Identification of the apex: Located at the 5th intercostal space in the midclavicular line, left of the sternum. Easily located by counting down the ribs from the collarbone otherwise known as the clavicle. The clavicle counts as rib one because the first rib lies underneath it making it inaccessible. Once you have counted down and located the fifth rib, the fifth intercostal space will be between that rib and the sixth rib. This landmark is important for the recording of electrocardiograms (ECG) and listening to heart sounds. Practise finding and feeling this area. If you have a willing companion, ask them to undertake some aerobic exercise then locate the area again. When the heart contracts with increased power to meet the intensified cellular demands associated with physical exercise, the heart can be easily felt pounding against the chest wall.
The Correct Answer and Explanation is:
Correct Answer:
The apex of the heart is located at the 5th intercostal space at the midclavicular line, on the left side of the sternum. This anatomical landmark is critical for clinical assessments like auscultation of heart sounds and placing ECG leads.
300-Word Explanation:
The apex of the heart refers to the pointed, lower portion of the heart, formed primarily by the tip of the left ventricle. It lies in the 5th intercostal space, along the midclavicular line—an imaginary vertical line drawn from the midpoint of the clavicle (collarbone) downward. This position is just to the left of the sternum and is a key landmark in clinical medicine.
To locate the apex accurately, you begin by identifying the clavicle, which is considered the starting reference point. Although not a rib itself, the clavicle lies above the first rib, which is typically inaccessible due to its position beneath it. Therefore, when counting ribs to identify the 5th intercostal space, the second rib is the first palpable rib below the clavicle. From there, each subsequent rib can be counted down until the fifth rib is reached. The space just below it is the 5th intercostal space.
This location is significant in clinical settings, particularly for cardiac auscultation, where heart sounds—especially the mitral valve closure—can be best heard at the apex. It is also used for electrode placement in ECGs, especially for lead V4.
The apex beat can often be palpated more distinctly after physical exercise, as the heart contracts with increased force to meet the body’s higher oxygen demands. This results in a stronger thrust against the chest wall, making the apex beat more pronounced. Practicing the identification of this landmark on oneself or another person is useful for clinical training and helps develop physical examination skills.
