<P> The filaments in a sarcomere are composed of actin and myosin . </P> <P> The gross anatomy of a muscle is the most important indicator of its role in the body . There is an important distinction seen between pennate muscles and other muscles . In most muscles, all the fibers are oriented in the same direction, running in a line from the origin to the insertion . However, In pennate muscles, the individual fibers are oriented at an angle relative to the line of action, attaching to the origin and insertion tendons at each end . Because the contracting fibers are pulling at an angle to the overall action of the muscle, the change in length is smaller, but this same orientation allows for more fibers (thus more force) in a muscle of a given size . Pennate muscles are usually found where their length change is less important than maximum force, such as the rectus femoris . </P> <P> Skeletal muscle is arranged in discrete muscles, an example of which is the biceps brachii (biceps). The tough, fibrous epimysium of skeletal muscle is both connected to and continuous with the tendons . In turn, the tendons connect to the periosteum layer surrounding the bones, permitting the transfer of force from the muscles to the skeleton . Together, these fibrous layers, along with tendons and ligaments, constitute the deep fascia of the body . </P> <P> The muscular system consists of all the muscles present in a single body . There are approximately 650 skeletal muscles in the human body, but an exact number is difficult to define . The difficulty lies partly in the fact that different sources group the muscles differently and partly in that some muscles, such as palmaris longus, are not always present . </P>

Which type of muscle tissue makes up the biceps