HEART. = 
The leading circumftances coneerni 1g the ramifications 
and ftructure of the arteries are mentioned under ARTERY : 
but we Aave fomething further-to flate on thefe f ubjects in 
the prefent place. ; ; 
Having arifen in tNe way juft defcribed from 
tricle of the heart, the aorta divides very {peedily into two 
portions; of which i 
c 
tht afcending paffes upwards to the 
while the defcending purfues 
The firit, 
ally, by this difpofition, 
‘eated to the bloo 
Bod 
and- are fubfequently 
continued under the terms of ramilications, twigs, &c. 
tis difficult to ftate accurately and generally how often 
the arteries divide 
mination in veins. 
have erred in affi 
Keil {lates that there are forty or fifty, and relies chiefly on 
this fuppofition for eee i 
great retardation of the blo 
“‘Much,”’ fa 
L have fometimes counted 
branches in the membranes of the 
fions: nor could there b 
or the lait, and the commencement 
of 
e exit 
_greatelt diltance from the 
Fiem. Phyfiol, t..1. p. 97. : 
‘Where arteries divide, or a branch is given off. from any 
trunk } j éti is ob j thei fid of the tube, rmed 
by the internal coat of the artery, and correfpondi i 
fituction to the angle formed by the feparation of the branch, 
and favouring the change in the courfe of the blood 
in ‘co. form and appearance 
7 NrAte L 
certainly muft, the number of 
-Veins.. 
trunk, the arrangement is exactly the inverfe of that lat de- 
feribed. An oblique circle is obferved at the mouth of. the 
artery, of which the moft projecting half is the nearett to 
art. 
he origin of the arterial trunks is tolerabl 
but that of the branches ia expofed to 
hardly meet with two fubjects exa@ily fimilar in this refpeét, 
This circumftance-correfponds to the com tion 
form obferved in the organs of the organic life. Neither 
does their diftribution obey the law of fymmetr Even in 
the limbs, which correfpond to each other, there are varie. 
i r nches. 
but the largeft trunks may produce yery fmall twigs ; thus 
the aorta gives origin to the 
two great portions of the aorta already mentioned : fuch are | 
sin the axille, and the 
confiderable intervals, and are, therefore, more ‘immediately 
expofed to the influence of the furrounding organs. They 
a 
hand, the movements of the arterial trunks 
g organs, -and even in the w 
limb, a very fenfible motion, a kind of agitation, which, in 
hand, 
cillate, and the motion follows exactly the pulfations of the 
knees croffed, the 
ed by each projection of blood 
the limb, and then finks again, To the 
ame caufe may be referred the motion of the brain, and 
that of tumours fituated over the trunks of large arteries. 
' The courfe of the arteries differs much from that of the 
i The trunks 
and the deep-feated branches are fmaller ; the cutaneous 
branches of the arteri 
he 
ion v: ccording to the nature of the angle. If the fition. It t, therefore, b ly afferted that 
os zle be a right one. the edge is circular, and equ ¥ mani- ‘ve; sonrg ta Rs ex! 3 
re the angle is acute, 
nx 
its form, like that of the o 
atwo make together an entire circle, which is placed ob- 
is an acute angle 
: et 1¢ trunk and the branch, and an. 
obtule one between the 
and the continuation of the 
. The verte 
throu e long canals of the tranfverfe proceffes, while 
the veins lie on the outfide 3 the radial, ulnar, tibial, eS 
neal, a ingual arteries, haye each a fmall vein clofe to 
. 
them, while the large trunks of the cephalic, baiilic, a 
phenzx, and external in 
cafions great 
tected fituation, 
* 
