any of several tubular bones between the ankle (tarsal) bones and each of the hindlimb digits, in land vertebrates corresponding to the metacarpal bones of the hand (forepaw). In humans the five metatarsal bones help form longitudinal arches along the inner and outer sides of the foot and a transverse arch at the ball of the foot. The first metatarsal (which adjoins the phalanges of the big toe) is enlarged and strengthened for its weight-bearing function in standing and walking on two feet.