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. 1994 Sep 15;479(Pt 3):487–497. doi: 10.1113/jphysiol.1994.sp020312

Limited independent flexion of the thumb and fingers in human subjects.

S L Kilbreath 1, S C Gandevia 1
PMCID: PMC1155766  PMID: 7837104

Abstract

1. We investigated whether human subjects can activate selectively flexor pollicis longus (FPL) and digital portions of flexor digitorum profundus (FDP). These muscles were selected because they are the only flexors of the distal phalanges. 2. Electromyographic activity (EMG) was recorded with intramuscular electrodes from one digital component of the deep flexors ('test') while subjects lifted weights by flexing the distal interphalangeal joint of the other digits in turn ('lifting' digits). Only recording sites at which single motor units were recruited selectively at low forces were used. The weights lifted represented 2.5-50% of the maximal voluntary contraction (MVC). We measured the lowest weight lifted which produced phasic and tonic coactivation in the 'test' muscle. 3. The extent of coactivation varied with the 'distance' between the test and lifting digits although no significant difference occurred in the pattern of coactivation thresholds among the digital flexors. The extent of coactivation increased when angular displacement or velocity at the distal interphalangeal joint of the lifting digit increased but was not critically dependent on restraint of the hand. 4. Because mechanical 'connections' could interfere with the ability to move a distal phalanx independently, the arms of nine cadavers were studied. The separation of tendons between the thumb (FPL) and the index portion of FDP, and between the index and middle portions of FDP, usually extended more proximally in the forearm than separation between the tendons to the middle and ring fingers and between the ring and little fingers. Direct intertendinous links were also noted. 5. It is not possible to direct a sufficiently focal motor command to flex selectively the distal joint of the fingers and thumb when forces exceeding 2.5% MVC are generated. For the middle, ring and little fingers in particular, movement of adjacent digits may also involve 'in-series' mechanical links between adjacent components of FDP.

