The Interdimensional Traveler: A Full Body Character Design - ZBrush Creature Design: Creating Dynamic Concept Imagery for Film and Games - page 150

Revising the Shoulders and Arms
Now we will make some changes to the shoulder girdle of the figure. This will include making alterations
to the shape of the muscular and skeletal forms in the shoulder area. We will also be adding an entirely
new set of arms later on, which will demand we have an understanding of how the anatomy of the shoulder
functions; otherwise, we will not be able to incorporate the new physiology in a convincing and functional
manner. Before we get too deep into these changes, let's take a look at what the shoulder girdle actually is
and how it functions.
The shoulder girdle is the skeletal structure that allows the arm to move through its full rotational axis
( Figure 3-52 ) . It consists of the collarbone, the shoulder blade, and the upper arm bone. These parts are more
properly known as the clavicle, scapula, and humerus ( Figure 3-53 ). Without these skeletal components, no
movement of the arm would be possible.
The shoulder girdle is manipulated by several important muscles. The most recognizable of them are the
sternomastoids and trapezius in the front and the trapezius and rhomboids in the back ( Figure 3-54 ) .
Figure 3-52: Here you can see some of the range of motion possible with the shoulder girdle.