Leg Anatomy: Complete Guide with Parts, Names & Diagram

Overview of Leg Anatomy

The legs are the lower limbs of the human body, located between the hips and the feet. They play a vital role in supporting body weight and maintaining balance. It also enables movement such as standing, walking, running, climbing, and even complex activities like dancing or jumping. The parts of leg anatomy comprise several key components, including bones, muscles, tendons, ligaments, joints, and nerves. They work together to provide strength, flexibility, and coordination. The largest bone in the body, the femur (thigh bone), connects the hip to the knee. Below the knee, the tibia (shin bone) and the thinner fibula form the lower leg. The thigh lies between the hip and the knee, while the calf comprises the back portion of the lower leg. The shin refers to the front part of the lower leg where the tibia is located.

Human legs are unique in evolution because they are specially adapted for bipedal locomotion (walking on two feet). This adaptation gives us efficiency in movement compared to most animals. Anatomical differences exist between male and female legs—for example, in hip angle, knee alignment, and bone length—but the overall structure and function remain the same.

In this article, we will explore leg anatomy in detail, covering the major bones, muscles, tendons, ligaments, joints, and nerves, to understand how our legs work and why they are so essential for daily activities and overall mobility.

Leg Anatomy Diagram

Parts of the Leg

Leg Bones

Femur
Patella
Tibia
Fibula

Joints

Hip Joint
Knee Joint
Ankle Joint
Subtalar Joint

Leg Muscles

Thigh
Gastrocnemius
Soleus
Tibialis Anterior
Peroneus Longus
Peroneus Brevis

Tendons

Achilles Tendon
Tibialis Posterior Tendon

Ligaments

Anterior Cruciate Ligament (ACL)
Posterior Cruciate Ligament (PCL)
Medial Collateral Ligament (MCL)
Lateral Collateral Ligament (LCL)

Leg Bone Anatomy

Femur

The femur or thigh bone is the longest, heaviest, and strongest bone in the human body. It plays a crucial role in supporting body weight, maintaining posture, and enabling smooth movements like walking, running, and jumping.

The femur is divided into three main parts:

Proximal end (upper part): It connects with the hip bone at the hip joint.
Shaft (middle portion): It is the long, cylindrical body of the bone.
Distal end (lower part): It connects with the tibia and patella (knee cap) to form the knee joint.

The femur also acts as a weight-bearing bone, transmitting forces from the hip to the knee and giving the body strength and stability. It serves as an anchor point for several muscles, ligaments, and tendons that control leg movement and balance.

Inside the femoral shaft, there are two types of bone marrow:

Red bone marrow – It is responsible for producing red blood cells, white blood cells, and platelets (essential for oxygen transport and immunity).
Yellow bone marrow – It mainly stores fat and serves as an energy reserve.

Because of its strength and vital functions, the femur is often studied in orthopedics, anatomy, and sports medicine to understand mobility, fractures, and overall skeletal health.

Detailed diagram of the human femur bone anatomy showing parts, names, and structure including head, neck, shaft, condyles, and functions. — Illustration of the human femur bone with labeled parts and structure for better understanding of anatomy.

Patella

The patella or kneecap is a triangular and flat bone in a central position at the front of the knee joint joint. It helps to connect the femur and tibia in the knee area.

The main role of the patella comes during the process of knee extension. Also, it has another critical function, which is to facilitate the easy movement of the knee during both flexion and extension.

Additionally, it acts as a protective shield for the anterior surface of the knee joint, safeguarding it from potential harm.

Tibia

The tibia, commonly known as the shin bone, is one of the two major bones in the lower leg. It serves as the main weight-bearing bone of the body. It is larger, stronger, and more vital for support compared to the fibula.

The tibia connects with the femur at the knee joint and with the fibula and talus at the ankle joint. It is positioned on the inner side of the leg, and runs parallel to the fibula, stretching from just below the knee down to the ankle.

From a functional perspective, the tibia is responsible for supporting body weight, maintaining balance, and ensuring stability during standing, walking, and running.

