Femur

Original Editor - Daphne Jackson

Top Contributors - Lucinda hampton, Kim Jackson, Evan Thomas, Admin, Daphne Jackson, Joanne Garvey, WikiSysop and Joao Costa

Introduction

The femur is the longest, heaviest, and strongest bone in the human body. The main function of the femur is weight bearing and stability of gait. An essential component of the lower kinetic chain.

The robust shape of the femur provides many sturdy attachment points for the powerful muscles of the hip and knee that contribute to walking and other propulsive movements.

Femur: Three Divisions

The femur acts as the site of origin and attachment of many muscles and ligaments, and can be divided into three parts; proximal, shaft and distal.

Proximal Femur: Composed of the head, neck, greater trochanter and lesser trochanter. The head of the femur articulates with the acetabulum of the pelvis to create the hip joint.

1. Femoral head: Supported by the neck of the femur.Is a globular form rather more than a hemisphere. It is directed caudally, medially and anteriorly, known as the angle of inclination. Normal 120 degrees, abnormal angles; coxa vara less than 125 degrees; coxa valga greater than 125 degrees. Its surface is smooth and coated in cartilage except for an ovoid depression, fovea capitis femoris (a little below and behind the centre of the head). The fovea allows for the attachment of the ligament of head of the femur.
2. The bulbous femoral head is joined to the shaft of the femur by the femoral neck. If there is a femoral neck fracture, the blood supply through the ligament becomes crucial, and there is a risk of avascular necrosis.
3. At the base of the neck are the medially oriented lesser trochanter and laterally placed greater trochanter. A rough line called the intertrochanteric line connects the greater and lesser trochanter on the anterior aspect of the femur, while the smoother intertrochanteric crest connects the trochanters posteriorly.

Femoral Shaft

The femoral shaft is almost cylindrical in form, being slightly broader superiorly and slightly arched, giving it a convexity anteriorly and concavity posteriorly which has a prominent longitudinal ridge of bone, the linea aspera. A variety of muscles have their origins at and insert into the femoral shaft (all, apart from gluteus maximus and vastus intermedius, interact with the posterior surface of the bone).

Distal Femur

Prominent lateral and medial condyles are found at the distal end of the femur. Projecting from each condyle is an epicondyle that act as attachment sites for the collateral ligaments. The lateral and medial condyles are separated by the intercondylar notch.

Blood Supply

The femoral artery is the main blood supply to the lower extremity. The foveal artery comes off of the obturator artery that runs through the ligamentum teres femoris as supportive blood supply to the femoral head, but it is not the main source during adulthood. The perforating branches of the deep femoral artery supply the shaft and distal portion of the femur.See also Functional Anatomy of the Hip - Neural and Vascular

Muscles

The thigh muscles are divided into the anterior, medial, and posterior and gluteal compartments. The femur sits within the anterior compartment.

1. Anterior compartment is composed of the hip flexors and knee extensors. Hip flexors include pectineus, iliopsoas, and sartorius muscle.
2. Medial compartment’s function is mainly leg adduction. See Hip Adductors
3. Posterior compartment muscles are mainly hip extensors and knee flexors. Hip extensors Knee Flexors
4. Gluteal muscles. 1.The superficial layer is composed of the gluteus maximus, medius, and minimus. Hip extension, abduction, and internal rotation is the superficial gluteal’s main function. 2. The deep layer is made up of the piriformis, obturator internus, quadratus femoris, and superior and inferior gemellus (deeper gluteal muscles help with external rotation of the hip).

Articulations

1. The femoral head of the proximal femur articulates with the acetabulum of the pelvis in which the femoral head acts at the ball and the acetabulum as the socket. Allows for movement at the hip in three planes: flexion and extension in the sagittal plane, abduction and adduction in the frontal plane, and internal and external rotation in the horizontal plane.
2. Distally, the convex femoral condyles of the femur articulate with the condyles of the tibia, ie tibiofemoral joint. Movement at the tibiofemoral joint occurs in two planes: knee flexion and extension in the sagittal plane, and internal and external rotation in the horizontal plane.
3. The patellofemoral joint is formed by the articulation of the patella with the intercondylar/trochlear groove of the femur. During flexion and extension of the knee, the articular surfaces of the patella and femur perform a sliding movement.

Injuries and Conditions

Femoral Shaft Fracture

See:

• Femoral fractures
• Femoral Stress fracture
• Patellofemoral pain syndrome ..
• Femoral Neck Fracture
• Greater Trochanteric Pain Syndrome