234 



POSTERIOR BRACHIAL REGION. 



Fig. 123. 1 



Ill the hand : after passing beneath the annular ligament, it is lodged in 

 the interspace between the two portions of the flexor brevis pollicis, and 

 afterwards in the tendinous theca of the phalanges. 



If the tendons of the last two muscles be drawn aside or divided, the 

 third muscle of this group will be brought into view, lying across the 

 lower part of the two bones. 



The PRONATOR QUADRATUS arises from the ulna, and is inserted into the 

 lower fourth of the oblique line, on the outer side of the radius. This 

 muscle occupies about the lo\ver fourth of the two bones, is broad at its 

 origin, and narrower at its insertion. 



Relations. By its anterior surface with the ten- 

 dons of the supinator longus, flexor carpi radialis, 

 flexor longus pollicis, flexor profundus digitorum, 

 and flexor carpi ulnaris, radial artery and veins, and 

 ulnar artery, veins, and nerve. By its posterior sur- 

 face with the radius, ulna, and interosseous mem- 

 brane. 



fictions. The pronator radii teres and pronator 

 quadratus muscles rotate the radius upon the ulna, 

 and render the hand prone. The remaining muscles 

 are flexors : two flexors of the wrist, flexor carpi ra- 

 dialis and ulnaris ; two of the fingers, flexor sublimis 

 and profundus, the former flexing the second pha- 

 langes, the latter the last ; one flexor of the last pha- 

 lanx of the thumb, flexor longus pollicis. The 

 palmaris longus is primarily a tensor of the palmar 

 fascia, and secondarily a flexor of the wrist and fore- 

 arm. 



Posterior Brachial Region. 



Superficial layer. 

 Supinator longus, 

 Extensor carpi radialis longior, 

 Extensor carpi radialis brevier. 

 Extensor communis digitorum, 

 Extensor minimi digiti, 

 Extensor carpi ulnaris, 

 Anconeus. 



Dissection. The integument is to be divided and 

 turned aside, and the fasciae removed in the same 

 manner as for the anterior brachial region. 



The SUPINATOR LONGUS muscle is placed along the radial border of the 

 fore-arm. It arises from the external condyloid ridge of the humerus, 

 nearly as high as the insertion of the deltoid, and is inserted into the base 

 of the styloid process of the radius. 



Relations. By its superficial surface with the extensor ossis metacarpi 

 pollicis, extensor primi internodii pollicis, and fascia of the fore-arm. By 



*The deep layer of muscles of the fore-arm. 1, The internal lateral ligament of the 

 elbow joint. 2. The anterior ligament. 3. The orbicular ligament of the head of the 

 radius. 4. The flexor profundus digitorum muscle. 5. The flexor longus pollicis. 6. 

 The pronator quadratus. 7. The adductor pollicis muscle. 8. The dorsal interosseous 

 muscle of the middle finger, and palmar interosseous of the ring finger. 9. The dorsal 

 iuterosser.us muscle of tht ring finger, and palmar interosseous of the little finger. 



