MOVEMENT-RELATED SKIN STRAIN ASSOCIATED WITH GOAL-ORIENTED LIP ACTIONS

It is generally accepted that sensory input contributes to the generat ion of natural movements. In most motor systems, muscle spindles, tend on organs, joint receptors, and cutaneous mechanoreceptors may provide proprioceptive information. However, the perioral area of the human f ace lacks muscle spindles, tendon organs, and joint receptors and is t herefore a model system for the study of cutaneous afferent contributi ons to proprioception. This investigation examined a series of skin st rains associated with lower-lip movements in human subjects to determi ne if such strains, which serve as stimuli for cutaneous mechanorecept ors, may underlie proprioception in the face. The results suggested th at strains associated with lower-lip movements were of sufficient magn itude to elicit cutaneous mechanoreceptor discharge, as shown in recen t human microneurographic studies. Further, the magnitude of multiple strains was predictive of lower-lip movement endpoints. These results highlight the potential importance of cutaneous mechanoreceptors as pu tative proprioceptors.