Localization of the motor hand area to a knob on the precentral gyrus. A new landmark

Abstract

Using functional magnetic resonance imaging (fMRI) we have evaluated the anatomical location of the motor hand area. The segment of the precentral gyrus that most often contained motor hand function was a knob-like structure, that is shaped like an omega or epsilon in the axial plane and like a hook in the sagittal plane. On the cortical surface of cadaver specimens this precentral knob corresponded precisely to the characteristic 'middle knee' of the central sulcus that has been described by various anatomists in the last century. We were then able to show that this knob is a reliable landmark for identifying the precentral gyrus directly. We therefore conclude that neural elements involved in motor hand function are located in a characteristic 'precentral knob' which is a reliable landmark for identifying the precentral gyrus under normal and pathological conditions. It faces and forms the 'middle knee' of the central sulcus, is located just at the cross point between the precentral sulcus and the central sulcus, and is therefore also visible on the cortical surface.

New coil positioning method for interleaved transcranial magnetic stimulation (TMS)/functional MRI (fMRI) and its validation in a motor cortex study

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“…In left motor cortex, response changes elicited a signal increase in the middle genu of the left precentral gyrus at the location of the hand motor representation area (Yousry et al, 1997;Fig. 5c).…”

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“…We also found that the individual centers of LPMC and SMC are close in proximity, resulting in a large overlapping area between the two regions. It is possible that this overlap is due to the variability inherent in the shape and extent of the central sulcus within (White et al, 1997;Rademacher et al, 2001b;Fesl et al, 2003) and between subjects (White et al, 1997;Yousry et al, 1997;Roland and Zilles, 1998;Moore et al, 2000;Rademacher et al, 2001b).…”