Summary
The effects of stretching the triceps surae muscle on the resting discharge of functionally isolated and identified γ-efferents in the medial gastrocnemius nerve were studied in intercollicular decerebrate cats. Extension of the muscle decreases the activity of 9 out of 25 γ-motoneurones. This inhibition becomes apparent at about 8 mm muscle length and increases with increasing extension. Only those γ-efferents exhibiting this length-dependent inhibition are found to be inhibited by repetitive antidromic stimulation of the ventral root or the homonymous muscle nerve. We suggest that inhibition of fusimotor neurones by muscle stretch is at least partly mediated by the recurrent collaterals of the α-motoneurones activated by the stretch. 11 γ-motoneurones were predominantly excited by muscle stretch applied to the detached Achilles tendon as well as by squeezing the tendon. Nociceptors within the tendon or surrounding fascia are probably responsible.
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Fromm, C., Haase, J. & Noth, J. Length-dependent autogenetic inhibition of extensor γ-motoneurones in the decerebrate cat. Pflugers Arch. 346, 251–262 (1974). https://doi.org/10.1007/BF00595711
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DOI: https://doi.org/10.1007/BF00595711