LEGS

Legs are the lower extremity or the lower limbs of the human body. They constitute almost 60% of the body's musculature. It is important to learn the anatomy of the legs in order to understand how to optimally train the lower body. Legs support the body when we stand and they provide us the ability to walk, run, climb stairs and perform various other movements. They act as the pillars on which the body stands. Healthy and strong legs muscle can delay degenerative diseases like osteoarthritis in weight bearing joints like the knee, ankle, hip etc. Fully developed and balanced leg muscles also add a lot of aesthetic appeal to the body. The leg encompasses three major joints – the ankle, hip and the knee joint.

  • The Hip joint is a ball and socket joint which provides movement in all directions. You could say it is responsible for circumduction.
  • The work of straightening (extension) and bending (flexion) of the legs is done at the knee joint.
  • At the ankle, the two major movements are plantar flexion and dorsi flexion.

Legs consist of many muscles. The major ones are as follows.

1. QUADRICEPS

2. HAMSTRINGS

3. GLUTEAL GROUP

4. CALVES

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QUADRICEPS


Also known as quadriceps femoris, this muscle is present in the front of the thigh. The word “quadriceps” means four-headed muscle. It is ranked among the strongest muscles of the human body. Its main function is knee extension, similar to the movement we perform on a leg extension machine. The quadriceps consists of four separate muscles that fuse into one common tendon to insert on the patella. Because of their common insertion point, all four muscles have similar functions which is knee extension. The four muscles of quadriceps are…

  • Vastus medialis - It originates from the medial aspects of the shaft of the femur and inserts into the tibial tuberosity. It performs the function of knee extension.
  • Vastus lateralis - It originates from the greater trochanter and inserts into the tibial tuberosity. It also performs the same function of knee extension.
  • Vastus intermedius - It originates from the anterior surface of the shaft of the femur and inserts into the tibial tuberosity. It also performs the same function as the above two, i.e. knee extension.
  • Rectus femoris - It originates from the iliac spine of the ileum and inserts into the tibial tuberosity. It performs the functions of knee extension and hip flexion.

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HAMSTRINGS


Hamstring is located in the posterior compartment of the thigh. It consists of three muscles. Out of these three, one muscle has two different origins but shares a common insertion point. The Hamstring crosses two joints, the hip and the knee, and can act as the extensor of the hip and flexor of the knee. Hamstrings are instrumental in the stability of the knee joint. Most of us have weaker hamstrings as compared to quadriceps. This often leads to knee injuries due to the neglect of proper hamstring training. Hamstring comprises of the following four muscles:

  • Biceps femoris short head- It originates from the linea aspera which is a ridge on the shaft of the femur about 2/3rd of the way up and inserts into the head of the fibula and lateral condyle of the tibia. The function of this muscle is knee flexion.
  • Biceps femoris long head- It originates from the tuberosity of the ischium and inserts into the head of the fibula and lateral condyle of the tibia. It performs the function of knee flexion and hip extension.
  • Semi Tendinosus- It originates from the tuberosity of the ischium and inserts medial to the tibial tuberosity. It performs the function of knee flexion and hip extension.
  • Semi membranosus- It originates from the tuberosity of the ischium and inserts into the medial condyle of the tibia. It performs the functions of knee flexion and hip extension.

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GLUTEAL GROUP


The gluteal group is very actively dominant at the hip performing hip extension, external rotation and abduction at the hip joint. It involves one of the strongest muscles of the human body and stabilises our locomotion. The gluteal group plays a major role in major lifts such as the squats and the deadlifts.

  • Gluteal maximus- It originates from the iliac crest, sacrum and coccyx and inserts into the gluteal tuberosity of the femur and iliotibial tract. It performs the function of hip extension and hip external rotation.
  • Gluteal minimus- It originates from the gluteal surface of the ilium underneath the medius and inserts into the medius and inserts on the greater trochanter of the femur.
  • Gluteus medius- It originates from the gluteal surface of the ilium under the maximus and inserts into the greater trochanter of the femur.

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CALVES


Calves support the first and most crucial weight-bearing joint of our bodies – the ankle. They are heavily involved in standing, walking, skipping, running etc. In short, all of the activities which involve the legs. Calves are also referred to as the second heart of the body. They have a great aesthetic value too. No matter how well developed and balanced one’s thigh muscles are, they will only look aesthetically appealing if the calves are equally well developed.

  • Gastrocnemius - It is a two headed muscle that originates from the condyle of the femur and inserts into the posterior of the calcaneous. The function of this muscle is plantar flexion. This muscle works majorly in standing calf raise.
  • Soleus - It originates from the head of the fibula, down till the 1 quarter of the fibula and medial border of the tibia and inserts into the calcaneous and it lies underneath the gastrocnemius. The function of this muscle is plantar flexion and it works majorly in seated calf raise.
  • Tibialis anterior- It originates from the upper 2/3rd of the lateral aspect of the tibia and inserts into the tarsal and the first tarsal.

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