Flexion at IP joint of thumbs - by flexor pollicis longus Nerves that may be involved in supracondylar humerus : 1. Median nerve - most common Paial injury occurs usually. i.e. fibers involved in forming AIN branch. 2. Radial nerve - less often 3. Ulnar nerve - least commonly involved. AIN supply: Flexor pollicis longus * Lateral 1/2 of flexor digitorum profundus * Pronator quadratus