Musculus ulnaris lateralis
The ulnaris lateralis is a lateral forearm muscle. It originates from the lateral epicondyle of the humerus and the olecranon and inserts on the accessory carpal bone and proximal fourth and fifth metacarpals. Its actions are to flex the carpus and extend the elbow. It is innervated by the ulnar nerve (roughly C8-T2). It is also called extensor carpi ulnaris and contains a strong tendon that can be palpated on the lateral forearm.
Origin: Lateral epicondyle of the humerus and olecranon
Insertion: Accessory carpal bone and proximal MC4/5
Action: Flexes the carpus; extends the elbow
Innervation: Ulnar nerve (C8-T2)
Isolated injury is uncommon. Relevant in evaluations of carpal flexion and after trauma to the lateral forearm.
## Overview Lateral forearm strain is overuse injury to the muscles on the outside of the forearm that flex the carpus, most often from repetitive galloping or jumping. It produces swelling, heat, an
Not a structure of primary practical concern for owners under normal circumstances.
## Overview Lateral forearm strain is overuse injury to the muscles on the outside of the forearm that flex the carpus, most often from repetitive galloping or jumping. It produces swelling, heat, and pain on the lateral forearm and lameness that is worse at speed. ## Causes Repetitive carpal flexion under load. ## Diagnosis Palpation of pain and swelling, ultrasound of the muscle, and lameness examination. ## Treatment Rest, anti-inflammatories, cold therapy initially, and gradual return to work. Address any contributing training or shoeing factors. ## Recovery and Prognosis Good with adequate rest. ## Prevention Progressive conditioning and avoidance of sudden increases in speed work. Signs include: swelling on the lateral forearm; pain on palpation; lameness worse at speed; heat over the area
Isolated injury is uncommon. Relevant in evaluations of carpal flexion and after trauma to the lateral forearm.
Not a structure of primary practical concern for owners under normal circumstances.
See the Ulnaris Lateralis on our interactive 3D horse model. Open 3D Model