NBME Anatomy , Embryology And
Cardiovascular System Exam with Verified
150 Q&A With Rationales
**Q1:** A newborn has a harsh continuous murmur heard at the left
sternum between the first two ribs. Arterial blood oxygen content is
slightly higher in the right hand than in the left hand. What is the
most likely diagnosis?
**A:** Patent ductus arteriosus
**Rationale:** PDA results from failure of the ductus arteriosus to
close after birth. The continuous murmur and differential cyanosis
(higher O₂ in right hand than left) are classic findings. The ductus
arteriosus connects the left pulmonary artery to the descending
aorta in fetal life .
**Q2:** A heart defect results from failure of the aorticopulmonary
septum to form. What condition does this produce?
**A:** Persistent truncus arteriosus
**Rationale:** The aorticopulmonary septum normally divides the
truncus arteriosus into the ascending aorta and pulmonary trunk.
Failure results in persistent truncus arteriosus .
,**Q3:** During development, the smooth part of the right atrium
derives from which embryonic structure?
**A:** Sinus venosus
**Rationale:** The sinus venosus contributes to the smooth-walled
portion of the right atrium. The trabeculated part derives from the
primitive atrium .
**Q4:** A newborn has a heart where the aorta arises from a
morphologic right ventricle. What is the most appropriate term for
this condition?
**A:** Taussig-Bing malformation
**Rationale:** Taussig-Bing malformation is a variant of
transposition where the aorta arises from the morphologic right
ventricle and the pulmonary artery overrides a ventricular septal
defect .
**Q5:** What embryonic structure forms the central tendon of the
diaphragm?
**A:** Septum transversum
,**Rationale:** The septum transversum is mesodermal tissue
projecting from the ventral body wall that partially separates thoracic
and abdominal cavities, forming the central tendon .
---
## Respiratory System
**Q6:** A newborn has abdominal viscera protruding through a
defect in the abdominal wall. What is the likely cause?
**A:** Incomplete fusion of the lateral body folds
**Rationale:** During the 4th week, lateral body folds move
ventrally and fuse in the midline. Incomplete fusion results in
gastroschisis .
**Q7:** Which respiratory structure is derived from neural crest
cells?
**A:** Laryngeal cartilage
**Rationale:** Laryngeal cartilages develop from neural crest cells .
, **Q8:** An infant born with flattened facial features, low-set ears,
and foot deformities. Pregnancy was complicated by severe
oligohydramnios. What is the most likely cause?
**A:** Failure of ureteric buds to develop
**Rationale:** This infant has Potter syndrome, caused by bilateral
renal agenesis from failure of ureteric bud development.
Oligohydramnios leads to the characteristic deformations .
**Q9:** What is the most common combination of congenital
tracheoesophageal septum malformation?
**A:** Proximal esophageal atresia with distal tracheoesophageal
fistula
**Rationale:** This is the most common TEF variant, presenting with
aspiration and feeding difficulties in newborns .
**Q10:** A congenital diaphragmatic hernia is normally only seen on
which side and why?
**A:** Left side; the liver blocks abdominal contents from invading
the right pleural cavity
Cardiovascular System Exam with Verified
150 Q&A With Rationales
**Q1:** A newborn has a harsh continuous murmur heard at the left
sternum between the first two ribs. Arterial blood oxygen content is
slightly higher in the right hand than in the left hand. What is the
most likely diagnosis?
**A:** Patent ductus arteriosus
**Rationale:** PDA results from failure of the ductus arteriosus to
close after birth. The continuous murmur and differential cyanosis
(higher O₂ in right hand than left) are classic findings. The ductus
arteriosus connects the left pulmonary artery to the descending
aorta in fetal life .
**Q2:** A heart defect results from failure of the aorticopulmonary
septum to form. What condition does this produce?
**A:** Persistent truncus arteriosus
**Rationale:** The aorticopulmonary septum normally divides the
truncus arteriosus into the ascending aorta and pulmonary trunk.
Failure results in persistent truncus arteriosus .
,**Q3:** During development, the smooth part of the right atrium
derives from which embryonic structure?
**A:** Sinus venosus
**Rationale:** The sinus venosus contributes to the smooth-walled
portion of the right atrium. The trabeculated part derives from the
primitive atrium .
**Q4:** A newborn has a heart where the aorta arises from a
morphologic right ventricle. What is the most appropriate term for
this condition?
**A:** Taussig-Bing malformation
**Rationale:** Taussig-Bing malformation is a variant of
transposition where the aorta arises from the morphologic right
ventricle and the pulmonary artery overrides a ventricular septal
defect .
**Q5:** What embryonic structure forms the central tendon of the
diaphragm?
**A:** Septum transversum
,**Rationale:** The septum transversum is mesodermal tissue
projecting from the ventral body wall that partially separates thoracic
and abdominal cavities, forming the central tendon .
---
## Respiratory System
**Q6:** A newborn has abdominal viscera protruding through a
defect in the abdominal wall. What is the likely cause?
**A:** Incomplete fusion of the lateral body folds
**Rationale:** During the 4th week, lateral body folds move
ventrally and fuse in the midline. Incomplete fusion results in
gastroschisis .
**Q7:** Which respiratory structure is derived from neural crest
cells?
**A:** Laryngeal cartilage
**Rationale:** Laryngeal cartilages develop from neural crest cells .
, **Q8:** An infant born with flattened facial features, low-set ears,
and foot deformities. Pregnancy was complicated by severe
oligohydramnios. What is the most likely cause?
**A:** Failure of ureteric buds to develop
**Rationale:** This infant has Potter syndrome, caused by bilateral
renal agenesis from failure of ureteric bud development.
Oligohydramnios leads to the characteristic deformations .
**Q9:** What is the most common combination of congenital
tracheoesophageal septum malformation?
**A:** Proximal esophageal atresia with distal tracheoesophageal
fistula
**Rationale:** This is the most common TEF variant, presenting with
aspiration and feeding difficulties in newborns .
**Q10:** A congenital diaphragmatic hernia is normally only seen on
which side and why?
**A:** Left side; the liver blocks abdominal contents from invading
the right pleural cavity
