CHAPTER V. 
and inner apophyfes: Thefe are fo contrived, partly from being projc&ed 
backwards, and partly from their fhapes, as to remove the centre of mo¬ 
tion very far behind the axis of the bone, which gives great power to the 
mufcles that extend this joint to raife the whole weight of the body, 
though it lellens the power of the benders which move the leg only; 
between thefe procefles the large veflels defeend fecurely to the leg. 
Patella (Tab. xxvii.) is featedat the forepart of the knee; its firft ap¬ 
pearance is in the center of the tendon, through which it foon extends, 
until the tendinous fibres are loft, and appear to be converted into bone; 
however, when this bone is broke, the original tendinous fibres feem to 
prevail, feeing the broken parts, unlike all other bones when fra£hired, 
unite with a tendon-like fubftance, which is rarely converted into bone, 
and efpecially in thofe cafes, where the joint recovers with moft motion; 
its ufe is to fecure the extenfors of the tibia, left palling over the joint, 
they might be too much expofed to external injuries; it alfo encreafes the 
advantage (mentioned in the laft paragraph) of removing the common 
axis of the extenfors of the tibia farther from the centre of motion, and 
is a moft convenient medium for thofe mufcles to unite in, to perform 
one common action. 
Tibia, (Tab. xxviii.) the Ihin bone, is large at its upper end, where are 
two fhallow fockets which receive the thigh bone; between thefe is a 
rough procefs, to which the crofs ligaments of this joint are connected. 
Near the upper end is a procefs, into which the ligament or tendon of 
the patella is inferted, and at the lower end is a procefs, which makes the 
inner ankle, and fecurcs this bone from dillocating outwards: Towards 
the upper end this bone is triangular, and even concave on the fide next 
the mufcles to make room for them; but lower, as the mufcles grow lels 
and tendinous, the bone grows rounder; that being upon the whole a 
ftronger form: It is not madefo ftrong as the thigh bone, though it bears 
a greater weight, which it is able to do by being {freighter, and bearing the 
weight of the body in a more perpendicular direction. 
Fibula (Tab. xxviii.) is feated on the outfide of the tibia; its upper end is 
joined to that bone below the joint of the knee, and its lower end is re¬ 
ceived into a {hallow finus of the fame bone, and below that makes the 
externa lancle; which procefs, with the procefs of the tibia, ftrengthens 
the ancle joint, which nevertheless being fo {mall would have been not 
ftrong enough, if it had been made for more motion. It is doubtful to me, 
whether or not this bone contributes to the fupport of the body; but its 
great ufe is for the origins of mufcles, and even its lliape is fuited to theirs. 
