%ما هو (من)٪ 1 - تعريف

In neuroscience, an F wave is one of several motor responses which may follow the direct motor response (M) evoked by electrical stimulation of peripheral motor or mixed (sensory and motor) nerves. F-waves are the second of two late voltage changes observed after stimulation is applied to the skin surface above the distal region of a nerve, in addition to the H-reflex (Hoffman's Reflex) which is a muscle reaction in response to electrical stimulation of innervating sensory fibers. Traversal of F-waves along the entire length of peripheral nerves between the spinal cord and muscle, allows for assessment of motor nerve conduction between distal stimulation sites in the arm and leg, and related motoneurons (MN's) in the cervical and lumbosacral cord. F-waves are able to assess both afferent and efferent loops of the alpha motor neuron in its entirety. As such, various properties of F-wave motor nerve conduction are analyzed in nerve conduction studies (NCS), and often used to assess polyneuropathies, resulting from states of neuronal demyelination and loss of peripheral axonal integrity.

With respect to its nomenclature, the F-wave is so named as it was initially studied in the smaller muscles of the foot. The observation of F-waves in the same motor units (MU) as those present in the direct motor response (M), along with the presence of F-waves in deafferented animal and human models, indicates that F-waves require direct activation of motor axons to be elicited, and do not involve conduction along afferent sensory nerves. Thus, the F-wave is considered a wave, as opposed to a reflex.