BONES AND MUSCLES OF LOWER EXTREMITY. 485 
lower extremities, this framework is much more firmly at¬ 
tached to that of the trunk, than is the case with that which 
supports the arms. It consists, on each side, of a hone which 
in the adult state is single, though at an early age it is com¬ 
posed of three distinct pieces ; and this is closely connected 
with the sacrum behind, while it meets with its fellow in 
front in such a manner as to form a sort of bason termed the 
Pelvis. The spreading sides of this, formed by the iliac hones 
(Fig. 213), afford support above to the viscera contained in 
the abdomen; and they give attachment by both surfaces to 
large muscles by which the thigh-bone is moved, and by their 
edges to large expanded muscles that pass upwards to the ribs 
and sternum, and form the walls of the abdomen. Below this 
spreading portion, we find the articular cavity of the thigh¬ 
bone, which is so deep as almost to form a hemispheric cup 
when it is completed by its cartilaginous border. The move¬ 
ments of the thigh-hone are consequently more limited than 
those of the arm ; hut it is much less liable to displacement. 
646. The thigh, like the arm, contains hut a single bone, 
which is named the Femur. Its upper extremity is bent at 
an angle ; and its rounded head is separated from the rest by 
a narrow portion which is termed its neck. At the point 
where this neck joins the shaft of the hone, there are two 
large projections termed trochanters , one on the outer side and 
the other on the inner ; these serve to give attachment to the 
muscles by which the thigh is moved. Of these muscles, one 
descends from the lumbar vertebrae, and passes-down with 
another that rises from the upper expanded surface of the 
pelvis, over the front border of the pelvis, to he attached 
to the smaller and interior of the projections just mentioned ; 
these with the assistance of other muscles raise or draw 
forwards the thigh,—an action which does not require in Man 
to he performed with any great force. The muscles which 
draw hack the thigh, on the other hand, arise from the under 
surface and hack of the pelvis, where they form a very thick 
fleshy mass ( n , 25 , fig. 226); and they pass to the larger and 
external projection, and to a ridge which runs from it down 
the thigh-hone. Other muscles which arise from the lower 
border of the pelvis, serve to rotate the thigh upon its axis. 
The lower end of the thigh-bone spreads into two large condyles ,, 
on which the principal hone of the leg moves backwards and 
