47. The sternal angle lies at the level of the _ costal cartilages. \( \begin{array}{l}\text { a. } 1^{\text {st }} \\ \text { b. } 2^{\text {nd }} \\ \text { c. } 3^{\text {rd }}\end{array} \) 48. Which ribs attach directly to the sternum? \( \begin{array}{ll}\text { a. vertebrocostal } & \text { d. false ribs } \\ \text { b. vertebrochondral } & \text { e. floating ribs }\end{array} \)

The sternal angle, also known as the manubriosternal joint, is located at the level of the 2nd costal cartilages. This anatomical landmark is significant as it serves as a point of reference for counting ribs and locating other structures in the thoracic cavity, such as the aortic arch and bifurcation of the trachea. Regarding rib attachment, the ribs that attach directly to the sternum are called vertebrocostal ribs, specifically the first seven pairs (ribs 1 through 7). These ribs connect directly to the sternum via their own costal cartilages, allowing for more mobility and protection for vital organs in the thoracic cavity.