FOREARM, WRIST, AND HAND. 



forearm into four parts; each part has a tendon. In the digi- 

 tal sheath each tendon splits in two parts which surround the 

 tendon of the deep flexor, then partly reunite, and then partly 

 decussate. Insertion; sides of second phalanx of each finger, 

 in two portions. The vincula accessoria are additional inser- 

 tions. They consist of triangular bands (ligamenta brevid), 

 which pass from each tendon, near its insertion, to the front of 

 the inter-phalangeal joint and head of the first phalanx; and 

 of narrow bands (ligamenta longa) , which run from the back of 

 each tendon to the upper part of the front of the first pha- 

 lanx. [341] 



Deep Layer. 



Flexor Prof undus Digitorum. Origin ; anterior and inner 

 surfaces of ulna, including inner side of olecranon process and 

 embracing insertion of Brachialis anticus; middle third of 

 inner half of interosseous membrane; deep fascia. Course; 

 its broad tendon divides in the palm into four tendons; the 

 index finger tendon is usually separate from the rest through- 

 out; each tendon pierces that of the Flexor sublimis opposite 

 the first phalanx. Insertion; base of terminal phalanx of each 

 finger. The tendons, like those of the Flexor sublimis digi- 

 torum, have vincula accessoria; ligamenta brevia attached to 

 the capsules of the second interphalangeal joints, and liga- 

 menta longa attached to the subjacent Flexor sublimis ten- 

 dons. [342] 



Lumbricales. These are four small muscles arising from the 

 Flexor prof undus tendons. Origin; (two outermost) radial 

 side of first and second tendons; (two innermost) adjacent 

 sides of second and third, and third 'and fourth tendons, each 

 by two heads. Insertion; radial side of each metacarpo- 

 phalangeal joint capsule, outer border of first phalanx, and 

 outer side of extensor tendon of each finger. [343] 



Flexor Longus Pollicis. Origin; middle two-fourths of 

 front of radius, from oblique line to insertion of Pronator 



[171] 



