When a myosin head attaches to an actin filament, the resulting connection is known as a?

When a myosin head attaches to an actin filament, the resulting connection is known as a cross-bridge. This term describes the interaction that occurs during muscle contraction, where the myosin heads pull on the actin filaments, leading to muscle shortening and force generation.

The process is fundamental to the sliding filament theory of muscle contraction, where the movement of myosin heads on actin filaments causes the sarcomeres, the basic units of muscle fibers, to shorten. Understanding this concept is critical because it not only explains how muscles contract but also how various factors such as calcium ions and ATP influence muscle function.

The other terms such as synapse, junction, and collagen fiber do not pertain to the specific interaction between myosin heads and actin filaments during muscle contraction, thus clarifying that cross-bridge formation is the accurate and relevant term in this context.