Ixxiv FIBROUS TISSUE. 



evident relation to the function of the membranes under which they lie. 

 Absorption readily takes place from the interstices of the texture, but that 

 process may be effected through the agency of blood-vessels as well as of 

 lymphatics. 



Larger and smaller branches of nerves also traverse this tissue on their 

 way to other parts ; but it has not been shown that any remain in it, and 

 accordingly it may be cut in a living animal apparently without giving pain, 

 except when the instrument meets with any of these traversing branches. 

 It is not improbable, however, that nerves end in those parts of the areolar 

 tissue, which, like that of the scrotum, contain contractile fibres ; but, if 

 present in such cases, the nerves, like the vessels of the fat, are, after all, 

 destined not to the areolar tissue but to another mixed with it. 



The physical properties of this texture have been sufficiently indicated in 

 the foregoing description ; also its want of sensibility. The vital contrac- 

 tility ascribed to certain portions of it is most probably due to the presence 

 of muscular tissue. 



With the exception of the epithelium, no tissue is so readily regenerated 

 as the areolar. It is formed in the healing of wounds and in the adhesion 

 of inflamed surfaces. It is produced also in many morbid growths. 



FIBROUS TISSUE. 



This substance is one of those which are serviceable in the body chiefly on 

 account of their mechanical properties, being employed to connect together 

 or to support and protect other parts. It is met with in the form of liga- 

 ments, connecting the bones together at the joints ; it forms the tendons of 

 muscles, into which their fleshy fibres are inserted, and which serve to attach 

 these fibres to the bones. In its investing and protecting character it 

 assumes the membranous form, and constitutes a class of membranes termed 

 "fibrous." Examples of these are seen in the periosteum and perichon- 

 drium which cover the bones and cartilages, in the dura mater which lines 

 the skull and protects the brain, and the fibrous layer which strengthens 

 the pericardium, also in the albugineous coat of the testicle, and the 

 sclerotic coat of the eye, which inclose the tender internal parts of these 

 organs. Fibrous membranes, named " aponeuroses " or " fascia;," are also 

 employed to envelope and bind down the muscles of different regions, of 

 which the great fascia inclosing the muscles of the thigh and leg is a well- 

 known example. The tendons of muscles, too, may assume the expanded 

 form of aponeuroses, as those of the broad muscles of the abdomen, which 

 form strong fibrous layers in the walls of that cavity and add to their 

 strength. It thus appears that the fibrous tissue presents itself under two 

 principal forms, the fascicular and the membranous. 



Physical Properties. The fibrous tissue is white or yellowish white, with 

 a shining, silvery, or nacreous aspect. It is exceedingly strong and tough, 

 yet peiiectly pliant ; but it is almost devoid of extensibility. By these 

 qualities it is admirably suited to the purposes to which it is applied in the 

 animal frame. By its inextensible character it maintains in apposition the 

 parts which it connects against any severing force short of that sufficient to 

 cause actual rupture, and this is resisted by its great strength, whilst its 

 flexibility permits of easy motion. Accordingly the ligaments and tendons 

 do not sensibly yield to extension in the strongest muscular efforts ; and 

 though they sometimes snap asunder, it is well known that bones will break 

 more readily than tendons of equal thickness. The fibrous membranes are 

 proportionally strong and alike inextensible ; they will gradually yield, it is 



