Which nerve is exclusively responsible for innervating the foot as a branch of the femoral nerve?

The saphenous nerve is a branch of the femoral nerve that provides sensory innervation to the medial aspect of the foot and leg. It is important to note that while the saphenous nerve does not innervate muscles, it plays a crucial role in sensation. This makes it unique among the options provided, as its primary function is associated with sensory pathways in the foot region.

In contrast, the other nerves listed have different origins and functions. The deep peroneal nerve, for example, arises from the common peroneal nerve (a branch of the sciatic nerve) and innervates muscles in the anterior compartment of the leg and provides sensation to part of the foot, but it is not directly a branch of the femoral nerve. The sural nerve, primarily a sensory nerve as well, also does not come from the femoral nerve and serves the posterior and lateral aspect of the leg and foot. The posterior tibial nerve, similar to the deep peroneal, originates from the sciatic nerve and innervates muscles in the posterior compartment of the leg and has sensory responsibilities in the plantar aspect of the foot.

Thus, the saphenous nerve stands out as the only nerve in the options