336 



APPLIED ANATOMY. 



-Extensor carpi radialis brevior 

 -Extensor carpi radialis longior 

 -Brachioradialis (supinator longus) 



The deep layer of the deep fascia covers the flexor sublimis digitorum and 

 passes downward beneath the flexor carpi radialis and brachioradialis muscles. It is 

 continuous below with the anterior annular ligament. 



The deep layer blends with the superficial layer to the radial side of the flexor 

 carpi radialis, and then merges with the posterior annular ligament to form the sheath 

 of two of the extensor muscles of the thumb. 



On the ulnar side the deep layer passes over the ulnar artery and vein and under 

 the flexor and extensor carpi ulnaris muscles, forming the posterior portion of their 



sheaths, and then merges with the pos- 

 terior annular ligament. 



The anterior anmilar ligament is 

 attached on the ulnar side to the pisi- 

 form bone and unciform process of the 

 unciform bone and on the radial side 

 to the trapezium and tuberosity of the 

 navicular (scaphoid). 



Over the anterior annular liga- 

 ment pass the ulnar artery and nerve, 

 the superficial volar artery, and the 

 palmar cutaneous branch of the median 

 nerve. 



Beneath the annular ligament pass 

 the median nerve, the flexor sublimis, 

 flexor profundus, and flexor longus pol- 

 licis tendons. These tendons are em- 

 braced in two sheaths, one for the 

 flexor longus pollicis and the other for 

 the flexors of the other four fingers, 

 the sheath for the little finger extend- 

 ing to the insertion of the profundus 

 tendon into the distal phalanx. The 

 tendinous sheaths accompany the ten- 

 dons for a distance of 2.5 to 5 cm. (i 

 to 2 in.) above the annular ligament. 

 Posteriorly. On the posterior 

 surface of the wrist the tendons may 

 be divided into two groups, an exten- 

 sor group and a radial group. The 

 extensor group is divided into a super- 

 ficial and deep set. The superficial set 

 is composed of the extensor communis 

 digitorum, the extensor minimi digiti 

 and the extensor carpi ulnaris. The 

 deep set is composed of the extensor 

 ossis metacarpi pollicis, extensor brevis 

 pollicis, extensor longus pollicis, and extensor indicis. The radial group, on the 

 posterior and outer surface of the radius, is composed of the extensor carpi radialis 

 longior, the extensor carpi radialis brevior, and the brachioradialis (Fig. 346). The 

 first two lie beneath the deep extensor muscles, thus practically forming a third layer. 

 All the tendons of the posterior and radial group of muscles, with the exception of 

 the brachioradialis, pass beneath the posterior annular ligament into the hand. The 

 brachioradialis inserts into the base of the styloid process of the radius. 



Posterior Annular Ligament. As the tendons pass down over the posterior 

 surface of the radius and ulna they are bound down by processes of the deep fascia 

 which form canals in which they run. The deep fascia of the posterior surface of 

 the forearm in the neighborhood of the wrist is strong, and forms the posterior 

 annular ligament. Its lower border is about level with the upper border of the 

 anterior annular ligament. It is attached externally to the posterior and outer edge 

 of the styloid process of the radius and internally to the posterior surface of the 



-Extensor ossis metacarpi pollicis 

 -Extensor brevis pollicis 

 -Styloid process of radius 



- Extensor carpi radialis longior 



- Extensor carpi radialis brevior 



- Extensor longus pollicis 



FIG. 346. Muscles of the radial side of the wrist. 



