(Adapted from)Mapping from the Motor Cortex to Biceps and Triceps Altered by Elbow Angle Graziano MSA, Patel KT, Taylor CSR. J. Neurophysiol. 92: 395-407 2004

"How this [apparently systematic] stimulation-evoked topography relates to the normal function of motor cortex is not yet clear.One hypothesis is that these results reflect a cortical map of desired joint angle[that is, of discrete arm postures]". Graziano, Patel, Taylor p. 395 - phrases in square brackets added to extract

See also: Motor primitives for arm movement and speech