FIBROUS TISSUE. 



203 



6. Tendons. These organs, which serve to 

 connect the muscles to the osseous system, 

 are composed of fibres so closely disposed 

 that some anatomists, but erroneously, doubt 

 their identity with the other fibrous organs. 

 This compactness is owing to the extreme con- 

 densation of the intervening cellular tissue, 

 which is also the cause of these bodies re- 

 sistini; for a longer period than the ligamen- 

 tous or fascial structures, the influence of ma- 

 ceration. 



Every tendon is united by one of its ex- 

 tremities to the fibres of the muscle to which 

 it belongs, and by the other it is connected 

 with the bone or other part on which the 

 muscle is destined to act. The exact mode 

 of connexion between the tendinous and mus- 

 cular tissues is difficult to determine. Ocular 

 and microscopical inspection seem to prove 

 that the tendinous fibres result from the con- 

 tinuation and condensation of those cellular 

 sheaths, which inclose and in part form the 

 muscular fibrils. It has, however, been stated 

 that there is an intermediate substance between 

 the muscle and the tendon, different from 

 both of them, and serving to connect them 

 together. The details relative to the mecha- 

 nical disposition of these organs belong to the 

 consideration of the muscular system. See 



AlfSCLE. 



II. YELLOW ELASTIC FIBROUS ORGANS. 

 ( Tela elastica. ) It was justly observed by 

 Hie hat that the ligaments placed between the 

 arches of the vertebra differ in their nature 

 from the other ligaments of the body; and 

 modern anatomists, admitting this distinction, 

 have enumerated the following structures as a 

 separate class of the fibrous organs : the yellow 

 ligaments of the spine ; the external and espe- 

 cially the middle or proper membrane of the 

 arteries, the fibrous covering of the excretory 

 ducts ; the ligamentous tissue joining the carti- 

 lages of the air-passages ; the fibrous envelope 

 of the cavernous bodies of the penis and clitoris, 

 and of the vesiculse seminales. 



Although the highest authorities consider 

 that the middle tunic of the arteries is com- 

 posed of this tissue, yet the correctness of this 

 opinion is very doubtful. It is true that, as 

 far as colour is concerned, the similarity is 

 well founded ; but the arterial fibrous coat is 

 endowed with a power of contraction, evi- 

 dently distinct from mere elastic contraction, 

 which is totally wanting in the true yellow 

 fibrous tissue. 



In addition to the parts above named, it is 

 necessary to add that in certain organs where 

 great elasticity is requisite there is a peculiar 

 yellow cellular substance, which, although it 

 does not present the dense and fibrous cha- 

 racter, appears to belong essentially to the 

 organs under consideration. This texture is 

 particularly distinct in the mucous folds 

 which constitute the superior boundary of the 

 glottis, a part that is remarkable for its extra- 

 ordinary elasticity.* 



It is staled by Sir E. Home (Lect. on Comp. 

 \ii.n . vol. ii. p. 49,) that this tissue enters into the 



It occasionally happens, as in th forma- 

 tion of the intervertebral substance, that the 

 yellow fibrous tissue and the common liga- 

 mentous are combined. A more striking 

 instance of this combination is seen in the 

 construction of the connecting ligament which 

 forms the hinge in bivalve shells, in which one 

 part, the external, is composed of ligamentous 

 matter, whilst another, the internal, consists 

 of a highly elastic fibrous tissue. 



Organization and properties. If the yellow 

 ligament of the spine or the ligaraentum nu- 

 chse in ruminants be examined, it will be seen 

 that each is smooth on its surface, and is made 

 up of a great number of longitudinal and 

 highly elastic fibres, which, in the latter in- 

 stance, are readily separated and unravelled 

 by the finger. This texture is, I believe, sui 

 generis, and is altogether distinct from the 

 common ligamentous structures. In a recent 

 publication,* M. Laurent conceives that this 

 tissue is intermediate in its characters to the 

 tutus tclireux (under which terra he proposes 

 to class the white fibrous organs, the cartilages 

 and bones,) and the muscular tissue; he there- 

 fore calls it tutu sclero-sarceux. Although it 

 is very doubtful if the elastic fibrous structures 

 have any thing in their organization similar to 

 the muscular fibre, yet it is certain that in 

 function they are intermediate between the 

 common ligaments and the muscles, a fact 

 which is kept in view in thellunterian Museum, 

 in which the elastic ligaments are placed next to 

 the muscles. 



The resistance and elasticity of these organs 

 enable them firmly to connect together the 

 parts to which they are attached, and at the 

 same time allow them to yield to double their 

 length on the application of an extending 

 force. In this manner they economise mus- 

 cular action, by substituting for that force the 

 power of elasticity. 



This employment of an elastic rather than 

 a muscular power is evinced in the yellow 

 ligaments of the spine, which pull the vertebrae 

 towards each other, and thus assist the muscles 

 in maintaining the upright posture. The same 

 thing is also seen in many of the lower ani- 

 mals ; as in the support of the head by the 

 ligamentum nuchae the retraction of the claws 

 in the feline carnivora by an elastic ligament 

 and the support of the abdominal organs in 

 many large quadrupeds by the elastic super- 

 ficial fascia. But the most interesting ex- 

 ample of this economy of muscular action 

 is displayed in the bivalve shell of the oyster 

 and other acephalous mollusca, in which in- 

 stance not only is the shell kept open by the 

 elastic ligament of the hinge for the purpose 

 of admitting the nutriment of the animal ; but 



formation of muscle ; but this is probably erro- 

 neous, us the elasticity of muscles depends on the 

 large proportion of clastic cellular membrane which 

 they contain. Lnbstein has also published some 

 observations in the Jour. Vniver. des Sc. Med. on 

 the tissue of the uterus, which he regards as ana- 

 logous to the so-called yellow tissue of the middle 

 arterial coat. 



* AnnalesFrancaises el Etrangircs il'.Anat. el de 

 Phyiiol. Jan. 1837. P. 59. 



