Joy Horner, age 12, of Davenport, Iowa, for her question:
HOW MANY BONES ARE IN THE LEG?
There are three main bones in the leg. Because these must bear a person's entire weight, they are thicker than any of the other bones in the body. The longest and largest is the bone of the thigh, the femur. The two bones of the lower leg are the fibula and the tibia.
When your doctor uses the term "leg," he is usually referring only to the part between the knee and the ankle. The part between the hip and the knee is called the thigh.
The tibia is also called the shinbone. It can be felt close to the middle front section of the leg. The fibula can be felt in the muscles of the side of the leg.
Seven muscles make up the calf, the fleshy part of the back of the leg. The gastrocnemius is the most prominent. These muscles allow a person to bend the toes and to raise the body on the balls of the feet.
The tendo calcaneus, or Achilles' tendon, connects three of the calf muscles with the heel bone. This tendon forms the prominent ridge on the back of the leg, extending upward from the heel to the lower calf. Four muscles on the front of the leg bend the foot upward and straighten the toes. Two additional muscles near the fibula bend the foot sideways.
Muscles are attached to the bones by tendons, strong cords of tissues.
The front of the thigh consists of a four parted muscle, the quadriceps femoris. This muscle allows a person to straighten the limb at the knee and to bend the thigh at the hips.
Three long muscles, called the hamstrings, allow a person to bend the knee and straighten the thigh. The tendons of these muscles connect with the leg bones and can easily be felt on either side of the leg behind the knee.
The quadriceps femoris and hamstring muscles are chiefly used for walking, kicking and climbing.
The knee joint, between the femur and tibia, acts like a hinge.
The knee joint also allows a little movement from side to side. The patella, or kneecap, is a shield shaped bone in front of the knee joint. The patella acts as a pulley for the tendon of the quadriceps femoris muscles.
Only human beings, other mammals and birds have kneecaps.
The femoral artery is the main artery that carries blood to the lower leg. It runs down the front of the thigh, then travels behind the knee, where it becomes the popliteal artery. Finally it branches to form the arteries of the leg.
The largest nerve of the entire body, the sciatic nerve, extends down the back of the thigh to the leg and foot. It supplies the nerves for the skin of the foot and most of the leg, for all the foot and leg muscles and for the muscles on the back of the thigh.
Leg muscles and bones act together to support the body and to provide movement when a person either stands, walks or runs.