DUPUYTEEN'S CONTEACTION. 143 



sac. If the theca of the tendons of the index, middle or ring 

 finger is the site of the mischief, it may be confined to the 

 digital part, but sometimes it may pass over the gap and involve 

 the common sac. If the theca of the flexor longus pollicis is 

 infected, suppuration may be limited to it, though occasionally 

 pus may find its way into the large palmar sac. 



If a thecal abscess is present, flexion of the terminal phalanx of 

 the digit becomes impossible, when the intermediate phalanx is 

 prevented from being flexed by the pressure of the surgeon's 

 finger against its palmar aspect. If the pus is superficial to 

 the sheath, this function of flexion of the terminal phalanx is pre- 

 served. An incision to evacuate the pus in a theca should be so 

 planned as to cause the least possible damage to the surrounding 

 structures. It is best to approach the sheath between the head 

 of the metacarpal bone and the first interphalangeal joint on the 

 palmar aspect, and in the median line of the digit. 



When incisions are needful higher in the palm of the hand, 

 they must not be carried nearer the wrist than the level of the 

 abducted thumb for fear of wounding the superficial palmar arch, 

 and should be in a line continued upwards from the middle line 

 of the finger. 



DISEASES OF FASCIA. 



Contraction of the Palmar Fascia (Dupuytren's) . The deep 

 fascia of the palm consists of three portions, the dense central 

 part or the palmar fascia proper, and the lateral portions, much 

 less important, covering the thenar and hypothenar muscles. 



The central portion consists of a strong, triangular layer of 

 white fibrous, almost ligamentous, tissue. The apex is attached 

 to the lower edge of the anterior annular ligament, and is con- 

 tinuous with the termination of the palmaris longus tendon, when 

 this is present. 



A very large number of fine bands pass from its superficial 

 aspect to become attached to the deep aspect of the skin. When 

 these are shortened, as in Dupuytren's contraction, they tend to 



