Final answer:
The angle of Louis, or sternal angle, is located between the manubrium and the body of the sternum and marks the attachment site for the second rib, which is important for rib identification and counting.
Step-by-step explanation:
The angle of Louis, also known as the sternal angle, is the junction line between the manubrium and the body of the sternum. It is a significant anatomical landmark as it marks the site for the attachment of the second rib to the sternum. This angle is not flat but forms a slight bend and is also near the manubriosternal joint, which is the cartilaginous joint that unites the manubrium and the body of the sternum, playing a role in the protection of the heart.
The sternum, which is the elongated bone located at the center of the anterior chest, consists of three parts: the manubrium, body, and xiphoid process. The manubrium is the upper portion of the sternum, while the body is the elongated, central portion.
The sternal angle and the attachment of the second rib are essential for the identification and counting of the lower ribs, as ribs 3-7 attach to the sternal body, and since the first rib is obscured by the clavicle, the second rib becomes the highest rib that can be identified by palpation.