COMSAE 107 EXAM STUDY GUIDE 2026 –
COMPLETE CONCEPT REVIEW &
PRACTICE MATERIALS (LATEST EDITION)
Anatomy & Embryology (15 Questions)
1. A 65-year-old man presents with progressive hoarseness and difficulty swallowing. Imaging
reveals a tumor at the lung apex eroding through the costal pleura. Which nerve is most likely
being compressed by this tumor?
A. Vagus nerve (CN X)
B. Phrenic nerve
C. Long thoracic nerve
D. Recurrent laryngeal nerve
E. Spinal accessory nerve (CN XI)
Answer: D. Recurrent laryngeal nerve. A Pancoast tumor at the lung apex can invade the
sympathetic chain (causing Horner's syndrome) and the recurrent laryngeal nerve (causing
hoarseness due to vocal cord paralysis). The left recurrent laryngeal nerve hooks under the
aortic arch and ascends in the tracheoesophageal groove, making it vulnerable here.
2. During a splenectomy, the surgeon must carefully ligate the splenic artery to prevent
hemorrhage. This artery is a branch of which of the following?
A. Celiac trunk
B. Superior mesenteric artery
C. Abdominal aorta
D. Common hepatic artery
E. Left gastric artery
Answer: A. Celiac trunk. The celiac trunk trifurcates into the left gastric, splenic, and common
hepatic arteries.
3. A patient suffers an anterior shoulder dislocation. Which structure is most at risk for injury
in this scenario?
A. Suprascapular nerve
B. Axillary nerve
C. Radial nerve
,D. Musculocutaneous nerve
E. Axillary artery
Answer: B. Axillary nerve. The axillary nerve and its associated posterior circumflex humeral
artery are tightly tethered against the surgical neck of the humerus and are the most commonly
injured structures in an anterior shoulder dislocation. This can lead to deltoid paralysis and loss
of sensation over the regimental badge area.
4. The "watershed area" of the colon, located at the splenic flexure, is a border zone between
the territories of which two arteries?
A. Superior mesenteric artery and Inferior mesenteric artery
B. Celiac trunk and Superior mesenteric artery
C. Middle colic artery and Left colic artery
D. Ileocolic artery and Sigmoid arteries
E. Right colic artery and Marginal artery
Answer: A. Superior mesenteric artery and Inferior mesenteric artery. The splenic flexure is
where the superior mesenteric artery (via the middle colic artery) and the inferior mesenteric
artery (via the left colic artery) anastomose. This area is vulnerable to ischemia in low-flow
states.
5. A newborn is diagnosed with Tracheoesophageal Fistula (TEF). The most common anatomic
variant of TEF is:
A. Proximal esophageal atresia with distal TEF
B. H-type fistula without atresia
C. Proximal and distal blind-ending esophageal pouches
D. Proximal TEF with distal atresia
E. Esophageal atresia without fistula
Answer: A. Proximal esophageal atresia with distal TEF. This is the most common type (~85%). It
presents with polyhydramnios in utero, and in the newborn, it manifests as
coughing/choking/cyanosis with feeds, and abdominal distension.
6. The cremasteric muscle, responsible for the cremasteric reflex, is derived from which layer?
A. External oblique
B. Internal oblique
C. Transversus abdominis
D. Transversalis fascia
E. Scarpa's fascia
,Answer: B. Internal oblique. The cremasteric muscle and fascia are formed from the lowermost
fibers of the internal oblique muscle. It is innervated by the genital branch of the genitofemoral
nerve (L1, L2).
7. A fracture of the medial malleolus would most likely affect the stability provided by which
ligament?
A. Anterior talofibular ligament
B. Deltoid ligament
C. Calcaneofibular ligament
D. Spring ligament
E. Anterior tibiofibular ligament
Answer: B. Deltoid ligament. The medial malleolus is the proximal attachment point for the
deltoid ligament, the primary medial stabilizer of the ankle. A fracture here suggests a failure of
the medial restraint, often part of a more complex ankle injury.
8. During development, the ligamentum arteriosum is the remnant of which fetal structure?
A. Foramen ovale
B. Ductus venosus
C. Umbilical vein
D. Ductus arteriosus
E. Umbilical artery
Answer: D. Ductus arteriosus. The ligamentum arteriosum is the fibrous remnant of the fetal
ductus arteriosus, which shunted blood from the pulmonary artery to the aorta, bypassing the
non-functional fetal lungs.
9. A patient presents with weakness in wrist extension, leading to "wrist drop." This is
characteristic of an injury to which structure?
