Musculus extensor digitorum lateralis
The lateral digital extensor originates from the lateral collateral ligament of the elbow and the lateral tuberosity of the radius. Its tendon passes over the lateral carpus and inserts on the dorsal surface of the proximal phalanx (P1). It extends the digit and assists carpal extension. It is innervated by the deep branch of the radial nerve (roughly C7–T1).
Origin: Lateral collateral ligament of the elbow and lateral tuberosity of the radius
Insertion: Dorsal surface of the proximal phalanx (P1)
Action: Extends the digit; assists carpal extension
Innervation: Deep branch of the radial nerve (C7-T1)
Isolated injury is uncommon. The tendon can be involved in lacerations or trauma on the lateral side of the limb.
## Overview Laceration of the extensor tendons on the dorsal cannon or pastern prevents normal limb protraction, causing knuckling or toe dragging. These injuries commonly result from wire cuts or in
Swelling or heat along the outside of the forearm or cannon after trauma should be evaluated.
## Overview Laceration of the extensor tendons on the dorsal cannon or pastern prevents normal limb protraction, causing knuckling or toe dragging. These injuries commonly result from wire cuts or interference wounds. ## Causes Sharp trauma severing the common or lateral digital extensor tendon. ## Diagnosis Visible wound plus functional deficit (knuckling). Ultrasound assesses the extent of tendon damage. ## Treatment Wound care, antibiotics, and external support (splint or cast) to maintain extension while the tendon heals. Surgical repair is performed in some cases. ## Recovery and Prognosis Fair to good with proper support. Complete severance has a more guarded functional outcome. ## Prevention Safe fencing and protective boots when indicated. Signs include: inability to extend the digit; knuckling; toe dragging; wound on the front of the cannon or pastern
Isolated injury is uncommon. The tendon can be involved in lacerations or trauma on the lateral side of the limb.
Swelling or heat along the outside of the forearm or cannon after trauma should be evaluated.
See the Lateral Digital Extensor on our interactive 3D horse model. Open 3D Model