Precentral gyrus

The internal pyramidal layer (layer V) of the precentral cortex contains giant (70-100 micrometers) pyramidal neurons called Betz cells, which send long axons to the contralateral motor nuclei of the cranial nerves and to the lower motor neurons in the ventral horn of the spinal cord.There is a precise somatotopic representation of the different body parts in the primary motor cortex, with the leg area located medially (close to the midline), and the head and face area located laterally on the convex side of the cerebral hemisphere (cortical homunculus).[1] As they travel down through the cerebral white matter, the motor axons move closer together and form part of the posterior limb of the internal capsule.After crossing over to the contralateral side in the medulla oblongata (pyramidal decussation), the axons travel down the spinal cord as the lateral corticospinal tract.Lesions of the precentral gyrus result in paralysis of the contralateral side of the body (facial palsy, arm-/leg monoparesis, hemiparesis) - see upper motor neuron.
frontal lobeAnatomical terms of neuroanatomyprimary motor cortexcytoarchitecturallyBrodmann area 4postcentral gyruscerebral hemispherecentral sulcusanteriorprecentral sulcusinferiorlylateral sulcusMediallyparacentral lobulecortexpyramidal neuronsBetz cellscranial nerveslower motor neuronsspinal cordcorticospinal tractupper motor neuronscortical homunculuswhite matterinternal capsulebrainstemsynapsemedulla oblongatapyramidal decussationlateral corticospinal tractventral corticospinal tractmiddle cerebral arteryanterior cerebral arteryparalysisfacial palsymonoparesishemiparesisupper motor neuronspeech disordersMotor cortexList of regions in the human brain