CHAPTER III. 
hence, I think, it feems that the almoft univerfal preference of that 
arm is not an arbitrary thing, but founded upon obfervation, that it is ca¬ 
pable of more per fed: actions than the other. 
The fpinal proedfes (Tab. x. xi.) of the fecond, third, fourth and fifth 
vertebra: of the neck are forked, the two laft long and horizontal, the 
three or four upper ones of the back like them, only a little declining, the 
middle ones of the back run obliquely downwards, and the proedfes of 
the remaining vertebra: become fuccellively thicker, ftronger, and lefs 
declining; thofe of the loins being horizontal, like the laft of the neck. 
The mufcles that arc inferted into the fpinal proedfes of the vertebra: of 
the neck and loins will ad: with more flrength than thofe of the back, 
becaufe their procefles being perpendicular to the fpine, they arc longer 
leavers; befidcs, thofe of the back almoft touch one another, to prevent 
much motion, becaufe it would interrupt refpiration; but more motion 
being necefiary in the neck and loins, their proceftcs are made fit for it. 
The tranfverfe proedfes (Tab. x. xi.) of the vertebra: of the neck arc per¬ 
forated, for the admiflion of the cervical blood-veflels, and bowed down¬ 
wards, and hollowed, for the paflage of the cervical nerves. The eight or 
nine upper ones of the back, receive the upper ribs; and the reft, with 
thofe of the loins, ferve only for origins and infertions of mufcles. 
Os facrum (Tab. xii.) has two upper oblique proceftcs, fome fmall fpi¬ 
nal procefles, and two foramina in each interftice of the bones it is com- 
pofed of, both before and behind. Ofla coccygis have none of thefe parts. 
Through every bone of the fpine, the ofla coccygis excepted (Tab.xiii.) 
is a large foramen, which together make a chanel through the fpine, in 
which is contained the medulla Ipinalis; and in each fpace between the 
vertebra: are two large holes for the nerves to pafs out. 
’Tis worth confidering, the provifion that is made to prevent luxations 
in this chain of bones, luch luxations being worfc than any other, becaufe 
of the fpinal marrow which is contain’d within thefe bones. The bodies 
of the vertebra: are all in the fame manner connc&ed by ftrong intervening 
ligaments or cartilages. In the neck the oblique procefles of the received 
bone are wrapped over thofe of the receiving bone, which forbids their 
1 uxating forwards. The tranfverfe procefles with a fmall apophyfis of the 
body of the fame bone, in like manner, fccures them from flipping back¬ 
wards, and an apophyfis on each fide of the body of the receiving bone, 
hinders them from flipping to either fide. The vertebra: of the back are 
hindered from diflocating forwards by the fame provifion with thofe of 
the neck; and from luxating backwards, by the ribs which are fattened 
