On the MUSCLES. 259 
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toftal, and forming a figure like the letter X, but in which the 
{troke reprefenting the external mufcle is more oblique than the 
other ; for the internal intercoftals are lefs oblique than the ex- 
ternal. See T. 3. fig. 5. 
Tuen I diffeted fmall bundles of the external and internal 
intercoftals, with their origins at a diftance from each other, 
but their infertions meeting in a point, in the rib above or in 
the rib below, fo as to form triangles, of which the rib made 
the bafe, (fee T. 3. fig. 6. and 7.); or I diffe&ted them with 
their infertions, as well as their origins, at a diftance from each 
other, as in T. 3. fig. 8. = 
In the laft place, I demonftrated a part of the ftructure 
which has not been fufficiently examined by authors ; to wit, 
that the cartilages between the ribs and the fternum, with the 
exception of the cartilage of the firft rib, are not fixed to the 
fternum in the fame manner as to the ribs; for the rib, which 
is hollowed, receives the cartilage, and is fo firmly united to it, 
that in a recent fubject, they cannot be feparated without la- 
cerating the cartilage; but the inner part of the cartilage is 
tied by a capfular ligament to the edges of the pit in the fter- 
num, and the concave part of the pit is connected by fine cel- 
lular threads only to the end of the cartilage, fo that the carti- 
lage and {ternum may, after cutting-the capfular ligament, be 
feparated from each other without tearing the cartilaginous fi- 
bres. Hence, when the ribs are moved, the capfular ligament 
is twifted, and the end of the cartilage rolls upon the fternum. 
See T. 3. fig. 1, 25 3. and 9. 
AFTER fully explaining the ftructure, I endeavoured to 
prove, as Dr HaLuer had done, but with fome additional ar- 
guments, that both rows of intercoftal mufcles confpired to e- 
levate the ribs, or that they were mufcles of infpiration ; and 
that, when the intercoftal mufcles alone acted, and the ribs 
‘were not forcibly kept down, they could have no other effect ; 
Kk2 and 
