Lower Body - Muscles and Joint Actions


Major Muscles of the Lower Body

The following list consists of the larger muscle groups primarily responsible for the gross movement for the lower body. 

Actions at the hip joint:

  • Flexion
  • External rotation
  • Anterior Pelvic Tilt
  • Actions at the hip joint:

  • Flexion
  • Abduction
  • Internal rotation
  • Actions:

    Flexion, abduction, and external rotation of the hip. Flexion of the knee

    Actions at the hip joint:

  • Extension
  • External rotation
  • The quadriceps are made up of 4 individual muscles (The Vastus Group - 3 in total, and the Rectus Femoris)

    Actions:

    Extension of the knee & flexion of the hip (rectus femoris only).

    *it may be important to note that the rectus femoris acts as a hip flexor while the vastus medialis, vastus lateralis, and vastus intermedius only extend the knee.

    The hamstrings are made up of 3 individual muscles (Semitendinosus, Semimembranosus, and Bicep Femoris)

    Actions:

    Flexion the knee & extension of the hip (bicep femoris only).

    *it may be important to note that the bicep femoris assists to extend the hip as well as contribute to knee flexion

    The calves are made up of 2 individual muscles (Gastrocnemius & Soleus)

    Actions:

    Plantar flexion of the ankle and flexion of the knee (gastrocnemius only)

    *it may be important to note that the gastrocnemius flexes the knee while both muscles contribute to plantar flexion at the ankle




    Smaller Muscles of the Lower Body

    The following list consists of the smaller muscle groups primarily responsible for stabilisation and or to act as a synergyst to the primary movers. Often these smaller muscles can be called postural muscles and contain a higher percentage of Type I muscle fibers.

    Actions at the hip joint:

  • Abduction
  • Internal rotation (anterior fibers)
  • External rotation (posterior fibers)
  • Purple is minimus, Red is medius.

    There are 5 hip adductors: (adductor magnus, adductor longus, adductor brevis, pectineus, gracilis)

    Actions: Hip adduction

    *it may be important to note that each of the muscles listed above performs other actions, but this information may be too in depth

    **you can remember the muscles which adduct the hip with the sentence: 3 ducks pecking grass

    There are 6 external hip rotators: (piriformis, obturator internus, obturator externus, superior gemellus, inferior gemellus, quadratus femoris)

    Actions: External rotation of the hip

    Action: Dorsi flexion of the ankle

    *often a weak anterior tibialis can contribute to 'shin splints', especially with activities which require active dorsi flexion (running, sprinting, walking uphill).

    *Not a muscle, included due to its relevance to training. The IT band is tendonous material that attaches to the iliac crest, gluteal muscles, as well as the tensor fascia latae and inserts on the outer edge of the knee.

    With unbalanced exercise programs or inadequate rest and recovery this band can contribute to knee pain associated with flexion and extension of the knee.

    Last modified: Monday, 25 February 2019, 10:32 AM