THE UPPER LIMB 



391 



at either side with the thenar and hypothenar portions of the pabnar 

 fascia. It covers the extensor tendons, with which it is intimately 

 connected. Besides this fascia there is another fascial investment, 

 which is placed beneath the extensor tendons. This deeper layer 

 covers the dorsal interosseous muscles, and, in the intervals between 

 them, it is attached to the dorsal aspects of the shafts of the meta- 

 carpal bones. 



Second Part of the Radial Artery. — ^The second part of the vessel 

 winds backwards below the styloid process of the radius to the back 

 of the wrist. It extends from a point on the front of the radius 

 about ^ inch internal to the stj'loid process to the upper end of the 



Posterior Annular Ligament _ , 1 



1 



Extensor Minimi Digiti^ // 

 Extensor Carpi Ulnaris - 



- - -Extensor Communis 

 Digitonim 



, Radial Carpal Exleasors 



Extensor Brevis Pollicis 



-~ Extensor Long^s Pollicis 



Fig. 208. 



—The Synovial Sheaths of the Extensor Tendons 

 (after L. Testut's 'Anatomie Humaine'). 



first interosseous space on its posterior aspect, where it dips between 

 the two heads of the abductor indicis muscle, and ends in the third 

 part. Its course is at first backwards and then downwards. 



Relations — Superficial. — The mtegument, radial vein, branches of 

 the radial nerve, tendons of the extensor ossis metacarpi pollicis, 

 extensor brevis pollicis, and extensor longus pollicis, the latter 

 crossing the vessel just before it disappears between the two heads of 

 the abductor indicis. At first it is deeply placed, but afterwards 

 it is superficial, and, in the living subject, pulsation may be felt 

 in it m the triangular hollow below and behind the radial styloid 



