Rhomboidal stretches of low amplitude and velocity were applied to extensor digitorum communis muscle in regionally anesthetized cats. These inputs, which selectively activate primary muscle spindles, were found to excite neurons in a restricted region of contralateral motorsensory cortex. This same region was determined to be 'motor cortex' for this muscle on the basis of evidence from both cyto-architectonic and intracortical microstimulation studies. This functional loop may be important for transcortical reflexes.