SKELETON. 



the foft parts have been allowed to putrefy and rot, and the 

 feparated bones, after being cleaned and dried, have been 

 joined again by wires, &c. fo as to be reunited artificially in 

 their former order, an artificial flceleton is formed. In the 

 fpine and the ribs, the places of the cartilages, which are loft 

 in cleaning the bones, are fupplied by portions of leather, 

 cork, or other materials. 



The latter, exhibiting merely the affemblage of the dried 

 bones, is applicable to the ftudy of olteology only in the 

 mechanical points of figure, fize, &c. ; and although ex- 

 tremely ufeful to the anatomift and furgeon, by reprefent- 

 ing the parts in their natural conneftion and relations, is lefs 

 convenient than the feparate bones for the itudy of many 

 points, particularly the articular ends of the bones. 



For the formation of artificial flceletons, the bones are de- 

 prived of their foft parts, either by boilmg, or by maceration 

 in wrater. The boihng muft be continued until the tendons, 

 ligaments, periofteum, &c. are fo loofened as to admit of 

 being eafily detached. The bony texture acquires in this 

 method a dirty and greafy appearance, which cannot be en- 

 tirely got rid of by any after-procefs. For the purpofe of 

 maceration, the bones, with the fleth, &c. roughly cut off, 

 muft be left in the fame water for fome months ; the fott 

 parts will then fall oft', and leave the bones of a much better 

 colour, and freer from greafe than when they have been 

 boiled. Expofure to the air, and frequently wetting them, 

 will make them beautifully white after they have been well 

 macerated. Their colour may be often much improved by 

 expofure to chlorine (oxymuriatic gas). The bones which 

 poffefs large medullary cavities (hould be bored at the arti- 

 cular ends, to get out the fatty fubftance. 



Emaciated and particularly anafarcous fubjefts are the 

 beft for making fl.:eletons ; becaufe there is no fat in the 

 bones, and they confequently continue dry and clean, when 

 they have been originally well prepared. Ferfons dying in 

 good health, or from fudden attacks, have fo much adi- 

 pous matter in the interior of their bones, that they continue 

 greafy, particularly at the articular ends, whatever pains 

 may be taken to clean them. 



In natural fl«letons, the cartilages, ligaments, and fyno- 

 vial membranes being all left, the joints poifefs their natural 

 mobility. But in order to keep them in this ftate, they 

 muft be preferved in fpirits, or fome other fluid capable of 

 preventing the putrefaftion of the foft parts. This is par- 

 ticularly neceffary with the ilveletons of young fubjeds, 

 which are in great part cartilagmous. When a natural flie- 

 leton is dried, the foft parts (hrmk and are ihrivelled up : 

 the cartilages become contracted, and thus the natural 

 figure is greatly impaired. The contraAiun of the carti- 

 lages diminifties the height by an inch or more. 



So long as the bones are compofed of feparate pieces, 

 and have more or lefs cartilage in their ftrufture, the 

 offeous fyftem can only be lludied in natural flceletons ; 

 but when the oftification is complete, artificial ll<eletons are 

 preferable. 



The bones, being the levers by which the motions of the 

 body are performed, have the mufcles or moving powers 

 fixed to them. But as they are fubfervient, in the con- 

 ftruftion of our frame, to other purpofes befides thofe of 

 motion, there are fome bones, though very few, to which 

 no mufcles are attached : fuch are the incus in the ear, the 

 ethmoid and inferior turbinated bones, and fome bones of 

 the carpus. 



Although the form of the bones is varioufly modified, 

 according to the figure of the parts in which they are placed, 

 or to their deftinations, they may be claffed under the three 



I 



divifions of bread or flat bones, cylindrical bones, and fhort 

 bones. The broad bones reprefent flat (hells, and confilt 

 of an inner ftratum of reticular or fpongy bony fub- 

 ftance, which is covered on its furfaces with thicker or 

 thinner plates of compatt bony matter. The cylindrical, 

 or long bones, form long ftiafts, expanded at their extre- 

 mities into thicker heads, and containing a medullary cavity 

 internally. The fhort bones are fuch as are nearly equal in 

 their length, breadth, and thicknefs ; varioufly fliaped, ac- 

 cording to their fituations and offices ; and confiil of the 

 loofe fpongy texture, covered by a thin rind of compaft 

 bone. 



The long bones belong in general to the locomotive ap- 

 paratus, where they form levers, moved by the mufcles m 

 various direftions : they arc all placed in the limbs, where 

 they form a central column, moveable in various direftions. 

 They diminifli in length, and increafe in number, fucceiCvely 

 from above downwards i from the humerus and femur to the 

 phalanges of the fingers and toes. Hence the upper part of 

 the bmbs is charafterifed by extent of motion, the lower by 

 multiplicity and variety of movements. 



The broad bones have not much to do with locomotion, 

 except as they afford extenfive furfaces for the attachment qS\ 

 mufcles. They compofe cavities, fuch as thofe of the cra- 

 nium and pelvis, for which their form is well adapted. Se- 

 veral are united to form one cavity, and this circumftance 

 add? to the folidity of the ftrufture, as the effeft of exter- 

 nal force is loft in the joints. They are generally concave 

 and convex on their two furfaces. 



The fliort bones are found in parts which unite mobility ^ 

 and folidity, as the vertebral column, the carpus, and tarfus. 

 They are always of inconfiderable fize, and therefore are 

 found in large number in the parts which they compofe. 

 Thefe parts are ftrong, becaufe external force is loft in the 

 articulations : they are moveable, becaufe the combinations 

 of feveral fmall motions produce a confiderable effeft. 



Of the firft produftion of the bones, and their gradual 

 developement while the foetus remains in utero, and of the 

 nouriftiment and growth of bone in general, an account is 

 given in the articles Embryo and Bone: in the latter of 

 which, and in Extremities, there is a defcription of their 

 external configurations, and of the difpofition of the bony 

 fubftance. The organization and properties of the fyftem 

 are confidered under the article Bone. Under Medul-. 

 L.\RY Syjlem and Cartilage the accounts of thefe fubjefts 

 will be found ; and the periofteum is defcribed under 

 Membrane. 



The flieleton is divided into the head, trunk, and extre- 

 mities or limbs. As almoft all the bones are formed ori- 

 ginally of more than one piece, which feparate portions of 

 ofleous matter gradually come together, and are ultimately 

 confolidated, the number of diftinft pieces of bone belong, 

 ing to the flteleton is different at different ages. The fol- 

 lowing is the number of bones, when the oflification is com- 

 plete ; that is, about the twentieth year. 



I. In the Head, confifting of the cranium, and the Face, 

 the former is made up of 



1 or 2 offa frontis, 



2 offa parietalia, 



1 OS fphenobafilare, or fpheno-occipitale, 



2 olfa temporum, 

 2 mallei, 



2 incudes, 

 2 ftapedes, 

 I OS ethmoideum. 



The 



