THE FOREARM AND HAND. 1207 
joints from the front, incise along the highest of the creases in front of the joints ; 
whereas to cut into the terminal joints, incise along the lowest of the creases in 
front of the joints. Posteriorly, the first and terminal interphalangeal articu- 
lations are opposite the distal of the various creases overlying the joints. 
The most important muscular landmarks upon the front of the forearm are the 
supinator longus, the flexor carpi radialis and the pronator radii teres. The 
« 
= -~. 
~ Base of fifth metacarpal 
* Styloid process of third metacarpal— 
Radial artery —~ - Styloid process of ulna 
Extensor longus pollicis—— 
Extensor carpi radialis longior— \ \ Extensor communis digitorum 
\ 
Extensor carpi radialis brevior ) Extensor minimi digiti 
. : ans Extensor carpi ulnaris 
Extensor brevis pollicis 
Fira. 814.—DorsaL ASPECT OF HAND. 
supinator longus is thrown into prominence by flexing the semi-prone forearm 
against resistance. At the junction of the upper and middle thirds of the forearm 
the pronator radii teres passes beneath the supinator longus; between the two is 
the radial artery. The tendon of the flexor carpi radialis forms a prominent 
landmark descending along the middle of the anterior aspect of the forearm 
towards the ridge of the trapezium; the tendon of the palmaris longus, when 
present, 1s seen to its Inner side. 
At the back of the forearm the intermuscular septum between the radial and 
common extensors corresponds to the upper part of a line extending from the 
external epicondyle of the humerus to the tubercle on the back of the lower end of 
the radius. The posterior interosseous nerve, at the point at which it emerges from 
the substance of the supimator brevis, will be found at the bottom of this septum, 
2 in. below the head of the radius; below this point the septum is the best line 
along which to cut down upon the posterior surface of the radius. Winding across 
