Final answer:
The result of the cross bridge of myosin forming linkages with actin filaments is a power stroke that moves the actin filament, causing muscle contraction and sarcomere shortening.
Step-by-step explanation:
When the cross bridge of the myosin molecule forms linkages with actin filaments, the result is a power stroke. This process begins when the myosin head, which has ATP or its hydrolysis products ADP and Pi bound to it, attaches to the actin filament.
Release of Pi increases the strength of the attachment, which leads to a conformational change in the myosin head, causing it to pull the actin filament towards the M-line. This movement of the actin filament results in the muscle sarcomere shortening, thus producing a muscle contraction. The power stroke is the phase where the myosin head pulls on the actin filament, and it's the critical action that leads to the sliding of the actin over the myosin, resulting in muscle contraction.
ATP then binds to the myosin head, causing it to detach from the actin, allowing the cross-bridge cycling process to begin again with the next round of muscle contraction. It is essential to note that in the absence of ATP, the myosin head will not detach from the actin, leading to a condition known as rigor mortis.