Medically reviewed by Sanja Jelic, MD Key Takeaways The diaphragm is the main muscle used for breathing. The diaphragm helps ...

The heart is a complex organ that pumps blood throughout the body. It sits in the chest, slightly left of center, behind the breastbone, and between the lungs. A heart that is not healthy does not ...

Your lungs are complex, yet delicate organs that replenish the oxygen in your blood with every breath you take. Each lung is divided into lobes and connected in the middle of your chest by your ...