crossbridge
noun
cross·bridge
| \ ˈkrȯs-ˌbrij
\
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Medical Definition of crossbridge
: the globular head of a myosin molecule that projects from a myosin filament in muscle and in the sliding filament hypothesis of muscle contraction is held to attach temporarily to an adjacent actin filament and draw it into the A band of a sarcomere between the myosin filaments