FLEXOR PROFUNDUS DIGITORUM. 



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sublimis digitorum, flexor carpi ul- 

 naris, median nerve, and ulnar ar- 

 tery, veins, and nerve. By its 

 posterior surface with the ulna, the 

 interosseous membrane, the prona- 

 tor quadratus, and the wrist-joint. 

 By its radial border with the flexor 

 longus pollicis, the anterior interos- 

 seous artery and nerve being inter- 

 posed. By its ulnar border with 

 the flexor carpi ulnaris. In the 

 hand : its tendons are in relation 

 superficially with the tendons of the 

 superficial flexor; and deeply with 

 the interossei muscles, adductor 

 pollicis, and deep palmar arch. In 

 the fingers : the tendons of the 

 deep flexor are interposed between 

 the tendons of the superficial flexor 

 and the phalanges, and give attach- 

 ment to yincula accessoria. 



The FLEXOR LONGUS POLLICIS 

 arises from the upper two- thirds of 

 the radius, and part of the interos- 

 seous membrane. Its tendon passes 

 beneath the annular ligament, to be 

 inserted into the base of the last 

 phalanx of the thumb. 



Relations. By its anterior sur- 

 face with the flexor sublimis digito- 

 rum, flexor carpi radialis, supinator 

 longus, and radial artery and veins. 

 By its posterior surface with the 

 radius, interosseous membrane, pro- 

 nator quadratus, and wrist-joint. 

 By its ulnar border it is separated 

 from the flexor profundus digitorum 

 by the anterior interosseous artery 



and nerve. In 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 deep layer of muscles of the fore-arm, 1. The internal lateral liga- 

 ment of the elbow-joint. 2. The anterior ligament. 3. The orbicular liga- 

 ment 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 dors"al interosseous muscle of the middle finger, and 

 palmar interosseous of the ring finger. Q. The dorsal interosseous muscle of 

 the ring-finger, and palmar interosseous of the little-finger. 



