UPPER EXTREMITY AND THORAX, ANTERIOR. 307 



Insertion. The inner side of the base of the first phalanx 

 of the little finger, and by an extension to the extensor 

 tendon behind. 



Nerve Supply. The ulnar, by filaments from the eighth 

 cervical. 



Action. Abduction and flexion of the metacarpophalan- 

 geal joint, with extension of the last two phalanges of the 

 little finger. (See action of lumbricales and interossei.) 



Plexor Brevis Minimi Diglti. Fig. 66. 



Origin. From the annular ligament and hook of the 

 unciform bone. 



Insertion. Into the inner side of the base of the first 

 phalanx of the little finger. 



Nerve Supply. Ulnar. Same as for the abductor. 



Action. Flexor of first joint of little finger. 



NOTE. Between the abductor and flexor muscles pass the deep palmar 

 communicating artery and nerve. 



The Lumbricales. 



Four in number. 



Origin. Begin at the lower border of the annular liga- 

 ment from the anterior surface and radial border of all the 

 tendons of the flexor profundus digitorum. In addition, 

 the two inner muscles are attached to the ulnar sides of 

 the adjacent tendons. 



Insertion. Into the radial sides of the aponeurosis of the 

 extensor communis digitorum muscle opposite the first 

 phalanx. 



Nerve Supply. The two outer by the median the two 

 inner from the deep branch of the ulnar. 



Action. Flexion, abduction (from median line of the 

 body) of the first set of phalanges of the fingers ; extension 



