Muscles of the Lower Limb | Anatomy Model

Overview of Leg Muscles

• Discussion focused on the muscles of the leg, from top to bottom.

Anterior Muscles of the Hip

Psoas Major

• Function: Prime mover for hip flexion.

Iliacus

• Function: Assists in hip flexion.

• Synergist to psoas major.

Sartorius

• Known as the tailor muscle.

• Functions:

  • Flexion at the hip and knee.

  • Lateral rotation (external rotation) of the leg.

Tensor Fasciae Latae

• Functions:

  • Flexion at the hip.

  • Medial (internal) rotation of the leg.

  • Tenses the iliotibial tract (IT band).

Quadriceps Femoris Group

• Consists of four muscles:

  • Rectus Femoris:

    • Function: Flexion at the hip and extension at the knee.

  • Vastus Medialis:

    • Function: Extension at the knee.

  • Vastus Lateralis:

    • Function: Extension at the knee.

  • Vastus Intermedius:

    • Function: Extension at the knee (deep to rectus femoris).

Gluteal Muscles

Gluteus Maximus

• Functions:

  • Extension at the hip joint.

  • Lateral (external) rotation at the hip joint.

Gluteus Medius

• Function: Abduction at the hip.

Gluteus Minimus

• Function: Abduction at the hip (deep to gluteus medius).

Lateral Rotators of the Hip

• Muscles include:

  • Piriformis: Lateral rotation.

  • Superior Gemellus: Lateral rotation.

  • Obturator Internus: Lateral rotation.

  • Inferior Gemellus: Lateral rotation.

  • Quadratus Femoris: Lateral rotation.

Hamstring Muscles

• Function: Extension at the hip and flexion at the knee.

• Muscles from lateral to medial:

  • Biceps Femoris:

    • Two heads (smaller and larger).

  • Semitendinosus:

    • Function: Extension at the hip and flexion at the knee.

  • Semimembranosus:

    • Function: Extension at the hip and flexion at the knee.

Adductor Muscles

• Functions: Adduction at the hip.

• Muscles include:

  • Adductor Magnus:

    • Primary muscle for adduction.

  • Adductor Brevis:

    • Deep to adductor magnus, also does adduction.

  • Gracilis:

    • Functions: Adduction at the hip, flexion at the knee, medial rotation.

  • Adductor Longus:

    • Function: Adduction at the hip.

  • Pectineus:

    • Function: Flexion at the hip.

SGT Muscles

• Refers to muscles inserting at the pes anserinus:

  • Sartorius - Flexes the hip and knee.

  • Gracilis - Adducts the hip.

  • Semitendinosus - Flexes the knee.

Muscles of the Lower Leg

Anterior Muscles

• Tibialis Anterior (Anterior Tibialis):

  • Function: Dorsiflexion and inversion at the ankle.

• Extensor Digitorum Longus:

  • Functions:

    • Dorsiflexion at the ankle.

    • Inversion of the ankle.

    • Extension of the digits.

• Peroneus (Fibularis) Muscles:

  • Peroneus Brevis (Fibularis Brevis):

    • Function: Eversion of the ankle.

  • Peroneus Longus (Fibularis Longus):

    • Function: Eversion of the ankle.

Posterior Muscles

• Gastrocnemius:

  • Two heads (medial and lateral).

  • Function: Plantar flexion.

• Plantaris:

  • Functions:

    • Flexion at the knee (to unlock the joint).

    • Plantar flexion.

• Soleus:

  • Function: Plantar flexion.

• Popliteus:

  • Function: Flexion at the knee (to unlock the joint).

• Flexor Hallucis Longus:

  • Function: Flexes the big toe.

• Tibialis Posterior:

  • Functions:

    • Plantar flexion.

    • Inversion at the ankle.

• Flexor Digitorum Longus:

  • Functions:

    • Flexes the digits.

    • Inversion of the ankle.

    • Plantar flexion.

Dorsiflexion is the movement of lifting the front part of the foot toward the shin, bringing the toes closer to the leg.

Inversion is the movement of the foot that turns the sole inward, toward the midline of the body.

Eversion is the movement of the foot that turns the sole outward, away from the midline of the body.

Origin and Insertion of Quadriceps FemorisThe Quadriceps Femoris group consists of four muscles:

1. Rectus Femoris:

   • Origin: Anterior inferior iliac spine (AIIS) and superior margin of the acetabulum.

   • Insertion: Tibial tuberosity via the patellar tendon.

2. Vastus Medialis:

   • Origin: Medial side of the femur.

   • Insertion: Tibial tuberosity via the patellar tendon.

3. Vastus Lateralis:

   • Origin: Lateral side of the femur.

   • Insertion: Tibial tuberosity via the patellar tendon.

4. Vastus Intermedius:

   • Origin: Anterior and lateral surfaces of the femur.

   • Insertion: Tibial tuberosity via the patellar tendon.