It acts as a crucial link between the thigh and the foot. It allows smooth movement while protecting the internal structures of the leg.

Fibula

The fibula is a long, thin bone in the lower leg, located on the outer side next to the larger tibia. Unlike the tibia, it does not carry much body weight, but it is essential for leg stability, balance, and ankle movement.

Upper End (Head & Neck): At the top, the fibula has a rounded head just behind the tibia’s head, followed by a narrow neck.
Shaft: The middle section of the fibula is called the shaft. It is triangular in shape with three surfaces—lateral (outer), medial (facing the tibia), and posterior (back).
Lower End (Lateral Malleolus): At the ankle, the fibula widens to form the lateral malleolus, the bony bump on the outer side of the ankle. This part connects with the talus bone, helping form the ankle joint and preventing excessive side-to-side movement.

The fibula is tightly linked to the tibia by the interosseous membrane. It is a strong sheet of connective tissue that runs between the two bones.

This connection provides stability and ensures proper leg function during walking, running, and standing.

Leg Muscle Anatomy

Thigh

The thigh is the upper part of the leg, located between the hip and the knee. Its main bone is the femur, the longest and strongest bone in the human body. The femur supports body weight and helps with movement.

The thigh is divided into three main compartments, and each has its own muscles, nerves, and blood vessels that work together for movement and stability:

Anterior Compartment – It contains the quadriceps muscles, which straighten the knee. They are important for walking, running, climbing, and kicking.
Medial Compartment – It is known as the adductor group. These muscles pull the legs inward toward the body’s midline. They help with balance, side-to-side motion, and controlled leg positioning.
Posterior Compartment – It includes the hamstring muscles, which bend the knee and extend the hip. These muscles are essential for sitting, standing, jumping, and sprinting.

All these compartments are separated by a strong connective tissue called fascia, which gives structure, protection, and support to the thigh muscle.

Detailed illustration of thigh muscle anatomy showing quadriceps (rectus femoris, vastus lateralis, vastus medialis, vastus intermedius), hamstrings (biceps femoris, semitendinosus, semimembranosus), adductors, and sartorius with labeled parts and functions. — Anatomical diagram of the thigh muscles, highlighting quadriceps, hamstrings, adductors, and sartorius with their key functions.

Gastrocnemius

The gastrocnemius muscle, commonly called the calf muscle, is one of the largest and strongest muscles in the lower leg. It has two parts (the medial and lateral heads) that start just above the knee and join together at the back of the leg, attaching to the Achilles tendon at the heel.

This muscle crosses three important joints:

Knee Joint
Ankle joint
Subtalar joint (in the foot)

Because it spans multiple joints, the gastrocnemius plays a key role in leg movement and stability. Its main functions are:

Plantar flexion – pointing the toes downward, such as when standing on tiptoe, walking, or pushing off the ground.
Knee flexion – helping bend the knee during movement.

These actions make the gastrocnemius essential not only for daily activities like walking, climbing stairs, and standing, but also for athletic movements such as running, sprinting, and jumping.

From a muscle fiber perspective, the gastrocnemius is rich in fast-twitch fibers, which are designed for quick and powerful movements. This makes the muscle highly effective for bursts of speed and strength, though less suited for long-term endurance compared to muscles with more slow-twitch fibers.

For sports, exercise, and rehabilitation, keeping the gastrocnemius strong and flexible is crucial. Proper strengthening and stretching improve ankle stability, balance, mobility, and overall athletic performance.

Soleus

The soleus muscle is important in the lower leg, located deep in the calf, and works closely with the gastrocnemius muscles. Together, these two muscles form a triceps surae.

The soleus has a complex structure. It has many muscle fibers that attach to different places on the leg bones. Most of these fibers start below the knee and go down to the heel bone, while some start at various spots on the back of the leg bones.

Some of them attach to a flat structure called the anterior aponeurosis. In contrast, others connect to another similar structure called the posterior aponeurosis. This muscle helps us stand and walk.

