| Brodmann area 21 | |
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| Details | |
| Identifiers | |
| Latin | area temporalis media |
| NeuroNames | 1016 |
| NeuroLex ID | birnlex_1752 |
| FMA | 68618 |
| Anatomical terms of neuroanatomy | |
Brodmann area 21, orBA21, is part of thetemporalcortex in thehuman brain. The region encompasses most of the lateral temporal cortex and is also known asmiddle temporal area 21. In the human it corresponds approximately to themiddle temporal gyrus.
BA 21 is a higher-order visual association cortex with medium myelin content.[1] As a lateral temporal region, it is likely to play a part in auditory processing and language. Language function is left lateralized in most individuals.
BA21 is a subdivision of thecytoarchitecturally definedtemporal region of the cerebral cortex.BA21 is superior toBA20 and inferior toBA40 andBA41. It is bounded rostrally by thetemporopolar area 38 (H), ventrally by theinferior temporal area 20, caudally by theoccipitotemporal area 37 (H), and dorsally by thesuperior temporal area 22 (Brodmann-1909).
Brodmann area 21 is a subdivision of the cerebral cortex of theguenon defined on the basis of cytoarchitecture. It is cytoarchitecturally homologous to the middle temporal area 21 of the human (Brodmann-1909). Distinctive features (Brodmann-1905): Compared toarea 20 of Brodmann-1909, the total cortical thickness of area 21 is greater, thegranular cells are less abundant, and the boundary with the subcorticalwhite matter is less distinct; themolecular layer (I) is wider; thepyramidal cells of sublayer 3b of the externalpyramidal layer (III) are larger; the internalgranular layer (IV) is less developed and contains fewer cells;ganglion cells of the internal pyramidal layer (V) are larger, rounder, and densely arrayed adjacent to layer IV; the boundary between layer V and themultiform layer (VI) is indistinct; and layer VI is wider and has no sublayers.
