Which structure is NOT part of the arcuate complex?

The correct answer highlights that the common peroneal nerve is not a part of the arcuate complex. The arcuate complex mainly comprises structures associated with the lateral aspect of the knee, particularly focusing on the support and stabilization of the knee joint.

The arcuate ligament, biceps femoris, and lateral head of gastrocnemius all contribute to the complexity and structural integrity of the knee. The arcuate ligament plays a role as a stabilizing structure, particularly in the posterolateral corner of the knee. The biceps femoris, which is one of the muscles of the hamstring group, also plays a significant role in lateral stability. Furthermore, the lateral head of gastrocnemius is one of the calf muscles that aids in knee flexion and provides additional support.

In contrast, the common peroneal nerve primarily runs along the lateral side of the leg and is responsible for innervating muscles in that region, but it is not anatomically or functionally part of the arcuate complex. It is important to distinguish between muscular/ligamentous structures that provide stability to the knee and neural structures that are responsible for muscle innervation, which is why the common peroneal nerve is the correct answer in this context.