Although diseases of bone generally, and those of its texture especially, have been the object of much valuable investigation, both clinically and anatomically, yet our knowledge of them is still very defective; and perhaps nowhere amongst the diseases of the solid organs is the need of chemical research keeping pace with anatomical inquiry more perceptible than in the subject now before us. And another circumstance, which renders it extremely difficult for the pathological anatomist to deduce his single results from numerous investigations, is the want of accurately distinguishing between different affections of bone, according to their local characters, as well as to the general symptoms, on the living patient; for regard is usually confined to syphilis, scrofula, and particularly to gout, when subsequent anatomical examination discloses changes of an entirely different nature.

1. Congestion Of Bone. Hemorrhage

Bones, like every kind of soft part, are subject to congestion, though, on account, probably, of the little attention which is generally paid to them in examinations after death, changes of their vascular condition are seldom noticed and estimated. Congestion is most frequently observed in the bones of the skull, the vertebral column, and the spongy articular extremities of long bones. In new-born children, and during childhood, considerable congestions of the cranial bones are met with: passive and mechanical congestions of the vertebrae, especially of the lumbar portion of the column, occur, even in advanced life, when the circulation through the ascending cava and vena portae is impeded: and cases of osteoporosis, rickets, etc, are accompanied by extreme congestion. There is no question that habitual congestions not unfrequently lead to hypertrophy of bone, especially in the form of induration: in cases of atrophy, where congestion coexists with expansion of bone, that is, with enlargement of its Haversian canals and cells, it may be produced by the wasting of the tissue of the bone.

Hemorrhage takes place from bone under various circumstances. The vessels of bone, periosteum, and medullary membrane pour out their blood when torn in the various injuries which happen to them. Occasionally very considerable bleeding takes place under the periosteum, in the spongy tissue, or in the medullary cavity, from the exposure and corrosion of vessels of various sizes, by caries. But the most interesting cases are those in which spontaneous hemorrhage, resulting from extreme congestion, originates from the delicate vessels that pass between periosteum and bone, and ramify in the grooves or half canals on the surface of the latter. The principal instance is that met with on the cranial bones of the new-born child, which is known by the name of Cephalhematoma. I shall have to advert to it again amongst the Diseases of the Bones of the Skull, where it can be more conveniently described.