During late embryogenesis, the legs and feet undergo a torsional development along their longitudinal axis. 
Stage 15, lower limb bud emerges (To view the true size of a Stage 14 Embryo, click here)
Stage 16, the plantar surfaces of the feet and posterior compartments of the legs face cephadly. 
Stage 17, the plantar surfaces of the feet and posterior compartments of the legs face medially, towards one another.
Stage 22, the legs have completed their torsional development, but the feet still remain in supinatus.



Structural Unwinding of the Legs and Feet during late Fetal Development
Adapted and Revised from the  Carnegie Human Embryo Collection