What is the name of the thicker of the two protein filaments involved in muscular contraction?

The thicker of the two protein filaments involved in muscular contraction is known as myosin. Myosin interacts with actin, the thinner filament, to facilitate muscle contractions through a process known as the sliding filament mechanism. During contraction, myosin heads attach to binding sites on the actin filaments, pulling them closer together and thus shortening the muscle fiber. This interaction is crucial for muscle function in various types of movements, making myosin essential for the overall process of muscle contraction. Other options listed, such as actin, collagen, and keratin, either play different roles in muscle function and support or serve structural purposes in various tissues throughout the body.