Thorax: FAQ topics warm-up session:
• The anterior border of the left pleural cavity deviates laterally between the fourth and sixth ribs to form the cardiac notch—a preferred route for needle insertion into the pericardial cavity.
• When upright, excess fluid tends to collect in the costodiaphragmatic recess.
• Introduction of air into the pleural space results in pneumothorax with loss of lung ventilation. Fluid or blood produces hydrothorax and hemothorax, both of which limit expansion of the lung with reduced ventilation/ perfusion ratio.
• The right mainstem bronchus is wider, shorter, and more vertical than the left mainstem bronchus, and therefore, is where large aspirated objects commonly lodge.
• The right lower lobar bronchus is most vertical, most nearly continues the direction of the trachea, and is larger in diameter than the left, and therefore, is where small aspirated objects commonly lodge, causing segmental atelectasis.
• A bronchopulmonary segment is defined by a segmental bronchus and accompanying segmental artery that lie centrally, as well as by intersegmental veins that form a peripheral venous plexus.
• Because the superior segmental bronchi of the lower lobes are the most posterior, and therefore dependent, when the patient is supine, they are most frequently involved in gastric acid aspiration pneumonia (Mendelson syndrome).
