<Dl> <Dt> Multipennate architectures </Dt> </Dl> <P> The fibers in multipennate muscles are arranged at multiple angles in relation to the axis of force generation, and are the most general and most common architecture . Several fiber orientations fall into this category; bipennate, convergent, and multipennate . While the determination of PCSA becomes more difficult in these muscle architectures, the same tradeoffs as listed above apply . </P> <P> Bipennate arrangements are essentially "V" s of fibers stacked on top of each other, such as in the rectus femoris . </P> <P> Convergent arrangements are triangle or fan shaped, with wide origins and more narrow insertions . The wide variation of pennation angles in this architecture can actually allow for multiple functions . For instance, the trapezius, a prototypical convergent muscle, can aid in both shoulder elevation and depression . </P>

Identify the structures that make up a skeletal muscle