COMSAE PHASE 1 GROSS ANATOMY
PRACTICE EXAM WITH ACTUAL
QUESTIONS AND VERIFIED ANSWERS,
PLUS EXPLAINED RATIONALES/EXPERT
VERIFIED FOR GUARANTEED 100% PASS
2026/LATEST UPDATE/INSTANT
DOWNLOAD PDF
Questions
1. A 24-year-old man sustains a penetrating injury to the posterior
triangle of the neck. Examination reveals that he can shrug his right
shoulder only weakly and has difficulty abducting the arm above the
horizontal plane. Sensation is intact. Which nerve is most likely injured?
A. Dorsal scapular nerve
B. Long thoracic nerve
C. Spinal accessory nerve
D. Suprascapular nerve
E. Axillary nerve
Answer: C. Spinal accessory nerve
Rationale: The spinal accessory nerve (CN XI) traverses the posterior
triangle superficially and innervates the trapezius and
sternocleidomastoid muscles. Injury produces shoulder drooping,
weak shoulder elevation, and difficulty with upward rotation of the
scapula. The long thoracic nerve causes winging of the scapula
through serratus anterior paralysis, whereas the suprascapular nerve
affects supraspinatus and infraspinatus.
1
,2. A patient develops a winged scapula after surgical removal of axillary
lymph nodes. When asked to push against a wall, the medial border of
the scapula protrudes posteriorly. Which muscle is dysfunctional?
A. Rhomboid major
B. Serratus anterior
C. Trapezius
D. Levator scapulae
E. Pectoralis minor
Answer: B. Serratus anterior
Rationale: Serratus anterior is innervated by the long thoracic nerve,
which runs along the lateral thoracic wall and is vulnerable during
axillary surgery. Paralysis prevents effective protraction and upward
rotation of the scapula and produces medial winging, particularly
during wall-pushing.
3. A 36-year-old woman has difficulty initiating abduction of her arm
from the side. Once the arm is abducted approximately 15°, she can
continue the movement normally. Which muscle is primarily responsible
for the impaired initial movement?
A. Deltoid
B. Teres major
C. Supraspinatus
D. Infraspinatus
E. Subscapularis
Answer: C. Supraspinatus
Rationale: Supraspinatus initiates the first approximately 15° of
shoulder abduction. The deltoid becomes the major abductor after this
initial range. Suprascapular nerve injury or supraspinatus tendon
pathology can therefore impair initiation of abduction.
2
,4. A fracture of the surgical neck of the humerus causes weakness in
shoulder abduction and numbness over the lateral aspect of the shoulder.
Which nerve is injured?
A. Radial nerve
B. Musculocutaneous nerve
C. Median nerve
D. Axillary nerve
E. Ulnar nerve
Answer: D. Axillary nerve
Rationale: The axillary nerve winds around the surgical neck of the
humerus with the posterior circumflex humeral artery. It supplies the
deltoid and teres minor and provides cutaneous sensation over the
superior lateral arm. Injury therefore causes impaired abduction and
sensory loss over the deltoid region.
5. A patient sustains a midshaft humeral fracture and subsequently
develops wrist drop. Which nerve is most likely injured?
A. Median nerve
B. Ulnar nerve
C. Radial nerve
D. Axillary nerve
E. Musculocutaneous nerve
Answer: C. Radial nerve
Rationale: The radial nerve travels in the radial groove on the
posterior humerus and is particularly vulnerable to midshaft humeral
fractures. It innervates the major wrist and finger extensors. Injury
produces weakness of extension at the wrist and fingers, resulting in
wrist drop.
3
, 6. A patient presents with inability to flex the distal interphalangeal
joints of the index and middle fingers. He also has difficulty pronating
the forearm. Which nerve lesion best explains these findings?
A. Ulnar nerve
B. Anterior interosseous nerve
C. Radial nerve
D. Posterior interosseous nerve
E. Musculocutaneous nerve
Answer: B. Anterior interosseous nerve
Rationale: The anterior interosseous nerve is a motor branch of the
median nerve. It innervates flexor pollicis longus, pronator quadratus,
and the radial half of flexor digitorum profundus. Dysfunction causes
impaired distal flexion of the thumb and index finger and weak
pronation.
7. A patient develops numbness involving the little finger and medial
half of the ring finger after striking the medial epicondyle of the
humerus. Which nerve was most likely affected?
A. Median nerve
B. Radial nerve
C. Axillary nerve
D. Ulnar nerve
E. Musculocutaneous nerve
Answer: D. Ulnar nerve
Rationale: The ulnar nerve passes posterior to the medial epicondyle
in the cubital tunnel, making it vulnerable to direct trauma. It supplies
sensation to the little finger and medial half of the ring finger and
innervates many intrinsic hand muscles.
