During a routine cardiovascular examination, the apex beat of the heart is palpated in a healthy adult. Its normal surface marking is:

• A Left fourth intercostal space, just lateral to the sternal border
• B Left fifth intercostal space, just medial to the midclavicular line ✓
• C Left fifth intercostal space in the midaxillary line
• D Left sixth intercostal space, just medial to the midclavicular line

Explanation

The apex beat is produced by the left ventricle striking the chest wall and is normally felt in the left fifth intercostal space just medial to the left midclavicular line, roughly 8 to 9 cm from the midsternal line. Displacement lateral to this line suggests cardiomegaly. Option D describes the position in gross left ventricular enlargement, while option A corresponds to where the sounds of the tricuspid area are best heard, not the palpable apex.

Reference: Snell's Clinical Anatomy by Regions, 10th ed.

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Written and medically reviewed by the StethoPrep medical team.