514
Abdomen
Answers
369.The answer is d.(Moore and Dalley, pp 270, 271.)During the first
month of development, the midgut communicates over its entirety with the
yolk sac. This connection narrows during the second month to form the
vitelline duct (yolk stalk, omphalomesenteric duct) as the midgut closes
and usually disappears during the ninth week. Because the vitelline duct
joins the ileum, this section of the gastrointestinal tract is the last to close.
Failure of closure results in a persistent vitelline fistula, whereas partial
obliteration results in an ileal diverticulum (of Meckel). The ileal diverticu-
lum and umbilical hernia would most likely be repaired at the same time.
Other regions (answers a, b, c and e)of the gastrointestinal tract are
unlikely to be attached to the anterior abdominal wall.
370.The answer is a.(Moore and Dalley, pp 257–258, 322–323.)Visceral
afferent pain fibers from the gallbladder travel through the celiac plexus,
thence along the greater splanchnic nerves to levels T5–T9 of the spinal
cord. Thus, pain originating from the gallbladder will be referred to
(appear as if coming from) the dermatomes served by T5–T9, which
include a band from the infrascapular region to the epigastrium. If the gall-
bladder enlarges sufficiently, then pain could be carried by the phrenic
nerve (answer c),but this would refer pain to the neck. Intercostal nerves
(answer b)would course above the diaphragm and thus are not involved.
The vagus (answer d)generally does not transmit pain information. Pelvic
splanchinics(answers e)receive pain information from pelvic organs and
thus are not involved.
371.The answer is b.(Moore and Dalley, pp 290–291, 295.)The gallbladder
lies on the inferior surface of the liver between the right and quadrate lobes
[thus not (answer a)]. The caudate lobe lies posteriorly between the right
and left lobes. The falciform ligament, a portion of the lesser omentum,
attaches to the liver at the incisura between the quadrate and left lobes as well
as along the fissure for the round ligament. Toward the superior surface of the
liver, the falciform ligament (answer c)splits to form the left and right