the chest diameter, is of normal size (answer b),but is shifted to the right.
Both the pulmonary trunk (answer d)and the left ventricle (answer e)
would be inferior to the arrow on the left heart border.
343.The answer is b.(Moore and Dalley, pp 117–118.)The fluid level in
the right pleural cavity is indicative of hemothorax caused by bleeding into
the pleural space. As blood collects, lung tissue is displaced and cannot
expand fully, thereby impairing ventilation. However, perfusion continues
so that the ventilation-perfusion ratio is altered. There would be nofluid
line if it were a pneumothorax (answer c).A puncture wound often pro-
duces a flailing chest [(answer a) moving inward as the rest of the thoracic
cage expands during inspiration]. Paralysis of the right hemidiaphragm
(answer d)would result in the diaphragm becoming stationary near its
normal expiration height.
- The answer is d.(Moore and Dalley, pp 118–119.)The usual loca-
tion of choice for a chest tube drain is in the midaxillary or posterior axil-
lary line, that is, the vertical line commencing at the middle or posterior
axillary fold, at the approximate level of the fifth or sixth intercostal space.
Since the lung is collapsed toward the hilum the exact level tends notto be
so important since the lung has pull cranial and medial. The needle is usu-
ally inserted just below the level at which percussive dullness occurs (if
hemothorax). The apex of the lung (answer a)is close to the brachial
plexus and subclavian vessels and thus is notused. The costomediastinal
recess on the left, adjacent to the xiphoid process (answer b)is used for
pericardiocentesis. The midclavicular line (answers c and e)isnotused
because tubes placed this far anteriorly tend to be in the way of the
patient. - The answer is b.(Moore and Dalley, pp 97, 102, 118–119.)The
upper two posterior intercostal arteries arise from the costocervical trunk;
the remaining arteries arise from the descending thoracic aorta. The poste-
rior intercostal arteries anastomose with the anterior intercostal arteries,
which arise from the internal thoracic artery. Laterally, the intercostal neu-
rovascular bundle lies in the costal groove along the internal surface of the
inferior border of each rib and between the innermost intercostal and inter-
nal intercostal muscles (answers c and e).Indeed, scalloping of the infe-
rior edge of the rib is a radiographic indication of increased collateral
482 Anatomy, Histology, and Cell Biology