DEEP FLEXOR OF THE FINGERS. 



219 



Fig. 181. 



The flexor profimdus digitorum, or flexor perforans, a large and thick 

 muscle, arises from the hollow at the inner side of the olecranon ; from the 

 inner and anterior surfaces of the ulna for three-fourths of its length ; 

 from the ulnar half of the interosseous liga- 

 ment for the same distance ; and from the 

 aponeurosis attaching the flexor carpi ulnaris 

 to the ulna. It divides inferiorly into four 

 tendons, only one of which, that for the index 

 finger, is distinct from the others above the 

 wrist the rest being connected together as 

 far as the palm. In the palm the tendons, 

 as they diverge, give origin to the lumbricales 

 muscles. Opposite the first phalanx, the 

 tendon of each finger passes through the 

 opening formed for its transmission in the 

 tendon of the flexor sublimis, and is inserted 

 into the base of the last phalanx. 



Fig. 181. DEEP ANTERIOR MUSCLES OF THE 

 FOREARM. 



The humeral muscles and the superficial muscles 

 of the forearm and hand, together with the lumbri- 

 cales, have been removed, and the place of the 

 anterior annular ligament of the carpus is marked 

 by two dotted lines, a, surface of the huraerus 

 above the coronoid fossa ; b, rough surface of the 

 ulna, into which the brachialis anticus is inserted ; 



c, head of the radius covered by the orbicular liga- 

 ment, and between this and a, the anterior ligament 

 of the elbow-joint; +, the internal lateral ligament; 



d, the lower end of the radius ; e, that of the ulna; 

 /, the scaphoid and trapezium bones ; g, the pisiform 

 l>one ; 1, supinator radii brevis ; 2, flexor longus 

 pollicis ; 3, flexor digitorum profundus ; 3', its four 

 tendons, where they are about to pass into the band 

 under the annular ligament ; 4, pronator quadratus 

 on the lower part of the radius ; 5, deep head of 

 flexor brevis pollicis ; 6, adductor pollicis ; 7, first 

 dorsal interosseous muscle ; 8, in the second space, 

 is placed between the first palmar and the second 

 dorsal interosseous muscles ; in the third space, 

 between the third dorsal and the second palmar ; 

 in the fourth space, between the fourth dorsal and 

 the third palmar. (For the lumbricales muscles, see 

 Figs. 180 and 186.) 



The upper extremity of this muscle embraces the 

 insertion of the brachialis anticus. On its surface 

 lie the median nerve and the ulnar artery and 

 nerve. The external border is parallel with the 



flexor longus pollicis, from which it is separated, on the interosseous membrane, by 

 the anterior interosseous vessels and nerve. The tendons are covered by the synovial 

 sacs, which have been mentioned in connection with the flexor sublimis. 



The lumbricales are four tapering fleshy fasciculi, passing from the 

 tendons of the flexor profundus to the first digital phalanges. They arise 

 by fleshy fibres from the outer or radial borders of the deep flexor tendons, 

 and proceed forwards to the radial sides of the fingers, where each ia 



