322 



^luscles 4^ the Arm. 



Radius 



Ulna 



~ Os pisiforiiic 



Os nietacarpale V 



Miu. interossei 

 volares 



Mm. interossei 

 dorsales 



Mm. 



^-lumbricales 

 (cut away) 



Phalanx I 



367. Mm. interossei volares manus dextrae. 



The vaginae teiidiuuiii digitales (sec Fig. 366) are four long sheaths, which on the volar 

 surface of the 2^^ 5*^ finger from the region of the capitulum oss. metacarpalis on, suiTound 

 the tendnns of the mm. flexores digitorum conmumes in common as far as the third jihalanx: 

 that of the 5'^ finger is connected in the adult with the vagina tendinum mm. fiexorum com- 

 munium. Each of these tendinous sheaths for the fingers is attached, for some distance, by a 

 ('onn(>ctive tissue sheath, lirfamenUan vaginalc , firmh* to the underlying hones and ligaments 

 (see also Fig. 241): in this sheath strung hands of fihers run, partly transversely, partly obliquely 

 and crossed, lir/amenta annuUaria and Ufjamenia cmciata digitorum maims (see Fig. 363). 



Mm. interossei volares (0. T. i)almar interossei), three flat, triangular, small muscles. 

 Position: in the depth of the pahn, in the mterspaces between the ossa metacarpalia IT ^V, 

 covered by all tlie otlier muscles of the palm. Origin: on the lateral surfaces of the ossa 

 metacarpalia the first on the idnar surface of the 2"^1 bone, the second and third on the 

 radial surfaces of the 4*^ and 5th (gp^ jiigo Fig. 150). Insertion: each of the narrow 

 tendons goes dorsalward from the lig. capitulorum transversum (see Fig. 241) on the same 

 sidi' (if the finger to the back of the first plialanx and to the triangular expansion of the 

 corresponding tendon of the m. e.xtensor digitorum communis (see Fig. 361). Action: they 

 draw the 2"fi, 4*^^ ;,nd Sth fingers toward the middle finger, flex the first phalanx and extend 

 the second and third phalanx of the 21^^ 4*^ and 5*^ finger. Innervation: ramus jtrofundus 

 of the ramus volaris manus n. ulnaris. 



