Meckel1812-1 Anatomy 2-4

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Meckel JF. Handbook of Pathological Anatomy (Handbuch der pathologischen Anatomie) Vol. 1. (1812) Leipzig.

Volume 1: General Anatomy. Part I | General Anatomy. Part II: 1 Mucous System | 2 Vascular System | 3 Nervous System | 4 Osseous System | 5 Cartilaginous System | 6 Fibro-Cartilaginous System | 7 Fibrous System | 8 Muscular System | 9 Serous System | 10 Cutaneous System | 11 Glandular System | 12 The Accidental Formations | Historic Embryology (1812)
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Handbook of Pathological Anatomy Volume I (1812)

Section Fourth - Of the Osseous System

§ 208. The bones(l) are solid parts, of a yellowish white color, connected by different kinds of attachment, and so firmly united as to constitute a whole, representing exactly the form of the body. They may be considered, 1st, In regard to themselves ; 2d, In relation to their connections with each other.


ARTICLE FIRST.

OF THE OSSEOUS SYSTEM IN THE NORMAL STATE.

I. OP THE BONES.

A. GENERAL REMARKS ON THE BONES.

§ 209. The bones differ principally from other organs by great hardness and solidity, which permits them in a measure to form the base of the whole body. These qualities render them susceptible of forming levers, on which the muscles act to produce motion. Hence they may be called the passive organs of locomotion.

§ 210. The great hardness of the bones is the immediate result of their chemical composition. In fact, they contain more of the phosphate of hme than any of the organic parts. A chemical analysis of the bones proves that they are formed principally of' two substances ; one soft and of an animal nature, the other hard and solid. The fii'st is principally gelatin, hence the form of the bones, and their slight degree of flexibility. The other consists almost entirely of phosphate

(1) Most authors, who have written on the bones, have not only described them generally, but also each particular bone. We shall mention, here the former only. Some treat of the bones only in their normal state, as A. Monro, Anatomy of the hones and nerves, Edinburgh, 1726. — Cheselden, Osteography, or the anatomy of the hones, London, 1733. — Berlin, Traité de osteologie, Paris, 1754. — J. Sue, Traité de ostêologie, with plates, Paris, 1759.— Blumenbach, Geschichte der Knochen, Gottingen, 1812. On the structure of the bones in general we may consult Malpighi, De ossium structura, in his Opp. posth., Venice, 1743. — D. Gagliardi, Anatome ossium novis inventis illustrata, Leyden, 1723. — Havers, Osteologia nova, or some new observations on the bones, London, 1691. — Description exacte des os, comprise en trois traités, by J.-J. Courtial, J. L. Petit and L. Lémery. — De Lasône, Mémoire sur l'organisation des os, in the Afém. de Paris, 1751. — J. P. Reichel, De ossium ortu atque structura, Leipsic, 1760. — B. S. Albinns, De constructione ossium, in the Annot. acad. lib. vii. c. 17. — Scarpa, De penitiori ossium structura commentarius, Leipsic, 1799. — Malacarne, Auctuarium ohservationum ad osteologiam et ostcopathologiam Ludwigii et Scarpæ, Padua, 1801. — As to the pathological anatomy of the bones, besides the works of Cheselden, Courtial, and Malacarne, the following are important to conBult : A. Bonn, Descriptio thesauri ossium morbosorum Hoviani, Amsterdam, 1783. — Musæum anatomicum Ac. Lmgd. descriptum ab. E. Sandifort, Leyden, 1793. — C. T. Clossius, Leber die Krankheiten der Knochen, Tubingen, 1798.


200


GENERAL ANATOMY.


of lime. From the latest and most accurate analysis of Berzelius, (1) the bones contain,


Of gelatin, completely soluble in water, 32,17

“ insoluble animal matter, 1,13

“ phosphate of lime, 51.04

“ carbonate of lime, - - - - 11.30

“ fluate of lime, 2.00

“ phosphate of magnesia, 1.16

“ soda and hydro chlorate of soda, 1.20


The proportions of these constituent principles, however, vary both in the same bones of different men, and in the different bones of the same man, to say nothing of the variations dependent on age and the state of health. Thus the petrous portion of the temporal bone contains in general more earthy substance than the other bones. (2)

§ 211. The color of the bones is yellowish white. We can make no general remarks in regard to their form ; they vary so much in this respect we are obliged to divide them into at least three classes, the long bones, the broad bones, and the short bones. All these bones differ from each other, not only in form, but in texture : this, however, presents certain general conditions in all bones, which should be first studied, more especially as the three classes differ only by trifling shades.

§212. All the bones resemble each other in texture, inasmuch as they are formed essentially of fibro-cellular tissue, of which the fibres and cells are closer, and consequently less apparent at the circumference than internally. Hence we distinguish in the bones a cortical or compact substance, {substantia compacta seu corticalis,) and an internal called the spongy, or cellular substance, or the diploe, (substantia Spongiosa, cetlulosa, s. diploe, s. meditullium). But this distinction is not essential: for 1st, it does not exist when the bones are formed, nor during the early periods of their existence, since we find only the spongy substance. 2d. We sometimes see the compact substance change into a spongy substance, or at least all differences between them are effaced when their vitality is exalted by disease. Farther, if the compact substance of regularly formed bones be treated by chemical agents, and the lime be removed, we recognize they are formed in the same manner as the diplo'é. Finally, there is always an inverse relation between the quantity of the two substances in different parts of the same bone ; that is, in thicker parts the compact substance alone exists, or at- least in greater proportion than the other,

(1) See in Gehlen, Journal fur die Chemie, vol. ill. part 1. p. 1. However, according- to the analysis of Pourcroy and Vauquelin, {Annales de Chimie, vol. 47, no. 141,) of Hildebrandt, (Schwcigger, Journal für Chemie und Physik, vol. viii. part 1, p. 1,) human bones seem not to contain magnesia.

(2) Several instances may bo seen in Monro, ( Outlines of the anatomy of the human body.) From the analyses of Davy in a subject, all the bones of the head contain more earthy substance than the long bones.


OP THG OSSEOUS SYSTEM IN THE NORMAL STATE. 201

'while in the parts which are more extended it forms only a thin layer, and incloses a considerable portion of the spungy substance.

§ 213. The fibres and laminæ which compose the bones are not simply applied one against the other, so as to extend the whole length, breadth, or thickness of a bone,(l) or to go from its centre to the circumference. They incline so many different ways, one against the other, and unite so frequently by transverse and oblique appendages and processes, that great anatomists have been deceived by this arrangement, and have doubted the fibrous structure of the bones. Nevertheless, this conclusion is not perfectly correct. Notwithstanding those curves and anastomoses of the fibres, the fibrous structure always remains very apparent, and it is coiTect to say that the dimension of length exceeds the other two in the texture of many bones. Tins predominance is very well marked during the first periods of osteogen 3 q for at a later time the fibres are so applied against each other that it is difficult to distinguish them. But these longitudinal fibres never exist alone ;(2) there are many oblique and transverse ones, from the first periods of ossification, and they are even from the beginning so multiplied, that _ the number of longitudinal fibres is not so much greater as at a subsequent period, when the fibres approach nearer, so that the transverse become oblique, until at last, from the increase of bone, the latter at first view seems composed of longitudinal fibres only. The transverse and oblique fibres do not form a separate system ; they continue uninterruptedly with the longitudinal, w'hich they unite to each other.

§ 214. The fibres and laminæ, arranged in this manner, unite in several superimposed layers, and form the thickness of the bones ;(3) these layers, it is said, are united only by fibres and intermediate laminæ, the mechanism of which, according to Gagliardi, who has imperfectly described them, is very complicated. It is true that continued maceration, the action of the air, and calcination, reduce the bones into several thin layers, adjusted to each other : it is also true that a part of a bone affected with necrosis is usually thrown off in a layer, varjdng in breadth and thickness ; but these three agents act too violently and too destructively for us to draw any certain conclusion from the phenomena they produce. As to necrosis, the form of the sequestrum depends only on the extent and thickness of the diseased part.

§ 215. The bones present eminences and depressions which differ much in form and importance. The eminences are of two kinds. One species serves for the insertion of the muscles or ligaments, and is consequently always connected with the fibrous organs, since the muscles are never attached to the bones Irut by a tendon. The others relate to the Idnd of motion performed by the bones. The former are usually rough and irregular, and are destitute of cartilage ; the latter

(1) According to Havers, loc. cit. p. 33-37.

(2) Hildebrandt pretends that the transverse or oblique fibres are formed after ihem, (Anatomic, vol. i. p. 77, § 54.)

(3) Gagliardi, Havers, Reichel.

VoL, I.


26


202


GENERAL ANATOMY.


are smoother, more regular, and surrounded with cartilage. The eminences which project and are long in proportion to the bod^y of the bone, are usually called processes, or apoplnjses {processus, apophysis) ; the tuberosities {tuber), and tubercles {lubercula), are those which are shorter, but broad and uneven ; the styloid process {stylus) is cylindrical and thin, and the spinoiis process {spina) is small, thin, sharp, and pointed ; the ci'est {crisla) is more extensive, smooth, and strongly projecting ; rough lines {lineic asperÅ“) are those which are extended, not very prominent, but so broad that we distinguish in them two lips, {labia,) as in some of the preceding.

The apophyses are designated by terms drawn from certain analogies. Thus a round articular process is called a head {caput), and a condyle {condylus) wheir flatter. The heads and condyles are usually supported by a narrow portion of bone, called the neck {collum, cervix) .

§ 216. The depressions serve for the articulations of the bones with each other, for the insertion of muscles and ligaments, for the passage of vessels and nerves, or for the nervous system in general.

The first are supplied with cartilages, the .second are roughened, and the third are always smooth and more or less round.

The glenoid cavity {cavitas glenoidea) is a shallow articular cavity ; a deep one is called an acetabulum, or a cotyloid cavity, {cavitas cotyloidea.) . The depressions, whether larger or smaller in the substance of the bone, and which have a narrow orifice, are called sinuses {antrum, sinus,) or cells {cellula) according to their size.

Most of those which serve for the attachment of muscles and ligaments, are called {fovea, sinus.)

Those which lodge vessels or nerves are sometimes narrow, and called grooves, {sulcus, semi-canalis,) sometimes they are broader, and called notches {incisura) when they occupy the surface only. When they traverse the bone from one part to another they are called j^sswres {fissura) or holes, (/oraine?i,) according to their size : if they extend some distance they are called channels {ca7ialis) or canals.

We must here remark generally that the arrangement of the depressions for the passage of the nerves and vessels, is not always perfectly similar even in two sides of the same subject, since we sometimes find a hole or canal on one side, while on the other is only a foramen.

The different eminences and cavities are formed sometimes only by a single bone, sometimes by the union of pieces of several bones ; the first is more common.

§ 217. Most of the important apophyses are formed by a special nucleus of bone which gradually unites with the rest of the bone, that is, with its boily, and which is not entirely blended with it until the stages of its growth are completed. It is generally believed that the elevations and the depressions inthebones result from mechanical causes, from pressure and the traction of the organs which are attached to them, or which are there inserted. In fact certain circumstances


OF THE OSSEOUS SYSTEM IN THE NORMAL STATE,


203


seem to justify this explanation. Thus the con-ugations for the insertion of the muscles are more apparent in proportion to the power of these muscles and their frequency of contraction : hence they are not very distinct in children, and always less so in the female than in the male. The origins of these corrugations are generally explained in this manner ; but the solidity and hardness of the bones do not allow us to admit such a theory ; probably the action of the muscles contributes only remotely to this result, increasing the nutrition in the whole part, and thus favoring the more perfect development of the bone. If these corrugations for the insertion of the muscles arose from a mechanical cause, we should not find depressions : but when examined with attention we often find a cavity in which the tendon lies, as is seen for example in the humerus, the radius, and the fibula. The depressions of the bones are produced immediately by the muscles opposing the development of the osseous substance in the place where they are inserted, so that when their actirdty is increased and their size augmented, the cavity of insertion becomes greater, because the development of the bone is prevented to a greater extent.

This is the only way in which we can admit that the furrows, destitute of cartilages, in which the tendons glide, are partially produced and enlarged by a cause pmely mechanical. The tendon, which is formed at the same time as the bone, prevents the formation of the latter in the part corresponding to it, and opposes its development still more, in proportion as its surface is oftener compressed.

The presence of a nerve or vessel opposes the accumulation of cartilaginous or osseous substance in the part corresponding to it. The channels of the arteries are eridently caused by the pulsations of the vessels, which not only hasten absorption, but prevent the deposition of new nutritious matter. In the fetus, where the bones of the skull are united to each other less firmly, and do not mclose the bram so strongly, so that the vessels of the dura mater caimot press on them with so much force, the arterial channels are scarcely visible ; they are very slight and superficial during the first year ; but they gradually become deeper as the bones of the skull are more closely united, because the pulsations of the arteries then act on a single point. This is proved especially by the depressions, and even the openings in the bones of the skull, which correspond to the glands of Pacchioni, which must be considered as the remote cause of the disappearance of the bone in the places on which they act.

