Musculus extensor carpi obliquus
Also known as the abductor pollicis longus, this muscle's tendon crosses obliquely over the dorsomedial carpus. It abducts and extends the carpus. Its tendon sheath is a common site of hygroma formation.
Origin: Lateral border of the radius
Insertion: Proximal MC2 (medial splint bone)
Action: Abducts the carpus medially; assists carpal extension
Innervation: Deep branch of the radial nerve (C7-T1)
The tendon sheath of this muscle frequently develops non-painful fluid swelling (hygroma) on the dorsomedial carpus.
The tendon sheath of this muscle frequently develops non-painful fluid swelling (hygroma) on the dorsomedial carpus. Signs include: Soft, fluctuant swelling on the medial-dorsal aspect of the knee; usually painless and cosmetic; may fluctuate in size; does not typically cause lameness; common in young horses.
See the Extensor Carpi Obliquus (Abductor Pollicis Longus) on our interactive 3D horse model. Open 3D Model