Muscles of the Leg

By Joe Stubits PTA

Muscles in the Leg

The muscle of the legs support, balance, and propel the body. These muscles can exert a lot of power while continuously making slight adjustments for balance whether the body is moving or at rest. From the big, strong muscles of the buttocks and legs to the little, fine muscles of the feet and toes, the muscle of the legs plays an important role in our everyday activities.

The large muscles of the leg contract and relax, they move skeletal bones to generate movement of the body. Smaller muscles assist the larger muscles to stabilize joints, aid with rotation of joints, and help with other fine-tuned movements.

What are the Biggest Muscles in the Leg?

The biggest muscle masses in the leg are found in the thigh and the calf.

Quadriceps or Quads

The quadriceps consist of four muscles. These four muscles are the strongest and leanest of all muscles in the human body. Located at the front of the thigh, the quadriceps are the major extensors (help to extend the leg straight) of the knee. They are made up of the:

• Vastus Lateralis: On the outside of the thigh, this is the largest of the quadriceps. It extends from the top of the femur to the kneecap or patella.
• Vastus Medialis (VMO): This teardrop-shaped muscle of the inner thigh attaches along the femur and down to the inner border of the kneecap.
• Vastus Intermedius: Between the vastus medialis and the vastus lateralis at the front of the femur, it is the deepest of the quadriceps muscles.
• Proximal rectus femoris: This muscle attaches to the kneecap. Of the quadriceps muscles, it has the least effect on the extension of the knee. This muscle also helps produce flexion at the hip joint.

Hamstring Muscles 

The hamstrings consist of three muscles at the back of the thigh that affect hip and knee movement. They begin under the gluteus maximus behind the hipbone and attach to the tibia at the knee. They are:

• Biceps femoris: This long muscle bends the knee. It begins in the thigh area and extends to the head of the fibula near the knee.
• Semimembranosus: This long muscle extends from the pelvis to the tibia. It extends the thigh, bends the knee, and helps rotate the tibia.
• Semitendinosus: This muscle also extends the thigh and bends the knee.

Muscles in the Leg: Calf Muscles 

The calf muscles are crucial to the movement of the ankle, foot, and toes. Some of the major muscles of the calf include:

• Gastrocnemius (calf muscle): One of the large muscles of the leg, it connects to the heel. It bends the knee and performs plantar flexion at the ankle (pointing toes away).
• Soleus: This muscle extends from the back of the knee to the heel. It is essential in walking and standing.
• Plantaris: This small, slender muscle is absent in about 10 percent of people. The plantaris is a weak plantar flexor at the ankle and flexor at the knee.

Perhaps the most significant tendon in terms of mobility is the Achilles tendon. This vital tendon in the back of the calf and ankle connects the plantaris, gastrocnemius, and soleus muscles to the heel bone. It stores the elastic energy required for running, jumping, and other physical activities.

Shin Splint Muscles

The muscles of the front of the lower leg which are notable due to having shin splints are labeling in the diagram below.

Written By: Joe Stubits PTA

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By: Joe Stubits PTA