General Anatomy, Applied to Physiology and Medicine, Vol. 2 (of 3)

by Xavier Bichat

The ancients described it as extending from one bone to another over the articulation, and thus forming a continuous sac for the whole skeleton. This idea is incorrect. At the junction of the bones, the periosteum intermixes with the ligaments which serve it as a means of communication, and it is in this way only that we can understand its continuity. The crown of the teeth is destitute of it, as well as all the osseous productions that grow upon the head of certain animals.

The periosteum is feebly united to the bone in infancy; it can then be separated with great ease, especially on the middle part of the long bones. In the adult, as the calcareous substance gradually encrusts its most internal fibres, the adhesion becomes very strong; it is extreme in old age, in which this membrane is often reduced to a very delicate layer by the progress of ossification. The constant pressure exerted by the muscles in their contractions, can also have a little influence upon this adhesion. Various elongations pass from the periosteum to the bone. They are much more numerous at the extremities of the long bones and upon the short bones, than upon the middle of the long bones, or the broad ones; which may easily be conceived of, from the much greater number of foramina in one than the other part. These elongations accompany the vessels, line the canals which pierce through the bone, are lost in those which terminate in its substance, do not penetrate the medullary cavity, and confined to the osseous texture alone, establish, between it and the membrane from which they arise, immediate relations.

It is the destruction of these relations, when the periosteum is diseased or destroyed for a considerable extent, that produces the death and separation of the bone. There is however this difference between this phenomenon and the death of the bone by the injury of the medullary membrane, that if this is disorganized, necrosis seizes upon the whole bone, whilst if we irritate and tear the periosteum in the middle part of a long bone, for an extent nearly equal to that of this medullary membrane, the external laminæ of the compact texture alone are detached by exfoliation, and the bone remains the same. I have made this experiment the year past upon two dogs. As to that which consists in removing the periosteum, not only from the middle part, but from the whole surface of the bone, I do not know that any one has been able to try it; it has appeared to me impossible; it might be practicable, but the animal would soon die from the extent of the injury, and thus we could have no result from it.

The relations of the periosteum with the neighbouring organs vary remarkably. In the greatest number of bones, there are muscles that slide upon it; the cellular texture unites it to them more or less closely according as the motions are more or less considerable. In consequence of inflammations, it loses this laxity, and often all motion ceases.

Organization of the Periosteum.

The direction of the fibres of the periosteum is nearly analogous to that of the bones, the long bones especially as well as the short; but it has not the radiated structure of the flat bones that it covers. These fibres placed upon each other, have different lengths; the superficial ones are the longest; those which correspond immediately with the bone run but a short distance. In general all become very evident in some diseases of the bones. I recollect among other examples of the preternatural development of the fibres, a man affected with elephantiasis, and at the same time a swelling of the compact texture of the tibia, which was of a remarkable thickness. The periosteum of this bone was very thick, and adhered so little to the bone, that the slightest effort was sufficient to raise it in its whole extent, and its fibres were so distinct, that it might have been taken, when separated from the bone, for a portion of plantar or palmar aponeurosis.

The periosteum borrows its vessels from those of the neighbouring parts. Their innumerable branches ramify in it ad infinitum, form there a net-work, which injections, especially in infants, make very evident, they are afterwards lost in it, or penetrate the compact texture of the bone, or return to the neighbouring parts to form anastomoses.

This membrane receives, as we have said, the insertion of almost all the fibrous system, of the tendons, the ligaments and especially the aponeuroses. This insertion has no connexion with the bone in infancy; but ossification soon seizing upon the most internal laminæ, all the fibrous organs appear to be identified with the bone in the adult. I would observe that this arrangement coincides with the prodigious power of drawing that the muscles, having become more developed, often exert at this age, and which only spent upon the periosteum, as it would have been without its ossification, would not have found in it a sufficient resistance, whereas acting also upon the bone, it moves it without endangering its covering. The general organization, the properties and the life of the periosteum are the same as those of the fibrous system; I shall not treat of them.

Development of the Periosteum.

In the fœtus, this membrane is soft, spongy, containing much gelatinous fluid; it melts easily in water; its fibres are not distinct; they become so as we advance in age, and at the same time the softness diminishes and the resistance increases. The periosteum in old age has extreme tenacity; it resists ebullition almost as much as the ligaments; those who prepare skeletons know this very well. It tears in various places, because its fibres in contracting are detached from the bone; but what remains becomes with great difficulty gelatinous.