Muscles of the Legs: Anatomy and Their Functions

No one really looks forward to leg day. It takes a lot of energy, has a longer recovery time, and takes longer to see results. However, training the legs is important for building your overall fitness. This is because the legs are the foundation for your body. Not only do they help you move, but they are the source of your balance. Training your legs makes you more athletic and helps you build up the strength in your other lifts. Additionally, having a well rounded training schedule helps you avoid injuries in the future. Muscle imbalances, and poorly conditioned hamstrings can lead to issues such as lower back pain and ACL injuries. The goal of this post is to break down the muscles in your legs and the role they play in your movement. This will help you target your muscles more effectively to get the most out of your workouts.

Gluteal Muscles

Everyone loves the butt. Did you know that the Gluteal muscles are a family of three muscles which make up your butt? The gluteus maximus, gluteus medius, and gluteus minimus all make up your butt muscles. They Originate from the hip and attach to the upper section of your femur.

Gluteus Maximus

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Gluteus Maximus. Taken from wikipedia

The gluteus maximus is the largest and the heaviest muscles in the human body. This muscle is regarded as one of the strongest muscles in the human body. It sites on top of all the other muscles in the gluteal family. The Gluteus maximus main role is to pull your leg back and rotate the hip joint away from your body.

Gluteus Medius

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Gluteus Medius. Taken from wikipedia

The gluteus medius sits underneath the gluteus maximus. Although it is not as large or as strong as the gluteus maximus, it is just as important. This muscle is responsible for the motions of your hips. It helps flex and extend your hip. Additionally, it helps you rotate your hip both in and out.

Gluteus Minimus

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Gluteus Minimus. Taken from wikipedia

The gluteus minimus is the smallest of the three gluteal muscles. It is a small triangular muscle located deep within your hip. It lays underneath the gluteus medius. This muscle functions very similar to the gluteus medius. This muscle is responsible for flexing the hip and rotating the thigh in and out. Additionally, this muscle is responsible for helping you maintain your balance while you are on one leg.

Hamstring

The hamstring is a well known muscle group that can often be forgotten. Since they are not as visible as the quads or the glutes, people can neglect training them. Similar to the glutes, your hamstrings are a family of four individual muscles: the long head of the biceps femoris, the short head of the biceps femoris, the semitendinosus, and the semimembranosus. All of these muscles sit on the back of your leg and are responsible for pushing your legs back or bending your knee.

Long Head of the Biceps Femoris

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Bicept femoris. Taken from wikipedia

This is a smaller but incredibly long muscle that is very important to our hip and leg movements. This muscle starts in the inside of the pelvis and inserts on the outside of the knee. The long head is on the outside of the leg. This muscle is responsible for flexing the knee, extending the hip, and when the knee is flexed. Additionally, this muscle rotates the thigh when the hip is extended.

Short Head of the Biceps Femoris

The short head of the biceps femoris starts from the halfway point of your femur and joins the long head on the outside of your knee. This muscle sits underneath the long head. Similar to the long head, the short head is responsible for flexing the knee. Additionally, this muscle rotates your lower leg away from the body when the knee is flexed.

Semitendinosus

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Semitendinosus. Taken from wikipedia

This muscle lies between the bicep femoris muscle and the semimembranosus muscle. It originates at the base of the pelvis, and inserts at the back of your knee. Since this muscle links the hip and the leg, it provides movements on both the hip and the knee joints. It is responsible for thigh extension, inward rotation of the hip, straightening of the knee, and internal rotation of the knee.

Semimembranosus

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Semimembranosus. Taken from wikipedia.

This muscle sits underneath the semitendinosus muscle and is located on the inner portion of the back of your leg. This muscle starts from the base of your hip bone and goes to the back of your knee. It is responsible for extending the thigh, flexing the knee, and rotating the tibia towards the body.

Quadriceps

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Rectus femoris is blue, vastus lateralis is yellow, vastus intermedius is green, and vastus medialis is red. Taken from Bodyparts3D

The quadriceps or the quads is a large muscle group that sits on the front of your legs. Similar to the hamstrings and glutes, the quads are a family of four muscles: rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius. All four of these muscles are powerful extenters of the knee joint and are crucial for walking, running, jumping, and squatting.

Rectus Femoris

This is the most predominant quad muscle because it is situated in the middle front of the thigh. This muscle originates at the front of your hip and attaches to the front of the knee. This muscle is responsible for flexing the thigh at the hip and the knee. Interestingly, when the hip is extended this muscle is weakened. This is because it becomes shorter so is not as effective at extending the knee. Your body will use the other three quad muscles for knee extension if your hip is flexed.

Vastus Lateralis

This muscle is located on the outside of your thigh and is the largest muscle of the quadriceps group. it starts from the upper outside of the femur and inserts on the front of the knee. This muscle works with your other quad muscles to help you extend your knee. Additionally, this muscle helps maintain your thigh and kneecap position while you are walking or running.

Vastus Medialis

This muscle is opposite of the vastus lateralis. It makes up the inner portion of your thigh. This muscle starts from the inner portion of your upper femur and attaches at the front of your knee. It is responsible for helping you extend your knee joint and works with the vastus lateralis to help you maintain your thigh and kneecap position.

Vastus Intermedius

This is the deepest of the quad muscles and is located below the other three. It originates on your upper femur and attaches to the front of your knee. This muscle is responsible for extension of your knee joint.

Calf Muscles

BodyParts3D, © The Database Center for Life Science licensed under CC Attribution-Share Alike 2.1 Japan. Calf muscles, gastrocnemius and soleus
Gastrocnemius and soleus muscles. Image from BodyParts3D

The calf muscles are the muscles that are on the back of your lower leg. It is a family of two muscles: the gastrocnemius, and the soleus. Although this muscle groups is smaller than the quads, hamstrings, and glutes, it is equally as important. During walking, running, or jumping, the calf muscle pulls the heel up to help you with forward movement.

Gastrocnemius

This muscle is the largest and most prominent muscle of the calf. This two headed muscle is located on the back of the calf. It starts from the lower inside and outside sections of the femur and attaches to the bottom of your heel. This muscle moves your foot in a downward motion and helps you flex your knee.

Soleus

The soleus is the smaller muscle of your calf and is located underneath the gastrocnemius on the back of your lower leg. It starts from the upper section of the fibula and the inside of the tibia. This muscle is very powerful and is responsible for flexing your foot in a downward motion.

Conclusion

The muscles that make up the leg are some of the most important muscles in your body. They are the foundations for your strength, balance, and movement. Having a balanced lower body helps prevent injuries and builds up your strength in other areas of your body.

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