PLATE VIII. 

 FRONT OF FOREARM, THIRD VIEW. 



This shows a still deeper dissection of the front of the forearm. The flexor sublimis 

 m has been cut away from its radial origin, and its origin from the internal 

 condyle, internal lateral ligament, and coronoid process turned inwards; its tendons 

 have been cut short at the wrist, showing the order in which they pass under the annular 

 ligament. The ulnar artery is thus also exposed with the deep layer of muscles. The 

 relation of the median nerve to the ulnar artery is well shown as the nerve passes 

 i.r! \\cfii the two heads of the pronator radii teres. If a comparison be made between 

 tin- radial artery in Plate VII. and the ulnar in this plate, it will be clearly seen how 

 superficial the radial lies and how easily it is reached by merely turning back the edge of 

 the supinator longus, whilst the ulnar is placed deeply and is not nearly so accessible, 

 lying as it does beneath the pronator and the flexor muscles arising from the internal 

 condyle of the humerus. 



Look out carefully for an occasional fusiform slip of origin of the flexor longus 

 pollicis, which arises from the ulna just below the deep origin of the pronator radii 

 teres, and runs down to join the ulnar border of the long flexor of the thumb. This 

 is, according to Professor Macalister, the remains of the obsolete superficial flexor of 

 the thumb. 



After finishing this layer of muscles, cut away the flexores profundus digitorum and 

 longus pollicis, and examine the pronator quadratus which lies beneath them covered in 

 by a special fascia of transverse fibres, in which, towards the radial side, are usually to be 

 seen a number of glistening longitudinal ones ; they are the degenerate remains of a 

 muscle called the flexor carpi radialis brevior (Wood), which in its fully developed 

 state arises from the radius just above the pronator, and, passing down, is inserted into 

 the second or third metacarpal bone, or, aborting, is attached to one of the carpal bonei 

 or fibrous tissue in front of the carpus. 



