Final answer:
The heart is located behind the costal cartilages between the fourth and fifth ribs at their junction just to the left of the sternum.
Step-by-step explanation:
The heart lies obliquely within the thoracic cavity, between the costal cartilages of certain ribs. The base of the heart is level with the third costal cartilage, while the inferior tip or apex of the heart is positioned just to the left of the sternum, between the junction of the fourth and fifth ribs at their costal cartilages. This is important to know for clinical practices such as auscultating heart sounds or examining cardiac images.