Organ
Precentral gyrus
Cortical output for voluntary movement
High-yield
Medial motor cortex is usually supplied by ACA branches and lateral motor cortex by MCA branches. This helps explain leg-predominant versus face–arm-predominant weakness, without making either pattern an infallible arterial diagnosis.
Overview
Primary motor cortex (area 4) occupies the precentral region just in front of the central sulcus. Its deep pyramidal neurons include Betz cells and contribute to descending motor pathways. Lower-limb representation is mainly medial; hand and face representations are more lateral. This broad map is useful, but the detailed organization also includes overlapping action networks.
Reference facts
- Location
- Frontal cortex between the precentral and central sulci, with medial continuation into the anterior paracentral lobule.
- Parts
- Area 4 with overlapping body and action representations; premotor and supplementary motor regions of area 6 lie anteriorly and medially.
- Blood supply
- ACA branches predominantly supply medial lower-limb cortex; MCA branches predominantly supply the lateral motor surface.
- Relations
- Descending output enters the corona radiata and internal capsule, joining pathways to brainstem and spinal motor circuits.
- Function
- Contributes to the execution and control of voluntary movement, especially skilled contralateral limb actions, in cooperation with other motor areas.
Clinical correlation
Damage can impair voluntary movement on the opposite side, particularly fine control. The affected body regions help localize the lesion, but small cortical injuries, neighboring damage and individual vascular anatomy can produce exceptions to the standard stroke pattern.
Frequently asked questions
Where is the precentral gyrus located?
The precentral gyrus lies frontal cortex between the precentral and central sulci, with medial continuation into the anterior paracentral lobule.
What does the precentral gyrus do?
Contributes to the execution and control of voluntary movement, especially skilled contralateral limb actions, in cooperation with other motor areas.
What are the parts of the precentral gyrus?
Area 4 with overlapping body and action representations; premotor and supplementary motor regions of area 6 lie anteriorly and medially.
What is the blood supply of the precentral gyrus?
ACA branches predominantly supply medial lower-limb cortex; MCA branches predominantly supply the lateral motor surface.