94 Anatomy Applied to Medicine and Surge* y. 



tached to the styloid process of the radius externally, and 

 to the ulnar styloid, the cuneiform and the pisiform bones 

 internally, forming the posterior annular ligament. This 

 ligament is somewhat oblique from without downwards 

 and inwards, and binds down the extensor tendons, with 

 their synovial sheaths, in the following order from without 

 inwards : Extensor ossis and extensor primi internodii 

 pollicis on the outer side of the styloid process ; extensor 

 carpi radialis longior and brevior behind the styloid pro- 

 cess ; extensor secundi on the inner side of a small bony 

 ridge about the middle of the lower extremity of the ra- 

 dius ; extensor communis digitorum and extensor indicis, 

 internal to the extensor secundi ; extensor minimi digiti, 

 between the ulna and the radius ; and, lastly, the extensor 

 carpi ulnaris behind the head of the ulna. On the back 

 of the hand, the extensor communis digitorum divides into 

 its tendons of insertion, which, after receiving the exten- 

 sor indicis and the extensor minimi digiti tendons, termi- 

 nate in expansions covering the backs of the first pha- 

 langes and are then inserted into the second and third 

 phalanges. These tendons on the back of the hand are 

 connected by small oblique slips, especially the tendon for 

 the ring finger, so that the latter finger cannot be freely 

 moved without, at the same time, moving the middle and 

 little fingers. The dorsal interossei are inserted in the same 

 manner as are the palmar interossei above mentioned. 



At the upper part of the radial side of this surface of 

 the hand is a triangular interval, formed by the extensor 

 ossis and the extensor primi internodii externally, and by 

 the extensor secundi internally. Its floor is formed by 

 the scaphoid and the trapezium with their connecting lig- 

 aments, while the radial vein and the cutaneous branches 

 of the radial nerve are found in the roof of the triangle. 

 This triangular space contains the radial artery in its 



