Meckel1812-1 Anatomy 2-5

Embryology - 19 Apr 2024        Expand to Translate
Google Translate - select your language from the list shown below (this will open a new external page)
العربية | català | 中文 | 中國傳統的 | français | Deutsche | עִברִית | हिंदी | bahasa Indonesia | italiano | 日本語 | 한국어 | မြန်မာ | Pilipino | Polskie | português | ਪੰਜਾਬੀ ਦੇ | Română | русский | Español | Swahili | Svensk | ไทย | Türkçe | اردو | ייִדיש | Tiếng Việt    These external translations are automated and may not be accurate. (More? About Translations)

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

Historic Disclaimer - information about historic embryology pages

Pages where the terms "Historic" (textbooks, papers, people, recommendations) appear on this site, and sections within pages where this disclaimer appears, indicate that the content and scientific understanding are specific to the time of publication. This means that while some scientific descriptions are still accurate, the terminology and interpretation of the developmental mechanisms reflect the understanding at the time of original publication and those of the preceding periods, these terms, interpretations and recommendations may not reflect our current scientific understanding.     (More? Embryology History | Historic Embryology Papers)

Handbook of Pathological Anatomy Volume I (1812)

Section V. Of the Cartilaginous System

Article First. Of The Cartilages In The Normal State

§ 255. The cartilages {cartilago){l) are solid, hard, smooth, slippery, very elastic, whitish, and apparently homogeneous bodies, possessing neither fibres nor laminæ.

§ 256. They form an organic system, which does not exert the same influence in the organism at all periods of life, since in the early periods, we find them in the places of the bones, but they gradually disappear. Hence the cartilages are divided into the 2)ermanent {C. j>ermanentes) and the temporary, {C. temporarice,) a distinction which is not exact, as many cartilages which are included in the first series, become bone in most subjects, although in fact much later than the others, and always incompletely. The term temporary cartilage is usually applied to those only which are replaced by bones, and which thus disappear completely at about the same period in all individuals. When the temporary cartilages are changed into bone, the permanent cartilages are found principally, 1st, at the ends of those bones which touch each other, whether movably or immovably articulated ; 2d, in the parietes of certain canals.

We can make no general remarks in regard to the forms of the temporary cartilages, as they assume those of the bones, which afterwards take their places. But the permanent cartilages, except the arytenoid and those small ones found between the thyroid cartilage and the hyoid bone, are very thin in proportion to their breadth and length, or at least in respect to one of these dimensions.

quently into a fibrous or a cartilag'inous substance. (Mémoire sur l'ossification morbide considérée comme une terminaison des phlegmasies, in the Archives générales de Médicine, vol. i., 1823, p. 313 and 489.) Hence we may judg-e that the history of abnormal ossifications is still very obscure. This name very probably comprises numerous accidental productions, which should be considered only as calculous concretions. In order that an abnormal formation should justly come within the osseous system, it must possess life, that is, it must be attached at least by vessels to the rest of the organism, and its structure must perfectly resemble that of the normal bones. But these two conditions are found, perhaps, only in the formation of callus, the regeneration of the bodies of the long bones, a nd the ossification of certain parts of the fibrous tissue. P. T.

(1) G. Hunter, O/' the structure and diseases of articulating cartilages, in the Phil, trans. n. 470, vi., p. 514-521. — Hérissant, Sur la structure des cartilages des côtes de l'homme et du cheval, in the Mém. de Paris, 1748; p. 355.— Delassone, Sur l'organisation des os, in the Mém. de Paris, 1752, p. 253-258. — J. G. Haase, De fiabricâ cartilaginum, Lèipsic, 1767. — C. F. Doorner, De gravioribus quibusdam cartilaginum mutationibus, Tubingen, 1798. — B. C. Brodie, Pathological researches respecting the diseases ofi the joints, in the Med. chir. tr.,vol. iv., no. xiii., § 5. — Laennec, Sur les cartilages accidentels, in the Diet, des sc. méd., vol. iv., p. 123-133.