A. Median nerve
B. Ulnar nerve
C. Radial nerve
D. Musculocutaneous nerve
E. Axillary nerve
Answer: C. Radial nerve. The radial nerve innervates the extensor muscles of the forearm and
hand. Injury in the radial groove of the humerus (e.g., from a mid-shaft humeral fracture) causes
wrist drop.
10. Which venous structure passes directly behind the portal hepatis in the liver?
A. Hepatic artery
B. Common bile duct
, C. Inferior vena cava
D. Portal vein
E. Cystic duct
Answer: D. Portal vein. The portal triad at the portal hepatis consists of the Hepatic Artery
(proper), Common Bile Duct, and Portal Vein, in the order A, D, V (from anterior to posterior).
11. The parasympathetic innervation for the entire foregut and midgut is provided by which
cranial nerve?
A. Facial nerve (CN VII)
B. Glossopharyngeal nerve (CN IX)
C. Vagus nerve (CN X)
D. Hypoglossal nerve (CN XII)
E. Trigeminal nerve (CN V)
Answer: C. Vagus nerve (CN X). The vagus nerve provides parasympathetic input to the foregut
and midgut (up to the proximal two-thirds of the transverse colon). The hindgut receives
parasympathetic input from the pelvic splanchnic nerves (S2-S4).
12. A patient with a pituitary macroadenoma undergoes transsphenoidal surgery. Post-
operatively, they report polyuria and intense thirst. Damage to which structure is the most
likely cause?
A. Anterior pituitary
B. Posterior pituitary
C. Pituitary stalk
D. Hypothalamus
E. Optic chiasm
Answer: B. Posterior pituitary. The posterior pituitary (neurohypophysis) stores and releases
ADH (vasopressin). Damage during surgery can cause Diabetes Insipidus due to a lack of ADH,
leading to an inability to concentrate urine.
13. Which of the following muscles is innervated by the deep branch of the ulnar nerve?
A. Abductor pollicis brevis
B. Opponens pollicis
C. Lumbricals 1 and 2
D. Adductor pollicis
E. Flexor pollicis longus
Answer: D. Adductor pollicis. The "ulnar paradox" involves the deep branch of the ulnar nerve,
which innervates most of the intrinsic hand muscles, including the interossei, the 3rd and 4th
lumbricals, and the adductor pollicis.
COMPLETE CONCEPT REVIEW &
PRACTICE MATERIALS (LATEST EDITION)
Anatomy & Embryology (15 Questions)
1. A 65-year-old man presents with progressive hoarseness and difficulty swallowing. Imaging
reveals a tumor at the lung apex eroding through the costal pleura. Which nerve is most likely
being compressed by this tumor?
A. Vagus nerve (CN X)
B. Phrenic nerve
C. Long thoracic nerve
D. Recurrent laryngeal nerve
E. Spinal accessory nerve (CN XI)
Answer: D. Recurrent laryngeal nerve. A Pancoast tumor at the lung apex can invade the
sympathetic chain (causing Horner's syndrome) and the recurrent laryngeal nerve (causing
hoarseness due to vocal cord paralysis). The left recurrent laryngeal nerve hooks under the
aortic arch and ascends in the tracheoesophageal groove, making it vulnerable here.
2. During a splenectomy, the surgeon must carefully ligate the splenic artery to prevent
hemorrhage. This artery is a branch of which of the following?
A. Celiac trunk
B. Superior mesenteric artery
C. Abdominal aorta
D. Common hepatic artery
E. Left gastric artery
Answer: A. Celiac trunk. The celiac trunk trifurcates into the left gastric, splenic, and common
hepatic arteries.
3. A patient suffers an anterior shoulder dislocation. Which structure is most at risk for injury
in this scenario?
A. Suprascapular nerve
B. Axillary nerve
C. Radial nerve
,D. Musculocutaneous nerve
E. Axillary artery
Answer: B. Axillary nerve. The axillary nerve and its associated posterior circumflex humeral
artery are tightly tethered against the surgical neck of the humerus and are the most commonly
injured structures in an anterior shoulder dislocation. This can lead to deltoid paralysis and loss
of sensation over the regimental badge area.
4. The "watershed area" of the colon, located at the splenic flexure, is a border zone between
the territories of which two arteries?
A. Superior mesenteric artery and Inferior mesenteric artery
B. Celiac trunk and Superior mesenteric artery
C. Middle colic artery and Left colic artery
D. Ileocolic artery and Sigmoid arteries
E. Right colic artery and Marginal artery
Answer: A. Superior mesenteric artery and Inferior mesenteric artery. The splenic flexure is
where the superior mesenteric artery (via the middle colic artery) and the inferior mesenteric
artery (via the left colic artery) anastomose. This area is vulnerable to ischemia in low-flow
states.
