To lift a cup, a muscle called the biceps brachii is actually the prime mover; however, because it can be assisted by the brachialis, the brachialis is called a synergist in this action ( Figure 11.2 ). The moveable end of the muscle that attaches to the bone being pulled is called the muscle’s insertion , and the end of the muscle attached to a fixed (stabilized) bone is called the origin .

To move the skeleton, the tension created by the contraction of the fibers in most skeletal muscles is transferred to the tendons. The tendons are strong bands of dense, regular connective tissue that connect muscles to bones.

muscle called the biceps brachii — actually the prime mover; however, because it can be assisted by the brachialis, the brachialis is called a synergist in this action ( Figure 11.2 ). insertion — end of a skeletal muscle that is attached to the structure (usually a bone) that is moved when the muscle contracts. origin — end of a skeletal muscle that is attached to another structure (usually a bone) in a fixed position. agonist — (also, prime mover) muscle whose contraction is responsible for producing a particular motion.

Be able to compare and contrast agonist and antagonist muscles; describe how fascicles are arranged within a skeletal muscle; explain the major events of a skeletal muscle contraction within a muscle in generating force.