It is generally known that the primary motor cortex (M1) is involved in the execution of movement. However, it is not too well understood how corticospinal neurons in M1 communicate with muscles through the spinal cord to orchestrate even the simplest movements such as grabbing a glass of water. Such a task requires precise groups of muscles to be contracted in synergy with moment-to-moment change depending on the stage of the task. TMS (transcranial magnetic stimulation) experiments attempt to characterize these corticospinal patterns of muscle activation in able-bodied human subjects by recording electromyography (EMG) while they contract muscles or perform limb movements. Typically, TMS-EMG studies use 1 bipolar montage to record muscle activity on a limb, however, since MEPs can be generated by non-target muscles, the limited coverage has inspired researchers to record from several muscles using up to 4 bipolar electrodes. Our group ambitiously developed a high-density electrode array (HDEA) with 150 surface electrodes embedded in a fabric that can be worn around the entire forearm like a sleeve. We recruited one subject for a pilot study who was asked to wear the HDEA sleeve and sit in a chair in a relaxed state while being magnetically stimulated in the forearm area of M1. We generated topographic maps of the forearm displaying corticospinal recruitment patterns indicative of muscle synergies. Future work will explore muscle synergies during functional tasks such as grabbing (a glass of water) and compare corticospinal recruitment patterns of able-bodied subjects with those of individuals with motor impairments from neurological injuries.