I want to discuss the anatomy of the shoulder girdle specifically because it's the most commonly misdrawn area in figure work and the one where understanding the mechanics makes the most immediate difference.

The shoulder is not a simple ball-and-socket joint attached to the ribcage. It's a complex three-joint system: the sternoclavicular joint connects the collarbone to the sternum, the acromioclavicular joint connects the collarbone to the scapula, and the glenohumeral joint is the actual shoulder socket.

What this means visually: the entire shoulder complex — collarbone, scapula, and upper arm — moves together as a unit. When the arm raises forward, the collarbone rises at the front. When the arm raises to the side, the scapula rotates on the back. The shoulder doesn't just move the arm; the whole surrounding structure reorganizes.

The most visible implication: the clavicle angle changes with arm position. Drawing the clavicle as always horizontal is wrong except when both arms are down. Getting the clavicle angle right makes shoulder positions read correctly.