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Compartmentalization of single muscle units in cat lateral gastrocnemius

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The distribution of muscle fibers in single muscle units in cat lateral gastrocnemius (LG) muscle was analyzed using the method of glycogen depletion. Single, type FF motor units in LG were identified by stimulation of dissected ventral rootlets and then activated to produce depletion of glycogen in their innervated muscle fibers. Serial histological sections were made of the entire triceps surae muscles and then reacted for the demonstration of glycogen. Projected tracings of the sections were used to compare the distribution of glycogen depleted muscle fibers to the heads of the LG muscle. Results of analysis of single muscle units indicate that the muscle fibers innervated by single cat LG type FF motor units are distributed to the same regions of muscle which are innervated by primary branches of the nerve to the LG muscle. The single units are thus compartmentalized. These results support the hypothesis that each of the neuromuscular compartments of LG contains a unique population of motor units. It is suggested that compartmentalization of muscles about primary branches of their muscle nerves may from a major organizational principle in the design of skeletal muscles.

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  1. Botterman BR, Hamm TM, Reinking RM, Stuart DG (1983) Distribution of monosynaptic Ia EPSP's in the motor nucleus of the cat semitendinosus muscle. J Physiol (Lond) 338: 379–393

  2. Burke RE, Edgerton VR (1975) Motor unit properties and selective involvement in movement. Exercise Sport Sci Rev 3: 31–81

  3. Burke RE, Tsairis P (1973) Anatomy and innervation ratios in motor units of cat gastrocnemius. J Physiol (Lond) 234: 749–765

  4. Burke RE, Levine DN, Tsairis P, Zajac FE (1973) Physiological types and histochemical profiles in motor units of the cat gastrocnemius. J Physiol (Lond) 234: 723–748

  5. Dum RP, Burke RE, O'Donovan MJ, Troop J, Hodgson JA (1982) Motor unit organization in flexor digitorum longus muscle of the cat. J Neurophysiol 47: 1108–1125

  6. Eccles JC, Sherrington CS (1930) Numbers and contraction values of individual motor units examined in some muscles of the limb. Proc R Soc London Ser Bio 6: 326–357

  7. Edstrom L, Kugelberg E (1968) Histochemical composition, distribution of fibres and fatiguability of single motor units. J Neurol Neurosurg Psychiat 31: 424–433

  8. English AW (1984) An electromyographic analysis of compartments of cat lateral gastrocnemius muscle during unrestrained locomotion. J Neurophysiol (in press)

  9. English AW, Letbetter WD (1982a) Anatomy and innervation patterns of cat lateral gastrocnemius and plantaris muscles. Am J Anat 164: 67–77

  10. English AW, Letbetter WD (1982b) A histochemical analysis of identified compartments in cat lateral gastrocnemius muscle. Anat Rec 204: 123–130

  11. English AW, Weeks OI (1982) Compartmentalization of muscle units in cat lateral gastrocnemius muscle. Abstr Soc Neurosci 8: 959

  12. English AW, Wolf SL (1982) The motor unit: Anatomy and physiology. Phys Ther 62: 1763–1772

  13. Fleshman JW, Munson JB, Sypert GW, Friedman WA (1981) Rheobase, input resistance and motor unit type in medial gastrocnemius motoneurons in the cat. J Neurophysiol 46: 1326–1339

  14. Letbetter WD (1974) Influence of intramuscular nerve branching on motor unit organization in medial gastrocnemius muscle. Anat Rec 178: 402

  15. Lucas SM, Binder MD (1984) Topographic factors in the distribution of homonymous group Ia afferent input to cat medial gastrocnemius motoneurons. J Neurophysiol 51: 50–63

  16. Lucas SM, Cope TC, Binder MD (1984) Analysis of individual Ia EPSPs in an homonymous motoneuron pool with respect to muscle topography. J Neurophysiol 51: 64–74

  17. McDonagh JC, Binder MD, Reinking RM, Stuart DG (1980) Tetrapartite classification of motor units of cat tibialis posterior. J Neurophysiol 44: 696–712

  18. Reinking RM, Stephens JA, Stuart DG (1975) The motor units of cat medial gastrocnemius: Problem of their categorization on the basis of mechanical properties. Exp Brain Res 23: 301–313

  19. Russell CJ, Dunbar DB, Rushmer DS, MacPherson JM, Phillips JO (1982) Differential activity of innervation subcompartments of cat lateral gastrocnemius during natural movements. Abstr Ann Meet Soc Neurosci 8: 948

  20. Vanden-Noven S, Hamm TM, Stuart DG (1983) Testing for reflex partitioning in the motor nucleus of the cat lateral gastrocnemius muscle. Abstr Soc Neurosci 9: 528

  21. Weeks OI, English AW (1983) Distribution of cell sizes in the cat lateral gastrocnemius motor nucleus. Anat Rec 205: 212A-213A

  22. Weeks OI, English AW (1982) Central organization of cat lateral gastrocnemius motor units. Abstr Soc Neurosci 8: 959

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Correspondence to A. W. English.

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English, A.W., Weeks, O.I. Compartmentalization of single muscle units in cat lateral gastrocnemius. Exp Brain Res 56, 361–368 (1984). https://doi.org/10.1007/BF00236292

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Key words

  • Neuromuscular compartments
  • Glycogen depletion
  • Motor units
  • Triceps surae