Leg · Long bone
Femur (Thigh Bone)
The femur is the thigh bone — the longest, strongest bone in the human body. It runs from the hip to the knee and carries the body's weight when standing, walking and running.
What it is
The femur is the single bone of the thigh and the largest bone in the body. Its rounded head fits into the hip socket, and its lower end forms part of the knee. Because it bears so much load, it is thick and strong, surrounded by powerful muscles.
Where it is
In the thigh, running from the hip joint (where its ball-shaped head sits in the pelvis) down to the knee joint.
What it does
Supports the body's weight, transmits force from the hip to the knee, and provides attachment for the large muscles that move the hip and knee — allowing standing, walking, running and jumping.
Connections
Joints and connections
- Hip joint (with the pelvis)
- Knee joint (with the tibia and kneecap)
When things go wrong
Common injuries and conditions
- Femoral shaft fracture (usually from major trauma)
- Hip fracture (neck of femur — common in older adults after a fall)
- Slipped upper femoral epiphysis (in children)
Education and reference only. This explains the anatomy in plain terms; it is not a diagnosis. A severe injury, a visibly deformed limb, or the inability to move or bear weight needs urgent assessment — call 999 or go to A&E for a serious injury.
Did you know?
An interesting fact
The femur is so strong it can support around 30 times an adult's body weight — stronger, weight for weight, than concrete.
Answers
Femur: frequently asked questions
What is the femur?
The femur is the thigh bone — the longest and strongest bone in the body, running from the hip to the knee. It carries your body weight and anchors the powerful thigh muscles.
How does a femur break?
The shaft of the femur is very strong and usually only breaks with major force (such as a car crash). In older adults, the weaker "neck" of the femur near the hip commonly breaks after a simple fall.
How long does a broken femur take to heal?
It varies with the injury and the person, but a femur fracture typically takes several months to heal and often needs surgery. Recovery and rehabilitation are guided by the treating team.
Explore the leg
Related bones
Sources
Where this is drawn from
- NHS — Anatomy and body systems
- Gray's Anatomy for Students (Drake, Vogl, Mitchell)
- TeachMeAnatomy — skeletal system
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