ANATOMY. 
and lungs,) are the long crooked bones placed at the fide 
of the chelt, in an oblique direftion downwards in refpebt 
of the back-bone. Their number is generally twelve on 
each lide ; though frequently eleven or thirteen have been 
found. Sometimes the ribs are found preternafurally con¬ 
joined or divided. The ribs, are all concave internally; 
where they are alfo made fmooth by the aftion of the con¬ 
tained parts, w hich, on this account, are in no danger of 
being'hurt by them ; and they are convex externally, that 
they might refill that part of the prelfure of the atmof- 
phere w hich is not balanced by the air within the lungs 
during infpualion. The ends of the ribs next the verte¬ 
bra; are rounder than they are after thefe bones have ad¬ 
vanced forwards, when they become flatter and broader, 
and have an upper and lower edge ; each of which is made 
rough by the action of the intercoftal mufcles inferted in¬ 
to them. Thefe nutfcles, being all of nearly equal force, 
and equally ftretched in the interftices of the ribs, prevent 
the broken ends of thefe bones, in a fracflure, from being 
removed far out of their natural place, to interrupt the 
motion of the vital organs. The upper edge of the ribs 
is more obtufe and rounder than the lower, which is de- 
prefled on its internal fide by a long folfa, for lodging the 
intercoftal velfels and nerves; on each fide of which there 
is a ridge, where the intercoftal mufcles are fixed. The 
folfa is not obfervable, however, at either end of the ribs; 
for, at the pofterior or root, the velfels have not yet reach¬ 
ed the ribs; and, at the fore-end, they are fplit away into 
branches, to ferve the parts between the ribs: which 
plainly teaches furgeons one reafon of the greater fafety 
of performing the operation of the empyema towards the 
fides of the thorax, than either near the back or the bread. 
At the pofterior end of each rib, a little head is form¬ 
ed, which is divided by a middle ridge into two plain or 
hollow furfaces; the lowed of which is the broadeft and 
deeped in mod of them. The two plains are joined to the 
bodies of two different vertebne, and the ridge forces it- 
felf into the intervening cartilage. A little w ay from this 
head, we find on the external furface a fmall cavity, where 
mucilaginous glands are lodged ; and, round the head, the 
bone appears fpongy, where the capfular ligament of the 
articulation is fixed. Immediately beyond this a flatted 
tubercle riles, with a fmall cavity at, and roughnefs about, 
Its root, for the articulation of the rib with the tranfverfe 
procefs of the lowed of the two vertebra;, with the bodies 
of which the head of the rib is joined. Advancing far¬ 
ther on this external furface, we obferve in mod of the 
ribs another fmaller tubercle, into which ligaments con¬ 
necting the ribs to each other, and to the tranfverfe pre¬ 
cedes of the vertebrae and portions of the longiflimus dorli, 
are inferted. Beyond this the ribs are made flat by the 
facro-lumbalis nutfcle, which is inferted into the part of 
this flat lurface fartheft from the fpine, where each rib 
makes a confiderable curve, called by fome its angle. 
Then the rib begins to turn broad, and continues fo to its 
anterior end, which is hollow and fpongy, for the recep¬ 
tion of, and firm coalition with, the cartilage that runs 
thence to be inferted into the fternum, or to be joined with 
fome other cartilage. 
To the fore-end of each rib a long, broad, and firong, 
cartilage is fixed, and reaches thence to the fternum, oris 
joined to the cartilage of the next rib. This courfe, how¬ 
ever, is not in a flraight line with the rib : for the carti¬ 
lages generally make a confiderable curve, the concave part 
of which is upwards ; therefore, at their infertion into the 
fternum, they make an obtufe angle above, and an acute 
one belowu Thefe cartilages are of fuch a length as ne¬ 
ver to allow the ribs to come to a right angle with the 
fpine ; but they keep them lituated fo obliquely as to make 
the angle very confiderably obtufe above, till a force ex¬ 
ceeding the eladicity of the cartilage is applied. Thefe 
cartilages, as all others, are firmer and harder internally 
than they are on their external furface ; and fometimes in 
©Id people all their middle fubftance becomes bony, w hile 
a thin cartilaginous lamella appears externally. The of- 
fification, however, begins frequently at the external fur¬ 
face. The greateft alternate motions of the cartilage* 
being made at their great curvature, that part remains 
frequently cartilaginous after all the reft is ollified. 
