ELASTIC TISSUE. 



hard, and brittle, when dried, but readily imbibes water again and regains 

 its original properties. It is resolved into gelatin by boiling. 



The fibrous tissue receives blood-vessels, but in general they are inconsi- 

 derable both in number and size compared with the mass of tissue to which 

 they belong. In tendons and ligaments with longitudinal fasciculi, the 

 chief branches of the vessels run parallel with and between the larger fasci- 

 culi, and, sending communicating branches across them, eventually form a 

 very open network with large oblong meshes. Some fibrous membranes, as 

 the periosteum and dura mater, are much more vascular ; but the vessels 

 seen in these membranes do not strictly belong to them, being destined for 

 the bones which they cover. The lymphatics of fibrous tissue are not suffi- 

 ciently known to be spoken of with certainty. 



As to nerves, their general existence in this texture has not been satis- 

 factorily demonstrated by anatomical investigation. Recent iuquiries into 

 this subject have shown that the smaller tendons contain no nerves, and the 

 larger only such nervous filaments as accompany and belong to the vessels ; 

 and the same is true of the ligaments. The fasciae and the sheaths of ten- 

 dons are also destitute of nerves. On the other hand, fine nerves have been 

 traced in the interosseous membrane of the leg, and nervous filaments are 

 even abundant in the periosteum, but the majority of them do not belong 

 to the membrane itself, but are destined for the subjacent bone. Nerves 

 have also been traced in the dura mater ; some accompany the vessels, 

 others appear destined for the membrane itself, and others again for the 

 bones. 



It has been proved by numerous observations and experiments, that the 

 tendons, ligaments, and other structures composed of fibrous tissue, are, in 

 the healthy state, quite insensible ; but then it is known, on the other hand, 

 that they occasion severe pain when inflamed, which cannot well be 

 accounted for on the supposition that they are entirely destitute of nerves. 

 Bichat, while he admitted their insensibility to cutting, burning, and most 

 other kinds of stimuli which cause pain in sensible textures, ascribed to 

 them a peculiar sensibility to twisting or to violent extension, and this 

 opinion has been supported by other authorities of weight, but the proofs 

 of it are not clear. 



Fibrous tissue readily heals and unites when divided, as is seen in cases 

 of broken tendo Achillis. It is very generally produced as a uniting 

 medium of broken bones when osseous union fails to take place ; and is com- 

 mon as a diseased production in various kinds of tumours. 



YELLOW OR ELASTIC TISSUE. 



Whilst the fibrous tissue is remarkable for its want of extensibility, and 

 owes its usefulness as a constituent of the frame in a great measure to that 

 character, the substance we have now to consider possesses this property in 

 a very high degree, and is employed wherever an extensible and highly 

 elastic material is required in the animal structure. 



Examples of this texture on a large scale are seen in the horse, ox, 

 elephant, and other large quadrupeds, in which it forms the great elastic 

 ligament, called ligamentum nuchce, that extends from the spines of the 

 vertebra to the occiput, and aids in sustaining the head ; in the same 

 animals it also forms an elastic subcutaneous fascia, which is spread over the 

 muscles of the abdomen and assists in supporting the contents of that 

 cavity. In the human body it is met with chiefly in the following situa- 

 tions, viz. : 



