Experimental Brain Research

, Volume 65, Issue 2, pp 271–281 | Cite as

Reflex pathways from group II muscle afferents

1. Distribution and linkage of reflex actions to α-motoneurones
  • A. Lundberg
  • K. Malmgren
  • E. D. Schomburg


The interneuronally mediated reflex actions evoked by electrical stimulation of group II muscle afferents in low spinal cats have been reinvestigated with intracellular recording from motoneurones to knee flexors and ankle extensors. The results of Eccles and Lundberg (1959) have been confirmed and extended. There was wide convergence from flexors and extensors of group II excitation to flexor and group II inhibition to extensor motoneurones. Some quantitative differences in the effect from the different nerves are described. Latency measurements suggest that the minimal linkage is disynaptic in the excitatory interneuronal pathways and trisynaptic in the inhibitory pathways. Disynaptic group II EPSPs were found in 14% of the ankle extensor motoneurones but were much more common in unanaesthetized high spinal cats (Wilson and Kato 1965). From these results and corresponding ones on flexors (Holmqvist and Lundberg 1961) it is postulated that secondary afferents in addition to the weak monosynaptic connexions (Kirkwood and Sears 1975) have disynaptic excitatory pathways and trisynaptic inhibitory pathways to both flexor and extensor motoneurones. It is proposed that the group II actions of the flexor reflex pattern characterizing the anaesthetized low spinal cat are due to suppression of the inhibitory pathway to flexor motoneurones and the excitatory pathway to extensor motoneurones. In some ankle extensor motoneurones the disynaptic group II EPSPs occurred in combination with IPSPs from the FRA (including group II and III muscle afferents). The possibility is considered that these group II EPSPs are mediated by an interneuronal group II pathway with little or no input from group III muscle afferents but probably from extramuscular receptors. In other ankle extensor motoneurones group II EPSPs were combined with EPSPs from group III muscle afferents, cutaneous afferents and joint afferents. It is postulated that these group II EPSPs are mediated by an interneuronal pathway from the FRA which also supply interneuronal pathways giving inhibition to extensor or/and flexor motoneurones and excitation to flexors as postulated by Eccles and Lundberg (1959) and Holmqvist and Lundberg (1961).

Key words

Low spinal cats Group II muscle afferents Motoneurones Disynaptic EPSPs Trisynaptic IPSPs 





