258 OBSERVATIONS 
thefe mufcles laid obliquely, and decuffating each other, I ufed 
to difleét fome portions of the two layers, in fuch a manner as 
to reprefent oblique mufcles, with their origins at a diftance 
from each other, but their infertions meeting in a point, or 
with their infertions, as well as their origins, at a diftance from 
each other. 
In the back part of the fpine, I very particularly demon- 
ftrated the obliquity of many of the mufcles, fome of which 
are called femifpinales, becaufe one end of them only is fixed 
to the fpinal procefles, and the fibres pafling obliquely, the 
other end of them is fixed to the tranfverfe proceffes, or other 
parts of the neighbouring vertebrz. 
In the extremities, I not only carefully demonftrated the 
obliquity of the flefhy fibres, in the half and whole penniform 
mufcles, but pointed out their conneCion with their tendinous 
aponeurofes, the different direction of the tendinous and flefhy 
fibres, and the ufes of the aponeurofes and tendinous fheaths 3. 
and that, by means of the fheaths, there was fo little difference 
between the length of the mufcles in the bended and extended 
{tate of the member, that fhort flethy fibres, efpecially whem 
placed obliquely, could produce a very extenfive motion. 
Burt in treating of particular parts, I dwelt chiefly on the 
ftru@ure and effeGts of the intercoftal mufcles, as a variety of 
opinions concerning their operation has, in the courfe of the 
laft hundred years, been propofed, and as no author had ex- 
plained the reafon of the obliquity of their fibres, nor of their 
being difpofed in two layers of decuffating fibres. 
Tuat their ftru@ture might be fully underftood, I firft laid 
bare the furface of the external intercoftal mufcles, and between 
the next two ribs, I cut off the external intercoftals, to fhew the 
internal, as in T. 3. fig. 4. - 
In another fpace, 1 fhewed a fmall bundle ‘of the external 
intercoftal, decuffating a fimilar bundle of the internal inter- 
coftal, 
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