THE HAND 87 



layer is reflected on to the tendon to become continuous with 

 the " visceral " layer,, so that the two enclose an elongated 

 bursal space. 



In the fcetus the tendon is invaginated into the synovial 

 bursa from behind, and at first possesses a " mesentery " 

 throughout its whole extent in the sheath. This complete 

 " mesentery " breaks down in places, but it persists as the liga- 

 mentum breve, a triangular fold attaching the terminal part of 

 the tendon to the floor of its canal, and as the ligamenta longa, 

 which connect it to the floor in two or three places at a more 

 proximal level (Fig. 29). 



The tendons of the flexor digitorum sublimis and profundus 



Transverse carpal ligament Tendons of flexor digitorum sublimis 



Median nerve 

 Tendon of flexor { 



pollicis longi 



Tendon of flexor 

 carpi radial 



Tendons of flexor digitorum profundus 



FIG. 31. Diagram of a Transverse Section through the Carpus, to show the 

 arrangement of the Synovial Sheaths. 



are provided with a single large sheath (the common palmar 

 sheath), which extends proximally as far as that of the flexor 

 pollicis longus. Its distal limit is oblique, reaching a more 

 distal level on the ulnar than on the radial side. The most 

 medial part of the sheath is carried distally on the tendons of 

 the little finger to their insertions (Fig. 32). 



Figure 31 represents a transverse section through the wrist 

 at the level of the transverse carpal ligament. From this it 

 will be seen that the tendons have been invaginated into the 

 common palmar sheath on its radial side, and have formed three 

 pouches one in front of the sublimis, pre-tendinous pouch ; one 

 between the two groups of tendons, inter -tendinous pouch ; and 

 a third, between the profundus and the floor of the carpal tunnel, 



6c 