The ribs then are articulated at each end, of which the 
one behind is doubly joined to the vertebras; for the head 
is received into the cavities of two bodies of the verte¬ 
brae, and the larger tubercle is received into the depreftion 
in the tranfverfe procefs of the lower vertebra. When 
we examine the double articulation, we muft immediately 
fee that no other motion can be allowed hepe than upwards 
and downwards; fince the tranfverfe procefs hinders the 
rib to be thruft back ; the refiftance on the other lide of 
the fternum prevents the ribs coming forward ; and each 
of the two joints, with the other parts attached, oppofe its 
turning round. But then it is likewife as evident, that 
even the motion upwards and downwards can be but fmall 
in any one rib at the articulation itfelf. But, as the ribs 
advance forwards, the diftance from their centre of motion 
increafing, the motion muft be larger; and it would be 
very confpicuous at their anterior ends, W'ere they not re¬ 
filled there by the cartilages, which yield fo little, that the 
principal motion is performed by the middle part of the 
ribs, which turns outwards and upwards, and occafions the 
twill remarkable in the long ribs at the place near their fore¬ 
end where they are moft refilled. 
The ribs are commonly divided into true and falfe. The 
true coftae are the feven upper ones of each fide, whole 
cartilages are all gradually longer as the ribs defeend, and 
are joined to the breaft-bone: fo that, being prefled con- 
ftantly between two bones, they are flatted at both ends; 
and are thicker, harder, and more liable toolfify, than the 
other cartilages that are not fubjedt to fo much prelfure. 
Thefe ribs include the heart and lungs : and therefore are 
the proper or true cuff odes of life. The five inferior ribs 
of each fide are the faj'e or bajla< d, whofe cartilages do not 
reach to the fternum ; and therefore, wanting the refiftance 
at their fore-part, they are pointed; and, on this account, 
having lefs prelfure, their fubftance is fofter. The carti¬ 
lages of tltele falle ribs are Ihorter as the ribs defeend. To 
all thefe five ribs lhe circular edge of the diaphragm is 
connected; and its fibres, inftead of being ftretched im¬ 
mediately tranfverfely, and fo running perpendicular to the 
ribs, are prelfed fo as to be often, efpecially in expiration, 
parallel to the plane in which the ribs lie. Nay, one may 
judge by the attachments which thefe fibres have fo fre¬ 
quently to the lides of the thorax a confiderable way above 
where their extremities are inferted into the ribs, and by 
the fituation of the vifeera always to be oblervedina dead 
fubjeft laid fupine, that there is confttlmtly a large conca¬ 
vity formed on each fide by the diaphragm within thefe 
baftard ribs, in which the liontach, liver, fpleen-, &c. are 
contained ; which, being only reckoned among the vifeera 
naturalia, have occafioned the name of bajlard cuffodes to 
thefe bones. Hence, in Ample fnhftures of the falfe ribs, 
without fever, the ftomach ought to be kept moderately 
filled with food, left the pendulous ribs, falling inwards, 
fliould thereby increafe the pain, cough, &c. Hence like¬ 
wife we may learn how to judge better of the feat of feve- 
ral difeafes, and to perform the operation of the empyema, 
and fome others, with more fafety than we can do if we 
follow the common praflice. 
The eight upper ribs were formerly clafled into pairs, 
with particular names to each two, viz. the crooked, the 
Jolid, the pecloral, and the tioijled. But thefe names are of 
fo little ufe, that they are now almoli obfiolete. The firft 
rib of each fide is fo fituated, that the flat fides are above 
and below, while one edge is placed inwards and the other 
outwards, or nearly fo ; therefore fufficient fpace is left 
above it for the fubclavian velfels and mufcles; and the 
broad concave furface is oppofed to the lungs. But then, 
in confequence of this fituation, the channel for the inter¬ 
coftal veflels is not to be found ; and the edges are diffe¬ 
rently formed from all the other, except the fecond ; the 
lower one being rounded, and the other lharp. The head, 
