ANA' 
the bony fibres are rigid, the periofteum is eafily ta¬ 
ken off. 
The ofiification of bones depends principally on their 
velfels being l"o difpofed, and of fuch diameters, as to fe- 
parate a liquor, which may eafily turn into a bony fub- 
ltance, when it is deprived of its' thinner parts; as feems 
plain from the obfervation of the callous matter feparated 
after fractures and ulcers, where part of the bone is taken 
out: for, in thefe cafes, the velfels extending themfelves, 
and the liquors added to them, are gradually formed into 
granulated flefh; which fills up all the fpace where the 
bone is taken from, then hardens till it becomes as firm 
as any other part of the bone. This happens frequently, 
even when the ends of the difeafed bone are at a confide- 
rable diftance from each other. 
The induration of bones is alfo greatly affifted by their 
being expofea more than any other parts to the ftrong 
preflure of the great weights they fupport, to the violent 
contraction of the mufcles fixed to them, and to the force 
of the parts they contain, which endeavour to make way 
for their own further growth. By all this preiTing force, 
the folid fibres and velfels of bones are thruft clofer, and 
fuch particles of the fluids conveyed in thefe velfels as are 
fit to be united to the fibres are fooner and more firmly 
incorporated with them, while the remaining fluids are 
forcibly driven out by the veins, to be mixed with the 
mafs of blood. In confequence of this, the velfels gradu¬ 
ally diminilh as the bones harden. From which again we 
can underftand one reafon why the bones of young animals 
fooner re-unite after a fra'Cture than thofe of old, and why 
cattle that are too foon put to hard labour, feldom are of 
fuch large fize as others of the fame brood who are longer 
kept from labour. 
That the ollifying of bones greatly depends on preflure, 
feems to be evinced from the frequent examples we meet 
with of other parts turning bony, when long expofed to 
the prefling force of the furrounding parts, or when they 
are fubjc-Cted to the like ciixumftances by their own fre¬ 
quent and violent contraction. Witnefs the bones found 
frequently near the bafe of the heart in fome old men, and 
in feveral other creatures. Nay, the mufcular fubftance of 
the heart lias been ofiified in fuch, and the arteries of old 
men often become bony. The cartilages of the larynx are 
generally ofiified in adults. In beads of burden, the carti¬ 
lages between the vertebra of the back very often change 
into complete bones ; and, being intimately united with 
the vertebrae, the whole appears one continued bone : nor 
is the periofteum exempted from fuch an induration. 
From the effects of preflure only it is that we can ac¬ 
count for the bones of old people having their fides much 
thinner, yet more denfe and Folid, while the cavities are 
much larger than in thofe of young people; and for the 
prints of mufcles, velfels, &c. being fo much more ftrong- 
ly marked on the furfaces of the former than of the latter, 
if they belong to people of near the fame condition in life. 
Preirure muft likewife be the caufe which, in people of 
equal ages, make thefe prints ftrongerin the bones of thofe 
who had much labour andexercife, than they are in people 
who have led an indolent and inactive life. 
Perhaps the caufes of ofiification may be affifted by the 
nature of the climate people live in, and the food they ufe. 
Whence, in hot countries, the inhabitants fooner come to 
their height of ftature than in the northerly cold regions : 
and thence feems to have arifen the common practice among 
the ladies, of making puppies drink brandy or fpirit of wine, 
and of bathing them in thefe liquors, to prevent their grow¬ 
ing big. Nay, it has been obferved, that much ufe of fuch 
fpirits has occafioned parts, naturally foft, to petrify in 
fome, and to oflify in other people of no great age. 
To exprefs the connexion of bones, anatomifts have con¬ 
trived a great number of technical terms ; about the mean¬ 
ing, propriety, and clafling, of which, there has unluckily 
Been variety of opinions. Some of thefe terms it is ne- 
celfary to retain, fince they ferve to exprefs the various 
circumftances of the articulations, and to underftand the 
Vol. I. No. 34. 
' 0 M Y, _ _ 533 
writers on this fubjeft. The articulations are mod com¬ 
monly divided into three dalles, viz. Symphyfis, Synar- 
throfis, and Diarthrofis. 
