Osteology

“ We are not less interested in tracing the formation of bone through its several stages, than in considering other parts of the human system. The formation of the Haversian canals for the passage of blood-vessels to nourish the bones, the earlier construction of bony tissue by a metamorphosis of cartilaginous substance, and also the commencement of ossification at distinct points, called centers of ossification, are all important subjects, requiring the student's careful attention. ”

“ As all the vessels that come to the tooth enter at its internal surface, and as the external is entirely free in the cavity of the membrane, the ossification in thickness is made especially at the expense of the internal cavity which is constantly contracting, as well as the marrow, an arrangement, the reverse of that of the other bones, the ossification of which commences at a point placed in the centre of the cartilage, and which at first solid in the middle, afterwards become hollow for the medullary cavities and those of the cells, which are always enlarging. ”

“ Primary Tumours—Osteoma.—When the tumour projects from the surface of a bone it is called an exostosis. When growing from bones developed in membrane, such as the flat bones of the skull, it is usually dense like ivory, and the term ivory exostosis is employed. When derived from hyaline cartilage—for example, at the ends of the long bones—it is known as a cartilaginous exostosis. This is invested with a cap of cartilage from which it continues to grow until the skeleton attains maturity. ”

“ For anatomy see Skeleton and Connective Tissues.
Bone Diseases and Injuries.—The more specific diseases affecting the bones of the human body are treated under separate 201 headings; in this article inflammation of bone and fractures are dealt with.
Ostitis (ὀστέον, bone) , or inflammation of bone, may be acute or chronic. Acute ostitis is one of the most serious diseases which can be met with in young people. It is due to the cultivation of virulent germs in the delicate growing Ostitis. tissue of the bone and in the marrow. ”

“ This general disposition to ossification in its whole course, proves that its nature is every where the same, and that notwithstanding the differences pointed out, I have had reason to consider it in an uniform manner, from the pulmonary capillary system to the general; for as I have already observed, an identity of diseases supposes an identity of nature. It is the frequency of ossifications of this membrane in the heart of old people, which renders extremely frequent the intermission of the pulse at that age. ”

“ But great thickening may take place in the situation of the valves, from deposition of cartilage, without any unevenness of their surface or alteration of their shape; and under these circumstances the membrane itself you may expect to find hitherto exempt from disease [4] .
Osseous depositions are always, I believe, originally formed beneath, or exterior to, the membrane, both in the heart and in the arteries. There are two circumstances especially worthy of remark in this process of ossification: sometimes it is a pure and unmixed process: bone is formed, and nothing else. ”

“ Hilaire and Cuvier, who agreed in thinking that ossification from a separate centre was the test of a separate bone, and that thus there were as many elementary bones in the skeleton as there were centres of ossification, Professor Owen points out that, according to this test, the human femur, which is ossified from four centres, must be regarded as four bones; while the femur in birds and reptiles, which is ossified from a single centre, must be regarded as a single bone. ”

“ The physical symptoms are very characteristic. The bone usually affected is the tibia, which is enlarged to a most marked degree, and often shows a pronounced bowing forward, similar to the bowing and thickening of the tibia seen in osteitis deformans. The bone is extremely dense and obviously heavier than normal. ”

“ In addition are the time of life at which centres of ossification appear and the union of epiphyses to the shafts of bones and bones with each other.
In intra-uterine life centres of ossification appear by the end of the sixth month in the os calcis, manubrium, and the bodies and laminas of the sacral vertebræ; by the seventh, in the first piece of the body of the sternum and the astragalus; by the eighth, in the second piece of the body of the sternum; at full term in the cuboid, third piece of the sternal body, first coccygeal vertebra, and the lower epiphysis of the femur. ”

“ If we pursue our researches into the interior of this animal, we find within the framework of the skeleton a great cavity, or rather, I should say, two great cavities,–one cavity beginning in the skull and running through the neck-bone, along the spine, and ending in the tail, containing the brain and the spinal marrow, which are extremely important organs. The second great cavity, commencing with the mouth, contains the gullet, the stomach, the long intestine, and all the rest of those internal apparatus which are essential for digestion ”

