[ no ] [Book 



CHAP. VII. 



BONES OF THE TRUNK. 



Spine or Back Bvnf. JJciu the Head is mo-TjeJ. The Thorax - 

 The Pf'vis. Principal Marks cf DijUiitlion letweea the Male and 

 Fttntde Skeleton* 



bones of the trunk are divided into thofe 

 -* of the fpine or back- bone, the thorax or chefl, 

 and the pelvis. The fpine confifts of twenty-four 

 pieces of bone called the vertebrae ; feven of thefe be- 

 long to the neck, twelve to the back, and five to the 

 loins. The thorax confifts anteriorly and latterly of 

 twelve ribs on each fide of the fternum or breaft- 

 bone, and part of the fpine behind. The pelvis is 

 compofed of four bones; two ofia innominata or hip- 

 bones; the os facrum, and the oscoccygis. 



That feries of bones called the fpine forms a co- 

 lumn larger below than above, fmooth and round 

 before, very rough and uneven behind, and hollow 

 within. The bones of the fpine are joined to each 

 Other by cartilages, in the centre of each of which is 

 contained a fluid ; a curious circumftance of ftrufture 

 firft difcovered by the kte Dr. Monro of Edinburgh. 

 The chief advantage of this ftruc~ture is, that this 

 fluid, when confined, has all the refinance of' a foiid 

 body, without its hardnefs, which in this part might 

 be attended with very bad confequences. 



The head is conn?cled to the upper vertebra of 



the neck bv two fmooth projections of that vertebra, 



which are called the condyls, being received into two 



correfponding cavicies in the under part of the cra- 



9 mum- 



