In order to understand what we face concerning how to properly draw the shoulder girdle, we will need to endure a bit of anatomy. Now it's not going to be a comprehensive coverage of the shoulder. We did all of that in the lecture on the shoulder you can view an excerpt of it here.
The following drawing depicts the construction of the shoulder girdle, which consists of the two clavicle bones in the front and two scapulae bones in the back. These four bones are not fused, they are joined and held together with ligaments and tissue. This allows for a great freedom of movement. Just what we need to assist our arms in reaching in almost any direction.
Now that we have broken down the area anatomically speaking, lets remember what we talked about in the very first Common Mistakes blog on massing. Massing is everything in figure drawing. Massing is King. No massing, no drawing. Drawing begins with large forms and then you add the smaller adjacent forms as well as filling in the smaller forms embedded in the larger mass. This order is crucial, as any possible detail you see on the model is just that–a detail that adds embellishment but which should always be secondary to the larger mass. That also means that if you don't get the large mass right, the detail will be in the wrong place.
As I start to draw, I remember to do the massing of the large body parts such as the rib cage and pelvis. If you do these two masses correctly, then you're half way there. If you choose to start with the rib cage, look for clues and landmarks that will give you references to the position of what you already know from anatomy, namely the shape, size and construction of the rib cage. And we just arrived at the common mistake. Most of us will try to determine the position, rotation, and orientation of the rib cage with the aid of placement of the shoulders. This is the common deceit of the shoulder girdle. By nature, the shoulder girdle is a floating device that sits atop the rib cage and has a fluid life of its own very different to the semi-rigid rib cage.
Avoid this deceit by orienting yourself by the bony bits on the body–the pits of the neck, the barely visible sternum, and the ribs showing just under the skin. Use these for landmarks and clues to help you reference what you already know from anatomy. The exception to this rule is not to use the shoulders to reference the rib cage.
The video counterpart of this blog entry has extra content that works better as a video. You can find it here.