FOREARM AND HAND 165 



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. 



Dissection. Open the carpal tunnel by making a vertical 

 incision through the middle of the transverse carpal ligament. 

 Clean the mucous sheaths from the flexor tendons, and separate 

 the tendons from one another, but be careful not to injure the 

 lumbrical muscles which spring from the tendons of the flexor 

 digitorum profundus. Be careful also not to injure the nerves 



Collateral interphalan- _-_ ^Flexor sheath 



geal ligament- 



lateral metacarpo- 

 phalangeal ligament 



brevia Vincula longa 



FIG. 72. Flexor Tendons of the Finger with Vincula tendinum. 



of supply from the lateral two lumbricals. They are twigs from 

 the digital branches of the median nerve, and have already been 

 found. The nerves to the medial two lumbricals are from the 

 deep division of the ulnar nerve. They will be found at a later 

 stage of the dissection. Clean the lumbrical muscles and then 

 examine the arrangement of the flexor tendons and the origins 

 and insertions of the lumbrical muscles. 



Flexor Tendons. The four tendons of the flexor sublimis 

 are arranged in pairs deep to the transverse carpal ligament; 

 those for the little and the index fingers lie dorsal to those 

 for the ring and middle fingers. Of the tendons of the 

 flexor profundus, only that for the index finger is distinct and 

 separate ; the other three, as a rule, remain united until they 

 emerge from under cover of the distal border of the transverse 

 carpal ligament. 



In the intermediate compartment of the palm the -flexor 

 tendons diverge from each other, and two, viz., one from the 

 flexor sublimis, and one from the flexor profundus, go to each 

 of the four fingers. From the tendons of the flexor profundus 

 the lumbrical muscles take origin, and those muscles, and the 

 volar digital nerves and arteries, will be seen occupying the 

 i 11 & 



