THE FOREARM AND WRIST 



67 



radius. When resistance is offered to flexion of the elbow, 

 the brachio-radialis stands out prominently on the lateral 

 aspect of the forearm. 



The individual Flexor and Pronator muscles cannot be 

 clearly distinguished proximally, as they are closely bound 

 together by the deep fascia. Nearer the wrist, however, certain 

 of the tendons provide important surgical landmarks. The 

 largest and most prominent tendon is that of the Flexor Carpi 

 Radialis, which lies just medial to the navicular tubercle. In 

 flexion of the wrist the Palmaris Longus tendon, absent in 

 10 per cent, stands out on the ulnar side of the flexor carpi 

 radialis. It is the guide to the median nerve, which lies 

 immediately behind it, or to its radial side, in the distal part of 

 the forearm. The tendon of the Flexor Carpi Ulnaris can be 

 gripped between the fingers and thumb by inserting the fingers 

 on the medial border of the forearm opposite the distal end of 

 the ulna. It may then be traced to its insertion into the pisiform 

 bone. 



A line drawn from the lateral epicondyle to the dorsal radial 

 tubercle demarcates the Radial Extensors of the Wrist from 



Insertion 

 of deltoid 



Head of radius Extensor carpi radialis longus 



Lateral | | Dorsal interosse- 

 epicondyle . ! ous nerve Abductor 



; ; : I Extensor carpi pollicis 



radialis brevis longus 



Radial nerve 

 Triceps, lateral head 



Tendon of triceps 



Olecrano 



Head of ulna 

 : Extensor carpi ulnaris 

 ; Dorsal border of ulna 

 ! Flexor carpi ulnaris and 

 ] flexor digitorum profundus 

 Anconoeus 



FIG. 24. Surface Landmarks on the Dorsal Aspect of the 

 Superior Extremity. 



the Extensor Digitorum Communis. One inch from its 

 proximal extremity, it crosses the head of the radius, and at a 

 point two inches lower down, the dorsal interosseous nerve 

 emerges from the substance of the supinator (brevis). In its 

 distal third, the line is crossed obliquely by the muscular bellies 

 of the Abductor Pollicis Longus (Ext. Oss. Metacarp.) and 

 the Extensor Pollicis Brevis. These muscles lie superficial 

 to the radial extensor tendons of the wrist and are thrown into 

 relief on dorsi-flexion of the hand. 



