How are muscles primarily attached to bones?

Muscles are primarily attached to bones by connective tissues known as tendons. Tendons are strong, flexible bands made predominantly of collagen that connect muscles to the bone, allowing for the transmission of force from muscle contractions, which enables movement. When a muscle contracts, the force it generates is applied through the tendon to the bone, resulting in joint movement.

Ligaments, mentioned in the first option, primarily connect bones to other bones at a joint and provide stability but do not serve to attach muscles to bones. Elastic tissues, while they do exist within certain parts of the body, do not serve the primary purpose of attaching muscles to bones. Muscle fibers themselves are the contractile elements of the muscle and do not directly attach muscles to the skeletal structure; rather, they act within the muscle to facilitate contraction and movement. Thus, the role of tendons as connectors is essential in the anatomy of the musculoskeletal system, making them the correct answer.