334.The answer is d.(Moore and Dalley, pp 132–133.)Innervation of the
bronchial smooth muscle is mediated by parasympathetic neurons carried
by the vagus nerve. Those nerves also stimulate secretion from the bronchial
glands. Excessive vagal activity may initiate bronchospasm or the asthmatic
syndrome. The intercostal nerves (answer a)innervate the intercostal mus-
cles. The phrenic nerve (answer b)innervates the diaphragm. Thoracic
splanchnic nerves (answer c)arise from preganglionic sympathetic nerves
that pass through the thorax to go on to innervate the gastrointestinal tract
within the abdomen.
335.The answer is d.(Moore and Dalley, p 155.)The presence of a sys-
tolic ejection-type murmur suggests that blood is becoming turbulent dur-
ing contraction of the ventricles, consistent with the aortic valve stenosis.
Aortic stenosis (often discovered in adults due to a congenital bicuspid aor-
tic valve) produces a jet of blood, which in turn causes the subsequent dila-
tion of the ascending aorta. Secondarily, the left ventricle hypertrophies in
size due to the increased resistance of forcing blood through a small valve.
Tetralogy of Fallot (answer a)would generally be diagnosed in cyanotic
newborns. Pulmonary valve stenosis (answer b)is unlikely since the pul-
monary trunk on this patient is normal. Atherosclerosis (answer d)has
nothing to do with the findings. A tricuspid valve defect (answer e)would
notprobably produce a systolic murmur.
336.The answer is d.(Moore and Dalley, pp 132–133.)The phrenic nerve,
which arises from cervical nerves C3 through C5, mediates sensation from
the diaphragmatic pleura and peritoneum, as well as from the pericardium;
in addition, it carries motor fibers to the diaphragm. Therefore, pain from the
diaphragmatic pleura or peritoneum, as well as from the parietal peri-
cardium, may be referred to dermatomes between C3 and C5, inclusive.
Those dermatomes correspond to the clavicular region and the anterior and
lateral neck, as well as to the anterior, lateral, and posterior aspects of the
shoulder. Cervical cardiac accelerator nerves (answer a)would be sympa-
thetic, generally from T1-5. The vagus (answer b)which is a cranial nerve
doesnotcarry referred pain back to the brain. The right intercostal nerve
(answer c)may carry referred pain from the parietal pleura to the chest wall.
The right recurrent laryngeal nerve (answer e)is a branch of the vagus and
doesnotcarry referred pain to the brain.
Thorax Answers 479