Flexor Hallucis Longus Anatomy

Extensor Digitorum Longus Muscle

Origin: Lateral condyle of the tibia, the proximal two-thirds of the medial surface of the fibula, the adjacent anterior surface of the interosseous membrane, the anterior intermuscular septum, and the septum between it and tibialis anterior.
Insertion: Divides into four slips and inserts at the base of each of the lateral four proximal phalanges. Each tendon then divides into three slips: an intermediate slip, which attaches to the base of the middle phalanx, and two collateral slips, which attach to the base of the distal phalanx.
Actions: Extension of the four lateral toes
Innervation: Deep peroneal nerve (L5, S1)
Blood Supply: Branches from the anterior tibial artery

Primary Actions of the Extensor Digitorum Longus

1.  Extension of the four lateral toes at the proximal interphalangeal joints

Agonists:

  • Extensor Digitorum Brevis

Antagonists:

  • Flexor Digitorum Longus
  • Flexor Digitorum Brevis

Lumbricals, dorsal interossei, and plantar interossei assist with extension of the four lateral toes at the proximal interphalangeal joints.

2.  Extension of the four lateral toes at the distal interphalangeal joints

Agonists:

  • None

Antagonists:

  • Flexor Digitorum Longus

Lumbricals, dorsal interossei, and plantar interossei assist with extension of the four lateral toes at the distal interphalangeal joints.

3.  Extension of the four lateral toes at the metatarsophalangeal joints

Agonists:

  • Extensor Digitorum Brevis

Antagonists:

  • Flexor Digitorum Longus
  • Flexor Digitorum Brevis
  • Flexor Digiti Minimi (fifth digit)

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Secondary Actions of the Extensor Digitorum Longus

1. Assists with dorsiflexion of the foot at the ankle
Agonists:

  • Tibialis Anterior

Antagonists:

  • Gastrocnemius
  • Soleus

Extensor hallucis longus and peroneus tertius also assist with dorsiflexion of the foot