Firft, fymphyfis, which properly fignifies the conception 
or growing together of parts, when ufed to exprefs the ar¬ 
ticulations of bones, does not feem to comprehend, under 
the meaning generally given 40 it, anything relating to the 
form or motion of the conjoined bones; but by it mod au¬ 
thors only denote the bones to be connected by fome other 
fubftance; and as there are different fubftances which ferve 
this purpofe, therefore they divide it into the three follow¬ 
ing fpecies. 1. Synchondrofs, when a cartilage is the con¬ 
necting fubftance : thus the ribs are joined to the fternum; 
thus the bodies of the vertebra are connected to each 
other; as are likewife the olfa pubis. 2. Synneurojis , or 
fyndefmofis, when ligaments are the connecting bodies, as 
they are in all the moveable articulations. 3. Syfarcofs , 
when mufcles are ftretched from one bone to another, as 
they muft be where there are moveable joints. 
The fecond clafs of articulations, the jynarthrojis, which 
is faid to be the general term by which the immoveable 
conjunction of bones is expreffed, is divided into three 
kinds. 1. The future is that articulation where two bones 
are mutually indented into each other, or as if they were 
fewed together; and is formed by the fibres of two bones 
meeting while they are yet flexible and yielding, and have 
not come to their full ex f ent of growth; fo that they mu¬ 
tually force themfelves into the interftices of each other, 
till, meeting witli fuch pefiftance as they are not able to 
overcome, they are flopped from fproUting out farther, or 
are refleded ; and therefore thefe indentations are very dif¬ 
ferent both in figure and magnitude: thus the bones of the 
head are joined ; thus epiphyfes are joined to the bones, 
before their full connection and union with them. Under 
this title of future, the haimonia of the ancients may be 
comprehended; fcarcely any unmoved bones being joined 
by plain furfaces. 2. Gomphofis is the fixing one bone into 
another, as a nail is fixed in a board : thus the teeth are 
fecured in their fockets. 3. Schindylcfs or ploughing, when 
a thin lamella of one bone is received into a long narrow 
furrow of another: thus the proceffus azygos of the fphe- 
noid, and the nafal procefs of the ethmoid, bone, are re¬ 
ceived by the vomer. 
The third clafs, or diarlhrofs, is the articulation where 
the bones are fo loolely connected as to allow large motion. 
This is fubdivkled into three kinds. 1. Enartkrofis, or the 
ball and focket, when a large head is received into a deep 
cavity; as the head of the os femoris is into the acetabu¬ 
lum coxendicis. 2. Arthrodia, when a round head is re¬ 
ceived into a fuperficial cavity; as in the articulation of 
the arm bone and fcapula. Thefe two fpecies of diar¬ 
throfis allow motion to all fides. 3. Ginglimus, which pro¬ 
perly fignifies the hinge of a door or window ; in it the 
parts of the bones mutually receive and are received, and 
allow of motion two ways: workmen call it charnal. 
The ginglimus is generally divided into three kinds; to 
which fome give the name of contiguous, dijlant, and com¬ 
pound. Ths firft kind of ginglimus is when a bone has fe¬ 
veral protuberances and cavities, which anfwerto as many 
cavities and proceffes of the other bone with which it is 
articulated ; as in the conjunction of the femur with the 
tibia. The fecond fpecies is, when a bone receives ano¬ 
ther at one end, and is received by the fame bone at the 
other end; as in the radius and ulna. The laft fort is, 
when a bone receives another, and is received by a third; 
as in the oblique proceffes of the vertebrae. 
With regard to the different opinions concerning the ufe 
of thefe technical names, it has been faid, that fymphyfis 
fhould be the name for the immoveable articulations, and 
fynarthrofis fhould be umierftood to be the conjunction of 
bones by fome connecting medium. Thofe who have ta¬ 
ken fymphyfis in the fenfe of its exprefling the conjunction 
of b> nes with a connecting fubftance, have difagreed in 
their definition of it; fome infecting, and others leaving 
out, its allowing motion. When they have agreed in their 
6 U definition. 
