On the intimate structure of bone, as composing the skeleton in the four great classes of animals, mammals, birds, reptiles, and fishes : with some remarks on the great value of the knowledge of such structure in determining the affinities of minute fragments of organic remains / by John Quekett.

  • Quekett, John, 1815-1861.
Date:
[1846]
Catalogue details

Licence: Public Domain Mark

Credit: On the intimate structure of bone, as composing the skeleton in the four great classes of animals, mammals, birds, reptiles, and fishes : with some remarks on the great value of the knowledge of such structure in determining the affinities of minute fragments of organic remains / by John Quekett. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    If wc consider wliat has been already mentioned as entering into the composition of a bone, viz., the medullary cavity, the Haversian canals, the canaliculi, and the bone-cells, we shall find that every part thus described has been more or less hollow; where, then, is the true bony substance ? This is no other than the small granules of ossific matter which are situated between the canaliculi of the bone-cells, each granule having an investment of soft animal matter, by which the whole mass of granules is liept in firm apposition. The parts, then, which a transverse or a longitudinal section of a long bone of a mamrnalian animal will exhibit, will be the Haversian canals, the concentric bony laminsje, the bone-cells and their canaliculi, although all these parts, except the bony laminae, may be seen in all mammalian bones, whether long or otherwise ; they are, nevertheless, so differently arranged in the flat bones, such as those of the skull, and in the irregular bones, such as the vertebraj, as to require a short description at this stage of our enquiry. The bones of the cranium are, in all cases, composed of two thin layers, of compact texture, which enclose another layer of variable thickness, which is cellular or cancellated. The two outer layers are called tables, the one being the outer, the other the inner table, and the middle or cancellated layer is termed the diploe : in this last the principal blood-vessels ramify. The outer table of the skull is less dense than the inner; the latter, from its brittleness, is termed by anatomists the vitreous table. When a vertical section of a bone of the skull is made, so as to include the three layers above mentioned, bone-cells may be seen in all, but each of the three layers will differ in structure : the middle or cancellated structure will be found to re- semble the cancellated structure in the long bones, viz., thin plates of bone, with one layer of bone-cells without Haversian canals; the outer layer will exhibit Haversian canals of large size, with bone- cells of large size and a slightly laminated arrangement; but the inner or vitreous layer will be found to resemble the densest bone, as the outer part of the shaft of a long bone for instance, and will ex- hibit both .smaller Haversian canals and more numerous bone-cells of ordinary shape around them. The same thing will hold good of the ribs, scapula, and os innominatum, and of the irregular bones, such as the vertebra), the small bones of the wrist, and ankle-joints, they being, in fact, nothing more than a cancellated or spongy tissue, enclosed by a compact layer of denser bone. It will be noticed that the bone- cells in all these bones are less regular in their size than in the long bones, and hence there will be required more caution before }iro-