Muscles of the lower leg:foot

Muscles in the Lower Leg

  • The leg consists of three main compartments:

    • Anterior Compartment: Contains muscles responsible for dorsiflexion.

    • Lateral Compartment: Contains muscles that assist in eversion and stabilization.

    • Posterior Compartment: Includes muscles primarily responsible for plantar flexion.

Major Muscles by Compartment

Anterior Compartment

  • Tibialis Anterior:

    • Responsible for dorsiflexion and inversion of the foot.

    • Origin: Lateral condyle and upper tibial shaft; Insertion: First metatarsal bone.

  • Extensor Hallucis Longus:

    • Extends the big toe and assists in dorsiflexion.

    • Origin: Anteromedial fibula; Insertion: Distal phalanx of big toe.

  • Extensor Digitorum Longus:

    • Extends toes 2-5 and assists in dorsiflexion.

    • Origin: Lateral condyle of tibia; Insertion: Proximal, middle, and distal phalanges of toes 2-5.

  • Fibularis Tertius:

    • Assists in dorsiflexion and eversion; may be fused with extensor digitorum longus.

Lateral Compartment

  • Fibularis Longus:

    • Functions to lower the sole of the foot and assists in eversion;

    • Origin: Upper portion of lateral fibula; Insertion: Base of first metatarsal and medial cuneiform.

  • Fibularis Brevis:

    • Similar functions to fibularis longus but primarily inserts at fifth metatarsal.

Posterior Compartment

  • Superficial Muscles:

    • Gastrocnemius:

      • Major muscle contributing to plantar flexion and shape of the calf.

      • Origin: Condyles of the femur; Insertion: Calcaneus via the Achilles tendon.

    • Soleus:

      • Assist with plantar flexion, located beneath gastrocnemius.

      • Origin: Superior tibia; Insertion: Calcaneus.

    • Plantaris:

      • Assists in flexing the knee and plantar flexing the ankle; can be absent in some individuals.

  • Deep Muscles:

    • Popliteus:

      • Helps with knee flexion and rotation.

    • Flexor Digitorum Longus:

      • Flexes toes 2-5; Origin: Posterior tibia; Insertion: Distal phalanges of toes 2-5.

    • Flexor Hallucis Longus:

      • Flexes the big toe; Origin: Midshaft of fibula; Insertion: Distal phalanx of big toe.

    • Tibialis Posterior:

      • Main action is plantar flexion and helps with inversion.

Intrinsic Muscles of the Foot

  • Purpose: Support the arches and facilitate toe movements.

  • Plantar Aponeurosis:

    • Deep fascia supporting the arch; inflammation can cause plantar fasciitis.

Dorsal Group

  • Extensor Digitorum Brevis:

    • Responsible for extending toes 2-5.

Plantar Group (Four Layers)

  • Layer 1:

    • Flexor Digitorum Brevis: Flexes toes 2-4.

    • Abductor Hallucis: Abducts and flexes the big toe.

    • Abductor Digiti Minimi: Abducts and flexes the small toe.

  • Layer 2:

    • Lumbricals: Assist in flexing the proximal phalanges and extending the toes.

    • Quadratus Plantae: Flexes toes 2-5.

  • Layer 3:

    • Flexor Hallucis Brevis: Flexes the big toe.

    • Adductor Hallucis: Adducts and flexes the big toe.

  • Layer 4:

    • Dorsal Interossei: Abduct toes.

    • Plantar Interossei: Adduct toes.

Movements Supported by the Muscles of the Leg

  • Dorsiflexion: Upward lifting of the foot (Tibialis Anterior).

  • Plantar Flexion: Pointing the foot downwards (Gastrocnemius and Soleus).

  • Inversion: Turning the sole of the foot inward.

  • Eversion: Turning the sole of the foot outward.

Real-Life Application

  • Physical Therapists: Play a crucial role in injury rehabilitation, providing assessments, therapeutic exercises, and recovery planning for muscle and joint injuries.