How do skeletal muscles facilitate locomotion?

Skeletal muscles facilitate locomotion primarily through the process of contracting or shortening. When a skeletal muscle contracts, it generates force that pulls on the associated bones, leading to the movement of joints and limbs. This action allows horses, and other animals with skeletal muscles, to perform a range of movements required for locomotion, such as walking, trotting, galloping, or jumping.

Muscle contraction is a fundamental biological process, involving the sliding filament theory, where actin and myosin filaments within the muscle fibers slide past each other to shorten the muscle. This shortening creates movement by pulling on tendons connected to bones, thus enabling coordinated motion essential for mobility.

While expanding and contracting independently could imply movement, it does not accurately describe how skeletal muscles work in concert with one another to produce coherent motion. The idea of only flexing joints does not encompass the full range of movements facilitated by skeletal muscles, which include extension, rotation, and more complex motions that contribute to overall locomotion. Working against gravity is relevant in certain contexts, but locomotion itself is primarily dependent on the interaction between muscle contractions and the skeletal structure they operate on, making contraction the key concept in facilitating movement.