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Sympathetic innervation of human muscle spindles
Author(s) -
Radovanovic Dina,
Peikert Kevin,
Lindström Mona,
Domellöf Fatima Pedrosa
Publication year - 2015
Publication title -
journal of anatomy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.932
H-Index - 118
eISSN - 1469-7580
pISSN - 0021-8782
DOI - 10.1111/joa.12309
Subject(s) - muscle spindle , sympathetic innervation , neuropeptide y receptor , proprioception , anatomy , free nerve ending , biology , receptor , medicine , neuropeptide , endocrinology , neuroscience , afferent
The aim of the present study was to investigate the presence of sympathetic innervation in human muscle spindles, using antibodies against neuropeptide Y ( NPY ), NPY receptors and tyrosine hydroxylase ( TH ). A total of 232 muscle spindles were immunohistochemically examined. NPY and NPY receptors were found on the intrafusal fibers, on the blood vessels supplying muscle spindles and on free nerve endings in the periaxial space. TH ‐immunoreactivity was present mainly in the spindle nerve and vessel. This is, to our knowledge, the first morphological study concerning the sympathetic innervation of the human muscle spindles. The results provide anatomical evidence for direct sympathetic innervation of the intrafusal fibers and show that sympathetic innervation is not restricted to the blood vessels supplying spindles. Knowledge about direct sympathetic innervation of the muscle spindle might expand our understanding of motor and proprioceptive dysfunction under stress conditions, for example, chronic muscle pain syndromes.