But the cavities developed within the bone and which open externally, as also those which communicate with the nasal fossae cannot be attributed to mechanical causes, though Ackermann has pretended they are produced by the air. They depend necessarily on the mode of development of the bones in which they are observed. This is dem^onstrated because we trace them even in the fetus, because they are not developed in certain parts of the bodytowhich the air has free access, and because their number, extent, and even existence in different animals,


204


GENERAL ANATOMY.


have not the least connection with the greater or less exposure to tho air of the bones which contain them.

§ 21S. The organic tissues which form an essential part of the structure of the bones, are 1st, ike 'periosUmn ; 2d, Ike vessels; and 3d, the medullary system.

§ 219. The periosteum belongs to the class of fibrous organs. (§16.) It covers the bones entirely, and is attached to them by a very short cellular tissue, and also by the vessels which pass into the bones. The only points to which it docs not extend, are those where the bones articulate with each other; it there passes from one to another, either in one piece or in several distinct fasciculi. The first arrangement is seen in the immoveable articulations, and the second in most of the moveable joints. In several bones, but not in all, the fibres of the periosteum are parallel to those of the bones which it surrounds, and the external are more extensive than the internal. The vessels ramify in its tissue before they penetrate the substance of â–  the bones. It furnishes prolongations which line their course, but which do not unite to the medullary membrane : hence it performs a certain part in the formation of the bone, and when destroyed to a considerable extent, that portion of the bone below it dies, although generally at the surface. In fractures, the osseous substance is never regenerated until a new periosteum forms ; thus it appears first in parts most remote from the fracture, where the periosteum has not been destroyed. These phenomena prove that the periosteum and bone are allied in regard to their mode of formation: but they do not authorize the assertion that in ossification the periosteum becomes bone.

§ 220. The opinion that bone is formed by the change of the periosteum, and not by the action of the vessels of this membrane, has been sustained by Duhamel, (1) and rests on the following arguments :

1st. In the fetus the periosteum of the same bone is membranous in some parts aird osseous in others : it presents the first character in its extremities, and the second in its centre. It is thicker at the extremities, and is there composed of several layers. (2)

2d. Several prolongations of the periosteum penetrate between the apophyses and the body^of the bone; the whole apophysis is even formed by the periosteum, as are also the adjacent ligaments and tendons. (3)

3d. In the fetus and during youth tho apophysis is attached to the body of the bone by the periosteum alone, so that it is only necessary to remove this membrane to separate them. (4)

4th. -I^he different colors of the osseous layers, when the animal has or has not been fed with madder, demonstrate the same thing.

(1) Memoir on the hones, Mem. 1 arul 2, iu the Mein, de Vac. des sciences. 1741 ; Mem. 3, ibid., 1742; Mem. 4-7, ibid., 1743.

(2) Mem., 1743, p. 132-1Ö4. •

(3) Ibid., p. 163.

(4) Ibid.


OF THE OSSEOUS SYSTEM IN THE NORMAL STATE. 205

5th. The same remark applies to the formation of callus. There the periosteum swells around the fracture and becomes proportionally harder, especially in its inner part ; dming the first days, the hardened parts above the fracture may be removed with the periosteum ; afterward this operation is no longer possible, and there then remains a layer of bone, while a portion of the tumor may be removed with the periosteum. Sometimes the extérnal periosteum unites with the internal to produce callus.

6th. The periosteum is sometimes hardened in exostosis.

§ 221. But 1st, the statements under the first head are not perfectly true, for although in the fetus we always find a thin, gelatino-cartilaginous layer between the periosteum and the bone, this is never continuous with the periosteum. We never find the periosteum osseous in one part and cartilaginous in another.

2d. The prolongations sent by the periosteum into the bone, do not prove that these two organs are the same, and that the first is changed into the second. In fact, the periosteum is united more intimately to the cartilage than to the bone : but still this does not demonstrate the identity of cartilage with it and with the tendons.

3d. It is not true that the cartilage is attached to the bone only by the periosteum, for even after this membrane is removed, continuity still exists between the two organs as before, without any medium.

4th. The difference in color of the layers of the bone prove only that the bone is formed by depositions from without.

5th. The phenomena of the formation of callus prove only that the periosteum inflames from the influence of a mechanical cause which has acted in it, and that a new substance forms between it and the bone, in which the new bone is developed, and which adheres to the latter. On the contrary, attentive examination of the formation of callus demonstrates that in this case, as in that of primitive ossification, a cartilage is formed, in which a bone appears afterwards.(l)

6th. The periosteum does not always thicken in exostosis, and even when this fhickening occurs, it proves nothing, as it may be merely a new phenomenon. (2)

Let us add also that bones often form without periosteum as in all abnormal ossifications.

§ 222. The vessels of the bones are not very large, and are generally of two Idnds. Some arterial trunks, although few in number, penetrate even the substance of the bones ; others ramify excessively in the periosteum before entering into their tissue. The first penetrate farther forward, and serve principally for the secretion of the marrow, or of a fluid analogous to it ; for whenever there is a medullary organ, they expand in tlfis membrane. They serve also to nourish the internal and looser tissue of the bone. The others remain in the external compact substance. These two orders of vessels, however, frequently anastomose together ; so that when the trunks are obliterated, we find their


(1) Mon. 1741.

(2) Ibid.


206


GENERAL ANATOMY.


branches and twigs full of blood, as in the normal state. There are as many kinds of veins to con'espond to the different kinds of arteries. These vessels have also special holes through which they penetrate into the bone ; those which give passage to the large trunks are called foramina { foramhi^ß nntriiia) of nutritions, although this term is not exactly applicable.(l) We do not find lymphatics, except on the surface of the bones ; nor do we distinctly perceive nerves in these organs.

§ 223. The marrow{2) {medulla ossium) is inclosed within the bones; it is an oily or fatty substance, and its characters vary in different parts.

In the cavities of the long bones, which are entirely filled, and hence are called the medullary canals, it is thicker, more solid, more yellow, and

(1) Tlie arteries enter the bones by three divisions : 1st, by ramuscules, which fill the capillary holes of the surface of the whole osseous system ; 2d, by branches which enter by larg-er foramina in the surfaces of the short bones and in the extremities of the long- bones ; 3d, by branches called nutritious, which penetrate the bones through the foramina of nutrition. The 1st and 2d divisions of these arteries are mostly formed of capillary branches ; they penetrate the osseous tissue, pass through it, and terminate in it exclusively : these are truly its arteries of nutrition. The 3d is composed of much larger branches, which proceed intothe internal cavities of the bones, through the canals of nvjtrition. The branches which compose it are distributed to the medullary membrane, and seem unconnected with the nutrition of the osseous tissue, which they do not penetrate.

The first two divisions are not accompanied with any vein. We observe them, on the contrary, around the third, and they correspond exactly to the number and volume of the arteries which compose it ; but they are not sufficient to return all the blood distributed to the bones by the three kinds of arteries, and carry back that only which was brought to the vascular membrane. The proper veins of the osseous tissue were discovered by Dupuytren (Prop, sur quelques points d' anatomie, dephys. et d' anatomie path., Paris, 1803) in the bones of the skull. They have since been recognized in all the other bones of the body, whence they emerge by numerous openings of a diameter sufficiently large, through which we do not observe that any arterial ramification enters, even after the most successful injection ; they are observed particularly in the flat and short bones, and in the extremities of the long bones. At some distance from where they emerge from the bones they terminate in the venous system. They arise from the osseous tissue by numerous radicles, which unite, like those of common veins, to form twigs, branches, and trunks, which, after passing through the spungy tissue, leave it, and penetrate the compact tissue to open into the adjacent veins, by a canal always smaller than that of which it is the, termination. The osseous canals, through which they pass, are formed of compact tissue, which apparently extends from the surface of the bones to their interior. In these canals, directly covered by the membrane of the veins, are numerous channels, through which the simple veins pour the blood which had existed in the osseous tissue. As to the veins themselves, they are composed simply of the internal membrane of the venous ^stem, folded into numerous valves. They have no cellular membrane externally. They resemble, then, the venous sinuses of the cerebrum, as the fibrous envelop furnished to the latter by the dura mater is replaced by bony walls, on the surface of which the thin, transparent, and unresisting internal membrane is closely applied, so as not to admit of motion, nor to exercise any action on the blood which traverses the venous canals.

There is a remarkable analogy between the spungy tissue of the bones and its venous canals, on one part, and the corpora cavernosa of the penis and clitoris, on the other. In fact, the veins are arranged to form the corpus cavernosum of the penis exactly in the same manner as the spungy tissue of the bones of the skull, and of the extremities of the long bones. Replace the osseous cells by a fibrous network, and line this network by the inner membrane of the veins, and we have an exact idea of the arrangement of the corpora cavernosa. In some anmials, the fibrous tissue does not exist, and the cavernous tissue is formed only by the veins, which then, by their numerous communications, resemble the spungy or reticulated tissue of the bones. F. T.

(2) Grutzmacher, De ossium medulla, Leipsic, 1758.


OF THE OSSEOUS SYSTEM IN THE NORMAL STATE.


207


contained in a proper and very thin membrane, which forms numerous small vesicles. Like the fat, it is composed of rormd globules, often varying in size ; so that the medullary organ seems to be only a portion of mucous tissue. The membrane which contains the marrow has been called the internal ‘periosteum ; but it is distinguished from thé true periosteum, the fibrous periosteum, although it resembles it in its great vascularity. In fact, it is in this that the nutritious vessels of the bones are expanded. (§ 222.)

The marrow of the broad, irregular, and short bones, that also in the ends of the long bones, differs much from that contained in the bodies of the long bones : 1st, because it is not surrounded with a membrane ; 2d, because it has less consistence, and contains less fat ; 3d, because it has a reddish color. It appears to be in immediate contact with the osseous tissue, and to arise from the vessels which penetrate within the bone.

We have not been able as yet to discover nerves in the medullary membrane; but, from the experiments of Duverney(l) and Bichat,(2) confirmed hy us, it seems to be very sensible. Bichat says its sensibility is more marked as we approach the exact centre of the bone. We have not found this to be the case. (3)

While the bone is cartilaginous, there is no appearance of marrow. We cannot say, with Bichat, that the medullary organ exists before the canal, and that it is filled only with a cartilaginous substance, which is afterwards replaced by the marrow.

The marrow does not develop itself till ossification commences. But several years after birth it is much redder and more fluid than in the adult, and not fatty.

This state reappears in disease, especially when nutrition is interrupted to a great degree, as in patients affected with phthisis.

The functions of the marrow are very obscure.

We may consider it as diminishing the brittleness of the bones.

It is difficult to decide if its uses relate directly to nutrition. Some have thought this to be the case, because bones die when the marrow is destroyed ; but this conclusion is not correct, since this phenomenon may depend solely on the intimate organic connection between the two organs.

We think the existence of the marrow is connected with the whole organism, rather than with one bone in particular, and, like the fat contained in the rest of the mucous tissue, that it is a provision of nutriment in reserve.

fl) De la struct, et du sent de la moelle, in the Mèm. de Paris, 1700.

(2) General anatomy, vol. iii. p. 112.

(3) Experiments and pathological observations leave us in doubt in regard to the

sensibility of the marrow, which some authors, and Bichat among the rest, have much exaggerated. Lebel, while extracting a sequestrum five inches long, most of which comprised all the thickness and all the circumference of the tibia, was obliged to tear the medulla, the surface of which was flesh-colored. He did not irritate it to discover to what extent it was sensible, but held it for some seconds ; the sick person did not complain ; and he was unable to determine what part it could take in the pain of extracting the sequestra. The medullary membrane was inflamed, and therefore was more sensible than in the natural state.— Jburn. compL, vol. v. pp. 312, 313. Jr. T,


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GENERAL ANATOMY.


§ 224, Although tho bones aro hard and solid, they have a certain degree of elasticity ; this property varies according to circumstances. They caimot change their volume by the action of irritating substances, but have the power of extending and contracting to a certain degree. This change, however, is not transknt : when they extend, there is almost always an increase in their mass ; and when they contract, there is a diminution in volume. The first case takes place when they are mechanically extended, and depends on a separation of their constituent molecules. The other seems to take place even when there is an increase in mass ; for instance, when a distended bone collapses, and an opening is obliterated by the wasting of the nerve or vessel to which it gave passage. A similar phenomenon is observed when the alveolar processes are absorbed after the extraction of the teetln

Tn the normal state the bones have no animal sensibility ; for the injuries which affect them cause no pain. Facts which seem to prove the contrary have been furnished by bones not entirely formed, or which are diseased, conditions in which sensibility is highly developed in them.

§ 225. This circumstance seems to contribute, at least in part, to the slowness with which ossification takes place. The bones are of all organs the last to appear, and arrive at perfection, either in the animal series or in the fetus ; all their diseases progress slowly, compared with those of other organs. But, on the other hand, this circumstance contributes to render ossification the most perfect of all the formative acts of the body ; for no other solid possesses the power of reproduction in so great a degree. Not only is a simple fracture united by a substance which, in form, chemical composition, and functions, is almost identical with the normal osseous substance, but portions of bone and whole bones, after having been destroyed, are repaired, not in fact in their form, but in their volume, their relations with the adjacent parts, and their functions, of which we shall treat more particularly when speaking of the anomalies of the bones.

