Femur is the bone of leg that articulates above with the hip bone to form hip joint and below with the tibia and patella to form the knee joint. It is the longest bone of human body.
Upper end of femur:
Upper end of the femur has a head, a neck and greater and lesser trochanters.
Head: Head forms about two thirds of a sphere and articulates at the hip joint with the acetabulum of the hip bone. In the center of the head, there is a small depression known as fovea capitis. The ligament of the head of the femur attaches at this depression. This ligament is an important structure because of part of the blood supply to the head of femur from the obturator artery comes through a branch that is enclosed within this ligament.
Neck: Neck connects the head to the shaft of bone. It passes downward, backward and laterally and makes an angle of about 125 degrees with the long axis of shaft of femur. The angle is slightly less in females and can be altered by disease.
Greater and lesser trochanters: These are large eminences situated at the junction of the neck and shaft. The two trochanters are connected on the anterior side by intertrochanteric line and on the posterior side by intertrochanteric crest. Quadrate tubercle lies on the intertrochanteric crest.
Shaft of femur:
The shaft of femur is smooth and rounded in form. Posteriorly there is a ridge known as linea aspera which bear attachment of the intermuscular septa and many muscles of thigh. Above and below the middle of shaft, the margins of linea aspera diverge to form lateral and medial lines. On the inferior aspect, the medial margin continues downward as the media supracondylar ridge and ends on the adductor tubercle that lies on the medial condyle. The lateral margin continues downward as the lateral supracondylar ridge, which ends on the lateral condyle. The shaft becomes broader as it continues downward and at its very distal end, it forms a flat, triangular area on the posterior surface. This flat triangular area is known as popliteal surface.
Lower end of femur:
Lower end of femur consists of lateral and medial condyles, which are separated from each other posteriorly by the intercondylar notch. On the anterior aspect, there is no separation and the condyles are joined by an articular surface for the patella. Both of the condyles take part in formation of knee joint. Above the condyles are the medial and lateral epicondyles on respective sides. Medial epicondyle bears a prominent tubercle known as the adductor tubercle.