5. A newborn is diagnosed with Tracheoesophageal Fistula (TEF). The most common anatomic
variant of TEF is:
A. Proximal esophageal atresia with distal TEF
B. H-type fistula without atresia
C. Proximal and distal blind-ending esophageal pouches
D. Proximal TEF with distal atresia
E. Esophageal atresia without fistula
Answer: A. Proximal esophageal atresia with distal TEF. This is the most common type (~85%). It
presents with polyhydramnios in utero, and in the newborn, it manifests as
coughing/choking/cyanosis with feeds, and abdominal distension.
6. The cremasteric muscle, responsible for the cremasteric reflex, is derived from which layer?
A. External oblique
B. Internal oblique
C. Transversus abdominis
D. Transversalis fascia
E. Scarpa's fascia
,Answer: B. Internal oblique. The cremasteric muscle and fascia are formed from the lowermost
fibers of the internal oblique muscle. It is innervated by the genital branch of the genitofemoral
nerve (L1, L2).
7. A fracture of the medial malleolus would most likely affect the stability provided by which
ligament?
A. Anterior talofibular ligament
B. Deltoid ligament
C. Calcaneofibular ligament
D. Spring ligament
E. Anterior tibiofibular ligament
Answer: B. Deltoid ligament. The medial malleolus is the proximal attachment point for the
deltoid ligament, the primary medial stabilizer of the ankle. A fracture here suggests a failure of
the medial restraint, often part of a more complex ankle injury.
8. During development, the ligamentum arteriosum is the remnant of which fetal structure?
A. Foramen ovale
B. Ductus venosus
C. Umbilical vein
D. Ductus arteriosus
E. Umbilical artery
Answer: D. Ductus arteriosus. The ligamentum arteriosum is the fibrous remnant of the fetal
ductus arteriosus, which shunted blood from the pulmonary artery to the aorta, bypassing the
non-functional fetal lungs.
9. A patient presents with weakness in wrist extension, leading to "wrist drop." This is
characteristic of an injury to which structure?
A. Median nerve
B. Ulnar nerve
C. Radial nerve
D. Musculocutaneous nerve
E. Axillary nerve
Answer: C. Radial nerve. The radial nerve innervates the extensor muscles of the forearm and
hand. Injury in the radial groove of the humerus (e.g., from a mid-shaft humeral fracture) causes
wrist drop.
10. Which venous structure passes directly behind the portal hepatis in the liver?
A. Hepatic artery
B. Common bile duct
, C. Inferior vena cava
D. Portal vein
E. Cystic duct
Answer: D. Portal vein. The portal triad at the portal hepatis consists of the Hepatic Artery
(proper), Common Bile Duct, and Portal Vein, in the order A, D, V (from anterior to posterior).
11. The parasympathetic innervation for the entire foregut and midgut is provided by which
cranial nerve?
A. Facial nerve (CN VII)
B. Glossopharyngeal nerve (CN IX)
C. Vagus nerve (CN X)
D. Hypoglossal nerve (CN XII)
E. Trigeminal nerve (CN V)
Answer: C. Vagus nerve (CN X). The vagus nerve provides parasympathetic input to the foregut
and midgut (up to the proximal two-thirds of the transverse colon). The hindgut receives
parasympathetic input from the pelvic splanchnic nerves (S2-S4).
12. A patient with a pituitary macroadenoma undergoes transsphenoidal surgery. Post-
operatively, they report polyuria and intense thirst. Damage to which structure is the most
likely cause?
A. Anterior pituitary
B. Posterior pituitary
C. Pituitary stalk
D. Hypothalamus
E. Optic chiasm
Answer: B. Posterior pituitary. The posterior pituitary (neurohypophysis) stores and releases
ADH (vasopressin). Damage during surgery can cause Diabetes Insipidus due to a lack of ADH,
leading to an inability to concentrate urine.
13. Which of the following muscles is innervated by the deep branch of the ulnar nerve?
A. Abductor pollicis brevis
B. Opponens pollicis
C. Lumbricals 1 and 2
D. Adductor pollicis
E. Flexor pollicis longus
Answer: D. Adductor pollicis. The "ulnar paradox" involves the deep branch of the ulnar nerve,
which innervates most of the intrinsic hand muscles, including the interossei, the 3rd and 4th
lumbricals, and the adductor pollicis.
