?68 SURGICAL APPLIED ANATOMY. [Chap xv. 



indicates the portion of nail formed during the illness, 

 and by watching its movement the rate of growth of the 

 nail can be estimated. The nail grows at the average 

 rate of -^nd of an inch per week. It may be noted that 

 each digital nerve gives a special branch of large size to 

 the pulp beneath the nail, and this explains the intense 

 pain felt when a foreign body is thrust under the nail. 



The fasciae. Beneath the skin of the palm is the 

 dense palmar fascia. This fascia gives almost as much 

 strength to the hand as would so much bone, while its 

 unyielding character, its comparative freedom from 

 vessels and nerves, render it well suited to withstand 

 the effects of pressure. The fascia gives slips to each 

 finger ; each slip sends fibres to join the digital sheaths 

 of the tendons, the skin, and the superficial transverse 

 ligament. In the disease known as Dupuytren's con- 

 traction, the palmar fascia, and especially its digital 

 slips, becomes contracted. One or more or all of the 

 fingers may be involved in the contraction. The first 

 phalanx is drawn or flexed towards the palm, and later 

 the second phalanx becomes bent also. The skin is 

 drawn in towards the fascia, since the two structures 

 are normally connected with one another. Experi- 

 ment shows that by dragging upon the fascia the first 

 phalanx can be readily bent, and also, but with less 

 ease, the second phalanx. 



The structures of the palm are divided into three 

 spaces by the fasciae (Fig. 27). Thus the muscles of the 

 thenar and hypothenar eminences are both enclosed in 

 a thin fascia proper to each. The two spaces formed by 

 these membranes are enclosed in all directions, and are 

 capable, though only in a feeble way, of limiting sup- 

 puration when it commences in them. Between these 

 two spaces is a third space, which is roofed in by the 

 palmar fascia. This cavity is closed in at the sides, 

 but is open above and below. Above there is a 

 free opening beneath the annular ligament and along 



