250 ARTICULATION. 



intended to obviate the ill consequences which fibre-cartilages the greatest quantity of fibrous 



must have resulted from the violent application tissue. 



of the neck of the femur against the bony It may be questioned whether that peculiar 



margin of the acetabulum : for, where the structure which intervenes between the base of 



margin of that cavity is ligamentous, viz., at the skull and the condyle of the lower jaw in 



the notch on its inner side, this fibro-cartilage the whalebone whale, (balana mysticetus) be- 



does not exist. longs to the class of fibro-cartilages, although 



c. The most remarkable and beautiful variety it seems to bear a nearer resemblance to that 

 of this structure belongs to the third class. It than to any of the other structures employed in 

 consists of nbro-cartilaginous laminae, generally the composition of joints. The following is 

 of considerable thickness, which intervene be- Sir Everard Home's description of it.* " Be- 

 tween two bones and adhere intimately to each, tween the condyles of the lower jaw and the 

 Examples of it are to be found between the basis of the skull is interposed a thick sub- 

 bodies of the vertebrae, (intervertebral sub- stance, made up of a network of ligamentous 

 stance) between the pieces of the sacrum in fibres, the interstices of which are filled with 

 early life between the sacrum and coccyx, oil, so that the parts move readily on each other, 

 and between the pieces of the latter also, be- The condyles have neither a smooth surface 

 tween the ossa pubis at the joint called the nor a cartilaginous covering, but are firmly 

 symphysis pubis. In this class of fibro-car- attached to the intermediate substance, which 

 tilages too, we may place that which is situ- in this animal is a substitute for the double 

 ated between the scaphoid and lunar bones in joint met with in the quadruped, and is cer- 

 the carpus. tainly a substitute of the most simple kind." 



It is evident that these fibro-cartilages are 4. Ligament. The term ligament, as it is 

 useful, not only as very powerful bonds of used by systematic writers on descriptive ana- 

 union, but also as elastic cushions placed be- tomy, is by no means confined to portions of 

 tween the bones to prevent the concussion the " fibrous system " of Bichat, although all 

 which must necessarily result, did the unyield- the articular ligaments (properly so called) be- 

 ing bony surfaces come together with any de- long to that system. Weitbrecht comprehends 

 gree of force. No where is this so beautifully under this term all fibrous structures in and 

 exhibited as in that chain of bones which about joints, including the fibrous sheaths of 

 forms the spinal column in the mammiferous tendons, and also all membranous folds, which 

 vertebrata, the strength and flexibility of are in any way concerned in maintaining soft 

 which result from the fibro-cartilaginous discs, parts or viscera in proprio situ. I apprehend, 

 which, placed between the bodies of the ver- however, that a better definition of articular 

 tebrae, are commonly called intervertebral car- ligament could not be given than the following, 

 tilages. which is that of Weitbrecht, the words printed 



As to the structure of articular fibro-cartilage, in italics being added, " Ligamentum est par- 



we can distinctly observe, without any process ticula corporis, plerumque albicans, interdum 



of dissection, that it is compounded of fibrous flava, ex fibris flexilibus, interdum elasticis, 



tissue as well as of cartilage. As these fibro- plerumque parallele concretis, in substantiam 



cartilages generally assume more or less of the tenacem fibrosam, ruptioni fortiter resistentem, 



circular form, we find that the fibrous tissue is et solidam compacta, eum in finem creata ut 



most abundant towards the circumference, and duae pluresve partes quae alias divulsae per se 



that the cartilage is most manifest at the centre, subsisterent, adunentur atque in situ respective 



In the intervertebral substance, the fibrous determinentur."t Most of the articular liga- 



tissue is arranged in concentric laminae, placed ments are employed to unite the bones which 



vertically behind one another. Each lamina is com pose a joint; they also will be found uniting 



composed of a series of interlacing fibres, which some of the interarticular cartilages within 



have intervals between them ; these intervals, joints, or passing from one part of a bone to 



as well as those between the laminae, are filled another (forming the " mixed" class of liga- 



by cartilaginous tissue ; towards the centre the ments of Beclard) ; and such is the vagueness 



fibrous laminae diminish in number, the inter- with which names are applied in descriptive 



vals become large, and at length the fibrous anatomy, that folds of the synovial membrane 



tissue disappears in toto; hence the gradually often receive this appellation without the least 



diminishing density towards the centre, which title to it. 



characterises the intervertebral substance. In Articular ligaments are divisible as regards 

 fishes, there is such a diminution of density, their forms into two species, the capsular and 

 that the central part is fluid, but here the sur- the funicular or fascicular.J 

 faces of the vertebrae are excavated, not plane Capsular ligaments are generally cylindrical 

 as in the mammiferous vertebrata, and the cha- in shape, or rather barrel-shaped, being wider 

 racter of the articulation is thereby materially in the centre than at the extremes. Each ex- 

 altered. The incompressible central fluid forms tremity envelopes one of the bones that enters 

 a ball, round which the cup-like excavations of into the formation of the joint, so that the arti- 

 the vertebrae play, while the fibro-cartilage at cular cavity is completely surrounded by and 

 the circumference is made available in the la- enclosed within the ligamentous capsule. Liga- 

 teral motions of the spine. 



Of the three varieties of fibro-cartilage above * Comp Anat> vol L 83 



enumerated, the menisci possess the most car- + Syndesmologia, 5. 



tilage in their structure, and the circumferential % Beclard, Anat' Gen. 



