CHRISTIANIA VIDENSK.-SELSK. FORHANDL. 1 883. No. II. 



59 



85. * E William Turner. 

 Human anatomi/. Edinburgh 1882. P. 95. 



The radio-ulnar joints are found between the two bones of 

 the fore-arm. The head of the radius rolls in the lesser sig- 

 moid cavity of the ulna. and is enclosed by the annular ligameut; 

 the shafts of the two bones are connected together by the inter- 

 osseous membrane; their lower ends by a triangular fibro-car- 

 tilage or meniscus and a capsular ligameut lined by a sacciform 

 synovial membrane. The radius rotates about an axis drawn 

 through the centre of its head and the styloid process of the ulna; 

 rotation of the fore-arm and hand forward is called pronation. ro- 

 tation backwards, supination. 



«S6. * E George Viner Ellis. 

 Demonstrations of a ua tonn/. London 1882. P. 315. 



Movements of the radius. The radius moves forwards and 

 backwards aroimd the ulna. The forward motion, directing the 

 palm of the hand towards the grouud, is called pronation; and the 

 backward movement. by which the palm of the hand is placed up, 

 is named supination. In pronation the upper end of the bone 

 rotates within the band of the orbicular ligameut without shifting 

 its position to the ulna. The lower end. on the contrary. moves 

 over the ulna from the outer to the inner side. discribing half a 

 circle; and the shaft crosses obliquely that of 'the ulna. In supi- 

 nation the lower end of the radius turus backwards over the ulna; 

 the shafts come to be placed side by side. the radius being exter- 

 nal; and the upper end rotates from within out in its circular 

 band. In these movements the radius revolves round a line. inter- 

 nal to the shaft. which is prolonged upwards through the neck 

 and head of the bone, and downwards through the centre of a 

 circle of which the small sigmoid cavity of the ulna is a segment 

 (Ward). The upper end of the bone is kept in place by the orbi- 

 cular ligameut; the lower end by the triangular fibro-cartilage; 

 and the shafts are united by the interosseous ligameut. which is 

 tightened in supination, aud is relaxed in pronation. 



