Gross Anatomy & Embryology Advanced
Practice Examination (2026–2027 Edition)
|Preparation | Challenging Multiple-Choice
Questions | Detailed Answer Rationales
Question 1
A 24-year-old man sustains a penetrating injury to the posterior
triangle of the neck. On examination, he has difficulty shrugging
his right shoulder and cannot easily abduct his arm above the
horizontal plane. Sensation is intact. Injury to which nerve most
directly explains these findings?
A. Dorsal scapular nerve
B. Long thoracic nerve
C. Spinal accessory nerve
D. Suprascapular nerve
Correct Answer: C. Spinal accessory nerve
Rationale: The spinal accessory nerve (CN XI) supplies the
trapezius and sternocleidomastoid muscles. Injury in the
posterior triangle can paralyze the trapezius, causing shoulder
,droop and impaired scapular upward rotation, which
compromises abduction above 90°. The dorsal scapular nerve
supplies rhomboids, the long thoracic nerve supplies serratus
anterior, and the suprascapular nerve supplies supraspinatus
and infraspinatus.
Question 2
A newborn presents with severe respiratory distress
immediately after delivery. Imaging reveals loops of bowel
occupying the left thoracic cavity and displacement of the
mediastinum toward the right. Which embryologic defect most
likely caused this condition?
A. Failure of the pleuropericardial membranes to fuse
B. Failure of the pleuroperitoneal membranes to close
C. Failure of the septum transversum to form
D. Persistence of the vitelline duct
Correct Answer: B. Failure of the pleuroperitoneal membranes
to close
Rationale: Congenital diaphragmatic hernia, classically a
posterolateral Bochdalek hernia, results from failure of the
pleuroperitoneal canals to close. Abdominal viscera herniate
into the thorax, causing pulmonary hypoplasia and mediastinal
,shift. The left side is more commonly affected because the liver
provides partial protection on the right.
Question 3
A surgeon performs an appendectomy through a McBurney
incision. During the procedure, the surgeon identifies the
appendix by following the taeniae coli of the ascending colon.
The appendix is found extending posteriorly behind the cecum.
Which position is being described?
A. Pelvic
B. Subcecal
C. Retrocecal
D. Preileal
Correct Answer: C. Retrocecal
Rationale: A retrocecal appendix lies posterior to the cecum and
is a common anatomical position. Because the appendix may be
partially or completely retroperitoneal in this location,
inflammation can irritate the psoas muscle and produce a
positive psoas sign.
Question 4
, A 7-year-old child has recurrent respiratory infections and
imaging demonstrates a congenital absence of the thymus.
Laboratory testing reveals profound T-cell deficiency. Failure of
development of which embryologic structure most directly
explains this condition?
A. First pharyngeal pouch
B. Second pharyngeal pouch
C. Third pharyngeal pouch
D. Fourth pharyngeal pouch
Correct Answer: C. Third pharyngeal pouch
Rationale: The third pharyngeal pouch forms the thymic
epithelium and inferior parathyroid glands. Abnormal
development can occur in DiGeorge syndrome, leading to
thymic hypoplasia or aplasia and impaired T-cell maturation.
The first pouch forms the auditory tube and middle ear cavity,
while the second contributes to the palatine tonsil epithelium.
Question 5
A patient develops sudden ischemia of the lateral cerebral
hemisphere due to thrombosis of a major cerebral artery.
Which cortical region would most likely be affected?
A. Medial frontal and parietal cortex
B. Lateral frontal, parietal, and temporal cortex
Practice Examination (2026–2027 Edition)
|Preparation | Challenging Multiple-Choice
Questions | Detailed Answer Rationales
Question 1
A 24-year-old man sustains a penetrating injury to the posterior
triangle of the neck. On examination, he has difficulty shrugging
his right shoulder and cannot easily abduct his arm above the
horizontal plane. Sensation is intact. Injury to which nerve most
directly explains these findings?
A. Dorsal scapular nerve
B. Long thoracic nerve
C. Spinal accessory nerve
D. Suprascapular nerve
Correct Answer: C. Spinal accessory nerve
Rationale: The spinal accessory nerve (CN XI) supplies the
trapezius and sternocleidomastoid muscles. Injury in the
posterior triangle can paralyze the trapezius, causing shoulder
,droop and impaired scapular upward rotation, which
compromises abduction above 90°. The dorsal scapular nerve
supplies rhomboids, the long thoracic nerve supplies serratus
anterior, and the suprascapular nerve supplies supraspinatus
and infraspinatus.
Question 2
A newborn presents with severe respiratory distress
immediately after delivery. Imaging reveals loops of bowel
occupying the left thoracic cavity and displacement of the
mediastinum toward the right. Which embryologic defect most
likely caused this condition?
A. Failure of the pleuropericardial membranes to fuse
B. Failure of the pleuroperitoneal membranes to close
C. Failure of the septum transversum to form
D. Persistence of the vitelline duct
Correct Answer: B. Failure of the pleuroperitoneal membranes
to close
Rationale: Congenital diaphragmatic hernia, classically a
posterolateral Bochdalek hernia, results from failure of the
pleuroperitoneal canals to close. Abdominal viscera herniate
into the thorax, causing pulmonary hypoplasia and mediastinal
,shift. The left side is more commonly affected because the liver
provides partial protection on the right.
Question 3
A surgeon performs an appendectomy through a McBurney
incision. During the procedure, the surgeon identifies the
appendix by following the taeniae coli of the ascending colon.
The appendix is found extending posteriorly behind the cecum.
Which position is being described?
A. Pelvic
B. Subcecal
C. Retrocecal
D. Preileal
Correct Answer: C. Retrocecal
Rationale: A retrocecal appendix lies posterior to the cecum and
is a common anatomical position. Because the appendix may be
partially or completely retroperitoneal in this location,
inflammation can irritate the psoas muscle and produce a
positive psoas sign.
Question 4
, A 7-year-old child has recurrent respiratory infections and
imaging demonstrates a congenital absence of the thymus.
Laboratory testing reveals profound T-cell deficiency. Failure of
development of which embryologic structure most directly
explains this condition?
A. First pharyngeal pouch
B. Second pharyngeal pouch
C. Third pharyngeal pouch
D. Fourth pharyngeal pouch
Correct Answer: C. Third pharyngeal pouch
Rationale: The third pharyngeal pouch forms the thymic
epithelium and inferior parathyroid glands. Abnormal
development can occur in DiGeorge syndrome, leading to
thymic hypoplasia or aplasia and impaired T-cell maturation.
The first pouch forms the auditory tube and middle ear cavity,
while the second contributes to the palatine tonsil epithelium.
Question 5
A patient develops sudden ischemia of the lateral cerebral
hemisphere due to thrombosis of a major cerebral artery.
Which cortical region would most likely be affected?
A. Medial frontal and parietal cortex
B. Lateral frontal, parietal, and temporal cortex
