NBME Gross Anatomy and Embryology 3 — Questions and Answers
Question 1: A newborn is found to have a single umbilical artery. This anomaly is most associated with which type of defect?
- Cardiac and renal anomalies (Correct answer)
- Neural tube defects
- Cleft palate
- Pyloric stenosis
Correct answer: Cardiac and renal anomalies
A single umbilical artery (instead of the normal two) is a marker for associated congenital anomalies, most commonly cardiovascular and renal defects.
Question 2: After a pelvic fracture, a male patient cannot dorsiflex the foot. Which nerve is most likely damaged?
- Femoral nerve
- Obturator nerve
- Sciatic nerve (common fibular division) (Correct answer)
- Tibial nerve
Correct answer: Sciatic nerve (common fibular division)
The common fibular (peroneal) division of the sciatic nerve innervates the anterior and lateral compartments of the leg; its injury causes foot drop.
Question 3: The gubernaculum in males guides testicular descent into the scrotum. In females, the gubernaculum persists as which structure?
- Broad ligament
- Ovarian ligament and round ligament of uterus (Correct answer)
- Uterosacral ligament
- Suspensory ligament of ovary
Correct answer: Ovarian ligament and round ligament of uterus
In females, the gubernaculum becomes the ovarian ligament (connecting ovary to uterus) and the round ligament of the uterus (connecting uterus to labia majora).
Question 4: An obstetrician identifies a fetal kidney with multiple non-communicating cysts that do not connect to the collecting system. This most likely results from failure of which structure?
- Pronephros to regress
- Ureteric bud to induce metanephric mesenchyme (Correct answer)
- Mesonephros to form
- Allantois to involute
Correct answer: Ureteric bud to induce metanephric mesenchyme
Multicystic dysplastic kidney results from failure of the ureteric bud to properly induce the metanephric mesenchyme, leading to non-functional cystic tissue.
Question 5: A patient with a femoral hernia would present with a bulge in which location?
- Superior and medial to the pubic tubercle
- Inferior and lateral to the pubic tubercle (Correct answer)
- Through the superficial inguinal ring
- Within the inguinal canal lateral to the inferior epigastric artery
Correct answer: Inferior and lateral to the pubic tubercle
Femoral hernias pass through the femoral ring, presenting inferior and lateral to the pubic tubercle, in contrast to inguinal hernias which are superior and medial.
Question 6: Which embryonic layer gives rise to the epithelium of the urinary bladder?
- Ectoderm
- Lateral plate mesoderm
- Endoderm of the urogenital sinus (Correct answer)
- Intermediate mesoderm
Correct answer: Endoderm of the urogenital sinus
The epithelium (transitional epithelium/urothelium) of the urinary bladder is derived from the endoderm of the urogenital sinus.
Question 7: Injury to the superior gluteal nerve results in which clinical finding?
- Inability to extend the hip
- Trendelenburg gait due to weak gluteus medius (Correct answer)
- Loss of sensation over the lateral thigh
- Inability to adduct the thigh
Correct answer: Trendelenburg gait due to weak gluteus medius
The superior gluteal nerve innervates gluteus medius, gluteus minimus, and tensor fasciae latae; its injury causes a Trendelenburg gait because the stance-side hip drops when the opposite foot is lifted.
NBME Gross Anatomy and Embryology 3
A newborn is found to have a single umbilical artery.
This anomaly is most associated with which type of defect?