Brodmann (1909) area 6

agranular frontal area

Brodmann area 6, or BA6, is part of the frontal cortex in the human brain. Situated just anterior to the primary motor cortex, it is composed of the premotor cortex and, medially, the supplementary motor area, or SMA. This large area of the frontal cortex is believed to play a role in the planning of complex, coordinated movements. Brodmann area 6 is also called agranular frontal area 6 in humans because it lacks an internal granular cortical layer (layer IV). It is a subdivision of the cytoarchitecturally defined precentral region of cerebral cortex. In the human brain, it is located on the portions of the precentral gyrus that are not occupied by the gigantopyramidal area 4; furthermore, BA6 extends onto the caudal portions of the superior frontal and middle frontal gyri. It extends from the cingulate sulcus on the medial aspect of the hemisphere to the lateral sulcus on the lateral aspect. It is bounded rostrally by the granular frontal region and caudally by the gigantopyramidal area 4 (Brodmann, 1909).

種類 Organ
親構造 Brodmann area
ラテン語名 agranular frontal area
FMA ID 68602

よくある質問

What is Brodmann area 6?
Brodmann area 6 (BA6) is a large cortical region in the frontal lobe that comprises the premotor cortex (lateral BA6) and the supplementary motor area (SMA, medial BA6). It lies immediately anterior to the primary motor cortex (BA4).
Where is Brodmann area 6 located?
BA6 is located in the frontal lobe, immediately rostral (anterior) to the primary motor cortex (BA4) in the precentral gyrus. It extends along both the lateral surface and the medial surface of the hemisphere.
What functions are associated with Brodmann area 6?
BA6 is involved in the planning and preparation of complex voluntary movements, motor sequencing, and the selection of appropriate motor programs. The supplementary motor area (medial BA6) is particularly involved in internally generated (self-initiated) movements and bimanual coordination.
What cytoarchitectural feature characterizes Brodmann area 6?
BA6 is classified as an agranular frontal cortex because it lacks a distinct layer IV (the internal granular layer). This distinguishes it from granular cortex like the primary somatosensory cortex, reflecting its motor rather than sensory specialization.
What happens when Brodmann area 6 is damaged?
Damage to the lateral premotor cortex (BA6) can cause contralateral arm weakness with particular difficulty with skilled, sequential movements. Damage to the SMA can result in the alien hand syndrome or akinesia (reduced spontaneous movement initiation).

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Data sources: Terminologia Anatomica, Foundational Model of Anatomy, Wikidata.