A really great post on the active shoulder by Tracy Fober; here's a snippet, read the rest over at her blog. I've always wondered why people give the cue 'shoulder-into-ears' for movements like the overhead squat.

At a weightlifting meet, you'll hear coaches yell "push" or "reach" to their athletes. The athlete must aggressively resist the downward forces of gravity and barbell to successfully receive the bar and complete the lift. Many people confuse this aggressive "push" with a shrug of the upper trap. Yes, the upper traps are strong, but we do not want to elevate the shoulder girdle and decrease approximation of the scapula on the rib cage; nor do even want to think we can hold that weight up with upper body muscular strength. We receive the bar at arms length, lock the wrist and elbow in a fully extended position, and maximize contact of the scapula with the thorax via serious isometric contraction of scapular stabilizers. The human body supports the overhead load with the greatest area of bony stability possible, and transfers that force over the entire musculoskeletal system.