66 CONNECTIVE TISSUE. 



again and regains its original properties. It is resolved into gelatin 

 by boiling. 



Vessels and Nerves. — The fibrous tissue receives tlood-vessels, but 

 in general they are inconsiderable both in number and size compared 

 with the mass of tissue to vrhich they belong. In tendons and liga- 

 ments Avith longitudinal fasciculi, the chief branches of the vessels run 

 parallel with and between the larger fasciculi, aud, sending communi- 

 cating 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. 



Lijmplmfics are contained in great abundance, as Ludwig and 

 Schweigger-Seidel'"-' have shown, ni the enveloping areolar-tissue 

 sheatlis of tendons and aponeuroses, where they form plexuses with 

 polygonal meshes. In addition to these a close net-work of lymphatic 

 vessels with elongated meshes may be injected in the deeper parts of the 

 tendons. A connection no doubt subsists between these lymphatics 

 and the cell-spaces of the fibrous structures : and it has been suggested, 

 with great probability, that those of the tendons are largely concerned 

 in the removal of matters derived from the attached muscles, in which 

 the existence of h^mphatic plexuses has not hitherto been established. 



As to n/rves, their existence in tendons and ligaments has not been 

 satisfactorily demonstrated by anatomical investigation. The fascia 

 and the sheaths of tendous 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 and ligaments 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. Bicliat, 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 sensi- 

 bility to twisting or to violent traction, and this opinion has been 

 supported by other authorities of weight, but the proofs of it are not 

 clear. 



Kegeneration. — 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 Itones when osseous union 

 fails to take place ; and is common as a diseased production in various 

 kinds of tumours. 



YELLOW OR ELASTIC TISSUE. 



Whilst the fibrous tissue is remarkable f(ir 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 



* Die Lymiiligefasse der Fascicen unci Schnfjn. Leipzig, 1870. 



