An alternative method to activate peripheral nerves, i.e., motor point stimulation (MPS) which delivers electrical stimulation over the muscle belly, has not been used to induce F‐waves. To induce F‐waves, transcutaneous peripheral nerve stimulation (PNS) is used, which activates nerve branches via transcutaneous electrodes over the nerve branches. The F‐wave is a motor response induced by electrical stimulation of peripheral nerves via the antidromic firing of motor nerves, which reflects the motoneuron excitability. (C), #1-in motor axons conducting orthodromic impulses of voluntary drive, voluntary and antidromic impulses will collide #2-reflex response which travels along motor axons cleared by the collision described in point #1 will contribute to the V-wave #3-presynaptic inhibition can influence afferent input to the motoneuron. (B), #1-a small number of motoneurons may discharge to produce F-waves after antidromic impulses reach their soma #2-at rest, F-waves are likely to be limited to large motoneurons due to reflex activation of smaller motoneurons and collision with the antidromic volley prior to the soma. (A), #1-electrical stimulus evokes a single afferent volley which recruits motoneurons for the H-reflex according to the size principle #2-presynaptic inhibition can influence afferent input to the motoneuron #3-tendon tap evokes multiple volleys which arrive at the motoneuron over 25 ms. Only the most critical elements are labeled so see text for a complete description of the factors which can influence each response. Schematic representation of the volleys and pathways involved in the production of the H-reflex, tendon jerk, F-wave, and V-wave.
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