REGION OF THE WRIST. 



34i 



If the hand is extended the tendon of the flexor carpi ulnaris stands out clearly. 

 In the hollow to its lateral (outer) side lie the ulnar nerve and artery. A rounded 

 muscular swell fills the space between the ulnar artery and the tendon of the palmaris 

 longus, it is caused by the flexor sublimis digitorum (see Fig. 350). It is here 

 that abscesses show when they travel up from the hand. 



Between the outer edge of the flexor carpi radialis tendon and the anterior outer 

 edge of the radius is a groove in which runs the radial artery. The position of the 

 extensor ossis metacarpi pollicis and extensor brevis pollicis which run together over 

 the outer surface of the radius can best be determined by abducting the thumb and 

 so making these tendons prominent (Fig 351). 



- Extensor longus pollicis 

 Extensor brevis pollicis 

 and extensor ossis metacarpi 

 pollicis 



"Anatomical snuff-box 



Tip of styloid process of 

 radius 



PIG. 3 si- Surface anatomy of the outer dorsal portion of the wrist, showing the anatomical snuff-box. 



In the same manner the extensor longus pollicis tendon can be made prominent 

 and followed to the posterior radial tubercle. By firm pressure the upper limits of 

 the first and second interosseous spaces can be felt. They mark the bases of the 

 metacarpal bones. The extensor carpi radialis longior passes across the snuff-box to 

 insert into the radial side of the base of the second metacarpal bone. The radial 

 artery as it dips down between the first and second metacarpal bones lies just to 

 its outer side. Crossing under the tendon of the extensor longus pollicis is the 

 extensor carpi radialis brevior, which proceeds to the top of the second interosseous 

 space to insert into the adjoining sides of the second and third metacarpal bones. 



In the chink between the radius and ulna lies the tendon of the extensor 

 minimi digiti. Between this tendon and the radial tubercle are the four tendons of the 



