THE VLXA 



123 



A triangular depressed surface, posterior to the sublimis tubercle, gives origin to 

 the upper fibres of the Hexor profundus digitorum. To the outer side of the rough 

 surface for the br((ch!ali.^ antlcm is a triangular space, the base of which is repre- 

 sented by the lesser sigmoid cavity, which receives the lateral articular surface of 

 the head of the radius; the anterior and posterior margins of this cavity afford 

 attachment to the orbicular ligament. The rest of the triangle is depressed, and 

 gives origin to the supinator brevis. 



Fig. 1-29.— The Left Ulna and Radius. (Antero-interual view.) 



Capsular ligament - 



Internal lateral ligament 



Tubercle for the flexor sublimis 

 digitorum 

 Internal lateral ligament 



Braehialis antieus 

 Pronator radii teres 'lesser head) 



Flexor longus poUicis 'aeeeesory head 



Interosseous membrane 



Flexor profundus digitorum 



Pronator quadratus 



Anterior radio-ulnar ligament 

 Internal lateral ligament 



GREATER SIGMOID FOSSA 



HEAD OF RADIUS 

 NECK OF RADIUS 

 Lower limit of orbicular ligament 



Oblique ligament 



BICIPITAL TUBERCLE 



Oblique ligament 

 Supinator brevis 



Flexor sublimis digitorum 



OBLIQUE LINE 



RADIUS 



Pronator radii teres 



Flexor longus pollicis 



Interartieular flbro-cartilage 



Pronator quadratus 



Supinator longus 

 External lateral ligament 



Anterior radio-carpal ligament 



The shaft throughout the greater part of its extent is prismatic, but tajiers 

 towards the lower extremity, becoming thin and rounded in its lower third. It has 

 three borders and three surfaces. 



Of the three borders, the outer (or interosseous) is the most marked: it 

 commences at the apex of the triangle from which the supinator brevis arises, be- 

 comes very prominent in the middle of the bone, but is indefinite near its termina- 

 tion; the interosseous membrane is attached to it. The anterior border is directly 

 continuous with the inner edge of the rough surface for the braehialis antieus, and 



