Human osteology : comprising a description of the bones ; with delineations of the attachments of the muscles, the general and microscopic structure of the bone and its development : to which is added a brief notice of the unity of type in the construction of the vertebrate skeleton / by Luther Holden.

  • Holden, Luther, 1815-1905.
Date:
1857
Catalogue details

Licence: Public Domain Mark

Credit: Human osteology : comprising a description of the bones ; with delineations of the attachments of the muscles, the general and microscopic structure of the bone and its development : to which is added a brief notice of the unity of type in the construction of the vertebrate skeleton / by Luther Holden. Source: Wellcome Collection.

Provider: This material has been provided by Royal College of Physicians, London. The original may be consulted at Royal College of Physicians, London.

    28/434 (page 16)
    and tliat from tliese canals other tul)es, infinitely more minute, and expanding here and there into reservoirs, radiate in all direc- tions for the purpose of nutrition ? General idea of Let US first get a general idea of the micro- thesubjeet. g^^^p-^ structure of bone, and go into details afterwards. If a transverse section from the shaft of a long bone be ground extremely thin, and examined with a power of about 20 diameters (Plate B, fig. 4), we shall see a number of holes, with dark spots grouped round them, in a series of tolerably (Concentric circles. These holes are sections of the canals (termed Haversian, after their discoverer, Clopton Havers*) which transmit blood-vessels into the substance of the bone. The dark spots are minute reservoirs, called bone corpuscles, bone cells, or lacunEe. One would imagine they were solid bodies, but they are really cavities; and their dark appearance in the dry bone is owing to the refraction of the Hght. As we examine the different parts of the section imder the microscope, we notice that the Haversian canals vary considerably in size - and shape. They are generaUy round or oval. Those neai-est to the circumference of the bone are very small; but towards the medullary cavity they gradually grow larger, and at last open out into the cells of the cancellous texture. Let us now examine the same section wth a higher power (Plate B, fig. 6), , and we shall find that the Haversian canals are surroundld by a series of concentric lines, reminding us of the tranverse section of the branch of a tree. These lines are termed the «laminae : they are in truth so many layers or rings of bone that have been developed within the Haversian canal. Understand that even the smallest Haversian canal was, when originally formed, a much wider space, and circumscribed by only a single layer of bone • but in process of growth the canal becomes graduaUy con- tracted by the deposit of successive layers of bone. We notice also that the dark spots, before alluded to as the lacunae, are situated between the laminae, and that now, under a higher magni- fying power, they look like spiders. The central part of the lacuna, representing the body of the spider, is hollow, and the dark fila- * An English physician of the 17th century.