What is the largest bone in the human body?
The femur, or thighbone, is the largest and strongest bone in the human body. In adults it makes up about a quarter of a person's height.
The femur runs from the hip to the knee. Its rounded top fits into the hip socket, forming a ball-and-socket joint that allows the leg to swing in many directions. At the bottom, it meets the shinbone at the knee.
The femur supports the weight of the upper body when we stand, walk and run. Its long, hollow shaft is filled with bone marrow, which helps make blood cells. Because it is so strong, breaking a femur usually takes a very powerful force, such as a car accident.
A clue for scientists
Because femur length is closely linked to overall height, archaeologists and forensic scientists can estimate a person's height from just this one bone. The second-longest bone is the tibia, or shinbone.
Did You Know?
The femur's neck is angled, which helps us walk efficiently. In older people, this area can become weak, which is why hip fractures are common in old age.
This answer is general information, not medical advice. For a personal health question, talk to a doctor.