"Act kindly towards woman, for woman is created from a rib, and the most crooked part of the rib is its top. If you attempt to straighten it, you will break it, and if you leave it, its crookedness will remain there. So act kindly towards women." - The Perfect Man - Muhammad (Peace and Blessings of Allah (The God) be upon him)

Reported by Abu Huraira (Hadith - Muslim, #3468)

i am not sure if women are made off men ribs but i guess it just signifies their similarities with facts like how ribs safeguard our heart and lungs yet is our weak point (i got several blows on my ribs and i know it hurts very bad) the woman protects a Man's house and is yet vulnerable. I would not disagree the other similarity of the crooked top of a rib. :P