Leg Muscles: Anatomy, Diagram & Functions

The muscles that provides support and balance are called leg muscles. These muscles also called lower limb muscles lies below the knee. Each lower limbs are divided into three parts: posterior, anterior, and lateral. The types of muscles in the leg differ in the upper leg and lower leg. Together they help maintain posture, walking, running and other physical activities where the legs are involved.

The two main muscles of the leg—the quadriceps and hamstrings—play a role in flexing and extending the hips and knees. The basis of the overall strength of the body is the strong leg muscles. These are essential for exercises requiring intense strength, such as lifting, climbing and sports.

Similarly, there are other important names of leg muscles that contribute to our daily life activities. Let’s discuss the topic in-depth along with some important questions.

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What are Leg Muscles?

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The legs in mammals as well as in human beings are the lower limbs of the body that provide support and movement in the ankle and foot for every individual. Leg muscles are made up of a variety of long muscles that help in stretching distances. Overstretching and excessive leg exercises may cause strain in leg muscles and even long-term leg injuries.

Depending on the part of the leg, the type of leg muscles varies. As discussed earlier, muscles of leg are composed of three groups: anterior, posterior, and lateral. The posterior part of leg muscle is a superficial layer made up of the gastrocnemius, plantaris, and soleus muscles, and a deep layer made up of the tibialis posterior, flexor hallucis longus, popliteus, and flexor digitorum longus.

The presence of leg muscles performs important functions in our human body such as:

• Movements
• Support
• Stretching
• Joint Stabilization & Rotation

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Anatomy of Leg Muscles 

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The anatomy of the leg muscles is complex and can be divided into components that include the muscles of the foot, lower leg, and thigh. These muscles serve a variety of purposes including support, stability, and movement. Upper leg muscles and lower leg muscles together make up the anatomy of the leg muscles.

Leg Muscles Anatomy

Upper Leg Muscles

The muscles of the upper leg provide more strength and support to the foot than the muscles of the lower limbs. These muscles extend from thighs to knees. The three muscles of the upper leg are: hamstrings, quadriceps and adductors which are discussed in detail below.

Hamstrings

The hamstrings are a group of three leg muscles that go down the back of the thighs. These muscles allow us to bend and flex our knees. Semimembranosus, semitendinosus, and biceps femoris together forms hamstring muscles. 

• These muscles play a major role in flexing and rotating the joints.
• Semimembranosus muscle are connected to the pelvis and the tibia via tendons.
• When the knee is flexed, these muscles help rotate the tibia on the femur, and when the hips are stretched, they help rotate the femur.
• Stretching the leg, bending the knee, and turning the knees outside the body are all assisted by the biceps femoris muscles.

The diagram of the hamstring leg muscles is shown below:

Quadriceps

The quadriceps muscles are composed of four muscles that lies in front of the thighs. The vastus lateralis, vastus medialis, and rectus femoris are the four quadriceps muscles. Knee extension, patella stabilization, hip flexion, and maintainence of posture are the important roles of quadriceps leg muscles. 

• The vastus lateralis muscles assist us to rise to a squatting position by strengthening the lower leg.
• The vastus medialis and vastus intermedius muscles help us stretch our knees.
• The rectus femoris muscles aid in knee extension and rise, as well as thigh flexion.
• The rectus femoris is the only muscle in the human body that can flex the hips.

Quadriceps Muscle

Adductors:

The adductors are a group of four leg muscles that are located on the inside of the thigh. It keeps the thighs securely in place. Adductor longus, adductor brevis, obturator externus, adductor magnus, and gracilis are the four adductor muscles. The adductor longus is a muscle in the thigh bone.

• The adductor magnus pulls and contracts the hip toward the midline of the body, allowing activities such as walking and running.
  By adducting the thigh at the hip joint, the adductor brevis assists in flexion and rotation of the thigh.
• The obturator externus muscles, together with other small muscles around the hip joint, contribute to stabilizing the joint.
• The gracilis muscles, which are located in the groin, are in charge of hip adduction and knee fleeing.

Lower Leg Muscles

The gastrocnemius, soleus, plantaris, tibialis, and peroneus muscles form the lower leg's five types of muscles. The gastrocnemius muscles are the calves' major muscles. The toes can point downward with the help of the Gastrocnemius muscles. The soleus muscles assist in walking and standing by supporting the knees.

Plantaris refers to the tiny muscles that run along the back of the lower thigh. The tibialis muscles can be found in both the front and rear of the lower leg. Only the extensors, tibialis posterior, flexors, tibialis anterior, and tibialis peroneal muscles are located in the front region of the lower leg.

Knee 

The knee connects the upper leg and lower legs. It comprises the knee ligaments, knee bones, and knee tendons. The leg muscles that provide support to the knee are the hamstrings and quadriceps muscles.

• Improper leg exercises and injury can lead to knee pain or even surgery in severe cases.
• Thus, the knee is covered with a knee cap to protect the knee from external damage.
• Leg exercises should be done only under the supervision of an expert so that there is no damage to the muscles of the legs.

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What are Leg Bones?

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Femur, tibia, fibula, and patella together form our leg bones. 

Anatomy of Leg Bones

Femur

The femur, or thigh bone, is the heaviest, strongest, and longest bone in the human body. It can withstand severe forces acting on the femur. The femur is the only bone found within the thigh. The femur is a bone that connects the pelvis to the lower leg bones. The femur's most notable feature is that it forms a ball-and-socket junction with the hip.

Tibia

The tibia is one of the two bones that make up the lower leg. It's also known as the shinbone or shank bone. The tibia is also the largest and most powerful bone in the lower leg. The tibia connects the ankle bone to the knee, according to anatomy.

Fibula

The fibula is the calf bone that links the upper and lower tibia. It can be found on the lateral side of the leg. The main role of the fibula is to connect muscles, rather than to carry weight. The lateral condyle of the tibia has three primary articulates with the fibula.

Patella

The patella is located at the meeting point of the femur and tibia bones of humans. It is also called knee cap which protects the knee from external shocks and injuries. In severe cases, when the injuries are so deep and severe, it can even damage the patella, which in turn causes damage to the knee.

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Things to Remember

• The femur is the longest, strongest, and heaviest bone in the human body. The femur bone's primary purpose is to support and stabilize gait.
• The calf is made up of the tibia or shinbone, which runs up the back of the lower leg, and the smaller fibula, which runs up the front. Cus or cnemis refers to the area of the leg between the knee and the ankle.
• The quadriceps are the biggest leg muscle in our body and runs from thighs to calves.
• Leg Cramps occurs due to dehydration, strain in muscles, overextension,

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Previous Year Questions

1. A deltoid ridge occurs in...[NEET 1990]
2. Number of cervical vertebrae in camel is...​[NEET 1990]
3. Stimulation of a muscle fiber by a motor neuron occurs at….[NEET 2014]
4. In human body which one of the following is an atomically correct ?​...[NEET 2007]
5. Which one of the following items gives its correct total number?...[NEET 2008]
6. ATPase enzyme needed for muscle contraction is located in -[NEET 2004]
7. Calcium is important in skeletal muscle contraction because it​...[NEET 2018]
8. Colle's fracture is associated with...[BHU UET 2009]
9. Inter-articulated disc is found in...[BHU UET 2005]
10. During strenuous exercise glucose is converted into...[BHU UET 2005]
11. Human vertebral column consists of 33 vertebrae and ________ bones...[BHU UET 2012]
12. Which of the following is correct for the pairs of cervical nerves and number of cervical vertebrae respectively ?​...[GUJCET 2009]