§ 226. The bones, both in respect to form and chemical composition, pass through several periods of formation before attaining their term of perfection ; and when they have reached it, they descend from it by several successive changes.(i) The changes which occur in them,

(1) Sue, Sur les proportions du squelette de l'homme, examiné depuis l'âge le plus tendre jusq' à celui de vingt-cinq, soixante ans, et au-delà, in the Mem. pres.^ à t'Ac. des SC., vol. ii., Paris, 1755_, p. 572-586. — H. Eyssoii, 'l'ractaius de ossibus infantis cognoscendis, conservandis, et curandis, Groning'en, 1659. — V. Coiter, Traetatus anatomicus de ossibus fœtus aboriivi, et infantis dimidium annum nati, Groningen, 1659. — R. Nesbitt, Human osteogeny, London, 1753, in 8vo. — J. Raster, De osteogenia, Leyden, 1731. — A. Vater, Osteogenia,^^ Utemherg, 1735. — B. S. Albinus, Icônes ossium fœtus, Leyden, 1737. — J. A. Ungebauer, üc ossium trunci corp. hum. epiphysibus sera osscis visis earumdemque genesi, Leipsic, 1739. — B. S. Albinus, I. De generatione assis. IL Quœdam de prima ossium natura disceptalio, in Annot. acad., 1. vi. — Idem, De generalionc ossium, in Ann. acad., 1. vii. no. 6, 1764 and 1766. — Perenotti, Mémoire sur la construction et sur l'accroissement des os, in Além. de l'urin, vol. ii. 1784. — C. F. Senff, Nonnulla de incremento ossium embryonum imprimis graviditatis mensihus, Halle, 1781. — J. P. Meckel, Considérations anat. et phys. sur les pièces osseuses qui envelopjient les parties centrales du syst. nerv., in the Journ. compL, vol. ii. p. 211. — M. 'Froja, Osservaziont cd esperimenti suite ossa, Naples, 1814. — M. Mcdici, Esperienze inlornu alla tessitura organica délie ossa, in the


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from their first appearance to their period of perfection, are remarkable, because their differeirt periods of development correspond, and often with surprising exactness, to permanent states in animals. Like all other organs, the bones are softer the nearer the fetus is to its origin. At first they are not firmer than the other parts. In a few weeks they harden; and are then cartilaginous, and become more and more consistent. The cartilages which at this period occupy the future places of the bones differ from the latter, as their structure is not fibrous, and as we can perceive neither cellules nor medullary cavities, and as they constitute a solid and entirely homogeneous mass ; but this mass possesses the external form of the bone, and like it is covered with a periosteum. Towards the eighth week the vessels of some of these cartilages commence carrying red blood instead of the colorless liquid they hitherto contained. It is then that ossification really commences. First the cartilage becomes softer and looser, always at its middle part ; it disappears finally, and in its place we see a fibro-cellular tissue, composed of gelatin and phosphate of lime. This change into cartilage and bone, does not commence in all the bones at once ; but there is this constant relation between these two acts, that the bones whose cartilages appear first are the first to ossify, and that* in each bone in particular the first osseous germs are found precisely in the points where the cartilages first show themselves.(l)

There are but a few bones formed of a single nucleus. In most of them we see different and separate osseous germs, which are connected together for a longer or shorter period only by cartilage, and which are gradually united ; so that it is only when the whole body has acquired its growth that all traces of the primitive separation are effaced. In certain bones, as the sacrum, these traces never disappear. In regard to the order of ossification for the different parts and for the whole bone, there are general laws with respect to the form, size, and number of the nuclei of bone, and to the period when ossification commences, either generally or particularly ; but we cannot discover the general cause of the succession to which entire bones and their different constituent parts are subjected in their appearance.

§ 227. The general laws of osteogeny are ;

Opusculi scientijici, Bolog'na, 1818, p. 93-107. — Medici, Considcrazioni inierno alia tessatura organica delle ossa, in riposta alle oppos. faite del S. D. C. Speranza et dal S. A. Scarpa, Bolog'na, 1819. — Rapport dc Cuvier sur Ic Traité des lois de V ostéogénie, by Serres, in the Journ. compl., vol. iii. p. 67. — Lebel, Réflexions sur la régénération des os, sanie journal, vol. v. p. 309. — Schulize, Considérations sur les premières traces du système osseux, saine journal, vol. vi. p. 113. — Béclard, Mémoire sur Vostéose, in the ]\ouv. journ. de médecine, vol. iv. 1819. — Dutrochet, Observations sur l'ostéogénie, in the Journ. de physique, 1822, Sept. — See also the first note to this section.

(1) J. Ho-wship has remarked that in many bones, especially in the diaphyses of the Ions' bones and (he central portions of the broad bones, ossification takes place immediately, that is, the osseous state is not preceded by cartilage. (See his Microscopical observations on the structure of bone, in the Medico-chirurg. trans., vol. â– vi.-x. London, 1815-1819.) Béclard, ( Gen. Ànat., trans. by Togno,) admits this opinion, and describes the progress of ossification very precisely in the following passage : “Ossification does not every w'here result from the transformation of cartilage into bone. The diaphysis of the long bones and the centre of the broad bones, which are developed at a very early period, pass immediately from the mucous to the osseous

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1st. Ossification commences in the substance of the cartilage ; so that the nucleons of bone is entirely surrounded with cartilage.

2d. Ossification begins in the centre of the whole bone and of each nucleus of bone. The bones increase from within outward ; so that the external layers appear after the internal. This arrangement is demonstrated by experiments made by feeding animals with madder. When killed after this substance has been mixed with their blood, the internal surface of the bone is always white, the external red. We may in this manner produce a number of layers alternately white and red, by suspending and resuming the use of madder. (1) Still the substance of the internal layers is also constantly renewed ; for if we kill an animal which is at first nourished without madder, but to whom the coloring matter is afterwards given, and then suppressed, the internal part of the bone is alone found red, and t he external is white. (2)

The bones increase in length and breadth ; so that the new substance is not only added to their extremities and edges, but penetrates the mass already existing. In truth. Hunter, having observed that two holes made in a long bone of a young animal were not separated from each other by its growth, has deduced another conclusion ;(3) but Duhamel's experiments, which were made previously and with greater care, prove that the English anatomist was wrong, and that the development of the bones at the centre is much slower and arrested much sooner than at their extremities. (4)

3d. In the successive formation of the different parts of bone, (§ 226,) the largest appear the first. We should hence conclude that the largest bones arc those which are first seen. But although, if we except the teeth and the small bones of the ear, the small bones appear

state. Tlie otlier parts of tlie system are at first cartilaginous, and in them the successive phenomena cf ossification may be be.st observed. Ttie cartilage, whicli for a longer or shorter period takes the place, and performs the functions, of the bone of which it has the form, and of whicli it gradually acquires the volume, is at first hollowed with irregular cavities, then with canals lined by vascular membranes filled with a mucilaginous or viscous fluid ; it becomes opaque, its canals become red, and ossification commences towards it.s centre. Tlie first point of ossification (punctum ossificationis) always appears in the substance of the cartilage, and never at its surface. It is surrounded by red cartilage at the place which is in contact with it, opaque and full of canals at a little distance from it, and at a still greater rlistancc homogeneous and without vessels, but only perforated with canals of blood-vessels which tend towards the osseous centre. The osseous point continually increases by growth at its surface, and also by interstitial addition in its substance. In proportion as the bone increases, the cartilage, successively perforated by cavities and canals lined by sheaths and blood- ves.sels, gradually diminishes, and at length disappears. The canals of the cartilages themsmve.s, which are very wide at the commencement of ossification, become smaller and smaller, and at length disappear when it is completed. In the place of a cartilage more or less thick, but at first full or solid, without cavities ami without distinct vessels, at a later period perforated with canals lined by vascular and secreting membranes, there is found a very vascular bone, full of areolar or spungy cavities, invested with membrane, and filled with adipose marrow. The bone afterward.s becomes less vascular as age advances.” F. T.

(1) Duhamel, tSur Ic dével. ct la crue des os, in the Mem. dc Paris, 1742, p. 497, 498.

(2) Home, Kxp. and obs. on the growth of bones, in the 'Plans, fur the imp. of men., vol. ii. xxiii.

(it) 'Pl ans, for the imp. of mod., vol. ii. p. 279.

(4) Cinquième memoire sur les os, in the Mein, dc Paris, 1743, p. 187, 188.


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later than the large hones, we also remark that the middle-sized bones are usually formed before the largest. Thus the scapula, the bones of the pelvis, and the long bones of the extremities, appear long after the clavicle and the lower maxillary bone are formed ; and there is a period when the clavicle, which in a full-grown man is scarcely one fourth of the size of the humerus, is equal to six times its volume.

4th. The bones and their different parts arrive at perfection in the order of their formation. Thus the two arches of the vertebrae appear long before the body, and their posterior extremities are fused together long before the anterior unite to the body.

5th. The cylindrical bones, with few exceptions, form and are perfected before the flat bones, and the latter before the short bones. Thus the clavicle, the ribs, the lower jaw, and the large bones of the extremities, are very far advanced when scarcely any traces appear of the occipital and frontal bones, which are flat bones, and the only short bone visible is the upper jaw. This law applies also to the constituent parts of the diflerent bones. Several short bones, especially those of the carpus or the tarsus and the patella, contain no nucleus of ossification in the full grown fetus, and it is only at the sixth month of pregnancy that ossification commences in the sternal cartilage. The body of the cylindrical bones and the arches of the vertebrae are formed and developed much sooner than the processes of the former and the bodies of the latter: but the parts which are here the last to appear correspond to the short bones in every respect. This law is very remarkable, because it is intimately connected with the power of reproduction in the different bones. In fact, the bones which are formed and developed the soonest are the most easily and the most completely reproduced when they have been accidentally destroyed ; the flat bones are reproduced with more difficulty than the long bones, and the short bones, slower than all the others. These two conditions seem to depend on the law, that the organic formation is founded on a force not differing from that on which the electrical phenomena depend, and which acts principally in the direction of the length.

6th. The order in which the bones are developed in the human fetus seems to depend on that according to which they appear in the animal series. We cannot doubt this in regard to the jaws and clavicle, which are so highly developed in the fishes, nor to the sternum, the bones of the pelvis, and the other bones of the extremities, which are developed so imperfectly in the fishes and the cetaceæ.

7th. The destination of the bones appears to exert some influence on the rapidity of their formation and development. This is instanced in the early appearance of the jaws, which are so much needed, and the slow development of the sternum and bones of the pelvis, which are the last to arrive at perfection, because the cavities which they circumscribe must necessarily be closed late.

8th. The same relation does not exist in the development of all the bones in regard to form and volume. In certain bones, particularly the long bones, the different pieces composing them do not unite until they


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begin to increase in length, or even fill this is tinislied. In others, such as the short bones, several flat bones, and some irregular bones, all the parts are united long before the bones have attained their full growth. Even at the age of twenty, maceration detaches the epiphyses from the bodies of the long bones, while the pieces of the sphenoid, frontal, and occipital bones and of the vertebræ are united in the early periods of existence.

9th. The mode of development of each bone, in relation to its appearance and completion in the form and volume of its pieces, is in general subject to laws ; but there are also exceptions to these laws, and these are more numerous in some bones than in others. Of all bones the sternum presents the most numerous and the greatest variations in regard to the number, size, form, and situation of the osseous nuclei Avhich gradually produce it, and even also in regard to the time of their appearance. This phenomenon is more remarkable, as the sternum is the very last bone which appears ; whence these variations in its formative type seem to occur, because the energy of the formative power begins in some measure to be exhausted. The bones too which form the arch of the skull are less constant in their development, since it is not rare that some of their component pieces are developed separately, and never unite to the others, which explains the formation of the ossa wormiana.

10th. The chemical composition of the bones is not the same at all periods of life. In general we may state as a principle, that the earthy substance is less in proportion to the animal parts, the younger the bone is. In a person even fifteen years old the proportion of the earthy to the animal substance was found to be nearly one fifth less than in an adult.(l)

11th. The structure of the bones is looser, more spungy, and softer in infancy, which coincides perfectly with their chemical composition. Thus, at first appears only a simple tissue of fibres and layers differently interlaced, in which there is no hard substance.

12th. As to the external form, the bones are rounder and less hard and angular in infancy than at a more advanced period ; their eminences and depressions are also much less marked. In general, therefore, their surfaces are smoother and more uniform.

13th. The bones are more flexible and elastic in youth than in advanced age. Hence why external violence produces at this period only slight changes, curves, and impressions, while they afterward give rise to solutions of continuity. Hence fractures are more common in aged people.

§ 228. The great difference in every respect between the cartilage and the bone has induced' anatomists and physiologists to seek out the cause of the change of cartilage into osseous tissue. To explain

(1) Davy (in Munro's Analomy of the kumanhody, Ediiibnrg'li, 1813, v®l. i. p. 36.) found, for instance, that the femur in a child fifteen years old was composed of .53 of animal substance and .47 of earthy substance, and in an adult, of .375 of animal matter and .625 of earthy matter.


UF THE OSSEOUS SYSTEM !N THE NORMAL STATE.


