Biomedical Engineering Reference
In-Depth Information
Table 3.1
Percentage
of total body mass
Mass (% of total
body mass)
Parts of body
Head
6.9
Trunk-neck
46.1
Upper arms (2)
6.6
Lower arms (2)
4.2
Hands (2)
1.7
Thighs (2)
21.5
Legs (2)
9.6
Feet (2)
3.4
Total (whole body)
100.0
Fig. 3.9
Simulated body
of a man
z
(m)
z
(m)
y
(m)
x
(m)
coordinates located on the ground between your feet, use a meter stick or a
tape measure.
The center of gravity of a person standing erect, with arms along the body, lies
on a vertical line that touches the floor around 3.0 cm in front of the ankle joint.
Its location is slightly in front of the second sacral vertebra or at 58 % of the height
of a person above the ground. Since the location of the C.G. in human beings is
relatively high above the area of support, their equilibrium is far from being stable.
As the position of the C.G. depends on the distribution of mass, any modification of
the shape of the body will change it. The center of gravity of men's body is slightly
higher related to the support area than that of women, because men have wide
shoulders and women large hips. During the last months of pregnancy, the C.G. of a
woman's body is displaced forward, and to equilibrate, she walks by placing the
torso and the head a little behind, seeming very proud of herself. People, who have
