Final answer:
The two sesamoid bones on the first metatarsal are separated by the intersesamoid ridge, a feature that helps to protect tendons from compressive forces.
Step-by-step explanation:
The two sesamoid bones on the first metatarsal (1st met) of the foot are separated by the intersesamoid ridge or groove, which is a feature on the plantar surface of the first metatarsal bone. The sesamoid bones in question are located on either side of this groove, embedded within the tendons of the flexor hallucis brevis muscle. These bones serve to protect the tendons by helping to dissipate the compressive forces that occur during walking and other weight-bearing activities.