FOREARM AND HAND 125 



tinguish two kinds, viz. vincula brevia and longa. In the 

 accompanying illustration (Fig. 50) the connections of these 

 may be seen. The vincula brevia are triangular folds, 

 which connect the tendons near their insertions to the 

 volar aspect of the adjacent phalanx. The vincula longa are 

 not invariably present. They are placed more proximally, 

 and are narrow, weak folds which pass between the tendons 

 and the bones. 



Insertions of the Flexor Tendons. The insertions of the 

 two flexor tendons can now be studied. On the volar side of 

 the first phalanx the tendon of the flexor sublimis becomes 

 flattened and folded round the subjacent cylindrical tendon 

 of the flexor profundus. It then splits into two parts, which 

 pass dorsal to the tendon of the flexor profundus, and allow 



Lateral interphalangeal _- ^ ^.Flexor sheath 



ligament- 



Lateral metacarpo- 

 phalangeal ligament 



_ 7 ^*^**^. 



brevia Ligamenta longa 



FIG. 50. Flexor Tendons of the Finger with Ligg. vaginalia. 



the latter to proceed onwards between them. Dorsal to the 

 deep tendon the two portions of the tendon of the flexor 

 sublimis become united by their margins, and then they 

 diverge, to be inserted into the borders of the body of the 

 second phalanx. 1 By this arrangement the flattened tendon 

 of the flexor sublimis forms a ring, or short tubular passage, 

 through which the tendon of the flexor profundus proceeds 

 onwards to the base of the ungual phalanx, into which it is 

 inserted. In each of the four fingers the same arrangement 

 is found ; the tendon of the flexor sublimis is inserted by two 

 slips into the margins of the volar surface of the second 

 phalanx, whilst the tendon of the flexor profundus is in- 

 serted into the volar aspect of the base of the terminal 

 phalanx. 



1 Where the margins of the two slips of the tendon of the flexor sublimis 

 are united behind the tendon of the flexor profundus, a decussation of fibres 

 takes place between the two slips. 



