THE MUSCLES 89 



comm., and its distal end separates the M. flex. ace. lat. from the M. 

 flex. ace. med. Since the MM. contrahentes digitorum (see below) 

 arise partly from the tendon of insertion of this muscle, as well as 

 from the carpalia, Ribbing concludes that they originally formed a 

 single muscle, and that the connexion with the carpalia is secondary. 



Innervation : From the R. medialis N. ulnaris. 



Function : It is the deep flexor muscle of the wrist. 



MM. contrahentes digitorum (m.c.d.). Ribbing (1907). 

 Flexor breves medii s. contrahentes digitorum 



Eisler (1895); McMurrich (1903). 

 Flexores digitorum profundi breves .... Osawa (1902). 

 (See also M. cap. long. muse, contra, for other homologies.) 



These form a series of small flexor muscles which lie deep to the 

 MM. flex, breves super., and superficial to the MM. flex. brev. prof. 

 They arise partly from the tendon of insertion of the M. cap. long, 

 muse, contra., and partly from the carpalia as follows : 

 The 4th digit. From the tendon and from the fourth and third 



carpalia. 

 The 3rd digit. From the tendon and mainly from the third carpal, 



but a few fibres arise from the second carpal also. 

 The 2nd digit. From the tendon and from the combined first and 



second carpal. 

 The ist digit. From the tendon and from the combined first and 



second carpal, not from the carpal of the prepollex (see also 



p. 42). 



All are inserted on the proximal ends of the corresponding proxi- 

 mal phalanges. Ribbing's result in not being able to find any con- 

 nexion between these muscles and the tendon of the M. flex. prim, 

 comm., described by McMurrich, is confirmed. Ribbing regards 

 the muscles as being derived from the M. cap long. muse, contra, 

 (see above). 



Innervation : From the palmar branches of the NN. ulnaris and 

 interosseus. 



Function : They serve both to flex the fingers and, to a less extent, 

 to approximate them towards one another. 



M. pronator prof undus (m.p.p.). Ribbing (1907). 



Flexor indicis digit! proprius .... Riidingcr (1868). 



Ulnari-metacarpi volares II-III . . . Hoffmann (1873-8). 



Palmaris profundus I . Eisler (1895); McMurrich (1903). 



Rotateur direct de la main (61) .... Perrin (il 



