66 THE SUPERIOR EXTREMITY 



thumb is extended, the tendons of the abductor pollicis longus 

 (ext. oss. metacarp.) and the extensor pollicis brevis can be felt 

 on the radial side of the wrist, and when the tendons are relaxed, 

 the apex of the Styloid Process of the radius is found under 

 cover of them, half an inch distal to the radial ridge. A tubercle 

 (of Lister) is situated on the dorsal aspect of the distal end of 

 the radius, in the line of the cleft between the index and middle 

 fingers. 



The Dorsal Border of the Ulna is subcutaneous throughout 

 its whole extent, and, in muscular subjects, its position is 

 indicated by a furrow. The Styloid Process of the Ulna can 

 be found by tracing the dorsal border distally. It is placed on 

 the postero-medial aspect of the head and lies from a quarter 

 to half an inch proximal to the styloid process of the radius. 

 It corresponds to the level of the wrist -joint. When the hand 

 is flexed, the rounded Head of the Ulna can be felt just proximal 

 to the level of the radial ridge by displacing the tendon of the 

 flexor carpi ulnaris either to the ulnar or to the radial side. 

 When the hand is prone, the lateral surface of the head stands 

 out prominently on the ulnar side of the back of the wrist. 



The Tubercle of the Navicular (Scaphoid) is felt about 

 three-quarters of an inch distal to the radial ridge at the proximal 

 border of the thenar eminence. If the most distal skin crease 

 at the wrist is followed, it will be found to cross the tubercle 

 of the navicular, on the radial side, and the Pisiform Bone, on 

 the ulnar side. This latter bone is most easily identified by 

 allowing the hand to hang in a passively flexed position to 

 relax the flexor carpi ulnaris, as it may then be pinched between 

 the examining finger and thumb and made to glide on the os 

 triquetrum (cuneiform). The Hook of the Hamate (Unciform) 

 lies one finger's breadth distal to the pisiform and on a line with 

 the ulnar border of the ring finger. On deep palpation the 

 superficial division of the ulnar nerve may be rolled to and fro 

 over the prominence. The Ridge on the Os Multangulum 

 Majus (Trapezium) is placed immediately distal to the navicular 

 tubercle. 



Muscular Landmarks. The muscular mass inthe proximal 

 and lateral part of the forearm consists of the Brachio-Radialis 

 and the Extensor Carpi Radialis Longus and Brevis, which 

 arise from the lateral epicondylic ridge and the lateral epicondyle. 

 The medial margin of this group is indicated by a line drawn 

 from the tendon of the biceps to the styloid process of the 



