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 c ...

of the

human Humans (''Homo sapiens'') or modern humans are the most common and widespread species of primate, and the last surviving species of the genus ''Homo''. They are Hominidae, great apes characterized by their Prehistory of nakedness and clothing ...

brain The brain is an organ (biology), 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 ...

. 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 Sulcus (neur ...

. 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 describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position pro ...

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 brains of vertebrates. It is sometimes confused with the longitudinal ...

in back (

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

), and the

lateral sulcus The lateral sulcus (or lateral fissure, also called Sylvian fissure, after Franciscus Sylvius) is the most prominent sulcus (neuroanatomy), sulcus of each cerebral hemisphere in the human brain. The lateral sulcus (neuroanatomy), sulcus is a deep ...

along the bottom (

lateral Lateral is a geometric term of location which may also refer to: Biology and healthcare * Lateral (anatomy), a term of location meaning "towards the side" * Lateral cricoarytenoid muscle, an intrinsic muscle of the larynx * Lateral release ( ...

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 homunculus. ...

and others, has the pattern of a

homunculus A homunculus ( , , ; "little person", : homunculi , , ) is a small human being. Popularized in 16th-century alchemy and 19th-century fiction, it has historically referred to the creation of a miniature, fully formed human. The concept has root ...

. 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. The term area 4 of Brodmann-1909 refers to a cytoarchitecturally defined portion of the

of the guenon. 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 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. It is the largest site of neural integration in the central nervous system, and plays a key ...

(V); lack of an

internal granular layer The internal granular layer of the cerebral cortex, also commonly referred to as the granular layer of the cortex, is the layer IV in the subdivision of the mammalian cerebral cortex into 6 layers. The adjective internal is used in opposition to ...

(IV) such that the boundary between the

external pyramidal 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. It is the largest site of neural integration in the central nervous system, and plays a key ...

(III) and the

(V) is indistinct; lack of a distinct external granular layer (II); a gradual transition from 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 mammal A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammal ...

(VI) to the subcortical

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

. (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