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ihis phenomenon satisfactorily, two problems must be resolved, viz. , 1st. On what ground is there a period when cartilage is changed into bone 1 2d. How does this change take place ? It is more than

doubtful if the first question is ever resolved with certainty. The phenomenon to which it relates belongs to a general law of every •organized formation, that the fluids predominate the more, the nearer the fetus is to its origin. We may attach to the second, two different senses, and ask either a simple statement of the phenomena presented by the change of cartilage into bone, which has been treated of above, or the mdication of the means by which this change takes place. But we cannot explain this phenomenon more readily than that of the successive changes which supervene in all the other organs. Besides, it is very singular that we should be lost in conjecture only in regard to the formation of bone, and that all the other organs, which present as great differences at different periods of life, are entirely neglected. The only thing certain is that all the theories of ossification are either vague or false ; and that in the latter case, the more media nical they are, the farther they are from the truth. Of this character are the following ; that the arteries are filled with osseous juice, which obstructs and tears-them ; that the arteries of the cartilages gradually ossify ; that bone takes the place of cartilage ; that the periosteum gradually changes into bone ; and that the cartilage is only penetrated by the osseous substance. Ossification essentially consists in the formation of a new organ different from cartilage. It is then an act of nutrition of an entirely different character which acts upon this part of the organism. The existing matter is taken up more rapidly in some places than in others ; hence the formation of a medullary canal and of cellular and spungy tissue, instead of a solid, homogeneous, cartilaginous substance. But at the same time the act of nutrition itself changes ; since a medullary organ and fibres composed of gelatin and phosphate of lime are formed. This change depends on that which occurs in the activity of the instruments of nutrition, the vessels designed for bringing and carrying away the nutritious fluid.

§ 229. When the bones have acquired their normal situation, and the different pieces which gradually unite to form them are fused in a single mass, they increase more or less in thickness also.

§ 230. But the thickness of the bones diminishes much in old age;(l) so that they lose their weight, and break more easily, as much for this reason as because they have become more fragile. The greater fragility depends principally on an increase of earthy matter ; for dead bones are broken more easily in proportion as they lose their animal substance. Davy found in the occipital bone of an adult 64.0 of earthy matter, and 69. in that of an old man. (2) Still this rule does not seem to apply to all bones ; at least Davy found that the

(1) F. Chaussard, Recherches sur l'organisation des vieillards, Paris, 1822. — Ribes, Sur les changemens que le tissu osseux subit par les progrès de l'âge et l'irtfiuence de diverses maladies, in the Bull, de lafac. de méd., vol. vi. p. 299.

(2) Davy, loc. cif., p. 36.


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lower jaw of an old person Avhere the alveolar processes were entirely effaced contained 43.4 of animal substance and 56.6 of earthy matter, while the relation between these two substances was as 42.8 to 57.2 in a child, and as 40.5 to 59.5 in an adult ;(1) but the lower jaw of the old person was more fragile.

§ 231. The sexual differences of the bones are generally the greater thickness, asperity, and prominence, of the processes in man ; the smallness and roundness of their form in woman. But many of the bones differ also in the two sexes very strikingly ; a change of form coincides with a difference of function, as especially in the bones of the pelvis. But these differences can be examined only in special anatomy. So too, and with greater reason, it is with the difference of races, as they appear principally in the form of the different bones.


B. PA,RTICIILARS OF THE DIFFERENT CLASSES OF BONES.

§ 232. The different classes of bones, (§ 210,) beside the general characters of bones, present certain peculiarities which deserve to be studied.

§ 233. The long bones are those in which the dimension of length much exceeds the other dimensions. We find the extremities {apophyses) broader than the central part, the body {diaphysis) ; this increases their lightness and their articulating surfaces, and renders luxations more difficult. The body is generally cylindrical, but we can almost always easily distinguish three faces, separated from each other by more or less acute edges. Some of the long bones form, in a measure, the transition from this class to that of the flat bones ; for, although long and narrow, they are not thick ; whence they appear not round, but flat; such are, for instance, the ribs. The lower jaw resembles the flat bones still more. The bodies of these bones are never perfectly straight, or at least except in rare cases, and only during the early periods of life. They are usually a little arched or curved, and do not possess the same thickness in every part. The form of the extremities of each long bone varies according to its uses ; it is in direct relation with the greater or less degree of mobility in the limb whose base it constitutes. As to their internal composition, these bones are peculiar ; as their body is more or less hollowed, and the medullary organ exists in their cavities. These cavities are not found towards the extremities of the bone ; but in their place there is a loose fibro-cellular tissue, which seems developed at the expense of the compact substance ; since the latter diminishes, and is insensibly reduced to a thm layer, in proportion as the spungy substance accumulates ; while in the centre, where the latter does not exist, it is very solid, and it is one or two lines thick in the largest long bones. The ribs and lower jaw, which by their external form mark the transition of the proper long bones to the flat bones, differ also from the real long bones


(1) Davy, loc. cit,, p. 3t>

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by the absence of a medullary cavity. They are entuely filled v/ith spungy tissue.

The long bones are principally found in the hmbs, of which they form the base. They diminish in volume, and increase in number, as their distance from the trunk increases. The number, form, and other relations of these bones are essentially the same in the corresponding parts of the extremities. The upper parts are the most movable ; still those which form the first articulation of the fingers and toes are more movable than those of the middle and anterior.

The cylindrical bones are generally formed of three pieces. We however find more in several of them. Of these pieces, one corresponds to the body, the other two to the extremities. The central piece developes itself long before the other two, and at the exact centre of the bone, in the form of a thin straight cylinder. The extremities do not ossify till after birth, and are not completely fused with the body until its growth is perfect. The spungy substance is not however confined to their inner parts ; it appears also in the extremities of the body properly so called ; but here it is finer and longer, and consequently is more fibrous, than in the extremities.

§ 234. The bones are nearly as broad as long, but they are less m thickness. Most of them are more or less convex on one face, and concave on the other : their outer and iimer faces are usually parallel. This form depends on the functions they fulfill ; for they serve especially to form cavities, which arise from a certain number of flat bones solidly articulated to each other. Many of them, especially those of the cranium, are surrounded with teeth, which, penetrating reciprocally, form the most solid species of articulation. These bones are not much thicker on the edges than elsewhere ; the other flat bones, however, resemble the long bones, inasmuch as their edges are very thick, particularly in those points where they articulate to each other, and also in those where muscles are attached to them.

The compact and spungy substances are uniformly extended every where in the flat bones. The compact substance forms an internal and an external layer or table, {tabula vitrea,) between which the spungy substance {diploæ) is formed. In a few of the flat bones, especially the smallest, as the ossa unguis and the lower portion of the septum bone of the ethmoid, the spungy substance is deficient ; and here the two tables are blended together into one. The proportion between the inner and outer substances is not the same in all. Thus, for instance, in the ossa ilia the external is much thinner and feebler, and the internal looser, than in the bones of the skull.

Still there are cavities more or less extensive in some flat bones ; but their uses are not the same as those of the cavities found in the long bones. They are not filled' with marrow, but contain air, open externally, and are appendages or prolongations of the nasal ca\'ity.

Most of the flat bones arise by several points of ossification, which form one after another. There are at least two lateral nuclei, which unite sooner or later on tire median line, as we see in the frontal bone,


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GENERAL ANATOWV


anti even to a certain extent in the parietal bones. But in some others also these lateral parts gradually develop themselves by several points, as in the occipital and sphenoidal bones, the ossa ilia, and the scapula. Here likewise, as in the long bones, the apophyses, which correspond to the short bones also, constitute at first as many distinct pieces of bone. The flat parts also, which may generally be termed the scahj or squaVI ous pariions, {sqnammÅ“, parles squammosce,) arise from several separate nuclei. The diflerent nuclei of these bones almost always join in the articulations, where ossification takes place last, while when the pieces touch in other jrarts, they soon unite. This arrangement is seen in the development of the coxal bones {ossa ilia) and of the occipital bone, where it seems to fix vor the eirlargement of the articular cavities, and perhaps depends partly on the mechanical action of the bones articulated on this point. 'I'he flat bones are formed not only by the successive union of several pieces of a certain extent, which remain separate a longer or shorter time : there are developed also at the circumference of the largest nucleus of bone, along its edge, and at various times, a number of other germs, which are entirely distinct, and very different in respect to number, size, and situation, and which gradually fuse with each other and with the principal piece, which primitively existed. Sometimes these small nuclei, and even larger .pieces, those which are formed after a more constant type, remain insulated, abnormally : thus we see different kinds of wormian bones appear, which result for tire most part from the development being suspended, and which occur most frequently in the parts where several bones come together so as to leave between them vacant spaces called fonlanclles.

§ 235. In the short or thick bones no one dimension much exceeds the others. 7'heir form is more or less rounded, and they are also distinguished from the other bones by their greater irregularity, hr their tissue they resemble the flat bones and the extremities of the long bones, as they have no cavity, and the compact substance is every where filled with spungy substance. These bones are always united in great numbers, either lengthwise, as in the vertebral column, or breadthwise, as in the tarsus and carpus, and are so disposed that as a whole they have extensive motions, while they move upon each other but slightly. I'liis is in part the ground of their great irregularity of form ; for their surfaces present numerous elevations and depressions, which serve for the attachmcirt of the ligaments. Some of these bones have a more complex form than others ; and the same is true of their functions: thus each vertebra has a large opening, and resembles a ring, because intended not merely as a lever for the attachment of the muscles which are there inserted, but also as the reservoir of an organ, the spinal marrow.

There is a particular class of short bones, the sesamoid bones, which we shall mention when speaking of the fibrous system.

§ 236. Be.sides these classes of bojies there is still a fourth, which may be called the mixed hones, for they seem produced by the blending


OF THE OSSEOUS SYSTEM IN THE NORMAL STATE.


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of bones of several classes, principally of the second and third, being composed of flat and short portions. The sphenoid, temporal, and ethmoid bones are examples of this class ; even the occipital bone belongs to it. The vertebrae mark the transition between it and the class of short bones. These bones are always developed by several nuclei, one of them haring the characters of the short bones, and the others those of the flat bones. The latter are usually more numerous than the others. Almost all these bones inclose cavities which commuiricate with the nasal fossae.

Finally, we will remark that comparative anatomy proves that the same bone changes its form in different animals in such a manner that it belongs to another class. These differences are not then very essential, and depend on the whole form.


II. OF THE ARTICULATIONS OF THE BONES.

§ 237. The articulations of the bones differ much in respect to their modes of union and to the extent of motion they permit. It is a general law, but subject at least to one exception, that the corresponding portions of bone are covered with cartilages (5th section) or with fibrocartilages, (6th section,) and that accessory fibrous ligaments (7th section) extend from one bone to another, which circumscribe and cover the poiifts surrounded with cartilage.

§ 238. Generally we may consider the difference of mobility and the arrangement of the modes of union as furnishing the base of a classification of the articulations. Still they are not perfectly identical, since the same degree of mobility may be obtained by different means. Thus, the bones which articulate by straight and even, or by very uneven surfaces, but which correspond perfectly, although not united, and which are firmly attached by very short and tense ligaments, have as little motion as those whose surfaces adhere to each other in all their extent by means of a mass of cartilage.

The best mode of classifying the articulations is according to the forms of their corresponding surfaces, and also to the arrangement of the means of union ; since on these depends the difference in their degree of mobility.

§ 239. The forms of the corresponding surfaces, and the arrangement of the means of union, are such that the bones can or cannot play upon each other. In the first case, the surfaces not covered with cartilage are not united except at their circumference, and there is no mean of union between them ; this is called a movable articulation. In the second case, a cartilaginous or fibro-cartilaginous mass extends from one surface to the other, and unites them together ; this is called an immovable articulation.

§ 240. The movable articulation, or the joint, {articulus, junctura, diarthrosis,) presents several varieties, depending on the form of the contiguous surfaces. These may be referred to five principal forms ;

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28


218


GENERAL ANATOMT.


let. The loose joint, {arthrodia,) where a large globular extremity, or a head, fits a plain surface of small extent. The articulation of this species possessing the most motion is that of the humerus with the scapula. We must refer to the same class those of the fingers and toes with the carpus and tarsus, and the radius with the humerus. Other things being equal, the motion is more free as this head is larger in relation to the surface to which it is applied, and as the head is rounder, and this surface is flatter. Farther, the form of the articular surfaces being the same, the degree of motion varies much, according to the tension and the greater or less number of the ligaments.

2d. Enarthrosis is where a large head corresponds to a deep rounded cavity. Many anatomists do not consider this species as a separate articulation, but call it an arthrodia. The articulation of the femur with the iliac bone and of the lower maxillary bone with the temporal bone, are examples. Here too the motions are freer, more capable of being performed in all directions, and more extensive in each direction, as the contiguous surfaces are rounder.

