THE RADIUS 



153 



the tendon of the biceps, and a smooth anterior surface in relation with a bursa 

 which is situated between the tendon and the tuberosity. 



The body [corpus radii] or shaft is somew^hat prismatic in form, gradually in- 

 creasing in size from the upper to the lower end, and slightly curved so as to be 

 concave toward the ulna. Three borders and three surfaces may be recognised. 

 Of the borders, the medial or interosseous crest [crista interossea] is best marked. 

 Commencing at the posterior edge of the tuberosity, its first part is round and in- 

 distinct, and receives the attachment of the oblique cord of the radius; it is con- 



FiG. 181. — The Left Ulxa and Radius. (Postero-lateral view.) 



Triceps i^^^*fe*» 



Artirular capsule ^^^^^|i Olecranon 



Subcutaneous surface 



-Anconeus 



Lower limit of annular ligament 



Biceps 



Supinator 



-Abductor pollicis longus 



Abductor pollicis longus - 



Extensor pollicis brevis- 



Radius 



An aponeurosis is attached to this 

 border from which the flexor and 

 extensor carpi ulnaris, and flexor 

 digitorum profundus arise 



Extensor pollicis longus 



Ulna 



— Extensor indicis proprius 



Grooves for abductor longus and ex- 

 tensor pollicis brevis 

 For extensor carpi radialis longus_ 

 and brevis 



Extensor poUicis longus- 



-Eitensor quinti digiti proprius 

 -iixtensor carpi ulnaris 



..Ulnar collateral ligament 



Extensor digitorum communis 

 extensor indicis proprius 



and Posterior Posterior radio-ulnar ligament 

 radio-carpal 

 ligament 



tinned as a sharp ridge which divides near the lower extremity to become Continu- 

 ous with the anterior and posterior margins of the ulnar notch (sigmoid cavity). 

 The prominent ridge and the posterior of the two lower lines give attachment to 

 the interosseous membrane, whilst the triangular surface above the ulnar notch 

 receives a part of the pronator quadratus. The interosseous crest separates the 

 volar from the dorsal surface. The volar border [margo volaris] runs from the 

 tuberosity obliquely dowmw^ard to the lateral side of the bone and then descends 

 vertically to the anterior border of the styloid process. The upper third, eonsti- 



