Flexion withdrawal reflex as recorded from single human biceps femoris motor neurones (2023)

Cited by (7)

  • Guidelines for single fiber EMG

    2019, Clinical Neurophysiology

    Citation Excerpt :

    The physiology of individual anterior horn cells can be studied by selective SFEMG recordings of F responses (Fig. 13) (Trontelj, 1973a) and H reflexes (Trontelj, 1973b). Polyneuronal reflexes such as the blink reflex, sacral reflexes and flexion reflex can be studied by measuring jitter in the SFAP responses after reflex activation (Trontelj and Trontelj, 1978; Vodušek et al., 1982; Janko and Trontelj, 1983). The SFE jitter in responses to transcortical electrical stimulation has been studied to assess the physiology of the entire motor pathway (Rossini et al., 1988).

    This document is the consensus of international experts on the current status of Single Fiber EMG (SFEMG) and the measurement of neuromuscular jitter with concentric needle electrodes (CNE – CN-jitter). The panel of authors was chosen based on their particular interests and previous publications within a specific area of SFEMG or CN-jitter. Each member of the panel was asked to submit a section on their particular area of interest and these submissions were circulated among the panel members for edits and comments. This process continued until a consensus was reached. Donald Sanders and Erik Stålberg then edited the final document.

  • Inhibition of the human flexion reflex by low intensity, high frequency transcutaneous electrical nerve stimulation (TENS) has a gradual onset and offset

    1987, Pain

    The present study examines the inhibitory effect of segmentally applied TENS on the nociceptive component of the flexion reflex elicited in various lower limb muscles, in an attempt to gain some insight into the underlying mechanism.

    The flexion reflex from 11 normal subjects was recorded electromyographically from the biceps femoris (BF), the tibialis anterior (TA), and in 2 subjects, the hip flexor (HF), in the manner described in a previous paper [9]. Amplitude and area values of the flexion reflex of each muscle were computerized prior to, during, and 50 min after the application of placebo or low intensity TENS at 100 Hz, for 30 min to the low back, at levels of segmentai innervation (L4-S1) similar to those of the muscles under study.

    In the majority of subjects, we found that:

    • 1.

      (1) Low intensity TENS caused a significant inhibition of the flexion reflex in proximal limb flexors. Thus, the BF measured 64% and 52%, and the HF 45% and 51%, of their respective mean control amplitude and area values at the time of maximum inhibition during TENS.

    • 2.

      (2) Moreover, less reduction of the mean values of the flexion reflex was observed in the TA, a distal limb (ankle) flexor.

    • 3.

      (3) It is noteworthy that in both the BF and HF, the time to peak maximum inhibitory effect took 30 and 20 min respectively after the onset of TENS, and the flexion reflex often did not return to control values even at 40–50 min after TENS.


    • 4.

      (4) In contrast, placebo TENS application resulted in no significant change of the flexion reflex in all the muscles examined.

    These findings showed that prolonged stimulation of large diameter fibers by conventional TENS application to the lumbosacral level, exerts a progressive and long latency inhibitory influence on a number of lower limb flexor motoneurons. In keeping with functional demand, this effect was found to be more prominent on the proximal than distal limb muscles. Furthermore, a gradual onset and offset of this inhibitory action is consistent with the results of some investigators demonstrating the possible involvement of endogenous opioids.

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(Video) 6th week: Spinal reflexes


What is the flexor withdrawal reflex? ›

Withdrawal reflexes coordinated by painful stimuli

The flexor reflex is initiated by cutaneous receptors, involving an entire limb. This is exemplified by pulling the hand back from a hot object, via flexing of the arm. Spinal flexor reflex pathways are slightly inhibited from descending influences of the brainstem.

What does the motor neuron in a withdrawal reflex stimulate muscles to do? ›

One pathway involves the somatic motor neuron exiting from the ventral horn to stimulate the flexor muscle of the ipsilateral limb, causing it to withdraw from the painful stimulus.

Which type of neural circuit is used in a flexor reflex? ›

Spinal cord circuitry responsible for the flexion reflex. Stimulation of cutaneous receptors in the foot leads to activation of spinal cord local circuits that withdraw (flex) the stimulated extremity and extend the other extremity to provide compensatory (more...)


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