Which nerve is NOT a branch of the femoral nerve?

The deep peroneal nerve is correctly identified as not being a branch of the femoral nerve. The femoral nerve primarily innervates the anterior compartment of the thigh and has several branches, including the saphenous nerve, which provides sensation to the medial side of the leg and foot.

In contrast, the deep peroneal nerve arises from the common peroneal nerve, which branches off the sciatic nerve. It is responsible for innervating muscles in the anterior compartment of the leg and providing sensory innervation to a small part of the foot. Therefore, it does not originate from the femoral nerve, making this option valid in the context of the question. Other options like the saphenous nerve are indeed branches of the femoral nerve, while the posterior tibial and sural nerves originate from the sciatic nerve and its branches. This distinction highlights the anatomical relationships of the nerves involved.