Extensor Pollicis Longus
Hand
Its tendon forms one border of the 'anatomical snuffbox' — that little hollow when you extend your thumb.
Function
Extends IP joint of thumb, assists in thumb abduction
Origin
Posterior middle ulna and interosseous membrane
Insertion
Base of distal phalanx of thumb
Innervation
Posterior interosseous nerve (C7-C8)