“ They exhibit a rough symmetry; they rarely attain any size; and they usually cease growing when the skeleton attains maturity—the conversion of cartilage into bone being then completed. While they originate from the ossifying junctions of the long bones, they tend, as the shaft increases in length, to project from the surface of the bone at some distance from the ossifying junction and to “point” away from it. They may cause symptoms by “locking” the adjacent joint or by pressing upon nerve-trunks or blood vessels. ”

“ If we take a slice of the bone and examine it, we shall find that it is very like this diagram of a section of the bone of an ostrich, though differing, of course, in some details; and if we take any part whatsoever of the tissue, and examine it, we shall find it all has a minute structure, visible only under the microscope. All these parts constitute microscopic anatomy or "Histology." These parts are constantly being changed; every part is constantly growing, decaying, and being replaced during the life of the animal. The tissue is constantly replaced by new material ”

“ One more example from the osseous system, and I shall pass to the softer structures. In the human wrist are eight small bones called carpals, and arranged in two rows; occasionally between the two rows we have a ninth bone called the os centrale. This os centrale is always present in the higher apes and some of the rodents. We also find that in every human fœtus at an early period a rudiment of this bone exists, but it has entirely disappeared by the fourth month of fetal life. ”

“ Complete ossification at these two places occurs only when the bone has ceased to increase in length; and, on considering what would have happened had the bone been ossified from end to end before its growth was complete, it will be seen how great an obstacle to growth is thus escaped. What holds here, holds throughout the organism: though structure up to a certain point is requisite for further growth, structure beyond that point impedes growth. How necessary is this relation we shall equally perceive in a more complex case—say, the growth of an entire limb. ”

“ In infancy, in which the first predominates, in the early stages of the formation of callus, in which it is exclusively found, in the softening of the bones in which it remains almost alone, all the vital phenomena become more evident and more powerful. On the contrary, as age accumulates in the bones the saline substance, as in certain animals this accumulation takes place by the natural laws of ossification in some external portions of the system with calcareous base, as in the horns of stags, the shells of crustaceous animals, &c. ”

“ Lining the medullary and cancellous cavities is a delicate connective tissue lining, the endosteum, which contains many bone-forming cells, while on the outside of the bone, except at the articular ends, is the periosteum with its outer protective layer and its inner vascular layer containing osteoblasts or bone-forming cells. The periosteum is essential for the growth of new bone where the old bone has died, and if the periosteum is removed from healthy bone the part beneath is liable to die, as it is by the constant growth of the osteoblasts that the bone grows and is renewed. ”

“ Osteomalā′cia, a disease in which the earthy salts disappear from the bones, which become soft and misshapen; Os′teophyte, an abnormal bony outgrowth.—adjs. Osteophyt′ic; Osteoplast′ic.—ns. Os′teoplasty, a plastic operation by which a loss of bone is remedied; Osteosarcō′ma, a tumour composed of intermingled bony and sarcomatous tissue; Os′teotome (surg.) , a saw-like instrument for cutting bones; Osteot′omy, the division of, or incision into, a bone; Ostī′tis, inflammation of bone. [L. osseus—os, ossis, bone; Gr. osteon, bone.] ”

“ A very tough skin—a sheathe—surrounds the neck with blood vessels, nerves, muscles, bones, ligaments, fascia, glands great and small, throat and trachea. In bones we find a great canal for spinal cord. It is well and powerfully protected by a strong wall of bone, so no outer pressure can obstruct the flow of passing fluids, to keep vitality supplied by brain forces, but with all the guards given to protect the cord, we find that it can be overcome by impact fluids to such degree as to stop blood and other fluids from supplying lungs and all below. ”

“ The broken extremities of the bones become intimately united by bony matter passing from one to the other. The mass of new bone on the outside, formed by the ossification of the callus, being no longer wanted, is absorbed; by degrees the whole of it disappears, and the bone is left having the same dimensions which it had before the occurrence of the accident.
The process of union is completed in young persons sooner than in those advanced in life; in the upper extremities sooner than in the lower; and in smaller animals more speedily than in man. ”

