Related Experiment Videos
H reflex analysis of segmental reflex excitability in flexor and extensor muscles
Neurology
|July 1, 1979
Summary
This study reveals that H reflexes, typically found in antigravity muscles, can also appear in antagonistic muscles like the peroneal (P) and extensor digitorum communis (EDC) during contraction, suggesting broader motor control roles.
Area of Science:
- Neuroscience
- Human Physiology
- Motor Control
Background:
- H reflexes are typically observed in antigravity muscles such as the calf and flexor carpi radialis (FCR) in healthy adults.
- These reflexes may exhibit a wider distribution under specific physiological conditions, particularly during agonist muscle contraction.
Purpose of the Study:
- To investigate the presence and extent of H reflexes in antagonistic muscles during voluntary contraction.
- To explore the role of group II afferent fibers in normal motor system activity.
Main Methods:
- Electromyography was used to record H reflexes in the peroneal (P) and anterior tibialis (TA) muscles of the leg, and the extensor digitorum communis (EDC) muscle of the arm.
- Muscle contractions were induced in the antagonistic muscles (calf and FCR).
- Passive wrist extension was also employed to elicit EDC H reflexes.
Main Results:
- H reflexes were successfully elicited in the P and TA muscles during calf muscle contraction.
- H reflexes were also observed in the EDC muscle during FCR contraction.
- Regular elicitation of H reflexes in the EDC was noted during passive wrist extension.
Conclusions:
- The findings suggest a physiological unity between similarly acting antigravity muscles and their antagonists in both upper and lower extremities.
- The results imply a significant functional role for group II afferent fibers in the normal functioning of the human motor system.