Lead V5 is parallel to Lead V4 in which axillary line?

Lead V5 is parallel to Lead V4 in which axillary line?

• A. Lead V4 in the anterior axillary line
• B. Lead V4 in the posterior axillary line
• C. Lead V4 in the midaxillary line
• D. Lead V4 in the midclavicular line

Answer: (C)

The key idea is how chest leads line up across the same horizontal level on the chest. V4 sits at the left midclavicular line in the 5th intercostal space. To keep the leads in the same plane as you move laterally, the reference line used for V5 in this context is the midaxillary line, so V5 is considered parallel to V4 in that line. That makes midaxillary the best answer because it describes the same horizontal plane across the chest as V4, aligning the two leads conceptually. Other lines (anterior, posterior, or midclavicular) would place V5 in a different plane and wouldn’t be described as parallel to V4.

The key idea is how chest leads line up across the same horizontal level on the chest. V4 sits at the left midclavicular line in the 5th intercostal space. To keep the leads in the same plane as you move laterally, the reference line used for V5 in this context is the midaxillary line, so V5 is considered parallel to V4 in that line. That makes midaxillary the best answer because it describes the same horizontal plane across the chest as V4, aligning the two leads conceptually. Other lines (anterior, posterior, or midclavicular) would place V5 in a different plane and wouldn’t be described as parallel to V4.