4
PRACTICE EXAM WITH ACTUAL
QUESTIONS AND VERIFIED ANSWERS,
PLUS EXPLAINED RATIONALES/EXPERT
VERIFIED FOR GUARANTEED 100% PASS
2026/LATEST UPDATE/INSTANT
DOWNLOAD PDF
Questions
1. A 24-year-old man sustains a penetrating injury to the posterior
triangle of the neck. Examination reveals that he can shrug his right
shoulder only weakly and has difficulty abducting the arm above the
horizontal plane. Sensation is intact. Which nerve is most likely injured?
A. Dorsal scapular nerve
B. Long thoracic nerve
C. Spinal accessory nerve
D. Suprascapular nerve
E. Axillary nerve
Answer: C. Spinal accessory nerve
Rationale: The spinal accessory nerve (CN XI) traverses the posterior
triangle superficially and innervates the trapezius and
sternocleidomastoid muscles. Injury produces shoulder drooping,
weak shoulder elevation, and difficulty with upward rotation of the
scapula. The long thoracic nerve causes winging of the scapula
through serratus anterior paralysis, whereas the suprascapular nerve
affects supraspinatus and infraspinatus.
1
,2. A patient develops a winged scapula after surgical removal of axillary
lymph nodes. When asked to push against a wall, the medial border of
the scapula protrudes posteriorly. Which muscle is dysfunctional?
A. Rhomboid major
B. Serratus anterior
C. Trapezius
D. Levator scapulae
E. Pectoralis minor
Answer: B. Serratus anterior
Rationale: Serratus anterior is innervated by the long thoracic nerve,
which runs along the lateral thoracic wall and is vulnerable during
axillary surgery. Paralysis prevents effective protraction and upward
rotation of the scapula and produces medial winging, particularly
during wall-pushing.
3. A 36-year-old woman has difficulty initiating abduction of her arm
from the side. Once the arm is abducted approximately 15°, she can
continue the movement normally. Which muscle is primarily responsible
for the impaired initial movement?
A. Deltoid
B. Teres major
C. Supraspinatus
D. Infraspinatus
E. Subscapularis
Answer: C. Supraspinatus
Rationale: Supraspinatus initiates the first approximately 15° of
shoulder abduction. The deltoid becomes the major abductor after this
initial range. Suprascapular nerve injury or supraspinatus tendon
pathology can therefore impair initiation of abduction.
2
,4. A fracture of the surgical neck of the humerus causes weakness in
shoulder abduction and numbness over the lateral aspect of the shoulder.
Which nerve is injured?
A. Radial nerve
B. Musculocutaneous nerve
C. Median nerve
D. Axillary nerve
E. Ulnar nerve
Answer: D. Axillary nerve
Rationale: The axillary nerve winds around the surgical neck of the
humerus with the posterior circumflex humeral artery. It supplies the
deltoid and teres minor and provides cutaneous sensation over the
superior lateral arm. Injury therefore causes impaired abduction and
sensory loss over the deltoid region.
5. A patient sustains a midshaft humeral fracture and subsequently
develops wrist drop. Which nerve is most likely injured?
A. Median nerve
B. Ulnar nerve
C. Radial nerve
D. Axillary nerve
E. Musculocutaneous nerve
Answer: C. Radial nerve
Rationale: The radial nerve travels in the radial groove on the
posterior humerus and is particularly vulnerable to midshaft humeral
fractures. It innervates the major wrist and finger extensors. Injury
produces weakness of extension at the wrist and fingers, resulting in
wrist drop.
3
, 6. A patient presents with inability to flex the distal interphalangeal
joints of the index and middle fingers. He also has difficulty pronating
the forearm. Which nerve lesion best explains these findings?
A. Ulnar nerve
B. Anterior interosseous nerve
C. Radial nerve
D. Posterior interosseous nerve
E. Musculocutaneous nerve
Answer: B. Anterior interosseous nerve
Rationale: The anterior interosseous nerve is a motor branch of the
median nerve. It innervates flexor pollicis longus, pronator quadratus,
and the radial half of flexor digitorum profundus. Dysfunction causes
impaired distal flexion of the thumb and index finger and weak
pronation.
7. A patient develops numbness involving the little finger and medial
half of the ring finger after striking the medial epicondyle of the
humerus. Which nerve was most likely affected?
A. Median nerve
B. Radial nerve
C. Axillary nerve
D. Ulnar nerve
E. Musculocutaneous nerve
Answer: D. Ulnar nerve
Rationale: The ulnar nerve passes posterior to the medial epicondyle
in the cubital tunnel, making it vulnerable to direct trauma. It supplies
sensation to the little finger and medial half of the ring finger and
innervates many intrinsic hand muscles.
4
