Abductor Pollicis Longus
Hand
Also involved in De Quervain's — that painful thumb tendinitis new parents get from lifting babies.
Function
Abducts and extends thumb at CMC joint
Origin
Posterior surfaces of radius, ulna, and interosseous membrane
Insertion
Base of 1st metacarpal
Innervation
Posterior interosseous nerve (C7-C8)