UPPER EXTREMITY AND THORAX, POSTERIOR. 379 



cuneiform bones. It is not attached to the ulna, but passes 

 over it, helping to hold it in place. 



By extensions from the inner surface of the ligament to 

 the ridges of the radius, the grooves upon the back of that 

 bone are converted into canals, through which the long 

 tendons of the muscles from the posterior of the forearm 

 to the hand pass. These canals are arranged as follows : 



Diag. 24. THE ANNULAR LIGAMENT OF THE WRIST AND THE APPROXIMATE 

 RELATIONS OF THE VARIOUS TENDONS. (/. S. /) i, Palmaris longus. 2, Middle 

 compartment of annular ligament, anterior, contains the tendons the flexor sublimis 

 and profundus digitorum, the flexor longus pollicis, and the median nerve. 3, Flexor 

 carpi radialis. 4, Extensor ossis metacarpi pollicis, extensor brevis pollicis. 5, Ex- 

 tensor carpi radialis longior and brevior. 6, Extensor longus pollicis. 7, Extensor 

 indicis, and 8, Extensor communis digitorum in one compartment. 9, Extensor minimi 

 digiti. 10, Extensor carpi ulnaris. n, Flexor carpi ulnaris. 12, Ulna. 13, Radius. 



Upon the outer side of the radius are the tendons of the 

 extensor metacarpi pollicis and the extensor brevis pollicis ; 

 upon the back of the radius at the outer side are the 

 tendons of the extensor carpi radialis longior and brevior, 

 separated, however, by the synovial membrane from each 



