264 



FIBROUS TISSUE. 



exposed; whilst the same cohesive property 

 enables the tendons, under all ordinary circum- 

 stances, to bear the immense force of muscular 

 contraction. 



Having considered the general characters of 

 these organs, I shall proceed to describe the 

 most essential properties of each individual 

 class. 



1. Of the periosteum. This may be regard- 

 ed as the most important of the fibrous tissues; 

 indeed so universal are its connexions, that if 

 any common centre of this system were sought 

 for, we should certainly coincide with Bichat 

 in considering this to be the periosteum. Dis- 

 carding the erroneous ideas of the ancients and 

 Arabian physicians, who imagined that the 

 membranes of the body were all continued 

 from those of the head, we shall find that, with 

 the exception of the perichondrium of the larynx 

 and the fibrous tunics of some glandular bodies, 

 all the fibrous organs are in connexion with the 

 periosteum. 



The inner surface of the periosteum firmly 

 adheres to the several bones by a multitude of 

 delicate processes passing into the openings 

 observed on their external surface. These pro- 

 cesses convey into the bones an amazing num- 

 ber of fine arteries and veins, called therefore 

 periosteal, and which may be regarded as the 

 principal, or as some anatomists contend, the 

 only proper vessels of the osseous tissue. 



The outer surface is rough, and is united by 

 the cellular tissue to the surrounding muscles, 

 tendons, ligaments, and fasciae ; in the nostrils, 

 sinuses, and tympanum, the periosteum is, 

 however, joined to the mucous membranes, 

 and in the skull the surface unattached to the 

 bones is lined by the arachnoid. 



The periosteum constitutes the nutrient 

 membrane of the bones, and thus bears an im- 

 portant part in the process of ossification and 

 in the reparation of fractured and diseased 

 bones ; it also serves as a medium for the 

 attachment of the ligaments, tendons, and 

 fasciae to the skeleton. 



2. Fascia. The fibrous fasciae or aponeu- 

 roses not only invest the surface of the limbs, 

 but also furnish a number of processes, which, 

 penetrating deeply among the several muscles, 

 form sheaths to those organs, by which they as 

 well as the bloodvessels and nerves are main- 

 tained in their proper situation. It is evident 

 that these partitions must exert a great influence 

 on the growth of various kinds of tumours, on 

 effusion of blood, on the extravasation of urine, 

 and on the formation of matter; so that their 

 relations form an important branch of surgical 

 anatomy. 



In order to give to these muscular envelopes 

 the necessary degree of tension, they are either 

 provided with special muscles, as in the case 

 of the tensor vaginae femoris and the palmaris 

 longus, or they receive processes from the 

 neighbouring tendons, as from the biceps cubiti, 

 semi-tendinosus, and so forth. 



The aponeuroses thus braced afford a firm 

 support to the parts they cover, and in this 

 manner they increase the powers of the muscu- 

 lar system ; whilst by their resistance they 



efficiently protect the vessels and nerves from 

 external violence, and at the same time proba- 

 bly assist in the circulation of the blood and 

 lymph, and so prevent varicose enlargement of 

 the deep-seated veins and oedema of the extre- 

 mities. See FASCIA. 



3. Tendinous sheaths. These are in their 

 office analogous with the last, excepting that, 

 instead of fixing the muscles, they secure the 

 tendons during muscular action. The thecal 

 ligaments of the hand and foot, the annular 

 ligaments of the wrist and ankle, and the fascial 

 sheaths around the knee are of this character. 

 They are distinguished by their great strength, 

 and as they are internally lined by synovial 

 membrane, they facilitate the play of the ten- 

 dons ; and in many instances, as in the trochlea 

 of the os frontis and the sulci of the carpal extre- 

 mity of the radius, they also modify the action 

 of the muscles whose tendons they transmit. 



4. Fibrous coverings. Certain organs are 

 provided, for the purpose of protection, with 

 dense ligamentous coverings ; of this order are 

 the dura mater, the sclerotic coat of the eye, 

 the loose portion of the pericardium, the proper 

 covering of the kidney, of the salivary glands, 

 mamma, spleen, thyroid gland, thymus, lym- 

 phatic glands, of the prostate, testicle and 

 ovary ; probably the exterior investment of the 

 nervous ganglia is of the same character. Some 

 of these envelopes, as the dura mater, pericar- 

 dium, and tunica albuginea testis, are lined on 

 one surface by a serous membrane, and thus 

 constitute fibro-serous membranes, or as they 

 are called by Beclard, compound fibrous mem- 

 branes. 



5. Ligaments. These bodies possess in an 

 eminent degree those properties by which the 

 whole fibrous system is distinguished ; and 

 consequently the term ligamentous is often em- 

 ployed to designate the whole of the fibrous 

 organs. 



The ligaments fulfil a very important office 

 in the animal economy by binding together the 

 various bones of the skeleton, an object which 

 they are enabled to effect in consequence of 

 their fibres being very firmly attached, and as 

 it were consolidated with the osseous system 

 through the medium of the periosteum. It is 

 stated by Portal, that after the bones have been 

 softened by the influence of an acid, the liga- 

 ments are observed to send processes into their 

 substance, which cause the ligaments to adhere 

 so firmly that, although by very great force 

 they may be torn, yet they cannot be separated 

 from the bones. 



Although these organs are dissimilar in 

 shape, yet there are three forms among them 

 which predominate: 1. the capsular, 2. the 

 funicular, 3. what, for want of a better ex- 

 pression, may be called laminated. The true 

 fibrous capsules which consist of cylindrical 

 bags lined internally by synovial membrane, 

 are confined to the shoulder and hip-joints, 

 although imperfect capsules exist in many 

 other articulations. The funicular and la- 

 minated ligaments are much more universally 

 diffused, assisting in fact in the formation of 

 every joint in the skeleton. 



