Brodmann area 4 refers to the

primary motor cortex The primary motor cortex ( Brodmann area 4) is a brain region that in humans is located in the dorsal portion of the frontal lobe. It is the primary region of the motor system and works in association with other motor areas including premotor ...

of the

human Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, culture, ...

brain The brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It consists of nervous tissue and is typically located in the head ( cephalization), usually near organs for special ...

. It is located in the posterior portion of the

frontal lobe The frontal lobe is the largest of the four major lobes of the brain in mammals, and is located at the front of each cerebral hemisphere (in front of the parietal lobe and the temporal lobe). It is parted from the parietal lobe by a groove b ...

. Brodmann area 4 is part of the precentral gyrus. The borders of this area are: the precentral sulcus in front (

anterior Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...

ly), the medial longitudinal fissure at the top ( medially), the

central sulcus In neuroanatomy, the central sulcus (also central fissure, fissure of Rolando, or Rolandic fissure, after Luigi Rolando) is a sulcus, or groove, in the cerebral cortex in the brain The brain is an organ that serves as the center of the ...

in back ( posteriorly), and the lateral sulcus along the bottom (

lateral Lateral is a geometric term of location which may refer to: Healthcare *Lateral (anatomy), an anatomical direction * Lateral cricoarytenoid muscle * Lateral release (surgery), a surgical procedure on the side of a kneecap Phonetics *Lateral co ...

ly). This area of cortex, as shown by

Wilder Penfield Wilder Graves Penfield (January 26, 1891April 5, 1976) was an American-Canadian neurosurgeon. He expanded brain surgery's methods and techniques, including mapping the functions of various regions of the brain such as the cortical homunculu ...

and others, has the pattern of a

homunculus A homunculus ( , , ; "little person") is a representation of a small human being, originally depicted as small statues made out of clay. Popularized in sixteenth-century alchemy and nineteenth-century fiction, it has historically referred to the ...

. That is, the legs and trunk fold over the midline; the arms and hands are along the middle of the area shown here; and the face is near the bottom of the figure. Because Brodmann area 4 is in the same general location as

, the

here is called the

motor homunculus A cortical homunculus () is a distorted representation of the human body, based on a neurological "map" of the areas and proportions of the human brain dedicated to processing motor functions, or sensory functions, for different parts of the bo ...

. The term area 4 of Brodmann-1909 refers to a

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 portion of the

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 c ...

. It is located predominantly in the precentral gyrus. Brodmann-1909 regarded it as topographically and cytoarchitecturally homologous to the human gigantopyramidal area 4 and noted that it occupies a much greater fraction of the frontal lobe in the monkey than in the human. Distinctive features (Brodmann-1905): the cortex is unusually thick; the layers are not distinct; the cells are relatively sparsely distributed; giant pyramidal (Betz) cells are present in the internal pyramidal layer (V); lack of an internal granular layer (IV) such that the boundary between the external pyramidal layer (III) and the internal pyramidal layer (V) is indistinct; lack of a distinct external granular layer (II); a gradual transition from the multiform layer (VI) to 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 distributi ...

. (English translation available by Laurence Garey as ''Brodmann's 'Localisation in the cerebral cortex' ''(1994) and later editions)

Image

File:Brodmann area 4 animation small.gif, Animation. File:Brodmann area 4 frontal.jpg, front view. File:Brodmann area 4 lateral.jpg, Lateral view. File:Brodmann area 4 medial.jpg, Medial view. File:Gray726-Brodman.svg, Lateral surface.

References

External links

List of Brodmann areas
{{DEFAULTSORT:Brodmann Area 4 04 Frontal lobe

Image

See also

References

External links