Final answer:
The groove for the tendon of the fibularis longus muscle is found on the base of the first metatarsal. This location is integral for the tendon's role in stabilizing the foot and assisting in plantar flexion.
Step-by-step explanation:
The groove for the tendon of the fibularis longus muscle is located on the base of the first metatarsal. This specific region allows for the passage and functioning of the tendon that contributes to foot flexion, particularly in the movements associated with the region near the big toe. The fibularis longus is important in the stabilization of the foot and its arch, and also in plantar flexion. To clarify, the metatarsal bones make up the anterior half of the foot and articulate with the bones of the toes, providing platforms for muscle attachment and leveraging movements. The detailed description of the base of the fifth metatarsal, its enlarged lateral expansion, and the articulating cuboid indicates where many tendons of the foot attach but does not describe the groove for the fibularis longus, which ultimately wraps around the base of the first metatarsal.