The heart weighs between 7 and 15 ounces and is a little larger than the size of your fist. Your heart is located between your lungs in the middle of your chest, behind and slightly to the left of your sternum.

Your heart has 4 chambers. The upper chambers are called the left and right atria, and the lower chambers are called the left and right ventricles. A wall of muscle called the septum separates the left and right atria and the left and right ventricles. The left ventricle is the largest and strongest chamber in your heart. The left ventricle’s chamber walls are only about half an inch thick, but they have enough force to push blood through the aortic valve and into your body.