ARTICULAR CARTILAGE. 
157 
arrangement of the capillaries of some of the largest 
specimens is represented in Fig. 122, a; similar pro- 
cesses, which no doubt secrete a fluid somewhat like 
synovia, are found within the sheaths of tendons, and 
upon those tendons which perforate or are perforated by 
others, as in the case of the flexor tendons of the fingers. 
Every part of the surface, both of the tendon and of 
the sheath in which it is contained, has a rich capillary 
network, except in such parts as are subjected to fric- 
tion. The vessels of the synovial sheath (Fig. 121) 
taken from the middle finger of an adult human subject 
are remarkable for the man- 
ner in which they are con- 
voluted into a somewhat he- 
liacal form, but the helices 
do not project far beyond the 
general surface of the syno- 
vial membrane. In another 
specimen, of larger size than 
the preceding, and which 
has been dried after injec- 
tion, the capillary net-work and the helices are beauti- 
fully shown, and still nearer the joint the vessels are 
more numerous. If a portion of this vascular mem- 
brane be removed and carefully examined with a power 
of two hundred and fifty diameters, the capillaries will 
he generally found to terminate in loops, but the synovial 
membrane itself extends some little distance beyond the 
vessels, in a few cases as far as ^th of an inch ; this non- 
FIG. 121 . 
Tortuous vessels from sheath of 
flexor tendon of the middle finger. 
