ORIGIN

Posterior surface of the lower middle radius

 

INSERTION

Base of the proximal phalanx of the thumb

 

ACTION

Extension of the thumb at the carpometacarpal and metacarpophalangeal joints

Wrist abduction

Weak wrist extension

 

INNERVATION

Radial nerve (C6, C7)

 

PRIMARY JOINT

Wrist joint (carpometacarpal & metacarpophalangeal)

 

KEY STRENGTH TRAINING EXERCISES

Isometric thumb adduction stretch

 

NEW STRENGTH TRAINING EXERCISES

Thumb adduction stretch using resistance bands

 

COMMON INJURIES

Overuse

Straining/stiffness

Tear