The lower leg is a part of the lower extremity, or leg. The lower leg lies between the knee and ankle and works with the upper leg and foot to help perform the key functions of the leg. There are a number of bones, muscles, and tendons in the area. Additionally, nerves and blood vessels run through the leg.

These complex components work together to play crucial roles in the body. They also provide strength and articulation for a person to be able to carry out various tasks.

In this article, we will discuss the bones, muscles, tendons, and nerves of the lower leg.

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Legs are the limbs on which a person or animal walks and stands. The lower leg forms part of the lower extremity. This refers to the body from the hip down. It consists of a few core regions, including the:

  • hip
  • thigh
  • knee
  • lower leg
  • ankle
  • foot

Each of these regions contains its own complex components and function. They all work together to perform the basic functions of the leg.

The lower leg is one of these regions, making up the portion between the knee and the ankle. The lower leg anchors to both the knee and ankle and works together with these regions to function.

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The lower leg plays a few key roles in basic functioning of the leg. It is involved in such functions as:

  • standing
  • walking
  • running
  • jumping
  • kneeling
  • crouching
  • lifting the toes
  • lifting from the legs, for example, when lifting weights or lifting boxes

There are two major bones in the lower leg: the tibia and fibula.

Tibia

The tibia, or shinbone, is the main weight-bearing bone in the lower leg. It is on the medial side of either leg, meaning it is closer to the midline of the body.

The upper head of the tibia connects to the femur and patella to create the knee. The base of the tibia connects with the tarsals of the foot to form the inner part of the ankle.

Fibula

The fibula is the smaller, thinner bone of the lower leg. It is on the lateral side of either leg, meaning it is away from the middle of the body on each side.

The head of the fibula attaches to the head of the tibia and does not make up part of the knee joint. The base of the fibula forms part of the outer ankle. At the base, the fibula attaches to the tibia, one of the ankle bones called the talus, and the calcaneus, also known as the heel bone.

There are a few different muscles in the lower leg that work to move the feet and ankles, including:

Gastrocnemius

The gastrocnemius muscle is one of the main muscles of the lower leg. It gives the calf of the leg its rounded, bulging appearance.

The gastrocnemius is on the posterior, or back, side of the leg. It attaches to the femur and the patella above the tibia, in the top of the area.

It also attaches to the Achilles tendon on the lower part of the leg, at the heel. Engaging the gastrocnemius pulls the heel up while extending the foot. It plays a fundamental role in walking and posture.

Soleus

The soleus muscle is a flatter muscle lying just beneath the gastrocnemius. It begins at the upper portions of both the tibia and fibula and attaches to the heel at the Achilles tendon along with the gastrocnemius.

The soleus engages to flex the ankle joint while moving the foot downward, especially when a person bends their knees, such as while sitting.

Plantaris

The plantaris is a small muscle in the back of the leg, originating above the back of the knee, with a muscle area in the back of the knee.

It has a long, thin tendon running down the middle of the leg to connect with the Achilles tendon and heel bone. However, the plantaris muscle is not always there. Up to 10% of the population do not have it.

Tibialis anterior

The tibialis anterior runs from the top of the tibia, along the front side of the leg and shin, and down into the cuneiform and metatarsal bones of the foot.

The tibialis anterior acts to dorsiflex the foot, which occurs when a person extends the toes toward the shin. It also helps invert the foot, which is the action of moving the soles to face inward.

Tibialis posterior

The tibialis posterior is a muscle deep in the back of the leg. It begins at the rear side of the tibia and fibula and stretches along the leg to connect at the navicular and cuneiform bones in the foot.

The tibialis posterior is a stabilizing muscle for the leg. It also supports the arch of the foot.

Peroneus

The peroneus muscles, also known as fibularis muscles, are a group of three muscles in each leg. They run on the outer side of the lower extremity.

The peroneus longus and peroneus brevis run on the outer side of the leg. They help evert the foot, angling it toward the inside of the body on the line of the toe. They also help execute plantar flexion of the foot, which occurs when a person points the toes and extends the ankle.

The peroneus tertius runs from above the ankle down into the foot. In addition to helping evert the foot, it helps with dorsiflexion, which is the action of pulling the toes back toward the shin.

The major tendon in the lower leg is the calcaneal tendon, or Achilles tendon.

It is a thick patch of responsive tendon tissue that deals with a lot of force from the leg. The Achilles tendon attaches the muscles of the calf to the calcaneus.

The action of the Achilles tendon allows for basic motions in the leg, such as walking and running. During these basic actions, the Achilles tendon may support loads of up to 10 times the body weight.

The tendinous portion of the plantaris muscle also runs down the back of the leg and blends with the Achilles tendon.

There are two major nerves in the lower leg: the fibular nerve and tibial nerve. They also connect to form a sensory nerve known as the sural nerve.

Tibial nerve

The tibial nerve is the major nerve in the area. It innervates all of the superficial and deep muscles in the calf. It branches off to the muscles, including:

  • gastrocnemius
  • popliteus
  • soleus
  • plantaris

A surface level branch of this nerve will become part of the sural nerve.

Fibular nerve

The fibular nerve, or deep peroneal nerve, originates above the back of the knee and innervates part of the hamstring muscles, coming down to the lateral side of the gastrocnemius.

It branches out to become the superficial fibular nerve and deep fibular nerve. The superficial fibular nerve innervates the side of the leg, while the deep fibular nerve innervates the leg’s front part.

Sural nerve

The sural nerve incorporates branches from the tibial and fibular nerves. It runs from the back of the knee to the foot and gives sensation to the skin of the lateral foot and ankle.

The lower leg refers to the portion of the lower extremity between the knee and ankle. This area consists of bones, muscles, tendons, and nerves that all work together to allow the leg to function.

The lower leg plays a key role in standing, walking, running, jumping, and other similar weight-bearing activities.