“ In the bony fishes (Teleostei) the membrane or dermal bones are still more numerous, and many of them are unrepresented in the mammalian skull, while others, which are there quite rudimentary, are very large. The chondro-cranium tends to disappear in the vault, but the base is fully ossified. Among other cartilage bones the five ossifications of the auditory capsule are seen, the pro-, epi-, opisth-, pter- and sphen-otics, all of which are found as centres of ossification in man. ”

“ Before we treat of the head, we must follow blood from the heart to all organs of the head. Not only look at the pictures in Gray, Morris, Gerrish, or some finely illustrated work on anatomy, but we must apply a searching hand and know to a certainty that the constrictors of neck, or other muscles or ligaments do not pull cervical and hyoid bones so close as to bruise pneumogastric or any other nerves or fibres that would cause spasmodic contraction of digastric, stylo-hyoid or the whole remaining group of neck muscles and ligaments, with which you are or should be very familiar. ”

“ Such is not my object, but to place the Osteopath's eye of reason on the hunt of the great whys that the knife is useful at all, I am sure it comes often to remove growths and diseased flesh and bone that have [Pg 155] gotten so by man's ignorance of a few great truths. 1st, If blood is allowed to be taken to a gland or organ, and not taken away in due time the accumulation will become bulky enough to stop the excretory nerves and cause local paralysis; then the nutrient nerves proceed to construct tumors, and on and on until there is no relief but the knife or death. ”

“ The term rarefying ostitis is applied to any process that is attended with excessive absorption of the framework of a bone, whereby it becomes more porous or spongy than it was before, a condition known as osteoporosis. ”

“ These internal exostoses seldom give rise to pressure symptoms, although, according to Wilks and Moxon, [77] they may push inwards the dura mater and even lead to idiocy and epilepsy. I have seen several cases of internal exostosis development, but in all cases their discovery was accidental.
Clinical characteristics. Exostoses vary greatly both in size and consistency. Some are densely hard—ivory exostoses—others possess a covering of compact bone, whilst their interior is made up of cancellous tissue continuous with that of the bone from which [328] they arise. ”

“ The ossification of the bones on the sides and upper part of the skull, for example, begins by a rounded spot in the middle of each one. From this spot the ossification extends outward in every direction, thus gradually approaching the edges of the bone. When two adjacent bones meet, there will be a line where their edges are in contact with each other, but have not yet united ”

“ Figure 2 shows a dorsal view of these structures in a young frog. The parts corresponding to these in 1,II. will be easily made out, but now ossification has set in at various points of this cartilaginous cranium. In front of the otic capsule is the paired pro-otic bone (p.o.) ; behind it at the sides of the parachordal ring is the paired ex-occipital (e.o.) ; in front of the cranium box, and behind the nasal capsules, is a ring of bone, the (median, but originally paired) sphenethmoid (s.e.) . -A paired ossification appears in the palato-pterygoid cartilage the pterygoid bone (pt.) ”

“ Hence why the cartilages especially are ossified; why those of the sutures disappearing, the bones of the cranium become continuous; why the larynx is finally almost all osseous; why the cartilages of the ribs are often as solid as the ribs themselves; why oftentimes many vertebræ united form a more or less considerable continuous mass. I would observe however that the arteries, which have so great a tendency to ossification, are not so evidently gelatinous as many other substances which ossify much less easily, as the tendons for example. ”

“ When the periostitis and ostitis is the result of a wound, and is complicated by caries or necrosis of the bone, the diseased portion of bone must in every case be laid bare and removed. It so happens that the majority of cases of this kind occur in positions where the diseased bone is easily got at. The lower margin of the os pedis or portions of the wings are commonly the seat of such changes. We meet with the former in cases of pricked foot, and with the latter in severe cases of tread, or as a complication in suppurating corn or in quittor. ”