The heart is a hollow muscular organ that is somewhat pyramidal in shape, found
between the lungs and within the ribcage, enclosed in a fibrous sac called the
It's placed behind the lower two-thirds of the sternum. It is not a symmetrical
organ. The heart has three surfaces
and an apex which points downward, forward, and to the left. An adult heart averages five inches in length, three inches in width,
and two inches and a half in thickness (approximately the size of a clenched
fist). It weighs in at approximately eleven ounces in males and nine ounces
Check out the 3D Rotatable Heart.