152 



THE SKELETON 

 THE RADIUS 



The radius (figs. 180-185) is the lateral and shorter of the two bones of the 

 forearm. Above, it articulates with the humerus; below, with the carpus; and 

 on the medial side with the ulna. It presents for examination a shaft and two 

 extremities. 



The upper extremity, smaller than the lower, includes the head, neck, and 

 tuberosity. The head [capitulum], covered with cartilage in the recent state, is 

 a circular disc forming the expanded, articular end of the bone. Superiorly it 

 presents the capitular depression [fovea capituli] for the reception of the capitulum 



Fig. 180. — ^The Left Ulna and Radius. (Antero-medial view.) 



Articular capsule' 

 Ulnar collateral ligament' 



\ ^^^ 



Head of radius 



Brachialis ff!^'^ '//#'" T' Neck of radius 



Pronator teres (lesser head) tiilil?^ 1 iiltk^l^ 'Lower limit of annular ligament 



Flexor pollicis longus (accessory head) MiiMiJIM. ^5 Oblique ligament 



Tuberosity 



Semilunar notch 



Tubercle for the flexor digitorum sublimis 

 Ulnar collateral ligament 



Ubia 



Interosseous membrane. 



Flexor digitorum profundus- 



Pronator quadratus 



Anterior radio-ulnar ligament MjlS;i;i!SlsS'"'«l 



Ulnar collateral ligament ^' 



Interarticular fibro-cartilage 



Oblique ligament 



Flexor sublimis digitorum 



Pronator teres 



Flexor pollicis longus 



Pronator quadratus 



Brachio-radialis 



Radial collateral ligament 



Anterior radio-carpal ligament 



of the humerus; its circumference [circumferentia articularis], deeper on the 

 medial aspect, articulates with the radial notch (lesser sigmoid cavity) of the ulna, 

 and is narrow elsewhere for the annular ligament l)y which it is embraced. Below 

 the head is a short cylindrical portion of bone, somewhat constricted, and known 

 as the neck. The upper part is surrounded by the ligament which embraces the 

 head, and below this it gives insertion antero-laterally to the supinator. Below 

 the neck, at the antero-medial aspect of the bone, is an oval eminence, the radial 

 tuberosity, divisible into two parts : a rough posterior portion for the insertion of" 



I 



