Precentral Gyrus Of The Brain

Description

Precentral gyrus (gyrus precentralis) crowns the posterior frontal lobe in a superior view, running anteroposteriorly as a sinuous ridge immediately anterior to the central sulcus. Medially, its upper end approaches the interhemispheric fissure and the paracentral lobule, while laterally it narrows toward the convexity where the “hand knob” region is typically located along the mid-portion of the gyrus. Posterior to it, the postcentral gyrus of the parietal lobe is separated by the central sulcus, a sharp landmark that anchors the boundary between primary motor and primary somatosensory cortex. Primary motor cortex (Brodmann area 4) is where corticospinal output is organized somatotopically, so small shifts along this gyrus correspond to face and tongue inferolaterally, upper limb around the mid-convexity, and lower limb and foot near the medial margin. Localization matters. Infarct in the superior division of the middle cerebral artery often maps to weakness that tracks the lateral precentral representation (face and arm), while anterior cerebral artery territory lesions more often affect the medial leg area. The fixed superior perspective also helps when teaching how to identify the central sulcus by its relationship to the superior frontal sulcus and the “omega-shaped” precentral hand region used in neurosurgical planning and functional mapping. Neuroanatomy and neurophysiology courses can pair this illustration with the motor homunculus and corticospinal tract diagrams to connect surface anatomy to exam findings like contralateral hemiparesis, pronator drift, or focal motor seizures. It also fits neurosurgery and neuroradiology publications discussing craniotomy corridors, tumor adjacency to eloquent cortex, or transcranial magnetic stimulation targets referenced to the precentral gyrus. Anatomical accuracy verified by SciePro's Medical Advisory Board.