0071509674.pdf

• The anterior borderof the left pleural cavitydeviates 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 pneumothoraxwith
  loss of lung ventilation. Fluid or blood produces hydrothorax and hemo-
  thorax, both of which limit expansion of the lung with reduced ventila-
  tion/perfusion ratio.


• The right mainstem bronchusis 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 seg-
  mental atelectasis.
  •A bronchopulmonary segmentis defined by a segmental bronchus and
  accompanying segmental artery that lie centrally, as well as by interseg-
  mental veins that form a peripheral venous plexus.


• Because the superior segmental bronchiof 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).

Heart

• The transverse cardiac diameter varies with inspiration and expiration
  but normally should not exceed one-half the diameter of the chest.

High-Yield Facts 49

THORAX

Thoracic Cage and Lungs

Inspiration External intercostals,interchondral portion of internal intercostals,

and the diaphragm

Expiration Internal intercostalsproper, transverse thoracic, and abdominal

muscles

RESPIRATORY MUSCULATURE

Function Muscles