32 AN ESSAY ON CHRONIC PODOTROCHOLITIS. 
the chief portion of the weight of the body falls upon the muscles, 
which ought to be considered as cords extended between the arti- 
culations ; and as the angles of these latter never become effaced, 
they act as distributors of the actual weight of the body. 
It is not, however, thus with the fore extremities : their perpen- 
dicular position causes the weight to fall more upon the bones 
than the muscles. This difference has already been established by 
Borelli*, the celebrated founder of the intromathematic school. 
The shoulder-blade forms with the arm an angle directed forwards; 
the angle of the arm with the fore arm and elbow has an opposite 
direction : from the elbow to the pastern the limb is perpendicular. 
Thus between these two points the line of perpendicular is not 
interrupted, for the carpus when supporting weight is, in fact, 
in a state of extension; while, under the same extension, the 
hinder extremity presents an additional angle. The perpendicular 
direction of the carpus being indispensable, when the weight falls 
upon the limb, this articulation being destined solely for the pur- 
pose of flexion, contributes nothing to the division of the force, 
and thus the fore extremity has one distributor less than the hind. 
A greater amount of weight descends upon the pastern thence to be 
transmitted to the foot. 
The muscular attachment of the shoulder-blade to the trunk, and 
the exceedingly moveable articulation formed by the scapula with 
the arm, give to these parts a great degree of elasticity, consi- 
derably surpassing the deadening power of the coxo-femoral arti- 
culation. While the lever-like arms presented by the long bones 
of the hinder extremities possess greater extension than those of 
the fore-legs, the femur and tibia are longer than the humerus 
and radius : the two former re-unite at the stifle in a less obtuse 
angle, and thus confer upon this articulation a more extensive 
motion than is possible for the humero-cubital joint to possess. 
The stifle, which may, at least, be compared with the shoulder in 
the effect with which it counteracts all reaction, surpasses the 
humero-cubital articulation in this respect; this being to the stifle 
what the coxo-femoral articulation is to the joint of the scapula 
and humerus. It is also remarkable that the coxa at its union 
with the sacrum possesses but a limited degree of mobility ; but 
this mobility being united with that with which the lumbar ver- 
* De motu animaliura, Neapol. 1734, 1. 127 : “ Iline forsan est quod pedes 
anteriores quadrupedum paucioribus et minus validis musculis donantur, quia 
scilicet articulis in directum extensis et perpendiculariter ad horizontum 
erectis insistene solent et ideo sua ossea duritie ad instar columnarum pondus 
animalis sustentare possunt. Cum e contra pedes posteriores quorum articuli 
nanquam directe extenduntur sed semper inflexi sunt dum animal stat, a vi 
musculorum retineri debent in tali curvatura.” 
