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 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-1909, the total cortical thickness of area 21 is greater, the
granular cells 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.
See also
*
Brodmann area
A Brodmann area is a region of the cerebral cortex, in the human or other primate brain, defined by its cytoarchitecture, or histological structure and organization of cells.
History
Brodmann areas were originally defined and numbered by the ...
*
List of regions in the human brain
The human brain anatomical regions are ordered following standard neuroanatomy hierarchies. Functional, connective, and developmental regions are listed in parentheses where appropriate.
Hindbrain (rhombencephalon)
Myelencephalon
* Med ...
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