USMLE ANATOMY EXAM WITH CORRECT ANSWERS AND RATIONALES
2026/2027 VERSION/ INSTANT PDF
1. A patient sustains a fracture of the surgical neck of the humerus. Which
nerve is most likely injured?
A. Radial nerve
B. Axillary nerve
C. Median nerve
D. Ulnar nerve
Correct Answer: B. Axillary nerve
Rationale: The axillary nerve winds around the surgical neck of the humerus and
supplies the deltoid and teres minor muscles.
2. A patient has difficulty abducting the arm from 15° to 90° after a shoulder
injury. Which muscle is primarily affected?
A. Supraspinatus
B. Deltoid
C. Teres major
D. Pectoralis major
Correct Answer: B. Deltoid
Rationale: The deltoid is the primary muscle responsible for arm abduction from
approximately 15° to 90°.
3. The first 15° of arm abduction is primarily initiated by which muscle?
A. Deltoid
B. Supraspinatus
C. Infraspinatus
D. Subscapularis
Correct Answer: B. Supraspinatus
Rationale: The supraspinatus initiates abduction before the deltoid becomes the
primary abductor.
4. A patient has a winged scapula after axillary surgery. Which nerve was
most likely injured?
,A. Dorsal scapular nerve
B. Long thoracic nerve
C. Suprascapular nerve
D. Thoracodorsal nerve
Correct Answer: B. Long thoracic nerve
Rationale: Injury to the long thoracic nerve causes paralysis of the serratus
anterior and medial winging of the scapula.
5. Which nerve innervates the serratus anterior muscle?
A. Axillary nerve
B. Long thoracic nerve
C. Thoracodorsal nerve
D. Spinal accessory nerve
Correct Answer: B. Long thoracic nerve
Rationale: The long thoracic nerve arises from C5–C7 and supplies the serratus
anterior.
6. A patient cannot extend the wrist after a midshaft humeral fracture. Which
nerve is most likely injured?
A. Radial nerve
B. Median nerve
C. Ulnar nerve
D. Musculocutaneous nerve
Correct Answer: A. Radial nerve
Rationale: The radial nerve travels in the radial groove along the shaft of the
humerus and supplies the extensor muscles.
7. Injury to the medial epicondyle of the humerus most commonly damages
which nerve?
A. Median nerve
B. Radial nerve
C. Ulnar nerve
D. Axillary nerve
, Correct Answer: C. Ulnar nerve
Rationale: The ulnar nerve passes posterior to the medial epicondyle.
8. A patient has weakness of elbow flexion and decreased sensation over the
lateral forearm. Which nerve is affected?
A. Musculocutaneous nerve
B. Radial nerve
C. Median nerve
D. Ulnar nerve
Correct Answer: A. Musculocutaneous nerve
Rationale: The musculocutaneous nerve supplies the anterior arm muscles and
continues as the lateral cutaneous nerve of the forearm.
9. Which muscle is the strongest flexor of the elbow regardless of forearm
position?
A. Biceps brachii
B. Brachialis
C. Triceps brachii
D. Pronator teres
Correct Answer: B. Brachialis
Rationale: The brachialis is the primary flexor of the elbow.
10. A patient has difficulty pronating the forearm. Which muscle is primarily
responsible for this movement?
A. Supinator
B. Pronator teres
C. Biceps brachii
D. Brachioradialis
Correct Answer: B. Pronator teres
Rationale: The pronator teres is a major pronator of the forearm.
11. Carpal tunnel syndrome results from compression of which nerve?
A. Ulnar nerve
B. Radial nerve
2026/2027 VERSION/ INSTANT PDF
1. A patient sustains a fracture of the surgical neck of the humerus. Which
nerve is most likely injured?
A. Radial nerve
B. Axillary nerve
C. Median nerve
D. Ulnar nerve
Correct Answer: B. Axillary nerve
Rationale: The axillary nerve winds around the surgical neck of the humerus and
supplies the deltoid and teres minor muscles.
2. A patient has difficulty abducting the arm from 15° to 90° after a shoulder
injury. Which muscle is primarily affected?
A. Supraspinatus
B. Deltoid
C. Teres major
D. Pectoralis major
Correct Answer: B. Deltoid
Rationale: The deltoid is the primary muscle responsible for arm abduction from
approximately 15° to 90°.
3. The first 15° of arm abduction is primarily initiated by which muscle?
A. Deltoid
B. Supraspinatus
C. Infraspinatus
D. Subscapularis
Correct Answer: B. Supraspinatus
Rationale: The supraspinatus initiates abduction before the deltoid becomes the
primary abductor.
4. A patient has a winged scapula after axillary surgery. Which nerve was
most likely injured?
,A. Dorsal scapular nerve
B. Long thoracic nerve
C. Suprascapular nerve
D. Thoracodorsal nerve
Correct Answer: B. Long thoracic nerve
Rationale: Injury to the long thoracic nerve causes paralysis of the serratus
anterior and medial winging of the scapula.
5. Which nerve innervates the serratus anterior muscle?
A. Axillary nerve
B. Long thoracic nerve
C. Thoracodorsal nerve
D. Spinal accessory nerve
Correct Answer: B. Long thoracic nerve
Rationale: The long thoracic nerve arises from C5–C7 and supplies the serratus
anterior.
6. A patient cannot extend the wrist after a midshaft humeral fracture. Which
nerve is most likely injured?
A. Radial nerve
B. Median nerve
C. Ulnar nerve
D. Musculocutaneous nerve
Correct Answer: A. Radial nerve
Rationale: The radial nerve travels in the radial groove along the shaft of the
humerus and supplies the extensor muscles.
7. Injury to the medial epicondyle of the humerus most commonly damages
which nerve?
A. Median nerve
B. Radial nerve
C. Ulnar nerve
D. Axillary nerve
, Correct Answer: C. Ulnar nerve
Rationale: The ulnar nerve passes posterior to the medial epicondyle.
8. A patient has weakness of elbow flexion and decreased sensation over the
lateral forearm. Which nerve is affected?
A. Musculocutaneous nerve
B. Radial nerve
C. Median nerve
D. Ulnar nerve
Correct Answer: A. Musculocutaneous nerve
Rationale: The musculocutaneous nerve supplies the anterior arm muscles and
continues as the lateral cutaneous nerve of the forearm.
9. Which muscle is the strongest flexor of the elbow regardless of forearm
position?
A. Biceps brachii
B. Brachialis
C. Triceps brachii
D. Pronator teres
Correct Answer: B. Brachialis
Rationale: The brachialis is the primary flexor of the elbow.
10. A patient has difficulty pronating the forearm. Which muscle is primarily
responsible for this movement?
A. Supinator
B. Pronator teres
C. Biceps brachii
D. Brachioradialis
Correct Answer: B. Pronator teres
Rationale: The pronator teres is a major pronator of the forearm.
11. Carpal tunnel syndrome results from compression of which nerve?
A. Ulnar nerve
B. Radial nerve
