On the MUSCLES. 259 



toftal, and forming a figure like the letter X, but in which the 

 ftroke 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. 



Then I difTected 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 differed 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 demonflrated a part of the ftruclure 

 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 fternum 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 twitted, and the end of the cartilage rolls upon the fternum. 

 See T. 3. fig. 1, 2, 3. and 9. 



After fully explaining the ftructure, I endeavoured to 

 prove, as Di"Haller 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 5 and 

 that, when the intercoftal mufcles alone acted, and the ribs 

 Were not forcibly kept down, they could have no other effect }, 



K k 2 and 



