Final answer:
The correct arrangement for a muscle whose fascicles are at an angle to a central longitudinal tendon is pennate. This design allows for a higher density of muscle fibers, producing more tension compared to parallel muscles, where fascicles run along the muscle's long axis.
Step-by-step explanation:
A muscle with fascicles arranged at an angle to a central longitudinal tendon is known as a pennate muscle. This type of muscle design allows the fibers to contract at an angle, enabling the muscle to hold more fibers and produce more tension. There are different subtypes of pennate muscles — unipennate, bipennate, and multipennate — defined by the arrangement of muscle fibers relative to the tendon. An example of a bipennate muscle is the rectus femoris, part of the quadriceps group, which is crucial for knee extension and hip flexion.
In contrast, parallel muscles have fascicles that run along the long axis of the muscle. These muscles, such as the biceps brachii, contract to produce a bulge at the belly. Parallel muscles can be flat or spindle-shaped, with muscle fibers arranged in the same direction as the long muscle axis.