3d. The turning joint, OÏ hinge joint, {gingtymvs.){l) It consists in such an arrangement of the articular surfaces as will admit of motion in only one direction ; so that the bones can only approach and recede from each other, be flqxed or extended. This effect is produced in two modes. Sometimes a simple surface having an oblong protuberance corresponds to another surface which presents the same form hollowed, and from one of the bones a considerable process extends o^n each side, which permits no motion except that from before backward : such is the articulation of the foot. Sometimes one of the articular surfaces has two lateral heads, separated by a large hollow ; and that which corresponds to it presents on the sides two hollows, between which is an elevation : we see an instance of this in the articulation of the humerus with the upper extremity of the ulna, and in that of the femur with the tibia. The articulations of the first phalanges with the second, and of the second with the third, of the fingers and toes, are between these two forms. We see in the first, the middle cavity and the eminence which corresponds to it are replaced by external processes. Still the articulation of the first offers a slight and indistinct index of the second form.

4th. The rotatory joint, {rotalio, diarihrosis, trochoides.) The corresponding surfaces are small sections of a cylinder, and one of the bones turns on its axis, at the same time revolving on that of the bone with which it articulates. But the motion is never sufficiently free for one of these bones to turn entirely on its own, axis ; and even where the arrangement of the surfaces would permit it, as, for instance, where the articular surface of one of the bones extends all round its extremity, there are other arrangements, dependent on the structure of the bone itself, which permit it to make at most but a semi-revolution on its axis. We see instances of this joint in the articulation of the upper and lower extremities of the radius with the ulna, and that of the first cervical vertebra with the odontoid process of the second.

(1) Isenflarnm resp. Schmidt, Dc ginghjmo, Erlangen, 1783.


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5th. The last kind of this movable articulation is the close joint, [amphiarthrosis, diarthrosis, s. juncturastricta, ambigua, synarthrotica.) Two straight or differently formed articular surfaces, having numerous elevations and depressions which exactly correspond, are forcibly applied against each other by short ligaments, which go from the circumference of one to that of the other. The usual consequence of this arrangement permits only an almost imperceptible sliding of the connected surfaces. This kind of articulation belongs particularly to the short bones, which unite to form in some measure a single bone flexible in several parts. We see it in the carpus, the tarsus, the vertebral column, and the ribs.

§ 241. The immovable articulation (synarthrosis) also offers several varieties in its form and degree of immobihty. As the corresponding osseous surfaces are generally united in all their extent by a cartilaginous or fibro-cartilaginous mass, they can never glide upon each other ; still the bones are sometimes slightly displaced, from the length and elasticity of the mass which unites them, and the flatness of their corresponding ^rfaces. Several anatomists admit also a third kind of articulation, between the movable and the immovable joint, called the mixed, or semi-movable, (articidatio mixta, amphiarthrosis, symphysis.) But, as this articulation is essentially the sami as the immovable in respect to the arrangement of the uniting substance, and as the articulations which become immovable by age were at first movable, when, the intermediate mass bemg softer and larger, the extremities of the bones were placed at a greater distance from each other, it appears more proper to consider the mixed articulation only as a species of synarthrosis. The different varieties of the latter are,

§ 242. 1st. Symphysis. It consists of two plain surfaces, united by a mass more or less thick and elastic, which allows them to separate and approach each other insensibly. When this intermediate mass is cartilaginous it is called synchondrosis, and synneurosis(l) when it is ligamentous or fibro-cartilaginous. The articulation of the different parts of the sternum is an instance of the first, and that of the ossa pubis and of the ossatlia with the sacrum, of the second.

§ 243. 2d. The suture, (sutura, ){2) an articulation found only in the head. It consists essentially in the union of long narrow surfaces or edges by a very thin layer of cartilage, whence results an entire want of motion. The degi'ee of this immobility varies with the arrangement of the contiguous surfaces. The principal kinds of sutures are,

a. The false suture, or harmonia, (harmonia, sidura spuria,) in which edges perfectly straight, or at least but slightly serrated, are connected : such are the ossa unguis and ossa nasi with the adjacent bones and with each other.

(1) This is not the usual acceptation of this word ; but we ought not to aitach any other meaning to it when we wish to mark the two kinds of symphysis by the nature of the mass which unites them.

(2) Duverney, Lettre concernant plusieurs tiouv. obs. sur l'ostêologie, Paris, 1689. — Bose, De suturarum cranii humani fabricatione et usu, Leipsic, 1755. — Gibson, On the use of the sutures in the skulls of -men and animals, in the Mem. of the society of Manchester, second aeries, vol. i. 1805, p. 317-328.


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b. The true sulnre, {sutura vera,) which also presents several varieties, according as the joint becomes more solid from the multiplicity of the points of contact.

Immediately after the harmonia comes,

1st. The scaly or squamous suture, {sutura squammosa.) The surfaces of the two adjacent bones are gradually formed like a swallow's tail, the one being sloped to receive the other for a considerable extent. At the same time the contiguous surfaces are more or less serrated, but the processes are feeble : we will mention as an instance the articulation of the temporal bones with the occipital bone.

2d. The serrated suture, {sutura serrata.) Small and plain projections and cavities alternate with each other, both from above downward and across, along the perpendicular and narrow edge, and correspond to similar cavities and processes of another bone ; so that each bone presents a double range of elevations and depressions. The upper part of the frontal suture is almost always formed after this type.

, c. The dentated suture {sutura denticulata) also arises by single processes and cavities, which alternate with each other on a perpendicular edge ; but the elevations are higher and the cavités deeper, and they form only one series. We see an instance of this arrangement in the sagittal suture.

d. The margined suture {sutura Hmhosa) much resembles the preceding ; but the processes and cavities are larger, and are often subdivided. It sometimes happens also that the processes of one bone are fitted obliquely to those of another. Still the first condition is the most essential, as the second also occurs more or less in the preceding sutures. The occipital suture belongs to this series.

Here we must observe that these four kinds of sutures rvith teeth pass from each other by insensible shades. Thus, the inferior part of tlie frontal suture generally makes the transition from the squamous to the dentated suture, since the frontal bone glides under the parietal bone to a considerable extent ; but the oblique portion by which the two bones are united is separated from the rest of the surface by a very sensible prominence, and its internal part is in fact perpendicular.

We find also in the same suture different parts, each of which belongs to the last three sutures, and others which cannot be referred to any. We should particularly consider that the same suture does not belong to the same class in all skulls. The sagittal and even the lambdoidal suture is sometimes only a dentated suture, while the frontal suture is often a very complex margined suture, and in other cases extends almost in a straight line. Even the squamous suture of the temporal bones is sometimes changed into a dentated suture. Generally, when one suture is more complex and consequently more solid than usual, the others are so in the same proportion, and vice versà ; so that the bones of the skull are articulated more firmly in some subjects than in others. It is also a rule, that one and the same suture is far more complex on its outer than on its inner face, Avhere it usually forms nearly a straight line.


or THE OSSEOUS SYSTEM IN THE NORMAU STATE. 221

The sutures are found only in the head, and arise necessarily from the manner in which the bones of that part are developed ; for ossification commences there in several points at once, and the bones increase by the â–  addition of new osseous substance to their outer circumference. Hence also they are often effaced in one point or another when the bones are entirely developed. Before this period the dentated edge which exists in them, and by means of which the parts of bone are attached to each other, is very important to the solidity of the articulations. Thus we find similar irregularities on these surfaces of bone, not provided with cartilage, which are joined so as to glide slightly on each other : as the bones of the pubis, the iliac bones, &c.

§ 244. 3d. Gomphosis is where a bone implants itself like a wedge in the cavity of another, which embraces it closely, envelops it iir most of its length, and retains it very solidly, although they are not united. This kind of articulation is seen only in the head : the insertion of the teeth in the jaws is an instance.

§ 245. The movable articulations do not change much during life, while those which are immovable, as at least the sutures and gomphosis, vary considerably. Iir the early periods, large spaces, filled by the internal and external periosteum, exist between the bones which are separated by 'a layer at first thin and mucilaginous, and afterward cartilaginous. Still their edges are more unequal during the early periods of uterine existence than in the adult, because the rays of bone which leave the point of ossification to go there are very numerous, and separated from each other. But this form does not seem to prove that the tendency to produce these sutures is manifested from that time, since at an earlier period, when the edges of the bone are already approximated, they are much straighter, and even more so than when the development is perfect. The edges do not even touch in a fully grown fetus, and we observe between them, in those parts where the several angles of the bones are afterwards united, large spaces called fontanelles, {fonticnli, fontes pulsatiles.) Even after the bones are in contact with each other, we may establish as a gerreral law, that the sutures gradually become more cornplex by age, and acquire still more solidity, not only by the inerease of the principal processes, but by the formation of secondary processes on their surfaces.

This union of the bones by sutures, which becomes in time more and more intimate, finally degenerates into complete fusion. There are general laws for the manner in which this fusion takes place, and the greater or less frequency with which certain sutures disappear ; but there are none for the period at which it commences.

The general law relative to the manner in which this fusion occurs is that the internal edge of the sutures disappears before the external edge. It is a common thing in young subjects to find all the sutures of the head effaced internally, while they are perfectly preserved externally. We never observe an opposite arrangement. So, too, one suture never disappears in all its extent at once ; but obliteration usu

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ally commences at a single point, whence it gradually extends to the whole suture.

In regard to the second general law, the bones of the face are blended together much more rarely than those of the skull. Even among the latter there are some which are united much oftener than others. But we shall reserve the details on this subject for the section in which we shall examine the bones of the head particularly.

What proves the impossibility of assigning any general law in regard to the period when the obliteration of the sutures commences, is that they are sometimes found entirely effaced in the fetus at birth, that they are sometimes though rarely fused during the early years of life, and that they are not unfrequently perfectly preserved in old subjects ; generally, however, the suture disappears only at the latter periods of life, while they fuse partially on the internal face very soon after the individual is perfectly developed ; and also in most subjects who have attained the age of thhty, the whole suture or some parts of it disappears on this side.

Gomphosis changes very much during life ; for the teeth are at first much smaller than the cavities which receive them, and which do not as yet compress them.


\ ARTICLE SECOND.

OF THE OSSEOUS SYSTEM IN THE ABNORMAL STATE.

I. OF THE BONES.

§ 246. The bones not unfrequently vary from the normal state in respect to all their characteristic qualities.

The primitive deviations of formation(l) arenot equally common in all the bones. Those of the cranium, and among them the occipital bone, are those which offer the most, and the bones of the extremities those which present the fewest. These defects of formation consist generally in a suspension of the development ; and their frequency must at least be ascribed in part to the circumstance, that in many animals, even those allied to man, the bones of the skull seem to stop regularly at these degrees of evolution. It is, howmver, remarkable, on the other hand, that the bones of the face usually vary little from the normal state to produce analogies with animals : for instance, the perfect development of the intermaxillary bone is very rare. It is not probable that such a difference depends on the high perfection of the brain of

(1) Sandefort, De ossibvs, diverso modo, c solitâ conformatione ahludentibus, in the Obs. anal, path., lib. iii. c. 10, lib. iv. c. 10, 'p. 136-141.. — Van Doeveren, Observationes osteologicæ, varias naturœ lusns in ossibus humanorum corporum exhib,, in the Obs. acad. specim., Leyden, 1765.— Rosenmüller, Dc ossium varietatibus, Leipsic, 1804.


OP THB OSSEOUS SYSTEM IN THE ABNORMAL STATE.


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man, since the anomalies of the skull are generally attended with the imperfect development of this viscus.(l)

§ 247. The deviationsin formation of thebones which may supervene at all periods of life are, first, solutions of continuity.

The bone is broken either by a cutting instrument, when there is a wound, or by a bruising body, which causes a fracture, {fractura.)

The solution of continuity may be total or partial. The fracture is transverse, oblique, -which is most common, or longitudinal. When the development is perfectly complete, they supervene with equal facility in all parts of the bone ; but when the epiphyses are not yet united, they are usually detached by mechanical lesion, or by those diseases which destroy the tissue of the bones. (2)

The parts may heal in both cases, not merely when there is simply a solution of continuity, but also a comminuted fracture, when the bone is broken into several pieces, and there is a considerable loss of substance. The detached fragments sometimes unite, even when placed in contact with healthy portions.

The progress of formation is exactly the same as in normal ossification. (3) A gelatinous substance is effused around and between the fragments, which gradually hardens, and becomes cartilage, within which several nuclei of bone afterwards appear, which fuse with each other and with the broken parts, surrounding those also which have been perfectly detached. At the same time the fragments and splinters become round, so that the adjacent parts may not be wounded by their asperities. (4) To produce this formation of new osseous substance, it

(1) Most of the principal deviations of formation in the bones are mentioned in the first volume of our Pathological Anatomy, under the heads Anencephalia, Hydrocephalus, Hernia cerebri, &c.

(2) Reichel's monograph on this subject is excellent, Ue epiphysium ab ossiumdiaphysi deductione, Leipsic, 1769.

(3) Boehmer, De ossium callo, Leipsic, 1748. — Id., De callo ossium è ruhiae Undorum pastu infectorum., Leipsic, 1752. — Haller, De ossium formaturà, in the Opp. min., vol. ii. p. 460. — P. Camper, Observationes circa callum ossium fractorum, in the Essays and observations phys. and liter., vol. iii., Edinburgh, 1771. — Bonn, De ossium callo annex, ejusd. descr. thess. oss. morb. Hovian, Amsterdam, 1783. — A. fl. Macdonald, De necrosi et callo, Edinburgh, 1799. — Bedard, Propositions sur quelques points de médecine, Paris, 1813.— Breschet, Quelques recherches historiques et expérimentales sur le cal, Paris, 1819. — J. Sanson, Exposé de la doctrine de Dupuytren sur le cal, in the Journ. univ. des sc. mêd., vol. xx. p. 131.

