Human leg in a straight line, which represents the mechanical longitudinal axis of the leg, the Mikulicz line. This line stretches from the hip joint (or more precisely the head of the femur), through the knee joint (the intercondylar eminence of the tibia), and down to the center of the ankle (the ankle mortise, the fork-like grip between the medial and lateral malleoli). In the tibial shaft, the mechanical and anatomical axes coincide, but in the femoral shaft they diverge 6°, resulting in the "femorotibial angle" of 174° in a leg with normal axial alignment. A leg is considered straight when, with
Vertical clinging and leaping phalangeal index, low intermembral index, femurs with cylindrical head and high, narrow patellar grooves, and fused fibula and tibia. The high phalangeal index is the elongation of the phalangeal finger bones, which helps vertical clingers who require increased prehensile power in their hands to support their large bulk. The low intermebral index is the total length of the humerus and radius in percentage of total length of the femur and tibia. The features of the femur is part of an evolution of elongated femurs that helps the primates' extreme range of flexion and extension, which allows them to perform their