Mammal, limb (Gross, Low)

Structure List Pectoral girdle (scapula) Humerus Radius Ulna Carpus Metacarpus Pelvic girdle Femur Tibia Fibula Tarsus Metatarsals Digits

The appendicular skeleton underwent many changes during the transition from water to land. The paired fins transformed into limbs and the girdles strengthened. Body weight could be transferred through these structures to the ground. The limbs are jointed and articulate with the girdle in such a way that they can be rotated forward, the feet placed on the ground, and thrusts developed that advance the body. Note that this plan consists of a single bone close to the body ("proximal") that articulates with the girdle, a medial segment consisting of two long bones in parallel, and a distal segment(s) consisting of several rows of bones, with a variable number in each row. The limbs of all tetrapods are fundamentally similar. Forelimbs and hindlimbs are also alike.