Shoulders are a fun body part to work because there are many different exercises.

Check out the following for detaild anatomy, physiology and kinesiology information:

http://AskTheTrainer.com/effective-shoulder-exercises.html

-and-

http://AskTheTrainer.com/best-shoulder-workout.html

-and-

http://AskTheTrainer.com/rotator-cuff-exercises.html