Firing properties of muscle spindles supplying the intrinsic foot muscles of humans in unloaded and freestanding conditions
| Autor: | Alexander R. Burton, Elie Hammam, Thomas P. Knellwolf, Vaughan G. Macefield |
|---|---|
| Rok vydání: | 2019 |
| Předmět: |
Adult
Male Posterior tibial nerve Adolescent Physiology Rest Posture 050105 experimental psychology Postural control Weight-Bearing Young Adult 03 medical and health sciences 0302 clinical medicine Foot muscles Humans Medicine 0501 psychology and cognitive sciences Muscle Spindles Foot business.industry General Neuroscience 05 social sciences Microneurography Anatomy body regions Female business 030217 neurology & neurosurgery Foot (unit) |
| Zdroj: | Journal of Neurophysiology. 121:74-84 |
| ISSN: | 1522-1598 0022-3077 |
| DOI: | 10.1152/jn.00539.2018 |
| Popis: | We recently developed an approach for recording from muscle spindles in the intrinsic muscles of the foot in freestanding humans by inserting a tungsten microelectrode into the posterior tibial nerve behind the medial malleolus of the ankle. Here we characterize the behavior of muscle spindles in the small muscles of the foot in 1) seated subjects with the leg horizontal and the foot naturally plantarflexed and 2) standing subjects. In the first study, recordings were made from 26 muscle spindle afferents located within flexor digiti minimi brevis ( n = 4), abductor digiti minimi ( n = 3), quadratus plantae ( n = 3), plantar interossei ( n = 4), flexor digitorum brevis ( n = 3), dorsal interossei ( n = 2), and lumbricals ( n = 2), with one each supplying abductor hallucis, adductor hallucis, and flexor hallucis brevis. The identity of another two muscle afferents was unknown. The majority of the units were silent at rest, only seven (27%) being spontaneously active. Because of the anatomic constraints of the foot, some spindles supplying muscles acting on the toes responded to movements of one or more digits. In the second study, 12 muscle spindle afferents were examined during standing. The ongoing discharge of eight spindle afferents covaried with changes in the center of pressure during postural sway. We conclude that the majority of spindle endings in the small muscles of the foot are silent at rest, which may allow them to encode changes in conformation of the foot when it is loaded during standing. Moreover, these muscle spindle afferents can provide useful proprioceptive information during standing and postural sway. NEW & NOTEWORTHY We have characterized the firing properties of muscle spindles in the intrinsic muscles of the human foot for the first time. The majority of the spindle endings are silent in seated subjects, and most fire tonically during standing, their discharge covarying with center of pressure during postural sway. We conclude that spindle endings in the intrinsic muscles of the foot provide useful proprioceptive information during free standing. |
| Databáze: | OpenAIRE |
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