Leg

Leg: Femur,Patella,Tibia,Fibula
The evolution of the leg mirrors is like arm.The single thight bone, the femur, is the serial homolog of the upper arm bone,the humerus. Likewise, the lower bones of the leg, the tibia and fibula,are serial homolgs of the radius and ulna. the largest sesamoid bone in the body, the patella,lies at the knee joint. The bipedal locomotor mode practiced by homonids has resulted in major specializations of leg bones.
Femur
is the longest,heaviest,and strongest bone in the body.it supports all of the body's weight during standing,walking and running.
because of its strength and density, it is frequently recovered in forensic, archaeological and paleontological contexts. The femur is valuable bone because of the information it can provide on the stature of an individual.
the femur articulates with the acetabulum of the os coxae. Distally, it articulates with the patella and proximal tibia. The leg's actions at the hip include medial and lateral rotation, abduction, flexion and extension. At knee, motion is far more restricted,confined mostly to flexion and extension. Although the main knee action is that of a sliding hinge, this joint is one of the most complex in the body.
femur parts are:
head
spiral line
pectinel line
femoral shaft
linea aspera
nutrient foramen
medial supracondylar line (ridge)
popliteal surface
lateral condyle
lateral epicondyle
popliteal groove
medial condyle
intercondylar fossa (notch)
patellar surface

the femur ossifies from 5 centers: one for shaft, head,distal end,each trochanter.

the femoral head has a fovea (fossa) and is more complete sphere than the humeral head
the femoral shaft is larger,has a thicker cortex and is rounder in cross section than any other shaft. It has only one sharp corner,the linea aspera.

For isolated femoral heads the fovea is medial and displaced posteriorly and inferiorly. The posterinferior head-neck junction is more deeply excavated than anterosuperior junction.