The brachialis works primarily with the biceps brachii and the brachioradialis to flex the elbow; it is unique in that it is a pure elbow flexor and maintains its leverage regardless of forearm position.
The sartorius plays an important role in stabilizing both the hip and knee. It works both synergistically and antagonistically with the tensor fasciae latae, gracilis, and semitendinosus to achieve these important functions.