(4) The most ancient explanation we possess on the mode in which these solutions of continuity of the bones unite, attributes this consolidation to a kind of viscous fluid, more lately termed the osseous juice, or the coagulable lymph. According to the ancients, this fluid exuded from the surfaces of the fracture, gradually became consistent, and reunited the fragments in the same manner as isinglass unites two pieces of wood. This opinion prevailed in the schools until the middle of the eighteenth century, when it was opposed by Duhamel, who published the results of his experiments. Haller's opinion was like that of the ancients. He thought to gain more knowledge by experiments, which were made by Dethlef under his direction, and which confirmed him in his opinion. He ascribed the callus to a juice coming from the fractured surfaces and from the marrow, a fluid which is eflused around the fragments, gradually thickens, becomes cartilaginous, and then osseous, while the periosteum does not concur to re-establish the continuity of the broken bone. Haller, in describing the mode in which callus is formed, says that this operation resembles ossification ; that the effused gluten, coming from the veseela or tissues of the broken surfaces and from the marrow, soon becomes consistent,


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is not necessary that the corresponding faces of the layers of bone,

and assumes the characters of cartilage ; that this cartilaginous substance passes to the slate of bone when its vessels are sulBciently dilated to allow the red blood to penetrate its thickness, and brings a saline matter which forms osseous points, which successively are increased in extent, and finally pervade all the cartilage. In another place, Haller pretends there is from the commencement a gelatinous matter, and shortly afterwards a cartilage, within which a ring forms, which ossifies the first, extends to the processes, and breaks the cartilage, which retreats before it, and of which it is divested as of an envelop. This last mode of considering callus is very incorrect, and it will be ea.sy for us to show it. Macdonald asserts that all the aut hors who have written before Haller, and even this great physiologist himself, are deceived when they pretend that the gelatinous matter of callus changes into cartilage. Haller, however, does not exactly say it forms cartilage, but that at a certain period we see organic molecules appear, which are not blood, and that when all the gelatinous mass has become opaque and elastic, it is then regarded as cartilage. Macdonald seems to think that the gelatinous substance never changes into cartilage, but that the matter considered as cartilaginous is a real, soft, flexible bone, which is afterwards hardened by the phosphate of lime. He thinks, from his experiments, that the newly formed bone is originally soft, elastic, easily divided, and curved, in a word, that it resembles cartilage. The proofs brought forward to demonstrate the osseous nature of this substance are that in nourishing an animal with madder, the callous substance reddens ; but this phenomenon does not appear in the cartilages. He supports his opinion too by the chemical analyses of the cartilages made by Allen. Finally, he has discovered the error into which Duhamel has fallen in attributing the formation of callus to the ossification of the periosteum. John Hunter, whose talent has thrown light upon so many points of physiology, considers callus as the result of the organic development of extravasated blood, and of its transition to the state of bone. J. Howship has lately developed Hunter's ideas more fully, and supported them with experiments. Hunter assorts that at first the space between the fragments of the bone and the surrounding parts is filled with blood coming from the ruptured vessels, that this blood coagulates, and that by an organization vessels areformed in it. Adhesive inflammation takes place at the ends of the fractured bones, and then a peculiar process commences. Inflammation supervenes also in the splinters which are still attached to the bone and the surrounding parts. It produces in them a disposition to interstitial absorption, by which the angles of the fragments are smoothed down, their extremities soften, and become conical ; now all these changes favor the ossification which is about to commence. Howship admits that Hunter's ideas are more correct than all which has been said in respect to callus, and that they agree in several essential points with his experiments. The conclusions he draws from his own researches are, that the first eflect of the fracture is the extravasation of blood in the thick parts around, and that this varies in quantity with the degree of contusion or of complication. This blood is effused principally in the tissue of the periosteum, and increases its thickness. It is effused also in the medullary canal and between the fragments, where it is variously changed, and becomes the centre in which the ossification of the callus commences. I'he red color which pervades the periosteum gradually disappears; this membrane becomes firmer, and by degrees assumes the appearance of cartilage. The mode of progress in this union of fractures seems to show that the principal object is to prevent all possibility of motion between the parts. The callous matter is deposited on the surfaces of the Ijones, near the parts where union ought to take place, then on the circumference of the ends of the fragments and in the medullary cavity. I'he deposit of the blood, and the successive degrees through which it passes before it becomes an osseous substance, are remarked on the circumference of the ends of the fragments sooner than in the spaces which separate them. To give the ideas of the author better, we shall say that the fracture by this process becomes very solid before the union or the osseous cicatrix between the fragments is finished. In this respect Howship agrees perfectly with Dupuytren and also with Breschet ; and we would remark that these facts had been published in France, either by Dupuytren or Breschet, and after numerous experiments, before the appearance of Howship's memoir. Finally, we say that if the fracture be compound, the vital operations to repair the injury are divided: on one side callus is deposited, on the other we see a manifest attempt to remove all the parts of the bone which have been separated, and where the circulation no longer exists. This elimination is conducted by the internal surface of the periosteum, which becomes granulated, extremely vascular, and pos

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which are separated from each other, should be in contact ; for tht

sesses a great absorbing' power. The analogy between this theory and the ancient mode of considering callus has caused us to speak of it in the same paragraph. Duhamel believed that the periosteum is to the bone what the bark is to the tree, and that fractures are often united by the agency of the membrane of the marrow. He thought it W£i3 the swelling of the periosteum and of the membrane of the marrow, their extension from one fragment to another in order to join and unite by ossification, which produced callus, and formed around the fractured bones sometimes a single sometimes a double ring, which fixed them firmly while it united them. This opinion has many advocates and many critics ; still we must acknowledge the exactness of many observations of Duhamel, and admire in his experiments a precision not to be expected from a stranger to medicine. DuhamePs theory, although false, has doubtless been useful to science, as it has drawn the attention of physiologists to the cicatrization of bones, and we owe to it the researches of Haller, Dethlef, Bordenave, Troja, &c., on the same subject. Fougeroux adopted, without any restrictions, the ideas of Duhamel, and endeavored by his experiments to reply to the attacks of Haller and Bordenave. The opinion defended by him was no longer quoted, except as matter of history, when Dupuytren revived Duhamel's opinion, and extended his ingenious theory to observations on pathological anatomy. He has known not only the periosteum to ossify, but also the laminar tissue, tlie ligaments, and even the fleshy part of the muscles, to form a sort of osseous ring, which kept the fragments together, and preserved their relations. According -to Dupuytren, we must admit two distinct epochs in the formation of callus, or rather two calluses which succeed each other in their formation. The first, which he calls the 'provisional callus, is completed when the medullary system of the two fragments is united, and a kind of osseous button exists within them which joins them, and the periosteum has formed externally, either alone or with the cellular tissue and even with the muscles, a ring which surrounds the extremities of the fragments, and adheres to them. Hitherto, the surfaces of the fracture are not yet united, nor even altered in the midst of the newly formed osseous tissue which constitutes the first callus. The solidity and resistance of the latter are less than those of the bone ; hence if a new fracture occurrs in the same bone, it will be exactly where the first existed. TYfien, after four or five months at most, the medullary canal begins to form again in the part where it was obliterated; when the accidental osseous substance produced by external ossification contracts and diminishes in volume ; when the periosteum, the cellular tissue, and the muscles, return to their natural state, or cease to be ossified, if the adaptation be perfect, and if there be no irregularity between the fragments ; finally, when the union takes place in the two ends and even on the surfaces of the fragments, then commences the second callus, or the definitive callus, which is not perfected till after eight months. This last period is characterized by the return of all the parts to their primitive state. This theory, however, which resembles that of Duhamel in several respects, since it assigns the periosteum as the seat of callus, differs from it much. In fact, Duhamel did not consider the osseous state of the periosteum as a provisionary state, while Dupuytren regards it only as a means to oppose the displacem«t of the fragments, and to favor the formation of the proper callus. He admits and demonstrates that fractures are united by two successive calluses, the one temporary or provisional, occurring on the outside of the bone and in the adjacent tissues, the other definitive, and situated in the medullary canal and at the ends of the fragments, as well as in the space which separates them. Dupuytren's theory is of the highest importance in its practical application to surgery, as it throws much light on the treatment of fractures. Bordenave was the first who regarded callus as a cicatrix analogous to that of the soft parts, that is, a cicatrix produced by granulations which proceed from one fragment to meet those of another, unite, and then receive the calcareous salt which gives the character of bone to the substance of the cicatrix. At first, the bones pour out from their broken extremities a fluid which is the primary matter of their union. This fluid gradually thickens, assumes the form of bone, and when the dilated vascular tissues furnish vessels which open in it, the canal becomes similar to the bone itself. Some modern authors, as Bichat and Richerand, have also regarded caUus as a cicatrix analogous to that of the soft parts, and depending upon the development of granulations which unite, and receive the phosphate ol lime, to reestablish the continuity of the osseous tissue. Callisen thought that callus was formed by vessels arising from the broken extremities, and extending between the fragments, and by the final deposit of osseous matter, that is, of the phosphate of lime. He explained by an enlargement of the vessels the union in a

VoL, I. 29


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cure is as perfect when they are simply at the side of each other, pro single callus of adjacent bones fractured simultaneously, as is sometimes seen in the leg and fore-arm. Bonn rigorously omits all explanation, and confines himself to the statement of wliat he has observed. His remarks rest entirely upon dissections of human bodies, and on a large number of wet or dry morbid preparations. Bonn does not appear to have experimented on animals ; but he has sought to enlighten himself by analogy and by facts observed by others. He maintains that callus while imperfect is ligamentous and membranous. Callus, he says, at first resembles flesh ; it then acquires the consistence and tenacity of leather. But its transition to bone is never preceded by the formation of real cartilage. Perfect callus is oiganized and identified with the bone : sometimes it is found entirely soli I, as in diseased bones, and again it is softened and dissolved by caries. J. Bell describes callus as being formed at first by a soft and flexible substance, situated between the fragments which it unites. It is the reëstablishment of the continuity of the vessels of the bone which produces it. Samuel Cooper, adopting all J. Bell's opinions, defines perfect callus to be a new bone, or osseous substance, which unites the ends of a fractured bone. Peter Camper thought that in the union of fractured bones the fragments united by a double callus, one external, formed from gelatin furnished by the vessels and osseous fibres, which condenses below the periosteum, and afterwards becomes osseous substance ; the other internal, produced by the lengthening and separation of the inner layers of bone, or the expansion of the compact tissue of the bones, to obliterate the medullary canal. Troja has seen the ends of a fracture covered in a few days with gelatinous matter, which soon became abundant, and was gradually converted into cartilage, then into bone. He has also observed, a swelling of the periosteum till a certain period when the thickness of this membrane diminishes, an internal ossification filling the medullary cavity near the fracture, and an external ossification which always exists. The facts related by Troja are strictly correct ; a careful observer, he states candidly what he has seen, and does not, like Duhamel, follow a favorite and exclusive idea. The results of his experiments are similar in many respects to those obtained by Breschet.

Having thus briefly stated the difi'erent opinions of authors with regard to the formation of callus, we shall now mention the principal facts established by the numerous experiments of Breschet, premising, however, that the apparent discrepances in the opinions of writers in regard to callus, gradually disappear when its peculiar naturels studied. We then easily discover the cause of error, and the points where observers have given too great latitude to isolated facts, or have admitted them as general. Perhaps, also, as Bedard says, the differences of opinion arise from the fact that the researches have not been made at every period, or at the same periods of union of the fractures. Breschet considers callus as depending, 1st, on the extravasation and the coagulation between the fragments of a little blood furnished by the ruptured vessels. 2d. On a fluid at first viscid, secreted and effused between the periosteum and coming from the neighboring tissues more or less connected in the fracture of the bone, and also from its broken surfaces. This formative lymph, (which may be compared to that exhaled from the edges of a wound of the soft parts, or that produced from several surfaces by inflammation, and which constitutes the membranous formations,) is at first mixed with a little blood ; but afterward it is secreted alone, and when the periosteum is altered or destroyed, it is effused or filtrates into the interstices of the fibres of the soft parts around the fracture, and there thickening, forms' a callus external to the fracture. 3d. On the gradual thickening of these fluids, (the blood and the formative lymph,) they unite gradually, and form stronger adhesions between the parts, which inflame and become real secrctor}!- organs. Considering abstractly the inflammation of the tissues near the fracture, we may compare the viscid fluid mixed with a little blood and its successive changes, to the camb of plants, and the changes which this organic principle of vegetables presents when effused between the bark and the woody part, or when secreted to cicatrize the wounds of vegetables. 4th. On the swelling and moderate inflammation ef the periosteum and adjacent soft parts, on the cicatrization of these parts, and sometimes on the deposition of matter within their layers. 5th. On the contraction of the central cavity of the bone, on the softening of the ends of the fragments, and on the deposit of a substance similar to that which collects in the periosteum, or in the plates of the tissues adjacent, in the medullary cavity, and between the ends of the fragments. 6th. On the condensation of this matter, on its organization by the development of the vessels. At first it has a granulating appearance, it then assumes a fibrous consistence, next a cartilaginous appearance, and finally becomes bone. These changes are observed, first, external to the fragmente.


