The femur (also thigh bone, latin: os femoris) is the only bone of the thigh, and it articulates with the hip and the knee.
The femur is a long bone that has three parts: a diaphysis or shaft in the middle of the bone, and two epiphyses or extremities (proximal and distal) at each end.
Proximal epiphysis of femur
The proximal epiphysis (or the upper extremity) of the femur features:
- head of femur, with
- fovea of head of femur,
- neck of femur,
- greater trochanter, with
- trochanteric fossa
- lesser trochanter,
- intertrochanteric line,
- intertrochanteric crest.
The head of the femur is the most upper part of the femur, it is directed upward, medialward and a little forward, and is globular-shaped. The femoral head is supported by the neck of the femur.
The fovea of the head of the femur is a depression within the femoral head for attachment of the ligament of the head of the femur.
The neck of the femur is the portion of the femur between the femoral head and the greater trochanter.
The greater trochanter is a large prominence on the superolateral aspect of the femur shaft for attachment of the gluteus medius, gluteus minimus and piriformis muscles.
The trochanteric fossa is a depression medial to the root of the greater trochanter of the femur. It is the origin site of the internal obturator and gemelli muscles.
The lesser trochanter is a small prominence on the posteromedial aspect of the proximal part of the femur for attachment of the iliopsoas muscle.
The intertrochanteric line is a rough anterior line between the diaphysis and neck of the femur, extending from the greater trochanter to lesser trochanter.
The intertrochanteric crest is a posterior bony ridge between the diaphysis and neck of the femur, running from the greater trochanter to lesser trochanter.
Diaphysis of femur
The diaphysis (or the body, or shaft) of the femur features:
- linea aspera, with
- lateral ridge,
- medial ridge,
- pectineal line,
- gluteal tuberosity,
- popliteal surface.
The linea aspera (from latin meaning: rough line) is a rough double line on the posterior aspect of the shaft of the femur for attachment of the two vasti muscles (vastus medialis, vastus lateralis) and the short head of the biceps femoris, and it is also the insertion site of the adductors, gluteus maximus, and pectineus muscles.
Above, the linea aspera is prolonged by three ridges: the lateral, the intermedial (also called the pectineal line), and the medial ridge.
The pectineal line is a bony ridge on the shaft of the femur extending downward from the lesser trochanter, nearly reaching the linea aspera. The pectineal line gives attachment to the pectineus muscle.
The gluteal tuberosity is a rough, oblong field on the shaft of the femur continuous with the linea aspera superolaterally. The gluteal tuberosity is the insertion site of the gluteus maximus muscle.
The popliteal surface is a triangular field on the posterior aspect of the femur on the distal part of the femoral shaft between the intercondylar line and the diverging lips of the linea aspera. The popliteal artery lies upon the popliteal surface.
Distal epiphysis of femur
The distal epiphysis (or the lower extremity) of the femur features:
- medial condyle, with
- articular surface of medial condyle,
- medial epicondyle,
- lateral condyle, with
- articular surface of lateral condyle,
- lateral epicondyle,
- patellar surface,
- intercondylar fossa.
The medial condyle is the medial knee joint surface of the femur, which has an articular surface and a medial epicondyle.
The medial epicondyle is a bony elevation on the medial aspect of the medial condyle.
The lateral condyle is the lateral knee joint surface of the femur, which also features an articular surface and an epicondyle.
The lateral epicondyle is a bony elevation on the lateral aspect of the lateral condyle.
The patellar surface is the surface of the femur that articulates with the articular surface of the patella.
The intercondylar fossa is a deep notch between the rear surfaces of the lateral and medial epicondyle of the femur.