210 PRACTICAL ANATOMY. 



Insertion Lower one-fourth of anterior and outer 



surface of radius. 

 Nerve Anterior interosseous. 



MUSCLES ON THE RADIAL SIDE OF FOREARM. 

 SUPINATOR LONGUS. 



Origin Upper half of external condyloid ridge of 



humerus. 



Insertion Styloid process of radius. 

 Nerve Musculo-spiral. 

 EXTENSOR CARPI RADIALIS LONGIOR. 



Origin From external condyloid ridge of humerus. 

 Insertion Posterior surface of the bases of the meta- 



carpal hone of index finger. 

 Nerve Musculo-spiral. 

 EXTENSOR CARPI RADIALIS BREVIOR. 



Origin From external condyloid ridge below the 



extensor carpi radialis brevior, and external epicon- 



dyle. 

 Insertion Posterior surface of the base of the meta- 



carpal of the middle finger. 

 Nerves Musculo-spiral and posterior interosseous. 



POSTERIOR MUSCLES OF FOREARM. 



Superficial Layer. 

 EXTENSOR COMMUNIS DIGITORUM. 



Origin External epicondyle and intermuscular septa. 

 Insertion Divides into four tendons, which are in- 

 serted on the dorsal and lateral surfaces of the first, 

 second, and third phalanges. 

 Nerve Posterior interosseous. 

 EXTENSOR CARPI ULNARIS. 



Origin External epicondyle of middle one-third of 

 posterior surface of ulna. 



