THORAX ABDOMEN AND PELVIS

Detailed explanation-1: -The apex (the most inferior, anterior, and lateral part as the heart lies in situ) is located on the midclavicular line, in the fifth intercostal space. It is formed by the left ventricle. The base of the heart, the posterior part, is formed by both atria, but mainly the left.

Detailed explanation-2: -The bottom of the heart (the apex) is formed by the tip of the left ventricle and is positioned just above the diaphragm to the left of the sternum at the fifth intercostal space, midclavicular line.

Detailed explanation-3: -The heart sits atop the diaphragm and its apex is close to the anterior surface of the thoracic cavity. With every beat, the heart twists forward and the apex taps against the chest wall, producing the apex beat. This can be felt in the fifth left intercostal space.

Detailed explanation-4: -5th Intercostal space at left sternal border (or 4th intercostal space in a child): Location of where tricuspid valve is best heard because the flow of blood out of this valve is directed toward this area. Note that in a child, this is located at the fourth intercostal space.