How are "precordial leads" numbered in an EKG setup?

The correct option details that precordial leads are numbered from V1 to V6, moving from left to right across the chest. This arrangement reflects the anatomical placement of these leads as they are positioned around the heart to provide a comprehensive view of the electrical activity during each heartbeat.

Starting with V1, which is placed in the fourth intercostal space at the right sternal border, the subsequent leads are placed sequentially across the chest to V6, which is located in the fifth intercostal space at the midaxillary line on the left side. This specific configuration allows the EKG to capture a detailed and accurate representation of the heart’s activity, particularly the anterior and lateral walls, helping in diagnosing various cardiac conditions.

The rationale for this setup is based on the electrical pathway of the heart and the anatomical layout of the chest, enabling the recording of various electrical vectors in different planes. Leads V1 to V6 are crucial as they provide essential information that can identify abnormalities in heart function and structure.