Brodmann area 21, or BA21, is part of the temporal

cortex Cortex or cortical may refer to: Biology * Cortex (anatomy), the outermost layer of an organ ** Cerebral cortex, the outer layer of the vertebrate cerebrum, part of which is the ''forebrain'' *** Motor cortex, the regions of the cerebral cortex i ...

in the

human brain The human brain is the central organ of the human nervous system, and with the spinal cord makes up the central nervous system. The brain consists of the cerebrum, the brainstem and the cerebellum. It controls most of the activities of the ...

. The region encompasses most of the lateral temporal cortex and is also known as middle temporal area 21. In the human it corresponds approximately to the

middle temporal gyrus Middle temporal gyrus is a gyrus in the brain on the temporal lobe. It is located between the superior temporal gyrus and inferior temporal gyrus. It corresponds largely to Brodmann area 21. The middle temporal gyrus is bounded by: * the superi ...

Function

BA 21 is a higher-order visual association cortex with medium myelin content. 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.

Location

BA21 is a subdivision of the

cytoarchitecturally Cytoarchitecture (Ancient Greek language, Greek ''wiktionary:κύτος#Ancient_Greek, κύτος''= "cell" + ''wiktionary:ἀρχιτέκτων#Ancient_Greek, ἀρχιτεκτονική''= "architecture"), also known as cytoarchitectonics, is th ...

defined temporal region of the cerebral cortex. BA21 is superior to BA20 and inferior to BA40 and BA41. It is bounded rostrally by the

temporopolar area 38 Brodmann area 38, also BA38 or temporopolar area 38 (H), is part of the temporal cortex in the human brain. BA 38 is at the anterior end of the temporal lobe, known as the temporal pole. BA38 is a subdivision of the cytoarchitecturally defined ...

(H), ventrally by the

inferior temporal area 20 Brodmann area 20, or BA20, is part of the temporal cortex in the human brain. The region encompasses most of the ventral temporal cortex, a region believed to play a part in high-level visual processing and recognition memory. This area is also ...

, caudally by the occipitotemporal area 37 (H), and dorsally by the

superior temporal area 22 Brodmann area 22 is a Brodmann's area that is cytoarchitecturally located in the posterior superior temporal gyrus of the brain. In the left cerebral hemisphere, it is one portion of Wernicke's area. The left hemisphere BA22 helps with generati ...

(Brodmann-1909).

Guenon

Brodmann area 21 is a subdivision of the cerebral cortex of the

guenon The guenons (, ) are Old World monkeys of the genus ''Cercopithecus'' (). Not all members of this genus have the word "guenon" in their common names; also, because of changes in scientific classification, some monkeys in other genera may have co ...

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 to

area 20 of Brodmann Brodmann area 20, or BA20, is part of the temporal cortex in the human brain. The region encompasses most of the ventral temporal cortex, a region believed to play a part in high-level visual processing and recognition memory. This area is also ...

-1909, the total cortical thickness of area 21 is greater, the

granular cell Juxtaglomerular cells (JG cells), also known as juxtaglomerular granular cells are cells in the kidney that synthesize, store, and secrete the enzyme renin. They are specialized smooth muscle cells mainly in the walls of the afferent arteriole ...

s are less abundant, and the boundary with the subcortical

white matter White matter refers to areas of the central nervous system (CNS) that are mainly made up of myelinated axons, also called tracts. Long thought to be passive tissue, white matter affects learning and brain functions, modulating the distribution ...

is less distinct; the molecular layer (I) is wider; the

pyramidal cell Pyramidal cells, or pyramidal neurons, are a type of multipolar neuron found in areas of the brain including the cerebral cortex, the hippocampus, and the amygdala. Pyramidal neurons are the primary excitation units of the mammalian prefrontal cor ...

s of sublayer 3b of the external

pyramidal layer A pyramid (from el, πυραμίς ') is a structure whose outer surfaces are triangular and converge to a single step at the top, making the shape roughly a pyramid in the geometric sense. The base of a pyramid can be trilateral, quadrilater ...

(III) are larger; the internal granular layer (IV) is less developed and contains fewer cells;

ganglion cells {{stack, A ganglion cell is a cell found in a ganglion. Examples of ganglion cells include: * Retinal ganglion cell (RGC) found in the ganglion cell layer of the retina * Cells that reside in the adrenal medulla, where they are involved in the s ...

of the internal pyramidal layer (V) are larger, rounder, and densely arrayed adjacent to layer IV; the boundary between layer V and the

multiform layer The cerebral cortex, also known as the cerebral mantle, is the outer layer of neural tissue of the cerebrum of the brain in humans and other mammals. The cerebral cortex mostly consists of the six-layered neocortex, with just 10% consisting of ...

(VI) is indistinct; and layer VI is wider and has no sublayers.

References

External links

* For Neuroanatomy of the middle temporal area 21 visi
BrainInfo
* For Neuroanatomy of Brodmann area 21 visi
BrainInfo
{{Prosencephalon 21 Temporal lobe

Function

Location

Guenon

See also

References

External links