154 ANATOMY OF UPPER EXTREMITY, ETC. 



The tendons of the flexor sublimis are to be divided and reflected 

 toward the fingers. 



The LUMBRICALES MUSCLES are small and delicate mus- 

 cular slips connected with the deep flexor tendons ; they 

 are usually four in number, sometimes only three, and 

 occasionally as many as six ; they arise from the radii 

 side of the tendon, near the annular ligament, and ai 

 partly concealed by the tendons of the flexor sublimis 

 digitorum; they are inserted into the tendinous expansions 

 of the extensor muscles covering the backs of the fingers. 



The tendons of the flexor profundus digitorum muscle, 

 the division of which takes place in the palm, enter the 

 sheaths of the tendons of the flexor sublimis, pass through 

 the split in these, and continue onward to be inserted into 

 the bases of the last phalanges. They are attached to the 

 phalanges and the capsules of the finger-joints along the 

 median line, by membranous folds, given off from their pos- 

 terior surface, and which contain elastic tissue ; these are 

 called the hgamenta brevia, or vincula subflava, and are 

 supposed to hold the tendons down when the fingers are 

 bent. 



The tendon of the flexor longus pollicis passes through 

 the annular ligament, externally to those of the flexor pro- 

 fundus, and turns outward between the heads of the flexor 

 brevis pollicis to be inserted into the last phalanx of the 

 thumb. 



The deep flexor tendons are to be divided and reflected toward the 

 fingers. 



The ADDUCTOR POLLICIS MUSCLE, obscured by the flexor 

 tendons at an earlier period of the dissection, is now seen 

 arising from the anterior two thirds of the metacarpal bone 

 of the middle finger, on its anterior aspect ; its fibres con- 

 verge to form a small tendon inserted into the inner side 

 of the first phalanx of the thumb. 



The radial artery enters the hand at the first interosse- 

 ous space, between the two heads of the abductor indicis 

 muscle. It furnishes a branch to the thumb, called the 

 princeps pollicis; this divides into two branches, which 

 pass along its sides and inosculate in its pulp ; another 

 branch, either from the radial or from the princeps pollicis, 

 supplies the radial side of the forefinger, and is known as 

 the radialis indicis; it unites at the end of the finger 

 with the digital branch furnished to the opposite side by 



