Skip to main content
PMC home page
The Journal of Physiology logoLink to The Journal of Physiology
. 1966 Dec;187(3):501–516. doi: 10.1113/jphysiol.1966.sp008106

Dynamic and static contributions to the rhythmic γ activation of primary and secondary spindle endings in external intercostal muscle

C von Euler, G Peretti
PMCID: PMC1395952  PMID: 16783909

Abstract

1. In cats anaesthetized with sodium pentobarbital 160 external intercostal muscle spindle afferents were identified by their pause in response to ventral root stimulation; the internal intercostal muscle was denervated.

2. In order to assignate the afferents to either primary or secondary endings they were tested for their responsiveness to vibration (Bianconi & Van Der Meulen, 1963). The maximal frequency which they were able to follow regularly for at least four cycles, termed `critical frequency', was determined.

3. The endings fell into two groups: low-f (frequency) sensitive endings with critical frequencies below 400 c/s and high-f sensitive endings with critical frequencies above 400 c/s. The latter were regarded as primary endings and the former as secondary ones.

4. The manner in which the spindle endings resumed activity after a pause produced by shocks to the ventral root, i.e. whether `phasic' or `tonic' (Granit & Van Der Meulen, 1962) was studied in all the spindle afferents.

5. All the secondary (low-f sensitive) endings were `tonic' except three for which the determination of critical frequency was questionable. Both `tonic' and `phasic' properties were found among the primary (high-f sensitive) endings.

6. The majority of the secondary endings (74%) showed inspiratory rhythmic fusimotor activation in parallel with the skeletomotor contraction as did the primary endings (79%).

7. Fifty-seven spindle endings which all showed marked rhythmic inspiratory γ activation were tested for respiratory variations in their dynamic responses to steady stretch and length changes introduced at low repetition rates.

8. The results indicate that both `dynamic' and `static' γ fibres are represented among the rhythmic γ fibres controlling primary muscle spindle endings, whereas rhythmic activation of secondary endings seems to be mediated only by `static' fibres.

Full text

PDF
505

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. ALNAES E., JANSEN J. K., RUDJORD T. FUSIMOTOR ACTIVITY IN THE SPINAL CAT. Acta Physiol Scand. 1965 Mar;63:197–212. doi: 10.1111/j.1748-1716.1965.tb04060.x. [DOI] [PubMed] [Google Scholar]
  2. BIANCONI R., van der MEULEN J. The response to vibration of the end organs of mammalian muscle spindles. J Neurophysiol. 1963 Jan;26:177–190. doi: 10.1152/jn.1963.26.1.177. [DOI] [PubMed] [Google Scholar]
  3. BOYD I. A. The innervation of mammalian neuromuscular spindles. J Physiol. 1958 Jan 23;140(1):14–5P. [PubMed] [Google Scholar]
  4. CORDA M., EKLUND G., VON EULER EXTERNAL INTERCOSTAL AND PHRENIC ALPHA-MOTOR RESPONSES TO CHANGES IN RESPIRATORY LOAD. Acta Physiol Scand. 1965 Mar;63:391–400. doi: 10.1111/j.1748-1716.1965.tb04079.x. [DOI] [PubMed] [Google Scholar]
  5. CORDA M., VONEULER C., LENNERSTRAND G. PROPRIOCEPTIVE INNERVATION OF THE DIAPHRAGM. J Physiol. 1965 May;178:161–177. doi: 10.1113/jphysiol.1965.sp007621. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. CRITCHLOW V., VON EULER INTERCOSTAL MUSCLE SPINDLE ACTIVITY AND ITS GAMMA MOTOR CONTROL. J Physiol. 1963 Oct;168:820–847. doi: 10.1113/jphysiol.1963.sp007225. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. CROWE A., MATTHEWS P. B. FURTHER STUDIES OF STATIC AND DYNAMIC FUSIMOTOR FIBRES. J Physiol. 1964 Oct;174:132–151. doi: 10.1113/jphysiol.1964.sp007477. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. CROWE A., MATTHEWS P. B. THE EFFECTS OF STIMULATION OF STATIC AND DYNAMIC FUSIMOTOR FIBRES ON THE RESPONSE TO STRETCHING OF THE PRIMARY ENDINGS OF MUSCLE SPINDLES. J Physiol. 1964 Oct;174:109–131. doi: 10.1113/jphysiol.1964.sp007476. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Corda M., von Euler C., Lennerstrand G. Reflex and cerebellar influences on alpha and on 'rhythmic' and 'tonic' gamma activity in the intercostal muscle. J Physiol. 1966 Jun;184(4):898–923. doi: 10.1113/jphysiol.1966.sp007956. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. EKLUND G., VON EULER, RUTKOWSKI S. SPONTANEOUS AND REFLEX ACTIVITY OF INTERCOSTAL GAMMA MOTONEURONES. J Physiol. 1964 May;171:139–163. doi: 10.1113/jphysiol.1964.sp007368. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. GRANIT R., HENATSCH H. D. Gamma control of dynamic properties of muscle spindles. J Neurophysiol. 1956 Jul;19(4):356–366. doi: 10.1152/jn.1956.19.4.356. [DOI] [PubMed] [Google Scholar]
  12. GRANIT R., VAN DERMEULEN J. P. The pause during contraction in the discharge of the spindle afferents from primary end organs in cat extensor muscles. Acta Physiol Scand. 1962 Jun-Jul;55:231–244. doi: 10.1111/j.1748-1716.1962.tb02436.x. [DOI] [PubMed] [Google Scholar]
  13. JANSEN J. K., MATTHEWS P. B. The central control of the dynamic response of muscle spindle receptors. J Physiol. 1962 May;161:357–378. doi: 10.1113/jphysiol.1962.sp006892. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. MATTHEWS P. B. The differentiation of two types of fusimotor fibre by their effects on the dynamic response of muscle spindle primary endings. Q J Exp Physiol Cogn Med Sci. 1962 Oct;47:324–333. doi: 10.1113/expphysiol.1962.sp001616. [DOI] [PubMed] [Google Scholar]
  15. MERTON P. A. Slowly conducting muscle spindle afferents. Acta Physiol Scand. 1953 Jun 26;29(1):87–88. doi: 10.1111/j.1748-1716.1953.tb01003.x. [DOI] [PubMed] [Google Scholar]
  16. SUMI T. The segmental reflex relations of cutaneous afferent inflow to thoracic respiratory motoneurons. J Neurophysiol. 1963 May;26:478–493. doi: 10.1152/jn.1963.26.3.478. [DOI] [PubMed] [Google Scholar]

Articles from The Journal of Physiology are provided here courtesy of The Physiological Society

RESOURCES