Exam category: Procedures → Thorax and Abdomen Why it matters: Nearly every positioning choice in this module exists to solve one specific diagnostic problem: magnification, superimposition, or gravity-dependent fluid and air.
Overview
Chest and rib imaging choices are all about getting gravity and geometry to work for you: which side is up, how far the tube is from the patient, and whether the patient inhales or exhales, all change what becomes visible.
1. The anatomy you need to read a chest image
Lobes: the right lung has three (superior, middle, inferior), the left lung has two (superior and inferior). The right is divided by two fissures, the left by a single oblique fissure.
Carina: the ridge of the lowest tracheal cartilage marking where the trachea bifurcates into the right and left primary bronchi, at about the level of T4–T5. It is a landmark, not a cartilage of the larynx and not the apex of the lung.
The right hemidiaphragm sits higher than the left. The liver occupies the right upper abdomen and pushes it up, making the right lung roughly 1 inch (2.5 cm) shorter than the left — on the order of half a rib space to a full rib space, not several. On a normal PA the right dome is the more superior of the two.
Jugular notch. The U-shaped dip at the top of the manubrium, between the clavicles, sits at T2 and T3. It is also called the suprasternal or manubrial notch. About 2 inches (5 cm) below it, the sternal angle (where the manubrium meets the body of the sternum) sits at the disk between T4 and T5. T1 is about 1.5 inches (4 cm) above the notch; the vertebra prominens (C7) is what you palpate posteriorly at the base of the neck.
Xiphoid process. This is the sternum's smallest and most distal part. It is cartilaginous early in life. Later, it may be partly or completely ossified, especially superiorly. Its shape varies, and it is often off-center.
Answer this to keep going. 14 more sections unlock below.
You trace the trachea down to the carina on a PA chest. At about what vertebral level does it sit?