366.The answer is e.(Moore and Dalley, pp 156–160.)A sonogram of the
heart (or echocardiogram) that suggests decreased posterior wall move-
ment is most likely due to local infarction or fibrosis of that portion of the
heart. Infarcted or fibrotic tissue would reduce blood flow. The major
blood supply to the left anterior ventricular wall in most hearts is the pos-
terior interventricular artery (or posterior descending), normally a branch
off the right coronary artery. If there is blockage (generally described as a
percent of normal) in a coronary artery, then there should be a concomitant
decrease in the blood within the vein that serves that region. The middle
cardiac vein runs with the posterior interventricular. The circumflex
branch of the left coronary artery runs with the great cardiac vein (answer a)
within the atrial ventricular sulcus for a short distance, but blood flow
reduction in those vessels does notfit with the echocardiographic results.
The right marginal branch of the right coronary artery runs with the small
cardiac vein (answer d),but they serve the right ventricle. The anterior
interventricular artery runs with the great cardiac vein (answer b),notthe
middle cardiac vein (answer c),but on the anterior aspect of the heart.
367.The answer is c.(Moore and Dalley, pp 150, 154.)The origin of the
pulmonary trunk is anterior and to the right of the ascending aorta. During
embryonic development the outflow tract of the heart (the truncus arteriosus)
becomes divided into the ascending aorta and pulmonary trunk by the
conotruncal ridges. Remember that semilunar valves form at these outflow
tracks. Both the aortic and pulmonary valves have right and left cusps.
Remember that the aortic valve has a right and left cusp, but also a poste-
rior cusp, since it is more posterior. In contrast, the pulmonary valve has
both right and left cusps and an anterior cusp since it is more anterior (each
semilunar valve has the single cusp that the first letter of its name does not
have); aortic has posterior; pulmonary has anterior. This also reminds you
that the aorta is posterior to the pulmonary trunk. Also remember that the
right ventricle is the more anterior chamber and thus gives off a more ante-
rior great vessel. The left ventricle is the more posterior chamber as it gives
off its outflow tract. As the great vessels proceed cranially, the aorta ends up
on the left as it arches over the split of the pulmonary arteries. The other
answers(answers a, b, d)are notcorrect.
368.The answer is d.(Moore and Dalley pp 91, 188–189.)Structures typ-
ically found at the same level as the sternal angle in an axial CT include: the
490 Anatomy, Histology, and Cell Biology