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Selected References

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  1. Aniss A. M., Gandevia S. C., Milne R. J. Changes in perceived heaviness and motor commands produced by cutaneous reflexes in man. J Physiol. 1988 Mar;397:113–126. doi: 10.1113/jphysiol.1988.sp016991. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Brink E., Jankowska E., McCrea D. A., Skoog B. Inhibitory interactions between interneurones in reflex pathways from group Ia and group Ib afferents in the cat. J Physiol. 1983 Oct;343:361–373. doi: 10.1113/jphysiol.1983.sp014897. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Burke D., Hagbarth K. E., Löfstedt L. Muscle spindle activity in man during shortening and lengthening contractions. J Physiol. 1978 Apr;277:131–142. doi: 10.1113/jphysiol.1978.sp012265. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Buys E. J., Lemon R. N., Mantel G. W., Muir R. B. Selective facilitation of different hand muscles by single corticospinal neurones in the conscious monkey. J Physiol. 1986 Dec;381:529–549. doi: 10.1113/jphysiol.1986.sp016342. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Caccia M. R., McComas A. J., Upton A. R., Blogg T. Cutaneous reflexes in small muscles of the hand. J Neurol Neurosurg Psychiatry. 1973 Dec;36(6):960–977. doi: 10.1136/jnnp.36.6.960. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Cheney P. D., Fetz E. E. Comparable patterns of muscle facilitation evoked by individual corticomotoneuronal (CM) cells and by single intracortical microstimuli in primates: evidence for functional groups of CM cells. J Neurophysiol. 1985 Mar;53(3):786–804. doi: 10.1152/jn.1985.53.3.786. [DOI] [PubMed] [Google Scholar]
  7. Cheney P. D., Fetz E. E., Palmer S. S. Patterns of facilitation and suppression of antagonist forelimb muscles from motor cortex sites in the awake monkey. J Neurophysiol. 1985 Mar;53(3):805–820. doi: 10.1152/jn.1985.53.3.805. [DOI] [PubMed] [Google Scholar]
  8. Edin B. B., Westling G., Johansson R. S. Independent control of human finger-tip forces at individual digits during precision lifting. J Physiol. 1992 May;450:547–564. doi: 10.1113/jphysiol.1992.sp019142. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Fetz E. E., Cheney P. D. Postspike facilitation of forelimb muscle activity by primate corticomotoneuronal cells. J Neurophysiol. 1980 Oct;44(4):751–772. doi: 10.1152/jn.1980.44.4.751. [DOI] [PubMed] [Google Scholar]
  10. Fritz N., Illert M., de la Motte S., Reeh P., Saggau P. Pattern of monosynaptic Ia connections in the cat forelimb. J Physiol. 1989 Dec;419:321–351. doi: 10.1113/jphysiol.1989.sp017875. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Gandevia S. C., Macefield G., Burke D., McKenzie D. K. Voluntary activation of human motor axons in the absence of muscle afferent feedback. The control of the deafferented hand. Brain. 1990 Oct;113(Pt 5):1563–1581. doi: 10.1093/brain/113.5.1563. [DOI] [PubMed] [Google Scholar]
  12. Gandevia S. C., McCloskey D. I. Effects of related sensory inputs on motor performances in man studied through changes in perceived heaviness. J Physiol. 1977 Nov;272(3):653–672. doi: 10.1113/jphysiol.1977.sp012065. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Gandevia S. C., McCloskey D. I. Joint sense, muscle sense, and their combination as position sense, measured at the distal interphalangeal joint of the middle finger. J Physiol. 1976 Sep;260(2):387–407. doi: 10.1113/jphysiol.1976.sp011521. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Gandevia S. C., McCloskey D. I., Potter E. K. Alterations in perceived heaviness during digital anaesthesia. J Physiol. 1980 Sep;306:365–375. doi: 10.1113/jphysiol.1980.sp013402. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Gandevia S. C., Rothwell J. C. Knowledge of motor commands and the recruitment of human motoneurons. Brain. 1987 Oct;110(Pt 5):1117–1130. doi: 10.1093/brain/110.5.1117. [DOI] [PubMed] [Google Scholar]
  16. Hongo T., Kudo N., Oguni E., Yoshida K. Spatial patterns of reflex evoked by pressure stimulation of the foot pads in cats. J Physiol. 1990 Jan;420:471–487. doi: 10.1113/jphysiol.1990.sp017923. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. Jenner J. R., Stephens J. A. Cutaneous reflex responses and their central nervous pathways studied in man. J Physiol. 1982 Dec;333:405–419. doi: 10.1113/jphysiol.1982.sp014461. [DOI] [PMC free article] [PubMed] [Google Scholar]
  18. Kilbreath S. L., Gandevia S. C. Neural and biomechanical specializations of human thumb muscles revealed by matching weights and grasping objects. J Physiol. 1993 Dec;472:537–556. doi: 10.1113/jphysiol.1993.sp019961. [DOI] [PMC free article] [PubMed] [Google Scholar]
  19. Lemon R. N., Mantel G. W., Muir R. B. Corticospinal facilitation of hand muscles during voluntary movement in the conscious monkey. J Physiol. 1986 Dec;381:497–527. doi: 10.1113/jphysiol.1986.sp016341. [DOI] [PMC free article] [PubMed] [Google Scholar]
  20. Linburg R. M., Comstock B. E. Anomalous tendon slips from the flexor pollicis longus to the flexor digitorum profundus. J Hand Surg Am. 1979 Jan;4(1):79–83. doi: 10.1016/s0363-5023(79)80110-0. [DOI] [PubMed] [Google Scholar]
  21. Loo C. K., McCloskey D. I. Effects of prior instruction and anaesthesia on long-latency responses to stretch in the long flexor of the human thumb. J Physiol. 1985 Aug;365:285–296. doi: 10.1113/jphysiol.1985.sp015772. [DOI] [PMC free article] [PubMed] [Google Scholar]
  22. Marsden C. D., Merton P. A., Morton H. B. The sensory mechanism of servo action in human muscle. J Physiol. 1977 Feb;265(2):521–535. doi: 10.1113/jphysiol.1977.sp011728. [DOI] [PMC free article] [PubMed] [Google Scholar]
  23. Marzke M. W. Evolutionary development of the human thumb. Hand Clin. 1992 Feb;8(1):1–8. [PubMed] [Google Scholar]
  24. Matthews P. B., Miles T. S. On the long-latency reflex responses of the human flexor digitorum profundus. J Physiol. 1988 Oct;404:515–534. doi: 10.1113/jphysiol.1988.sp017303. [DOI] [PMC free article] [PubMed] [Google Scholar]
  25. Schieber M. H. Individuated finger movements of rhesus monkeys: a means of quantifying the independence of the digits. J Neurophysiol. 1991 Jun;65(6):1381–1391. doi: 10.1152/jn.1991.65.6.1381. [DOI] [PubMed] [Google Scholar]
  26. Serlin D. M., Schieber M. H. Morphologic regions of the multitendoned extrinsic finger muscles in the monkey forearm. Acta Anat (Basel) 1993;146(4):255–266. doi: 10.1159/000147465. [DOI] [PubMed] [Google Scholar]
  27. Shinoda Y., Yokota J., Futami T. Divergent projection of individual corticospinal axons to motoneurons of multiple muscles in the monkey. Neurosci Lett. 1981 Apr 9;23(1):7–12. doi: 10.1016/0304-3940(81)90182-8. [DOI] [PubMed] [Google Scholar]
  28. al-Falahe N. A., Nagaoka M., Vallbo A. B. Response profiles of human muscle afferents during active finger movements. Brain. 1990 Apr;113(Pt 2):325–346. doi: 10.1093/brain/113.2.325. [DOI] [PubMed] [Google Scholar]

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