Tibialis anterior

The tibialis anterior muscle is the largest muscle in the front part of the lower leg. It starts from the upper section of the shin bone (tibia) and extends downward toward the foot.

This muscle performs two main movements:

Dorsiflexion – lifting the foot upward toward the shin.
Inversion – turning the sole of the foot inward.

Although the tibialis anterior is a muscle, it works closely with important foot and ankle bones such as the calcaneus (heel bone), talus (ankle bone), navicular, cuneiform bones, and the first three metatarsals. Together, they make smooth and controlled foot movement possible.

The tibialis anterior is vital for walking, running, climbing stairs, and balance. It lifts the foot during movement, supports the natural arch, and helps reduce strain on the lower leg and foot.

A strong tibialis anterior is important for healthy gait mechanics, foot stability, and injury prevention. Weakness or injury in this muscle may cause issues such as foot drop, shin pain, or walking instability.

Peroneus Longus

The peroneus longus is one of the two main muscles on the outer side of the lower leg, along with the peroneus brevis. It is supplied with blood by the fibular artery and branches of the tibial artery. Its movements are controlled by the superficial fibular (peroneal) nerve, which comes from the spinal nerves L5–S2.

This muscle begins at the upper and outer surface of the fibula (the long bone of the leg) and extends downward toward the foot. It attaches at the base of the first metatarsal and the medial cuneiform bone near the big toe.

Key Functions of the Peroneus Longus

Plantarflexion – pointing the foot downward.
Eversion – turning the sole of the foot outward.
Arch support – helping stabilize the transverse arch of the foot.

This muscle works together with the peroneus brevis & ensures smooth foot movements, balance, and stability during walking, running, and side-to-side activities.

The peroneus longus can be affected by:

Strains or tears – often from sudden twisting motions.
Tendonitis – inflammation caused by overuse or repetitive stress.
Ankle sprains – especially in sports like basketball, football, or running.

Symptoms may include pain in the outer ankle, swelling, weakness, or difficulty moving the foot.

Peroneus Brevis

The peroneus brevis is an important muscle on the outer side of the lower leg. It is located just beneath the peroneus longus.

Its main role is to help turn the foot outward (eversion) and point the toes downward (plantar flexion). These movements are essential for walking, running, and keeping proper balance.

This muscle gets its nerve supply from the superficial peroneal nerve and its blood supply from the peroneal artery.

It begins from the lower part of the fibula (the thin bone on the outside of the leg) and attaches to the base of the fifth metatarsal bone on the outer edge of the foot.

Unlike the longer and slimmer peroneus longus, the peroneus brevis is shorter and thicker, which makes it more stable. Its tendon runs slightly above the outer ankle bone (lateral malleolus), curves around the ankle, and firmly attaches to the fifth metatarsal.

This strong attachment helps stabilize the ankle and protects it from common injuries such as ankle sprains.

Detailed diagram of hip muscle anatomy showing major muscles, their names, locations, and functions in human movement — Visual guide to the major muscles of the hip, highlighting their anatomical positions and roles in movement and stability.

Leg Anatomy: Joint

Hip Joint

The hip joint is also known as a ball-and-socket joint. It has a “ball” at the top of the thigh bone (femur) that fits into a “socket” in the hip bone (acetabulum).

This design allows the hip joint to move in many directions. It can bend and straighten (flexion and extension), rotate (internal and external rotation), and move sideways (abduction and adduction).

One of the main jobs of the hip joint is to support the weight of your body when you are standing, walking, or running. It also helps transfer force from your upper body to your legs, allowing you to move.

The hip joint is strong and stable, partly because of the deep socket that holds the femur in place. There is also a ring of tough cartilage called the acetabular labrum around the edge of the socket, which helps keep the joint secure.

This cartilage has a few important roles:

It helps spread the pressure when you put weight on your hips.
It creates a suction that helps keep the joint stable, like a vacuum seal.
It also helps control the fluid flow that lubricates the joint, which keeps everything moving smoothly.

