femurs

The femurs, or thigh bones, are the longest and strongest bones in the human skeleton. Each extends from the hip to the knee and together they bear substantial body weight during standing and locomotion. Their robust structure allows them to withstand substantial compressive and bending stresses.

Structure. The proximal femur includes the spherical head that articulates with the pelvis at the acetabulum, a constricted neck, and the greater and lesser trochanters for muscle attachments. The shaft, or diaphysis, is a cylindrical, dense bone with the posterior roughened linea aspera for attachment of leg muscles. The distal femur expands into medial and lateral condyles that form part of the knee joint, with the patellar groove on the anterior surface guiding the patella.

Growth and development. The femur forms from primary ossification in the shaft before birth and secondary centers in the ends. Growth in length occurs at the growth plates near the ends and typically finishes in late adolescence or early adulthood as the epiphyses fuse.

Blood supply and nerves. The bone receives arterial blood mainly from the profunda femoris and its perforating branches, plus contributions from the medial and lateral circumflex femoral arteries. Nerve supply comes from branches of the femoral nerve, with additional input from surrounding nerves.

Clinical relevance. The femur is prone to fractures, especially in the neck (femoral neck fracture) and subtrochanteric region after trauma or in osteoporosis. Fractures may require surgical fixation or hip replacement. Other conditions include osteoarthritis, avascular necrosis of the femoral head, and bone tumors.