Motor Unit Action Potential Recruitment Analysis and Clinical Utility

The spatial and temporal summation of all the single muscle fibers’ electrical activity corresponding to that AHC depolarization is referred to as a motor unit action potential (MUAP/MUP; Fig. 2). In other words, the MUAP is essentially the electrical correlate to the anatomic motor unit. The above noted MUAP’s respective “spatial” and “temporal” qualifiers are related to the fact that: 1) all of the single muscle fibers belonging to one anterior horn cell are distributed in muscle tissue within a so called motor unit territory approximating a cylindrical volume of roughly 6 mm in diameter extending the length of the muscle, and 2) the voltage associated with all those single muscle fibers summate electrically based on their individual arrival times at the recording electrode.