FLEXOR PEOFUXDUS. LU^EBRICALES. 



213 



The fiexor profundus digitorum, or flexor perforans, a large and 

 thick mnsele, arises from the hollow at the iuner 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 inter- 

 osseous ligament for the same distance ; Fig- 175. 

 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. 

 In front of the fingers they are bound to 

 the first and second phalanges in the 

 sheath common to them with the per- 

 forated tendons by the vaginal ligaments. 

 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. 175. — Deep Anterior ]\Iuscles of the 

 Forearm. (A. T.) ^ 



The superficial muscles of the forearm and hand, 

 together v/itli the lumbricales, have been removed, 

 and the place of the anterior annular ligament of the 

 carpvis is marked by two dotted lines. «, surface of 

 the humerus above the coronoid fossa ; b, rough sur- 

 face of the ulna, into which tJie brachialis anticus is 

 inserted ; c, head of the radius covered by the orbicu- 

 lar ligament, and between this and a, the anterior 

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

 ligament ; cl, the lower end of the radius ; c, tliat of 

 the ulna; /, tlie scaphoid and trapezium bones; 1, 

 supinator radii brevis ; 2, licxor longus pollicis ; 3, 

 flexor digitorum profundus ; 3', its four tendons, 

 where they are about to pass under the annular liga- 

 ment ; 4, pronator quadratus on the lower part of the 

 radius ; 5, deep head of flexor brevis pollicis ; 6, ad- 

 ductor pollicis ; 7, first dorsal interosseous muscle ; 

 S, 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 lumbri- 

 cales muscles, see Figs. 174 and 180.) 



Relations. — The upper extremity of this muscle embraces the insertion of the 

 brachialis anticus. On its sui-face lie the median ner^-e 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 men- 

 tioned in connection with the flexor sublimis. 



The lumbricales muscles are four tapering fleshy fasciculi, passing 

 from the tendons of tlie flexor profundus to the first digital phalanges. 

 Eacli_miiscle rises by fleshy fibres from the outer or radial border of one 



