460 



MYOLOGY 



longus and brevis; (3) about the middle of the dorsal surface of the radius, for the 

 tendon of the Extensor pollicis longus; (4) to the medial side of the latter, for the 

 tendons of the Extensor digitorum communis and Extensor indicis proprius; (5) 

 opposite the interval between the radius and ulna, for the Extensor digiti quinti 

 proprius; (6) between the head and styloid process of the ulna, for the tendon of 

 the Extensor carpi ulnaris. The sheaths lining these compartments extend from 

 above the dorsal carpal ligament; those for the tendons of Abductor pollicis longus, 

 Extensor brevis pollicis, Extensores carpi radialis, and Extensor carpi ulnaris 

 stop immediately proximal to the bases of the metacarpal bones, while the sheaths 

 for Extensor communis digitorum, Extensor indicis proprius, and Extensor digiti 

 quinti proprius are prolonged to the junction of the proximal and intermediate 

 thirds of the metacarpus. 



Proper digital artery and nerve 



Ulnar artery and nerve 



FIG. 425. Tl 



ir aponeurosis. 



Palmar Aponeurosis (aponeurosis palmaris; palmar fascia') (Fig. 425). The 

 palmar aponeurosis invests the muscles of the palm, and consists of central, lateral, 

 and medial portions. 



The central portion occupies the middle of the palm, is triangular in shape, and 

 of great strength and thickness. Its apex is continuous with the lower margin 

 of the transverse carpal ligament, and receives the expanded tendon of the Pa) 



