The legs are the two lower limbs of the body. They provide support and a range of movements.

Each leg contains five regions. They’re known as the:

  • upper leg
  • knee
  • lower leg
  • ankle
  • foot

Upper leg anatomy and function

The upper leg is often called the thigh. It’s the area that runs from the hip to the knee in each leg.

Upper leg bones

  • Femur. Also called the thigh bone, this is the longest bone in the body. It’s also one of the strongest. It can account for about a quarter of someone’s height.

Upper leg muscles


The hamstrings are three muscles located on the back of the thigh. They allow the knees to bend.

The three hamstrings are the:

  • semimembranosus
  • semitendinosus
  • biceps femoris

Learn how to prevent and treat hamstring pain.


The quadriceps are four muscles located on the front of the thigh. They allow the knees to straighten from a bent position.

The four quadriceps are the:

  • vastus lateralis
  • vastus medialis
  • vastus intermedius
  • rectus femoris

Try these three quadriceps stretches if you’re a runner.


The adductors are five muscles located on the inside of the thigh. They allow the thighs to come together.

The five adductors are the:

Learn how to strengthen your adductors.

Knee anatomy and function

The knee joins the upper leg and the lower leg. It’s also the largest joint in the body. In addition to bearing the weight of the upper body, the knee allows for walking, running, and jumping. It also allows for rotation and pivoting.

Knee bones

  • Patella. Also called the kneecap, the patella serves as a point of attachment for different tendons and ligaments. It also helps protect them from damage.

Knee ligaments

Ligaments are bands of connective tissue that surround a joint. They help support joints and keep them from moving too much.

The knee contains four major ligaments:

  • Anterior cruciate ligament. This prevents the tibia in the lower leg from moving too far forward.
  • Posterior cruciate ligament. This prevents the knee from moving too far backward.
  • Medial collateral ligament. This provides stability for the inner knee.
  • Lateral collateral ligament. This helps stabilize the outer knee.

Knee tendons

Tendons are also bands of connective tissue. They’re found on the ends of muscles, where they help attach muscle to bone. The largest tendon in the knee is the patellar tendon. It attaches the tibia to the patella. The quadriceps tendon attaches the quadriceps muscle to the patella.

What’s the difference between tendons and ligaments? Find out here.

Other important structures

The knee contains a variety of structures that help it support weight and allow a range of movements. Some of the most important structures include:

  • Bursa. Bursae (plural) are small sacs filled with fluid in the knee joint. There are about 14 of them in each knee. They help reduce friction and inflammation in the knee.
  • Meniscus. The knee contains two menisci (plural), known as the medial meniscus and lateral meniscus. They’re discs of cartilage that act as shock absorbers. In addition, they help evenly distribute weight, providing balance and stability.

Leg diagram

Explore the interactive 3-D diagram below to learn more about the leg.

Lower leg anatomy

The lower leg extends from the knee to the ankle. This area is commonly referred to as the calf.

Lower leg bones

  • Tibia. Also called the shin bone, the tibia is the longer of the two bones in the lower leg. It acts as the main weight-bearing bone of the leg.
  • Fibula. The fibula is located next to the tibia. It mainly serves as an attachment point for the muscles of the lower leg.

Lower leg muscles

  • Gastrocnemius. This is one of the main muscles in the calves. It allows for a type of movement called plantar flexion in the ankle. This allows the toes to point downward.
  • Soleus. This large muscle is located behind the gastrocnemius. It also helps with plantar flexion.
  • Plantaris. This is a small muscle in the back of the lower leg. Like the gastrocnemius and soleus, it’s involved in plantar flexion.
  • Tibialis muscles. These muscles are found on the front and back sides of the lower leg. The muscles in the front allow for dorsiflexion. This involves pointing the toes upward. The muscles in the back help with plantar flexion and supporting the arch of the foot.
  • Peroneus muscles. These muscles are located on the front side of the lower leg. They help with dorsiflexion.

Other important structures

  • Fibular nerves. Fibular nerves stimulate the muscles of the front part of the lower leg.
  • Tibial nerves. These nerves are branches of the sciatic nerve. This is one of the main nerves in the leg. Tibial nerves stimulate muscles in the back of the lower leg.
  • Achilles tendon. The Achilles tendon attaches the muscles of the calves to the bones of the ankle and foot.

Ankle anatomy

The ankle is a joint that connects the lower leg to the foot. Its main function is to allow for plantar flexion and dorsiflexion of the foot.

Ankle bones

The ankle is made off the tibia and fibula of the leg as well as the talus of the foot.

Ankle ligaments

The ankle contains two groups of ligaments:

  • the medial ligaments, sometimes called the deltoid ligaments, in the inner ankle
  • the lateral ligaments, in the outer ankle

Both groups of ligaments help stabilize the ankle and prevent it from turning too far inward or outward.

Foot anatomy

The feet are made up of many bones, muscles, and ligaments. In fact, nearly one-quarter of the bones in the body are found in the feet.

Foot bones


The tarsal bones are found near the ankle, in the middle of the foot, where they form an arch. The seven tarsal bones are the:


The metatarsal bones are found between the tarsal and phalange bones.

The five metatarsals are the:

  • first metatarsal
  • second metatarsal
  • third metatarsal
  • fourth metatarsal
  • fifth metatarsal


These are the bones that make up the toes. There are 14 of them in each foot. Except for the big toe, each toe has three phalanges, known as the:

The big toes only have proximal and distal phalanges.


Sesamoids are bones that are embedded in tendons. They’re found in multiple joints throughout the body.

There are two small sesamoids in the ball of the foot. They help absorb weight and help give a mechanical advantage to the tendon.

Foot muscles

Each foot contains more than 20 muscles that provide support and allow for a range of movements.

Some of the main muscles of the foot include the:

  • Extensors. These help raise the toes upward.
  • Flexors. These help the toes curl inward.
  • Tibialis posterior. This supports the arch of the foot.
  • Tibialis anterior. This allows the foot to move upward.
  • Tibialis peroneal. This controls movement of the outer ankle.

Foot ligaments

The ligaments of the foot help hold together the bones that support the arch. The main ligaments of the foot include the:

  • Plantar fascia. This is the longest ligament in the foot. It runs from the heel to the toes, forming the arch.
  • Plantar calcaneonavicular ligament. This ligament is found in the sole of the foot, where it connects the calcaneus and the navicular bones.
  • Plantar calcaneocuboid ligament. This ligament helps the plantar fascia support the foot’s arch. It also connects the calcaneus and tarsal bones.