The extrinsic muscles are the long flexors and extensors. The extrinsic muscle groups are the long flexors and extensors. Stretching the flexors and extensors is helpful, as are strengthening exercises. The extensors generally belong to the anterior compartment and the flexors to the posterior. Tendons are classified as flexors (flex a joint) or extensors (extend a joint). The 2nd compartment contains extensors carpi radialis longus and brevis. All four quadriceps are powerful extensors of the knee joint. Three of the anterior muscles are extensors. The short intrinsic extensors and the plantar and dorsal interossei radiates into these aponeuroses. Therefore, increasing strength of wrist extensors will decrease the level of upper extremity disability. Combining single-limb squats and decline angles have been used to rehabilitate knee extensors. The primary function of the extensors is to straighten out the digits. The extensors are situated within 6 separate compartments.