… X-ray diffraction patterns from relaxed invertebrate muscles reveal the thick filament
symmetries and crossbridge configurations. The cross bridges are substantially angled to
the filament axes. The results on symmetry are generally consistent with Squire's model. …
If the bridges are attached to actin in a right-angled configuration before the power stroke of
the contractile cycle, then some angular movement of the bridges must occur on activation
or initial attachment in these muscles. Our results on cross-bridge configuration depend on …