Detailed diagram of the human hip bone anatomy showing all parts, including ilium, ischium, pubis, acetabulum, and sacroiliac joint with labeled names and functions. — Comprehensive hip bone anatomy showing key structures like ilium, ischium, and pubis with labeled functions.

Knee Joint

The knee is the largest joint in our body. It is mainly operating as a hinge for bending and straightening the leg. Its structure involves two key articulations: the tibiofemoral and patellofemoral joints, which create a compound synovial joint together.

This joint is essential for efficient walking, running, and jumping. The bones involved in knee articulation are complex.

The femur has a slight inward slant, while the tibia is almost vertical. The patella, the largest sesamoid bone in the body, sits at the front of the knee. It serves as the endpoint for the quadriceps tendon and shields the front surface of the femur.

The articulating surfaces at the knee include the lateral and medial condyles of the femur and tibia and the front-to-back connection between the patella and femur.

Detailed labeled diagram of knee anatomy showing bones, ligaments, cartilage, tendons, and muscles that support joint movement and stability. — Anatomy of the human knee joint with labeled parts, including bones, ligaments, and muscles, that enable movement and support body weight.

Ankle Joint

The ankle joint is formed by joining three bones: the talus, tibia, and fibula. It is a socket where the talus bone sits, surrounded by the tibia and fibula. The bony prominence on the lower fibula, the malleoli, helps form the edges of this joint.

During walking, the ankle adjusts to different surfaces. It can move in four main ways, pushing your toes down (plantarflexion), pulling them up (dorsiflexion), tilting the sole of your foot inwards (inversion), or tilting it outwards (eversion).

Subtalar Joint

The subtalar joint is also known as the talocalcaneal joint. It is where the talus bone and the calcaneus bone meet in the foot.

There are three points where they connect, two in the front and one in the back. These connection points are called facets, with one at the back, one in the middle, and one in the front.

At the front and middle connections, the shape of the talus fits into the shape of the calcaneus, with the talus being convex and the calcaneus being concave. In the back connection, the talus is concave, and the calcaneus is convex.

The middle connection has a structure called the sustentaculum tali as its floor, and the front connection fits snugly against the head of the talus.

Sometimes, the middle and front connections are combined into one. The back connection is the largest and is separated from the others by a tarsal canal structure.

This joint allows the foot to move from side to side (inversion and eversion). However, it does not have much to do with moving the foot up or down (dorsiflexion or plantarflexion).

FAQ’s

1. What are the main parts of the human leg?

The human leg consists of bones, muscles, joints, ligaments, tendons, blood vessels, and nerves. Major bones include the femur, tibia, fibula, and patella.

2. How many bones are in the leg?

Each leg has four main bones: the femur (thigh bone), tibia (shin bone), fibula (outer lower leg bone), and patella (kneecap). Together, they provide structure and support for movement.

3. Which muscles are found in the leg?

The leg muscles are divided into groups: quadriceps and hamstrings in the thigh, calf muscles (gastrocnemius and soleus), and smaller muscles that help with ankle and toe movements.

4. What is the function of the femur bone?

The femur is the longest and strongest bone in the body. It supports body weight, connects the hip to the knee, and plays a vital role in walking, running, and jumping.

5. Why is the tibia called the “shin bone”?

The tibia is commonly called the shin bone because it forms the front portion of the lower leg. It bears most of the body’s weight and connects the knee to the ankle.

6. What is the difference between the tibia and fibula?

The tibia is larger, weight-bearing, and forms the shin. The fibula is thinner, lies beside the tibia, and provides stability to the ankle but does not bear much weight.

7. Which nerves control the leg muscles?

The sciatic nerve is the largest nerve supplying the leg. It branches into the tibial and common peroneal nerves, which control movement and sensation in the thigh, calf, and foot.

8. Why are the leg muscles important for balance?

Leg muscles, especially the quadriceps, hamstrings, calves, and gluteal muscles, stabilize the joints and work together to maintain posture, balance, and smooth movement.

Leg Anatomy: Complete Guide with Parts, Names, Functions & Diagram