Human: Bones

During the first trimester, the femur may be confused with the similarly sized and shaped humerus and tibia. Beginning in the second trimester, the femur distinguishes itself as the longest of the bones. The humerus, femur, and tibia are three of the body's long bones. Cast from real bones, these 3 postcranial skeletal elements are excellent representations of human osteology at this stage of early second trimester development.