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227


vided no foreig'n substance is interposed between them, and that they are kept in contact. It matters httle, too, whether the fragments which are approximated belong to the same or to different bones : the cure is not less perfect ; only anchylosis exists.(l)

In all these cases, the extremities of the bones become round, and are completely closed. The bone becomes entirely solid where it was fractured, and its medullary ca\ity is divided into two halves. Hence a single bone in fact forms two. It is more solid in the place of the fracture, than in any other part, so that it is rare that a bone breaks there a second time, although the life of the osseous cicatrix is more feeble than in other bones.

to constitute the provisional callus, and afterwards appear in the cavity of the bone, and between the ends of the fracture. 7. On the return of the soft parts which surround the fracture to their primitive state, after the callus has successively passed throng'd all the degrees we have mentioned. This return takes place only after the re-establishment of the medullary canal, and this canal is re-established, only when the osseous substance by which the extremities are joined, is entirely solid. Then, the external callus which was formed first, gradually diminishes, and finally disap g ears, if the fragments have been accurately joined arid there is no displacement.

ut if there be a displacement either in the length or direction of the axes of the two fragments, then the ends of the fracture continue closed, the medullary canal is not re-established, the newly formed external osseous matter, instead of being absorbed, remains to strengthen the callus, and its greatest quantity corresponds to the portion where there is the most displacement, and where the efforts to be resisted by the bone are the greatest. When we seek to compare the development of callus with the cicatrization of the soft parts, we find they differ greatly, if we admit the existence of granulations. But these pretended granulations are only illusory. We can easily demonstrate the identity of the process of nature, to unite all the tissues accidentally divided. One difference seemingly offered by callus, compared with the cicatrization of the soft parts, is the development of a substance, which exists only for a time, and which is formed externally to the fragments, in the medullary cavity. This substance is, perhaps, much more marked in the bones only because it is formed by a firmer and consequently by a more perceptible substance, or because it remains a longer time, and its quairtity is in relation to the resistance it must present to give the bones all their force and all their solidity. We'may say also, that the duration of its existence depends on the trifling degree of vitality of the bones, and on the slowness with which it is re-absorbed, or on its great utility. In fact, it serves not only to cicatrization, but also opposes the displacement of the parts ; it maintains their relations, and lessens, in sume measure, the disadvantages resulting from a want of contact or correspondence between the ends of the fragments. If we could observe fractures when the relations of their fragments were unchanged, and the ends of the bones were unmoved, and these bones were provided with a power of vitality similar to that of the soft parts, we should probably see in the formation and arrangement of the callus, a perfect similarity with the cicatrization of the other tissues. The practical consequences to be drawn from these experimental researches on callus, are, that the union of the fracture is not real, till the definitive callus is formed, and that then the organ can fulfill its functions without danger of unnatural curves. The provisional callus situated principally between the bone and periosteum, is only to retain the parts together, to favor the formation of the definitive callus. The first callus once formed, all apparatus may be removed ; but immobility is necessary, and when the second callus is completed, the organ has regained its firmness, aud can fulfill all its functions. In the treatment of fractures, then, two periods exist : in the first, we employ means to reduce it, and to hold the fractured parts together; in the second, the affected parts remain at rest, and the dressings of the fractures are removed ; it coincides with the definitive callus. F. T.

(1) H. Park, Account of a new method of treating diseases of the joints of the knee and elbow, London, 1783. — Cases of the excision of carious joints, by H. Park and P. F. Moreau, with observations by J. Jeffrey, Glasgow, 1806. — Wächter, Diss. de articul. extirp., Groningen, 1810. — Moreau, De la résection des os, Paris, 1816. — Roux, De la résection, des os, Paris, 1822.


GENERAL ANATOMY.


2 28

When the conditions are perfectly normal, the subject is in good health, and the fragments of the broken bone are placed in contact, the osseous substance is never produced in excess. If a portion of bone has been entirely removed, as in amputation,(l) the extremity of the stump becomes round, shrinks a little, and covers itself with a compact substance more or less dense. The fractures and injuries of the bones, however, are not always cured so completely, nor do we always see bones which have been destroyed to a greater or less extent by any cause whatever, completely regenerated. The causes of this difference are dynamical or mechanical. To the first class belong, 1st, age ; 2d, general weakness; 3d, diseases which affect the bones, as the scurvy and rickets, especially the former ; 4th, the concentration of the formative power in some other organ, which prevents the union of a fracture(2) during pregnancy, and the period of lactation, although it does not always operate. (3) The same causes, especially the first, dispose the callus to soften, particularly when the fracture has not been long united.

The second class of causes comprises all that prevent the pieces of bone from touching, as an absolute defect in fitting them, and the continual derangement of the fracture by the motions of the part. Hence the reason that fractures of the ribs and patella are not often perfectly healed.

In these cases an artificial joint {articulus abnormis s. artißcialis,) is formed, and the limb is useless, at least in some measure, since it is deficient in firmness.

The state of the parts is not always the same in the artificial joints. (4)

Sometimes the fragments adhere by means of a ligamentous or cartilaginous mass. (5) Sometimes they remain separate, and are connected like the moveable joints, by a capsular tissue. (6) Finally, sometimes muscular or tendinous fibres are formed between them. The first state resembles the symphyses, and the second the synovial joints.


(1) P. G. Van Hoorn, Diss. deiis, qvæ in partibus mcmbri, prœsertim osseis, amputatione rulneratis, notanda sunt, Leyden, 1803, p. 36-129. — Brachet, Mémoire de phys. pathol. sur ce que de vient le fragment de Vos, après une amputation; in the Bidletin de la soc. méd. d'émulation, Paris, 1822.

(2) Alanson, in the Med. obs. and inq. vol. iv, p. 414.

(3) Fab. Hildan, Obs. cher. cent. v. obs. 87 ; cent. vi. obs. 68. — Hertod, in the Eph. A. C. D. 1. no. 1, obs. 25. — Schurig-, Syllepsiologia, 1731, p. 517. — Alanson, Med. obs. and inq., vol. iv, n. 37.

(4) Wardrop, Case where a seton was introduced, etc. ; in the Med. chir. tr. vol. V. p. 367. — Salzmann, De artic. analogie quÅ“ fracturis ossium superreniunt, Strasbourg', 1718. — H Kuhnholz, Considérations sur les fausses articulations, in the Journ.compL, vol. iii, p. 289.

(6) Van DÅ“veren, Spec, obs.'acad., p. 204. — Walter, Anatom. Museum, vol. ii. no. 650-656.— Morand, yjescrtpt. du cab. durai, inMukon, Hist, nat.gén., \o\. iü. p.. 76. pl. i. — Cooper, in the Med, records and researches, vol. i. — Bonn, l'hes. oss. morb, clxx, clxxxiii, clxxxiv. — Langenbeck, On the formation of false articulations consequent to fractures ; in the Neue. Bibi, für Chirurgie, Gottingen, 1815, cah. i, p. 94, 95.

(6) Koehler, Beschreib, von Loder's Prœparaten, p. 66-105, — Walter, loc. cit. n. 651, 652, 653, 654, 656, 657..^Home, Trans, of a soc. for the impr. of'med. and surg. Icno^cl. vol. i. p, 233.


OF THB OSSEOUS SYSTEM IN THE ABNORMAL STATE. 229


In the latter case the extremities of the bone are rounded, smooth, and here and there are cartilaginous. Usually, one is excavated, and the other is elevated, so that they represent, the first the cavity of a joint, and the other its articulating head.

The extremities of the bones are sometimes swelled, but usually this is not the case. The capsule of the joint secretes synovial fluid. Sometimes cartilages and unnatural bones form in these false joints, similar to those not unusual in the natural joints.(l)

When dynamical causes oppose the formation of callus, it is formed when they cease to act, although its formation may be very slow ; for instance it may continue during the whole period of pregnancy. When the obstacles are mechanical, the ends of the bones are almost always cicatrized, and the cure takes place by the efforts of nature alone. The formation of callus, however, may be stimulated by proper means, which are not the same in all circumstances, but all of which tend to the same end, that of changing the cicatrized surfaces into a recent wound, and of stimulating the vitality of the bone locally. (2)

These phenomena are seen not only in fractures of a single bone, (3) but even in those of two adjusted to each other.(4)

§ 248. The power of reproduction in the bones develops itself with more energy, when an entirely new bone is formed in the place of an old one, which by some means has become dead. It is not the reproduction of the bone, but its death, which constitutes the essence of the disease necrosis ; for, the regeneration is always accidental, and is never a disease, although it almost always attends the death of bone.

This power is seen particularly in the cylhrdrical bones, which possess it in the highest degree. (5)

The principal conditions of their reproduction are as follows ;

When a part of a bone is dead, which does not necessarily imply a

(1) Home, loc. cit., has given the best description of an artificial capsular joint of this kind.

(2) White, Cases in surgery, London, 1770, p. 69-93. — Inglis, Ohs. on the cure of those unnatural articulations which are sometimes the consequences of fractures in the extremities ; in the Edinb. Med. Journ., vol. i. p. 419.— Rowlands, A case of an un-united fracture of the thigh cured by sawing off the ends of the bone ; in the Med. chir. tr. vol. ii. n. v. — VVe find an excellent account of the different modes with several interesting cases in Wardrop's Memoir mentioned above. — Delpech, art. Cal, in the Diet. des. sc. méd., vol. iii.p. 451-453.

(3) As Boyer thinks. Leçons sur les les malad, des os vol. i. p. 69.

(4) White, loc. cit., p. 79. — Wardrop. Inglis.

(5) The principal works on this interesting subject are, Chopart, De necros. ossium theses anat. chir., Paris, 1776. — Louis, Sur la nécrose dé Vos maxill. inf. ; in the Mém. de chir. de Paris, 1772, p. 355, Paris, 1782. — Troja, De novorum ossium in integris aut maximis, ob morbos, deperditionibus, regeneratione expérimenta, Paris, 1775. — David, Observ. sur une maladie connue sous le nom de nécrose. — Weidmann, De necrosi ossium, Erfort, 1793.— Russell, Practical essay on a certain disease qf the hones called necrosis, Edinburgh, 1794. — Koeler, Expérimenta circa regenerationem ossium, Gottingen, 1786. — Macdonald, De necrosi et callo, Edinburgh, 1799. — Macdonald, in Urowther, Pract. obs. on the diseases of the joints, London, 1808. — Macartney, in Crowther, Practical observations on the diseases of the joints, London, 1808. — Charmeil. De la régénération des os, Metz, 1821. — Knox, in the Edin. med. andsurg. journal, 1822, im.


230


GENERAL ANATOMY.


great change in its form, color,(l) or chemical composition, (2) it is detached from the healthy portion, because nutrition does not extend beyond the limit which separates it, and absorption acts more rapidly upon it.

But at the same time the formation of a new bone commences. It results from a considerable development of the vessels of the periosteum, and of the adjacent cellular tissue, which also becomes softer. As the bone dies, a gelatinous fluid is effused in all the surface between it and the periosteum. This fluid gradually thickens, and is changed into real osseous substance. It first becomes cartilaginous, and afterwards, but rarely in less than twenty-four days after the commencement of the disease, points of bone are seen in the cartilage. The new bone finally unites and fuses with the healthy parts of the old bone.

As the progress of these two actions, the mortification and the detachment of the old portion of the bone, and the formation of the new bone, and its union with the sound extremity of the old bone is nearly equal, the patient does not generally lose the use of his limb, although it often happens that the body of the old bone is entirely detached. But it is sometimes lost, because the dead bone detaches itself before the new bone has time to unite with the healthy portions. Besides, since when the old bone dies it detaches itself from th<e periosteum, and as the new bone forms below this membrane which is usually uninjured, to which it unites by the anastomoses of their respective vessels, and as the tendons are inserted in the periosteum, it is natural that these latter, when detached from the old bone, should be inserted in the new, as is usually the case.

Even when the periosteum dies, these essential conditions are not changed, for it is replaced by a new periosteum, formed from the surrounding cellular tissue.

The newly formed bone perfectly resembles the old one in several respects : it also differs in some.

Its hardness, length, and connections with the neighboring parts are the same ; but its form and thickness differ. It is generally larger, because it surrounds the old bone, around which it forms. It is more or less shapeless and massive, and its fibres are not so regular. Its surface is very uneven and very rough, because not included in the primitive plan of the organization. It has then, like allaccidental ossifications, a form less distinctly marked, and which would be even less so if the ancient bone did not serve as a model. The thickness of the new bone is sometimes very considerable. It often exceeds an inch- in the large bones, as the humerus and femur. Usually it is increased in this manner ; when the the dead portion is thrown off from within the new bone, in one of the ways we shall mention directly, the cavity of the latter is almost always obliterated, by the increase which continues within, so that no regular medullary canal remains, and the new bone is entirely solid. (3)

(1) Weidmann, Denecrosi ossium, p. 19.