§ 257. The outer surface of the cartilages situated on the ends of the bones, is sometimes unattached ; they are then called articular cartilages, (C. articular es.) Sometimes these cartilages form a layer, the two faces of which are united with the bones. They are then called the cartilages of the sutures, (C. suturarur.i.)

§ 258. The articular cartilages are found in all the movable joints : they line the corresponding extremities of the bones, imitating their forms perfectly, and are united with them so closely, that one can break the bone sooner than separate them. The cartilage, which exists at first in the place of bone, is perfectly homogeneous, yet, when the latter is entirely developed, the articular cartilage is not a prolongation of it, since there is no continuity of tissue between them, even after the gelatin and the earthy salts have been liberated from the bones by acids. The loose surface of these cartilages is smooth because it is connected with the internal layer of the articular membrane. This arrangement diminishes remarkably the friction consequent upon motion.

The articular cartilages are generally a little thinner on their circumference ; this is particularly seen in those attached to the extremities of the bones which project very much, as the heads of the humerus and femur. On the contrary, the articular cartilages of the cavities which receive these heads are thickest on their edges, and are often strengthened in that part by a cartilaginous band. The cartilage has a unifoim thickness in all other points of its surface.

§ 259. The second kind of the cartilages which are placed between the bones, form a simple, very thin band, situated between two adjacent bones, which they unite to each other so as not to permit the least motion. These cartilages have usually a conical shape, and are broader on their external than on their internal face. This arrangement explains, at least in part, why the sutures of the bones of the head, in which the cartilages we speak of are found, always disappear on the inner sooner than on the outer face of the skull.

The costal cartilages form in some measure an intermediate section between these cartilages and those of the second class ; for their posterior extremities are connected with the ribs, like the articular cartilages, while their anterior ends articulate with the sternum, which is itself covered with an incrustation of cartilage. Some are even united to this bone by an articular capsule also. Besides, they differ from aU the others, because their length much exceeds their breadth and thickness.

§ 260. The cartilages of the second class are much more independent than those of the first, for they constitute the base of certain organs which are almost entirely formed by them. Thus the larynx is chiefly composed of cartilages, and the form of the trachea depends principally on that of the cartilaginous rings which form its parietes. The same may be said of the cartilages of the nose and the ear. Hence the forms of these cartilages differ more than those of the preceding. In fact they form sometimes layers, sometimes rings, and sometimes thick masses.

They vary also in tissue ; some, as those of the larynx, the trachea, and the septum of the nose, are much harder than those of the aliæ of the nose, of the ear, and of the ej^elids. They are generally more flexible than the cartilages which are connected with the bones. Many of them, which articulate together so as to admit motion, as for instance in the laiynx, present articular processes lined with capsular ligaments and retained in place by fibrous layers which are continuous with the perichondrium : but most of them are united only by this membrane, by mucous tissue, and the membranous expansions which extend from one to another.

§ 261. Although at first view the cartilages do not seem to have an organic tissue, (§ 255,) nevertheless, by having recourse to different processes, such as continued maceration and the action of acids, we can demonstrate more or less clearly, that they are formed of fibres and of layers. This tissue is slightly flexible, so that it breaks if we endeavor to bend it. The cartilage putrifies with difficulty: it is one of those substances wdiich resists decomposition the longest.

All the cartilages, however, have not the same tissue ; among those which are attached to the bones, the articular cartilages are formed of a multitude of short fibres, which are implanted in the circumference of the bones, and become softer towards their unattached extremity. The costal cartilages are composed of oval laminae, adjusted to each other from within outward, and kept in place by the transverse fibres. Morgagni(l) pretends that the cartilages of the larynx, or at least the cricoid and arytenoid cartilages, often have a cellular structure, and inclose marrow, even although they are not ossified. We have never observed any thing like this.

§ 262. The chemical composition of the cartilages resembles that of bone : they are formed of an animal substance and of phosphate of lime ; but the proportions of these two principal constituents, perhaps also the nature of the animal material, are different. In fact, from the latest researches of Davy,(2) the articular cartilages contain.

