not all muscles alike?

[helix139]

Why is it that my chest hurts days after my routine and not any other body part? I train chest (in my garage, as is with all exercises) with decline dumbbells (10 sets) and dumbbell flys (4 sets) only. The next days are the same # of sets...back for chins, pull downs, and low rows. Shoulders for smith presses, smith close grip pulls to chin, and finally bent over flys. I work arms separately. Biceps on Monday with alternative curls, and Friday with kickbacks (my right elbow has been killing me after d-bol cycle and skull crushers!) I do maybe 4 sets of arms. No legs because I run and have naturally big legs!
I do switch up my routine from time to time because of a sore body part or pain, but for the most part I find that this routine works for me. I just don't understand why my back isn't hurting anymore and shoulders don't ache.
I want all body parts to ache after a workout!
thanks!