THE HAND 



eminences respectively. The central portion is exceedingly 

 dense, and prevents the forward spread of pus or blood. 

 Proximally, it blends with the transverse carpal ligament ; 

 distally, it widens out and breaks up into four slips, which become 

 continuous with the fibrous digital sheaths. 



On the palmar aspect of the fingers,, the deep fascia is 

 attached to the borders of the phalanges and to the inter- 

 phalangeal ligaments. On the terminal phalanx it is attached 

 to the palmar surface of the bone immediately beyond the 

 insertion of the tendon of the flexor digitorum profundus. In 

 this way it forms a fibrous sheath for the flexor tendons, which 

 lie in an osteo-fascial canal on the front of the fingers. The 



Vinculum breve 



Vinculum longum ! 



Insertion of flexor digitorum sublimis tendon | 



Fibrous sheath | 



Flexor digitorum sublimis tendon | 



Flexor digitorum profundus tendon 



FIG. 29. Longitudinal Section through the Third Finger, to show the 

 arrangement of the Fibrous and Synovial Sheaths. 



Light blue = articular cartilage. Green = periosteum. 



Dark blue = ligaments. Red = synovial membrane. 



sheath is thinner and weaker opposite the inter-phalangeal 

 joints, to allow of free flexion (Fig. 29). 



In the early stages of Dupuytren's Contraction the 

 metacarpo-phalangeal joints, generally of the ring and little 

 finger, become flexed, owing to an interstitial fibrosis of the 

 medial part of the central portion of the palmar aponeurosis. 

 Later, the inter-phalangeal joints also become flexed, as the 

 fibrosis attacks the weak areas which are present in the fibrous 

 digital sheaths opposite the joints. 



In Congenital Contraction of the Fingers, which also 

 affects the ring and little fingers, the metacarpo-phalangeal 

 joints are hyperextended and the inter-phalangeal joints are 

 flexed. This contraction, therefore, is not caused by the action 

 of the aponeurosis, but is suggestive of some functional in- 

 capacity of the lumbricals supplied by the ulnar nerve (p. 84). 



Qa 



