Figure 1.

Schematic showing effects of stretch‐shortening on MuSC orientation and deformation. The myofiber is ensheathed by the sarcolemma (yellow) and the basal lamina (BL) surrounded by a collagen fiber reinforced matrix (gray sheath with black crossing lines). Top figure is a segment of an unstrained myofiber. Below the myofiber is an enlarged lateral view of the MuSC in its niche, illustrating the well‐known transmembrane proteins, anchoring the MuSC to sarcolemma and BL. While the myofiber is unstrained, MuSCs in their niches are also in an unloaded state. Upon myofiber shortening, the sarcolemma will move relative to the BL. Since, the MuSC is anchored to both sheaths, it is likely to twist from a longitudinal orientation towards a more radial orientation (direction of arrow). As the myofiber is shortening, the sarcolemma and BL are likely moving at varying speeds, the relative movement of the sheaths will impose a shear force onto the MuSC, with subsequent cellular deformation. Myofiber lengthening will stretch both the sarcolemma and the BL (direction of arrow), which may induce a tensile stress on the MuSC.