Which intrinsic muscle of the foot originates on the calcaneus and acts in flexion at the joints of toes 2-5?

The intrinsic muscle of the foot that originates on the calcaneus and acts in flexion at the joints of toes 2-5 is the flexor digitorum brevis. This muscle is located in the first layer of the foot's plantar muscles. It plays a key role in facilitating flexion of the middle phalanges of the second through fifth toes. Its action contributes to balance and stability during walking and standing.