Brodmann_area_4 References

Brodmann area 4
Brodmann area 4
	Brodmann area 4 (orange)
	Brodmann area 4 of human brain.
Details
Part of	Precentral gyrus
Identifiers
Latin	area gigantopyramidalis
NeuroNames	2394, 1014
NeuroLex ID	birnlex_1735
FMA	68600
	Anatomical terms of neuroanatomy [ edit on Wikidata

Brodmann area 4 refers to the primary motor cortex of the human brain. It is located in the posterior portion of the frontal lobe.

Brodmann area 4 is part of the precentral gyrus. The borders of this area are: the precentral sulcus in front ( anteriorly), the medial longitudinal fissure at the top ( medially), the central sulcus in back ( posteriorly), and the lateral sulcus along the bottom ( laterally).

This area of cortex, as shown by Wilder Penfield and others, has the pattern of a homunculus. 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 primary motor cortex, the homunculus here is called the motor homunculus.

The term area 4 of Brodmann-1909 refers to a cytoarchitecturally defined portion of the frontal lobe 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 (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.^[1]