Muscles in the Back of the Leg: Origin and Function

The muscles in the back of the leg are an important part of the overall leg anatomy. There is more than one muscle group present in the back of your leg, and understanding these muscle groups will help you identify which part of the muscles in the back of the leg plays what role.

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The muscles in the back of the leg

Muscles in back of leg (Photo via Clem Onojeghuo/Unsplash)

Usually, when someone speaks of the muscles in the back of the leg, they’re referring to the hamstrings. However, it’s important to note that hamstrings are one part of the muscles back there, and not the entire muscle group.

Here are the muscles in the back of the leg:

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Gastrocnemius

The most superficial and largest calf muscle is Gastrocnemius. It starts right above the knee joint and extends itself into the heel through the Achilles tendon. The muscle group is responsible for moving the ankle joint to point the toes downwards.

Soleus

Within the Gastrocnemius, there’s a flat muscle known as the Soleus. Since it’s deep within the Gastrocnemius, its origin and end are the same as the Gastrocnemius muscle. However, its primary responsibility is to maintain balance and posture.

Plantaris

Along the Gastrocnemius runs a muscle known as the Plantaris and its origin and end is the same. Additionally, its function is the same as the Gastrocnemius.

Popliteus

The Popliteus is the most notable behind-the-knee muscle. This small muscle is responsible for unlocking the knee joints by ensuring proper internal rotation of the tibia on the femur. This is important in movements where the knee needs to rotate, such as changing direction when running quickly or in other activities.

Flexor hallucis longus

This is a muscle that is found on the leg’s inner side and behind the tibia bone. It starts from the posterior side of the fibula and extends to insert into the big toes. It’s responsible for the movement of the big toe.

Flexor digitorum longus

This muscle is located towards the inner side of the legs, and behind the tibia bones. This starts from the posterior of the tibia and extends to insert into the toes. Its primary responsibility is flexing the toes.

Now, let’s turn our focus to hamstrings.

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Muscles in the back of the leg: What are hamstrings?

Hamstring exercises (Photo via Big Dodzy/Unsplash)

Hamstrings are located at the back of the thigh muscle and include three muscles:

Bicep femoris

The muscle group in the hamstrings has two parts: the long head and the short head.

The short head originates from the thigh bone (femur) and inserts itself into the fibula. This is a smaller bone between the two in the lower leg.

The long head, on the other hand, is also inserted into the fibula but it originates from a bone from the pelvis, ischial tuberosity.

This muscle group is primarily involved in knee flexion and hip extension.

Semitendinosus

This is another muscle group involved in hip extension and knee flexion. This muscle originates from the ischial tuberosity like the bicep femoris but inserts into the tibia (this is the larger out of the two bones of the lower leg).

Semimembranosus

Finally, this muscle group is involved in hip extension and knee flexion as well. Like the Semitendinosus, this originates at the ischial tuberosity and extends into the tibia.

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The hamstring muscles play a vital role in jumping, walking, running, and other types of lower body movements. They work alongside the quadriceps muscles that are located in the front of the thigh muscles, and together the muscle groups allow a wide range of lower body exercises.

Usually, the hamstring muscles behind the thigh are worked on during leg day workout routines. Some exercises such as deadlifts, sumo squats, leg curls and others focus on working on the hamstring muscles.

When you’re training your hamstrings, it’s important to understand that the other muscles in the back of the leg are also functioning at the same time. They might not be the primary muscle group that is getting impacted, but they’re definitely a part of the secondary muscle groups involved in compound exercises for hamstrings.