cytoarchitecturally it is bounded caudally by the angular area 39 (H), rostrally and dorsally by the caudal postcentral area 2, and ventrally by the subcentral area 43 and the superior temporal area 22 (Brodmann-1909).
Cytoarchitectonically defined subregions of rostral BA40/the supramarginal gyrus are PF, PFcm, PFm, PFop, and PFt. Area PF is the homologue to macaque area PF, part of the mirror neuron system, and active in humans during imitation.