posterior biceps and semitendinosus


anterior biceps and semimembranosus


gastrocnemius and soleus


flexor digitorum and hallucis longus




tibialis anterior and extensor digitorum longus


extensor digitorum brevis

SPM or separately, Per br and Per 1

peroneus longus, tertius and brevis together


posterior nerve from knee joint






skin division of superficial peroneal


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  1. Appelberg B, Johansson H, Kalistratov G (1977) The influence of group II muscle afferents and low threshold skin afferents on dynamic fusimotor neurones to the triceps surae of the cat. Brain Res 132: 153–158Google Scholar
  2. Appelberg B, Hulliger M, Johansson H, Sojka P (1983) Actions on γ-motoneurones elicited by electrical stimulation of group II muscle afferent fibres in the hind limb of the cat. J Physiol (Lond) 335: 255–273Google Scholar
  3. Baldissera F, Hultborn H, Illert M (1981) Integration in spinal neuronal systems. In: Brooks VB (ed) Handbook of physiology, Sect I. The nervous system, Vol II, Motor control. Am Physiol Soc, Bethesda, MD, pp 509–595Google Scholar
  4. Boyd IA, Davey MR (1968) Composition of peripheral nerves. E & S Livingstone Ltd, Edinburgh and LondonGoogle Scholar
  5. Bradley K, Eccles JC (1953) Analysis of the fast afferent impulses from thigh muscles. J Physiol (Lond) 122: 462–473CrossRefGoogle Scholar
  6. Brown AG (1981) Organization in the spinal cord. Springer, Berlin Heidelberg New YorkGoogle Scholar
  7. Cangiano A, Lutzemberger L (1972) The action of selectively activated group II muscle afferent fibers on extensor motoneurons. Brain Res 41: 475–478PubMedGoogle Scholar
  8. Eccles RM, Lundberg A (1959) Synaptic actions in motoneurones by afferents which may evoke the flexion reflex. Arch Ital Biol 97: 199–221Google Scholar
  9. Ellaway PH, Murphy PR, Tripathi A (1982) Closely coupled excitation of γ-motoneurones by group III muscle afferents with low mechanical threshold in the cat. J Physiol (Lond) 331: 481–498Google Scholar
  10. Fedina L, Hultborn H (1972) Facilitation from ipsilateral primary afferents of interneuronal transmission in the Ia inhibitory pathway to motoneurones. Acta Physiol Scand 86: 59–81Google Scholar
  11. Fu TC, Schomburg ED (1974) Electrophysiological investigation of the projection of secondary muscle spindle afferents in the cat spinal cord. Acta Physiol Scand 91: 314–329Google Scholar
  12. Fu TC, Santini M, Schomburg ED (1974) Characteristics and distribution of spinal focal synaptic potentials generated by group II muscle afferents. Acta Physiol Scand 91: 298–313Google Scholar
  13. Holmqvist B, Lundberg A (1961) Differential supraspinal control of synaptic actions evoked by volleys in the flexion reflex afferents in alpha motoneurones. Acta Physiol Scand 54: Suppl 186Google Scholar
  14. Hongo T, Kudo N, Yamashita M, Ishizuka N, Mannen H (1981) Transneuronal passage of intraaxonally injected horseradish peroxidase (HRP) from group Ib and II fibers into the secondary neurons in the dorsal horn of the cat spinal cord. Biomed Res 2: 722–727Google Scholar
  15. Hongo T, Ishizuka N, Kudo N, Mannen H, Sasaki S, Yamashita M (1983) Intraspinal morphology of group II muscle spindle afferents. Abstract. Symp.: Reflex organization of the spinal cord and its descending control. Canberra, AustraliaGoogle Scholar
  16. Houk JC, Rymer WZ (1981) Neural control of muscle length and tension. In: Brooks VB (ed) Handbook of physiology, Sect I. The nervous system, Vol II. Motor control. Am Physiol Soc, Bethesda, MD, pp 257–323Google Scholar
  17. Hulliger M (1984) The mammalian muscle spindle and its central control. Rev Physiol Biochem Pharmacol 101: 1–110Google Scholar
  18. Hunt CC (1953) Diameter and function of afferent fibres from muscles. Abstract. XIX Int Physiol Congress, MontrealGoogle Scholar
  19. Hunt CC (1954) Relation of function to diameter in afferent fibres of muscle nerves. J Gen Physiol 38: 117–131Google Scholar
  20. Kirkwood PA, Sears TA (1975) Monosynaptic excitation of motoneurones from muscle spindle secondary endings of intercostal and triceps surae muscles in the cat. J Physiol (Lond) 245: 64P-66PGoogle Scholar
  21. Laporte Y, Bessou P (1959) Modification d'excitabilité de motoneurones homonymes provoqées par l'activation physiologique de fibres afférentes d'origine musculaire du groupe II. J Physiol (Paris) 51: 897–908Google Scholar
  22. Lloyd DPC (1943) Neuron patterns controlling transmission of ipsilateral hind limb reflexes in cat. J Neurophysiol 6: 293–315Google Scholar
  23. Lloyd DPC (1946) Integrative pattern of excitation and inhibition in two-neuron reflex arcs. J Neurophysiol 9: 439–444Google Scholar
  24. Lundberg A (1959) Integrative significance of patterns of connections made by muscle afferents in the spinal cord. Symp XXI Int Physiol Congr, Buenos Aires, pp 1–5Google Scholar
  25. Lundberg A, Voorhoeve P (1962) Effects from the pyramidal tract on spinal reflex arcs. Acta Physiol Scand 56: 201–219Google Scholar
  26. Lundberg A, Malmgren K, Schomburg ED (1975a) Characteristics of the excitatory pathway from group II muscle afferents to alpha motoneurones. Brain Res 88: 538–542Google Scholar
  27. Lundberg A, Malmgren K, Schomburg ED (1975b) Group II excitation in motoneurones and double sensory innervation of extensor digitorum brevis. Acta Physiol Scand 94: 398–400Google Scholar
  28. Lundberg A, Malmgren K, Schomburg ED (1977) Comments on reflex actions evoked by electrical stimulation of group II muscle afferents. Brain Res 122: 551–555Google Scholar
  29. Lundberg A, Malmgren K, Schomburg ED (1987a) Reflex path-ways from group II muscle afferents. 2. Functional characteristics of reflex pathways to α-motoneurones. Exp Brain Res 65: 282–293Google Scholar
  30. Lundberg A, Malmgren K, Schomburg ED (1987b) Reflex path-ways from group II muscle afferents. 3. Secondary spindle afferents and the FRA; a new hypothesis. Exp Brain Res 65: 294–306Google Scholar
  31. Lüscher H-R, Ruenzel P, Fetz E, Henneman E (1979) Postsynaptic population potentials recorded from ventral roots perfused with isotonic sucrose: connections of groups Ia and II spindle afferent fibers with large populations of motoneurons. J Neurophysiol 42: 1146–1164Google Scholar
  32. Matthews PBC (1972) Mammalian muscle receptors and their central actions. Edward Arnold Publishers Ltd, LondonGoogle Scholar
  33. Munson JB, Sypert GW, Zengel JE, Lofton SA, Fleshman JW (1982) Monosynaptic projections of individual spindle group II afferents to type-identified medial gastrocnemius motoneurons in the cat. J Neurophysiol 48: 1164–1174Google Scholar
  34. Oscarsson O (1973) Functional organization of spinocerebellar paths. In: Iggo A (ed) Handbook of sensory physiology, Vol II. Somatosensory systems. Springer, Berlin Heidelberg New York, pp 339–380Google Scholar
  35. Rymer WZ, Houk JC, Crago PE (1979) Mechanisms of the claspknife reflex studied in an animal model. Exp Brain Res 37: 93–113Google Scholar
  36. Stauffer EK, Watt DGD, Taylor A, Reinking RM, Stuart DG (1976) Analysis of muscle receptor connections by spiketriggered averaging. 2. Spindle group II afferents. J Neurophysiol 39: 1393–1402Google Scholar
  37. Wilson VJ, Kato M (1965) Excitation of extensor motoneurons by group II afferent fibers in ipsilateral muscle nerves. J Neurophysiol 28: 545–554Google Scholar

Copyright information

© Springer-Verlag 1987

Authors and Affiliations

  • A. Lundberg
    • 1
  • K. Malmgren
    • 1
  • E. D. Schomburg
    • 1
  1. 1.Department of PhysiologyUniversity of GöteborgGöteborgSweden

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