Biomechanical Modeling of the Shoulder - Fundamentals and Assessment Tools for Occupational Ergonomics - page 563

Parametric analyses have been provided for changing values f, z, and function of a. The positions of the
humerus head were calculated for each angle of elevation abduction a 0 8 -170 8 , and for the four para-

/ ¼

metric conditions: (1) f 90 8 , z 0 mm (Figure 27.2a); (2) f 90 8 , z 0-32 mm (Figure 27.2b); (3)

¼ ¼ ¼ ¼

f 0-32 mm (Figure 27.2d and f). In

the four geometrical structures related to joint articulations, the concavity of the glenoid fossa was reduced
to a tangent to the glenoid surface. The deltoid lateral part was attached directly to the glenoid fossa or at
the certain distance (Figure 27.2).
For the first conditions (Figure 27.2a) where f

10 8 -170 8 , z 0 mm (Figure 27.2c and e); (4) f 10 8 -170 8 , z

¼ ¼ ¼ ¼

90 8 (a tangent to the glenoid fossa was a vertical line)

¼

and z 0 mm (the deltoid lateral part was attached directly to the glenoid fossa), the distance along the

Y-axis was:

¼

r

L 2 sin aþ

R

y ¼ R (27 : 8)

L 2 sin a R

(a tangent to the glenoid fossa was a vertical
line) and z ranged from 0 to 32 mm (the deltoid lateral part was attached at a certain distance from the

For the second condition (Figure 27.2b) where f 90 8

¼

Y Y

(a)

(b) Y

z

(c)

Z f

Z

Z

Y

Y

(d) (e)

(f)

Y

f

z

f

f

Z

Z z

Z

FIGURE 27.2 The geometrical structures related to joint articulations. (a) The conditions where f 90 8 ,

¼

z 0 mm. (b) The conditions where f 90 8 , z 0-32 mm. (c) The conditions where f 0 8 -90 8 , z 0 mm.

¼ ¼ ¼ ¼ ¼

(d) The conditions where f 0 8 -90 8 , z 0-32 mm. (e) The conditions where f 90 8 -180 8 , z 0 mm.

¼ ¼ ¼ ¼

(f) The conditions where f 90 8 -180 8 , z 0-32 mm.

¼ ¼