BONE, NORMAL ANATOMY. 



436 



bone in the living animal is a pale pink, which 

 becomes much deeper in case of inflammation, 

 whilst a deadened portion puts on a yellowish 

 white appearance. When animals are drowned 

 or strangled, their bones assume a darker hue ; 

 and in cholera the colour is so deep, and so 

 thoroughly pervades the osseous tissue, that 

 no length of maceration will remove it. In all 

 these cases the colour obviously depends on 

 the blood contained in the osseous vessels. 

 2d. It was discovered accidentally by Belchier, 

 in 1736, that the bones of animals fed on food b 

 tinged with madder very quickly become red ; 

 (a sensible change is produced in young ani- 

 mals in twenty-four hours ;) now, whether we 

 explain this, with most physiologists, by saying 

 that the earthy matter is coloured in the blood 

 before it is deposited, or, with Gibson, that it 

 receives its dye in the bone, the presence of 

 bloodvessels is equally necessary to account 

 for the phenomenon. (See OSTEOGENY.) 

 3d. Tlie most satisfactory proof of vascularity 

 in bone is afforded by injection. A young 

 bone may be completely coloured in this way : 

 the vessels are seen to enter it, and if the 

 earthy part be removed by an acid, they may 

 be followed in their fine ramifications through 

 its tissue. 



Arteries are found to enter bone under three 

 modifications. 1st. Numerous small vessels 

 fill the minute foramina, which may be seen 

 in the compact substance every where : 2d, a 

 larger set enter the holes which we see on the 

 short bones, and near the extremities of the 

 long ones : and 3d, about the centre of the 

 long bones considerable branches pass into the 

 medullary canal, and ramify on the medullary 

 membrane. These last have been called the 

 nutritious arteries, a name to which they have 

 no claim : they are destined for the marrow. 

 The two first sets are the true nutritious ves- 

 sels. All, however, freely anastomose with 

 each other. 

 The veins merit particular notice. They 



Fig. 187. 



have been investigated by Dupuytren,* and 

 their course in some of the bones, espe- 

 cially the flat bones, splendidly figured by 

 Breschet.t In./fgs. 187, and 188, copied from 

 one of Breschet's plates, a indicates these veins 

 in the diploe of the cranium : they may be 

 very easily exposed in the cranium by filing 

 away the external table with a coarse file. 

 The first two sets of arteries have no accom- 

 panying veins, but with the last there always 

 are veins of a corresponding size. These do 

 not appear large enough to return all the blood ; 

 we therefore have others leaving the bone by 

 foramina, which are proper to them, and 

 through which no artery passes. They arise in 

 the spongy tissue by numberless radicles, re- 

 ceive branches like other veins in their course, 

 and, after issuing from the compact tissue by 

 a constricted opening, empty themselves into 

 the vessels of the neighbouring soft parts. 

 The canals through which they pass have a 

 lining of compact substance continuous with 

 the external surface. The veins, while in the 

 bone, have only one coat, the internal, which 

 adheres closely to the osseous canal, and can 

 enjoy no change of size or form. They are, 

 notwithstanding, furnished with valves. 



Nerves, doubtless, exist in bone, although 

 we cannot demonstrate them in the osseous 

 substance. But it is not to be supposed that 

 a part so highly vascular would be destitute 

 of nerves. Nerves are seen to enter with the 

 nutritious vessels, and minute filaments pass 

 into some bones, as the frontal. These nerves, 

 we may be sure, ramify through every part. 

 The sensibility of an inflamed bone indeed 

 settles the question. 



Lymphatics have not been found in the inte- 

 rior of the osseous substance; but they may 

 be seen on the surface.} In a tissue such as 

 that of bone it would be no easy matter to 



* Propositions sur quelques points d'Anatomie, 

 de Physiologic, et d'Anatomie Pathologique. Par. 

 1803. 



t Rccherches Anat. sur le systeme vciueux. 

 Par. 1829. 



t Beclard. Grainger. 



