Musculus extensor digitorum lateralis
The lateral digital extensor of the hind limb originates from the lateral collateral ligament of the stifle and the proximal fibula. Its tendon passes under the lateral malleolus of the tibia and joins the long digital extensor tendon. It extends the hind digit and assists hock flexion. Innervation is via the peroneal (fibular) nerve (roughly L5–S2).
Origin: Lateral collateral ligament of the stifle and proximal fibula
Insertion: Joins the long digital extensor tendon
Action: Extends the hind digit; assists hock flexion
Innervation: Peroneal (fibular) nerve (L5-S2)
Isolated injury is uncommon. Trauma or laceration on the lateral hock or cannon can involve the tendon.
## Overview Peroneal (fibular) nerve paralysis affects the nerve that runs over the outside of the stifle. Injury, often from prolonged lateral recumbency on a hard surface, causes knuckling of the f
Swelling or lameness localized to the outside of the hock or cannon after injury should be checked.
## Overview Peroneal (fibular) nerve paralysis affects the nerve that runs over the outside of the stifle. Injury, often from prolonged lateral recumbency on a hard surface, causes knuckling of the fetlock, dragging of the toe, and inability to flex the hock and extend the digit. A characteristic goose-stepping gait may be seen during recovery. ## Causes Compression during anesthesia or recumbency, or direct trauma. ## Diagnosis Characteristic gait and neurologic examination. The horse cannot extend the digit or flex the hock properly. ## Treatment Supportive care, protection of the dorsum of the fetlock, and time. Most compressive injuries improve over days to weeks. Physical therapy helps. ## Recovery and Prognosis Good for compressive injuries if secondary trauma to the limb is prevented. Complete severance has a poorer outlook. ## Prevention Adequate padding during anesthesia and recumbency. Signs include: knuckling of the fetlock; dorsal hoof dragging; inability to flex the hock and extend the digit; goose-stepping gait during recovery
Isolated injury is uncommon. Trauma or laceration on the lateral hock or cannon can involve the tendon.
Swelling or lameness localized to the outside of the hock or cannon after injury should be checked.
See the Lateral Digital Extensor (Hind) on our interactive 3D horse model. Open 3D Model