This section is from the book "Applied Anatomy: The Construction Of The Human Body", by Gwilym G. Davis. Also available from Amazon: Applied anatomy: The construction of the human body.
For the sake of convenience in description and record, the chest has been divided into various regions and marked by certain longitudinal lines.
Seven longitudinal lines are used. They run parallel with the long axis of the body. 1. The median line means the midline of the body. This runs down the middle of the sternum anteriorly and the middle of the back posteriorly.
2. The parasternal line runs parallel to the edge of the sternum and midway between it and the midclavicular line.
3. The midclavicular line, also called the mammary line, is a longitudinal line passing through the middle of the clavicle. This usually passes 1 to 2 cm. internal to the nipple.
Fig. 211. - The longitudinal lines of the chest used in physical diagnosis.
5. The midaxillary line passes through the middle of the axilla.
6. The posterior axillary line passes through the posterior fold of the axilla.
7. The scapular line passes longitudinally through the lower angle of the scapula.