Of albumen, 44.5

“ water, 55,0

“ phosphate of lime, - - - - - 0.5

According to Allen, (3) on the contrary, the animal matter is also of a gelatinous nature, and the earthy material, mostly a carbonate of lime, forms only one hundredth part of the whole mass. Hatchett says, they are formed of coagulated albumen, containing some traces of phosphate of lime.

§ 263. The cartilages have no vessels which carry red blood, although in cutting them we often perceive vessels distinct from their substance. Lymphatics have not as yet been discovered in them. They are destitute of nerves.

§ 264. All the cartilages, if we except the articular, are enveloperl with a fibrous membrane called the perichondrium. This membrane is connected with them in a mechanical or dynamical relation, less intimately than the periosteum is wth the bones. The articular cartilages are destitute of this perichondrium, and their unattached face is blended with the synovial membrane.

(1) Advers. anat., i., an. 23.

(2) In Monro, Outlines of anatomy, vol. i., p. 68.

(3) Macdonald, IJe necrosi etccdlo, Edinburgh, 1799, p. 104, 105.

§ 265. The cartilages are very elastic ; hence they are found in those places where this property is requhed ; for instance, in the ends of the long bones, in the parietes of those cavities which change their size and which shoiald never collapse, as the nose, the organs of voice and of respiration. They possess, however, but a slight degree of contractility and dilatabihty. Their want of nerves explains their entire insensibility in the normal state. The phenomena of life progress in them with extreme slowness.

§ 266. During the early periods of existence the cartilages are mucous and soft. They gradually become consistent, and are finally very brittle. Towards the middle of life they are more elastic, because then they are more distant from the two opposite states in which they are met with at the beginning and end of existence.

As certain cartilages, those called teinporarij, ossify regularly and very early, so too some of the permanent cartilages are totally or partially changed into osseous pieces : at least this happens very often in regard to some of them ; but they generally ossify much later than the others. Those which present this phenomenon most frequently are the cartilages of the larynx, and less frequently those of the ribs, and the rings of the trachea. It is never seen in those of the nose, the ears, or the eyelids. This change is very rare in the articular cartilages. Still we must mention here those uncommon cases where all the joints are fused in a greater or less degree at an advanced age, and where, consequently, all the articular cartilages are ossified. Between the permanent and the temporary cartilages, we may rank to a certain extent those which unite two bones together in such a manner as not to allow motion, for they also change into osseous substance, and hence the sutures disappear, although the change occurs almost always long after that of the temporary cartilages. The form of the connected siufaces of the bones appears to influence this change to a certain extent, although it occurs where the points of contact are more numerous and closer, as in the dentated sutures, or within the skull, sooner than between smooth faces, as around the unguiform bones, between the upper maxillary bones, &c. But this law is evidently obedient to other laws also ; for on one side the tw'o portions of the lower jaw, whose surfaces touch in the same manner as those of the upper jaw, always unite early ; so on the other side, we often see superficial sutures, as the squamous, disappear, while others which are very deep and supplied with numerous indentations are permanent.

The proportional size of the cartilages remains abou t the same at all periods of life ; those of the sutures are the only exceptions to this rule. In fact, during the early periods of existence, whüe the bones of the head play on each other, and while then teeth are not inserted into each other, these cartilages are broader than they are afterwards.

Article Second - Of The Cartilaginous System In The Abnormal State

§ 267. The cartilages rarely present anomalies(l) in regard to their external or internal form ; their deviations-of formation are rarely congenital and usually result from anomalies presented by the bones and ligaments.

We may consider as congenital déviations of formation the deficiency of certain cartilages, for instance those of the ribs.

