Your drawings remind me of George Bridgman's work! He has a wild linework style but his proportions and understanding of anatomy are top notch. When you're studying anatomy, you want to be as accurate as possible with proportions. You have the shape and slant of the ribcage correct, but keep in mind these general proportional rules: Ribcage is 1.5 heads tall, 1.25 heads wide, 1 head deep. The thoracic arch is the midway point between the pit of the neck and the bottom of the ribcage. Good luck :)