Name Abductor pollicis brevisPronunciation (ab-DUK-tor POL-uh-sus BREV-is) Origin/Proximal Attachment Distal border of flexor retinaculum Trapezium &scaphoid tubercles Insertion/Distal Attachment Lateral aspect of base of proximal phalanx of thumb +/- slip to tendon of extensor pollicis longus Action/Relevance Abducts thumb (at MCP joint) Assists to flex thumb (at MCP joint) If attached to extensor pollicis longus may assist to extend thumb Innervation Median nerve - recurrent branch (C8, T1) | 