(2) Davy, in Monro, Outlines of the anatomy of the human body, vol. i. p. 39.

(3) Russell, 60-63.


OF THE OSSEOUS SYSTEM IN THE ABNORMAL STATE.


231


Although this is common, it does not always take place ; for sometimes a regular medullary canal is found, extending the whole length of the bone, but possibly this is formed afterward.(l)

The old dead bone seldom, in fact never, remains in the cavity of the new bone. (2) Sometimes it gradually disappears ; sometimes it comes out of itself, either in one portion, or in different pieces, or it is removed by art. It passes off through several smooth, round openings, which penetrate entirely through the new bone into its cavity, and communicate with the skin by fistulous openings, which do not close till after the sequestrum is thrown off, being continued by its irritation, as a. foreign body.

We must remark, that the commencement of the openings appears , when the new bone is first formed, for we can perceive in the gelatin which is effused, dry and opaque points, which soon change into them.

The death and reproduction of a cylindrical bone rarely extend beyondits body,and its spungyextremities remain unaffected, although the whole body perishes. This phenomenon is seen not only in youth, when the body and the extremeties form separate and distinct bones, but also in the advanced periods of life, at least very often.

The bone never perishes in its whole thickness ; often and from the nature of the causes, only its internal or its external portion decays. The first case may be confounded with the mortificatoin of the whole bone, because then it usually happens that the remaining part swells also, and openings are established for the separation of the dead portion. Still it may be distinguished, not only because the exfoliation is almost always smaller in every respect, but because the outer surface is very rough, while in a bone which has decayed in all its extent, this surface is' very smooth.

The fiat bones not unusually die ; but they are not generally, or but very imperfectly, reproduced. If they grow anew, the progress of nature is essentially the same. But the new bone does not surround the old one, as in the cylindrical bones, and it is in fact formed by the growth of the edge, which has preserved hfe. The short bones also rarely die, and are as rarely regenerated.

§ 249. The deviations of formation of the bones, which are developed at all periods of life, are in regard to their mass and volume. They result in the unnatural enlargement or diminution of these organs.

The bones are, perhaps, of all organs, the most subject to an unnatural enlargement. Sometimes they increase in all their circumference, which constitutes hyperostosis. Sometimes only a tumor is developed in some part of their extent ; this is called exostosis. Then their structure is normal, or it is altered : the latter is most common. The bone,

(1) Russell, loc. cit. in the appendix, case 1st.

(2) 'Voi^tel says, (Pathol, anat. vol. i, p. 195) that “the new bone is seldom hollow, covering the remains of the old bone, which are loose withih it, as in a tunnel -p but in all the cases he reports, the cure was not perfect, as the openings of the new bone were not closed.


232


GENERAL ANaTOMV.


when altered, is sometimes looser and more spungy ; sometimes harder, more solid and heavier than usual. Swelling of the hones, with diminu* tion in density, is called spina ventosa.{^) Swelled bones are at first more spungy ; but when cured, they become harder and more solid. Osteosteatoma, or exostosis steatomides, resembles exostosis, and probably often, if not always, is an imperfect swelling of the bone, with a change in its chemical composition. (2)

The bone rarely diminishes in size, unless the other organs are similarly changed, as when the process of nutrition is deranged from paralysis. A change in their mass is observed less rarely, and this state is almost always accompanied with a change in their chemicalcomposition.

§ 2-50. The diseases of the last kind, which cause anomalies by a spontaneous alteration in nutrition, lead so much more naturally to alterations in texture and. chemical composition, that their influence is rarely exerted on the form alone. On the other hand, the form appears more or less changed in the anomalies of the bones, where the prevalent character consists in a change in texture and chemical composition. The principal changes in the texture of the bones are as follows ;

1st. Inflammation, and its consequences, which differ from those seen in other organs, by their slow progress. Thickening, often also exostosis, especially the swelling of the bones, attended with diminution in their density, {spina ventosa) are manifestly the results of inflammation, terminated by exudation. Suppuration is called caries, and mortification, necrosis. The principal phenomena of this last have already been mentioned. (§ 248.)

2d. Diminution of hardness and solidity, of which there are different degrees. In rachitis, this exists in the slightest degree ; the bones are soft, spungy, flexible, and curved, either in the places where they are acted on by muscles, whose power they cannot resist, or in those where they sustain some weight. At the same time they receive more blood. The periosteum undergoes analogous changes. The chemical composition is not every where the same. In fact, we do not always find the same relations between the respective proportions of phosphoric acid and lime, as sometimes there is too much,(3) and sometimes too little(4) acid; and again, the proportion between the animal substance and the earthy portion varies much. Sometimes the quantity of animal matter is much enlarged, so that its relations are as 74.26 . and even as 75.8 ; 24.2 ;(5) or finally as 79.54 ; 20. 5. (6) Sometimes it does not differ from what is found in the normal state, and is even less, being as 25.5 : 74.5 :(7) although the bones are spungy. These differences

(1) Augustin, De spina ventosa ossium, Halle, 1797.

(2) Hundertmark, Osteostcatomatis casus rarior, Leipsick, 1757. — Herrmann, De osteatomatc, Leipsick, 1767.

(3) Jager, Diss. acid, phosph. tanquam morb. quorumd, causs. prop., Stuttgardt, 1793.

(4) Ackermann, Comment, med. de rachitide, Utrecht, 1794.

(5) Davy, loc. cit. p. 38.

(6) Bestock, in the Med. and chir. trans. of London, vol. iv, p. 38.

(7) Davy, loc. cit. p. 39.


OF THE OSSEOUS SYSTEM IN THE ABNORMAL STATE.


233


are probably owing to the degree, and especially to the period, of disease; but they at least prove that rachitis does not essentially consist in a deficiency of earthj' matter. This disease is seen in children particularly. In rachitis the bones are generally, proportionally speaking, too short and too thick : the head is larger, and the points of ossification of the bones of the skull are very distinct.

In softening of the bones [osteomalacia, osteosa7xosis) this state exists in a higher degree. The bones then become still softer, fleshy, or lardaceous, so that they may be easily cut. Their cellular structure disappears, and they become a homogeneous substance. At the same time they are more or less swelled. They present curves which are greater in proportion as the bone is softer. This is more frequent in females. The teeth are usually but not always free from it.(l) The results are deformity and crookedness of the extremities, or of the whole body, according as the disease of the bones is partial or general, and according as the bones yield to the efforts of the muscles, and to the weight of the whole body.

A state resembling this is the excessive brittleness of the bones, although it sometimes arises from an excess of earthy matter. This fragility is often so extensive, that the bones break from the least exertion, as from turning in bed, &c. It not unfrequently attends the softening of the bones, but it is usually found alone. The diseased bones do not lose their cellular structure, as in osteosarcosis, but it often becomes more distinctly marked. The principal causes of this state of the bones are general diseases which are of long duration, which affect to a greater or less extent all the systems, as scurvy, cancer, and syphilis.


II. OF THE ARTICULATIONS OF THE BONES.

§ 251. The joints vary from the normal state in two ways. The corresponding ends of the bones may be too loosely or too firmly united with each other.

§ 252. The too slight union of the bones may result from rupture or forcible extension, or from the relaxation of the means of union. These different states give lise to luxation, (luxatio,) which consists essentially in the separation of the movable extremities of the bones united together, and in the contact of a movable with an immovable bone in a place which is not normal, towards which it has been drawn by the muscles placed near the joint. Luxation takes place more easily, and consequently is more frequent, as the motions of the bones are more extensive ; and it is usually attended with distension of the ligaments when it happens to the movable articulations, but they are broken if the joints are less movable.

It always occurs naturally in the direction where the resistance of the articulating surfaces, the ligaments, and the adjacent parts, is the least.

(1) J. S. Plank, De osteosarcosi commentatw, Tubingen, 1782.

VoL. I. 30 '


234


GENERAL ANATOMY.


When tho bone does not resume its natural place, either by itself or the assistance of art, a new joint is formed, and the old one disappears. The bone with which the dislocated bone comes in contact usually forms a superficial hollow, which is covered first with periosteum, and afterward partially or wholly with cartilage, the edge of which is more or less turned over. At the same time the articulating head becomes flatter and more unequal than before, and often partially or wholly loses its cartilage, being pressed against the other bone by the muscles.

Sometimes a cavity is formed in the bone which was provided with an articulating head, to which corresponds a proportional head which grows on the surface of the other bone.

The immovable articulations are sometimes dislocated, or are less firm from an original deviation of formation.

The latter is seen in hydrocephalus, and when the bones of the pubis are not joined. The former, if we except the symphysis pubis at the end of pregnancy, arises only from mechanical violence, the action of which is sudden and strong, or slow and gradually increasing.

In congenital and normal separation, the uniting medium is distended or leirgthened ; it is ruptured when they are separated accidentally.

§ 253. An unnatural solidity in the joints constitutes anchylosis: (1) this is false (A. spuria) when the means of union are only contracted or too stiff, and true {A. vera) when the bones v/hich were separated in the healthy state are joined together by osseous matter. The consequence of anchylosis is the immobility of parts once movable.

In this case, either the fibrous ligaments are ossified, or osseous substance is deposited below them, and unites the surfaces of the two bones hke a bridge, or the two bones . are fused together in the whole extent of their corresponding surfaces, so that the cartilage which incrusts them and the compact substance disappear, and we find only a spungy substance, uniformly extending the whole length of the bone. The first two forms are found naturally in old age. The last is seen after inflammation and suppuration of the ends of the bones.

Sometimes, without any known cause, a tendency to ossification shows itself m several, and even in all the joints ; which is attended with stiffness of the whole body.

ARTICLE THIRD.

OF ACCIDENTAL OSSIFICATION.

§ 254. The accidental devolopment of bone is a very frequent phenomenon,(2) and is seen principally in certain systems, but is not ge (11 J. T. van de Wynpersse, De ancylosi, Leyden, 1783.

(2) J. van Heckeren, De osteogenesi prceternaturali, Leyden, 1797.


OF ACCIDENTAL OSSIFICATION.


235


nerally manifested till the latter periods of life. It appears especially in the left side of the heart, and in the system of the aorta, particularly its inner membrane (p. 151). It is not much more unfrequent in the serous membranes. It is seen less frequently in the fibrous organs, among which the periosteum furnishes the most examples. Accidental bones often form also in the internal genital organs, especially tlie uterus, in some fibrous bodies, in the thyroid gland, and in the ovaries.

Accidental ossifications present themselves under two different forms. Sometimes the osseous substance forms a connected whole with the parts in the midst of which it is. developed, a part of the substance in which the bone forms, is changed into it. Sometimes it forms a separate body, a new formation, which is connected with the part in which it is rooted only by the relation of nutrition, and sooner or later is insulated when this relation ceases.

Accidental ossifications of the first kind are developed principally in the vascular system, and in several parts of the serous system. The second species is usually seen in the synovial capsules, and in the natural and the accidental mucous bursæ ; and also m several serous membranes, especially the tunica vaginalis testis.

The latter forms more or less extensive layers which project but little or not at all above the surface of the parts in which they are developed. The former have the form of round bodies with peduncles, and are developed most frequently in those joints exposed to frequent concussions ; they are sometimes single, sometimes very numerous, and always communicate at one time or another with the synovial membrane.

Finally, these accidental osseous productions pass through the same periods as the noimal bones.(l)

(I) Broussais, in his Histoire des phlegmas. chron., Paris, 1808, -vol. i., attributes these accidental substances, both osseous and calcareous, to a chronic inflammation of the lymphatics. This opinion was revived by him in 1816, in his Examen. Boisseau, admitting' inflammation as the most common cause_of accidental ossification, thinks that it occurs only when inflammation is followed by a diminution in nutrition, and that we cannot admit the continuance of the inflammatory state in atissue which is accidentally ossified. [Reflexions sur la nouvelle doctrine médicale, in the Journ. univers, des sc. mêd., vol. vii., 1817, p. 43.) In answer, Broussais distinguishes two kinds of accidental ossifications : 1st, the inorganic osseous coircretions, the secondary results of a low degree of irritation, which form in the extravasated lymphatic fluids, or in tissues partly disposed to vital inflammation ; 2ndly, the pure and simple ossifications without previous altera.tion of the organization, consisting in those anomalies of nutrition consequent upon the progre.ss of age. (Journ.univ.des sc.medic., vol. viii., p. 156.) Gimelle afterward established that these accidental osseous substances never have the form nor the structure of the primitive bones, and that accidental ossification is always the result of a chronic inflammation, \vhich, using the vital properties of an organ to exalt them above their natural type, changes the intimate nature of the affected part, and communicates to it the power of incrusting itself with phosphate of lime. (Mémoire sur les ossifications morbides, in the Journ. univ. des sc. méd., vol. xviii., 1820, p. 5.) Rayer has since advocated the opinion that morbid ossification is always the result of an inflammatory process. He divides it, 1st, into that which occurs in a tissue of the primary formation, where the form and structure are not changed, so that it cannot be mistaken ; 2d, into that develpeod in an accidental tissue which has experienced no change ; and 3d, into that which supervenes in a primitive or accidental tissue, which has been changed most fre