§ 268. The slowness of the vital phenomena which marks the cartilages generally (§ 265) is seen also in the manner of their action on external morbific causes, and the degree of their power of repairing a loss of substance, their reproductive power. The wounds of the cartilages do not heal, like those of other parts, by the union of their divided surfaces. Long after the accident, these surfaces present no change which indicates the least tendency to union: they are smooth and level; but the parts which cover the cartilage, especially the perichondrium when it exists, adhere, and form the new substance which is deposited between the lips of the wound. Hence why it so often happens that a cartilage destroyed in any manner is never reproduced, although layers of cartilage are sometimes developed on the surfaces of the false articulations. But this last phenomenon is not common. Articular cartilages are rarely or never formed in the new articular cavities which appear after luxations. In fact in the false joints consecutive to fractures, we sometimes find cartilages between the disunited ends of the bones, and farther the artificial joint is formed because they are not ossified ; but, in this case, it is not a cartilage which is reproduced, nor even a permanent cartilage which forms, but only a temporary cartilage, or rather a new bone, the development of which has been arrested.

When the articular cartilages are destroyed, the most favorable occurrence is the fusion of the contiguous surfaces of the two bones, and the formation of anchylosis.

For these reasons, inflammation of the cartilages is unfrequent, and very slow : they resist the action of deleterious causes longer even than the bones ; and the changes which occur in them seem to be passive and chemical, rather than active and vital, since cartilages, when separated from the body and exposed to the same agents, are affected in the same manner.

We shall not here discuss the opinion of Laennec, who admits that destroyed cartilages may be regenerated. We consider those thin points of articular cartilage usually found in several articulations at once in the same subject, as new productions of cartilage, as real cicatrices, which are never as thick as the old cartilage. But it is not proved, that these thin points do not arise from a wasting of the cartilage ; and the circumstances in which we have sometimes observed this phenomenon, render this last opinion not improbable.

(1) Doerner, De gravioribus quihusdam cartilaginum mutationib-us, Tubiugen, 1798. — Cruveilhier, Observations sur les cartilages diarthrodiaux et les maladies des arliculatwne diarthrodiales, inthe ArcAiti. gêner, de méd., Feb. 1824, p. 161.

§ 269. Active changes also occur in the cartilages. These take place particularly in those which do not concur in forming the articulations, because they receive more vessels, and enjoy a more active existence. In fact the cartilages not unfrequently inflame, and this inflammation terminates in ossification. The articular cartilages rarely experience these alterations, but they are not always exempt from them ; thus in diseases of the joints, they become red, partly lose their density, soften, and swell. Inflammation most generally terminates in suppuration and the destruction of the cartilages, which it is remarkable does not necessarily produce the formation of pus. It is probably from these changes that the wasting of the articular cartilages takes place.

The cartilages are exposed to induration and ossification, anomalies of which we have spoken above, (§ 266.) When in this state they become subject to the usual diseases of the bones. They inflame, become carious, die, and are thrown off. This phenomenon occurs not unfrequently in some cartilages of the larynx, particularly in the arytenoid cartilages. We must not confound this with the formation of a white substance, probably urate of soda, which develops itself in the place of the articular cai'tilages, when the latter disappear from the effects of gout.

§ 270. The cartilages not unfrequently develop themselves accidentally. In general, when this anomalous formation is seen, we may admit a tendency to accidental ossification. The solidity, form, and situation of these accidental cartilages vary much. They differ so much from each other in the first respect, that Laennec thought to make two classes, the perfect and the imperfect. But this classification hardly seems admissible; for the difference is purely gradual and accidental, and every thing would induce us to think that it depends entirely upon the period when the observation is made. Farther, the accidental cartilages are presented under three principal forms ;

1st. As broad layers adhering more or less strongly by their two faces to the parts in which they are found. This form is the most common. Accidental cartilages of this kind are developed principally between the internal and the fibrous tunics of the arteries, generally on the external face of the internal membrane of the system of red blood, and on the outer face of the serous membranes, so that as this resembles very much the internal membrane of the vessels, the formation of the cartilaginous layers may be considered one of the most usual morbid alterations,

2d. In the form of more or less round, irregular, and more or less solid masses, which are imbedded in the substance of the different organs, especially the uterus, the thyroid gland, and the ovaries.

3d, As rounded, flat, smooth concretions attached to fine filaments, and which are often separated from the parts whence they arise, so that they seem perfectly loose. This kind of accidental cartilage occurs particularly in the internal face of the synovial membranes. They are more rare in the serous membranes. It is the first degree of the formation of accidental articular bones. (§ 254.)