The human heart is a muscular, four chambered organ about the size of a clenched fist. It is located in the thorax between the lungs (mediastenum) and above the central depression of the diaphragm. It is somewhat cone-shaped with the broader end (base) upwards, and the blunt end (apex) lying on the diaphragm. It is slightly oriented towards the left. The heart weighs about 300 grams in males, and is usually slightly smaller in females.