Of the _flexors of the wrist_ the _flexor carpi radialis_ is inserted into the base of the index and usually of the third metacarpal bone, the _flexor carpi ulnaris_ into the fifth metacarpal, the pisiform and the unciform bones, while the _palmaris longus_ goes to the anterior annular ligament of the wrist and the palmar fascia of the hand. The _flexor sublimis digitorum_ is inserted by four tendons into the second phalanges of the fingers, while the _flexor profundus digitorum_ arises from the upper part of the ulna and is inserted into the last phalanges of the fingers. The _flexor of the thumb_ arises from the middle of the radius and is inserted into the last phalanx of the thumb. Which joint is flexed by a muscle depends upon the origin and insertion of the muscle, all those included between being affected. Thus, the _flexor sublimis digitorum_, which has its origin in part at least from the condyle and is inserted in the second phalanges of the fingers, flexes the forearm, wrist, and all the finger-joints but the last, while the _flexor profundus digitorum_, arising from the ulna, though it flexes the wrist and fingers, has no power of flexing the forearm. The _pronator radii teres_, besides arising from the supra-condylar ridge, rises from the coronoid process of the ulna. It is inserted into the middle of the outer surface of the radius and serves to pronate the forearm. The other pronator, the _pronator quadratus_, is a small quadrilateral muscle extending transversely across the radius and ulna just above their carpal extremities. It rises from the anterior surface of the ulna and is inserted into the anterior external border of the radius. On the back of the forearm the _anconeus_ serves to extend the forearm only, being inserted into the upper part of the posterior surface of the ulna. The _extensors of the wrist_ are inserted into the bases of the various metacarpal bones and have some power to extend the forearm as well as the wrist. The _extensors of the thumb_, as their names imply, go one to the metacarpal bone and one to each of the phalanges, the longest one extending the whole thumb, the others only a part. They rise from the ulna and radius, not the condyle. The _extensor communis digitorum_ goes to all the phalanges of all the fingers, the _extensor minimi digiti_ to those of the little finger only, and the _extensor indicis_ to those of the index finger, the last two arising short of the condyle. Of the _supinators_ the longer one is inserted into the styloid process of the radius, while the shorter one, the _supinator brevis_, is inserted into the upper part of the same bone, both thus serving to turn the radius on the ulna.