1 Exampromax - Stuvia US 2025/2026
First Aid USMLE Step 1: MSK Questions with Detailed
Verified Answers (100% Correct Answers) /Already
Graded A+
Anterior drawer sign
Ans: Movement of tibia anterior relative to femur due to ACL injury
Posterior drawer sign
Ans: Movement of tibia posterior relative to femur due to PCL injury
Abnormal passive abduction
Ans: Movement of knee laterally (valgus) causes medial space widening of
Exampromax - Stuvia US
tibia due to MCL injury
Approved By:
Abnormal passive adduction
Ans: Movement of knee medially (varus) causes lateral space widening of
tibia (LCL injury)
McMurray Test
Ans: Knee externally rotated with pain/popping: medial meniscal tear
Knee internally rotated with pain/popping: lateral meniscal tear
Unhappy triad
Ans: ACL, MCL, and medial meniscus injuries (although lateral meniscus
injury is more common)
Prepatellar bursitis
Ans: Caused from repeated trauma or kneeling, otherwise known as
"housemaid's knee" (in front of knee, compared to Baker's cyst, which is
behind the knee)
Baker Cyst
, 2 Exampromax - Stuvia US 2025/2026
Ans: Popliteal fluid collection commonly related to chronic joint disease
(behind knee, compared to prepatellar bursitis, which is in front of knee)
Name the rotator cuff muscles and nerves that innervate them
Ans: Supraspinatus (suprascapular nerve), infraspinatus (suprascapular
nerve), terres minor (axillary nerve), subscapularis (upper and lower
subscapular nerves)
What branches of brachial plexus innervate rotator cuff muscles
(supraspinatous, infraspinatous, terres minor, subscapularis)
Ans: C5-C6
Most common rotator cuff injury? How is it assessed
Exampromax - Stuvia US
Ans: Supraspinatous (innervated by suprascapular nerve) assessed by
empty/full can test
Approved By:
Action of supraspinatous (rotator cuff innervated by suprascapular nerve)
Ans: Abducts arm (before deltoid action)
Action of infraspinatous (rotator cuff innervated by suprascapular nerve)
Ans: Laterally rotates the arm
Rotator cuff injury commonly hurt while pitching
Ans: Infraspinatous (suprascapular nerve)
Action of terres minor (rotator cuff innervated by axillary nerve)
Ans: Adducts and laterally rotates arm
Action of subscapularis (rotator cuff innervated by upper and lower
subscapular nerve)
Ans: Adducts and medially rotates arm
Golfer's elbow
, 3 Exampromax - Stuvia US 2025/2026
Ans: Medial epicondylitis due to repetitive flexion or idiopathic; pain near
medial epicondyle
Pain near medial epicondyle
Ans: Medial epicondylitis
Pain near lateral epicondyle
Ans: Lateral epicondylitis- tennis elbow due to repetitive extension
Tennis elbow
Ans: Lateral epicondylitis due to repetitive extension or idiopathic; pain
near lateral epicondyle
Exampromax - Stuvia US
Name the carpal bones
Approved By:
Ans: Scaphoid, lunate, triquetrium, pisiform, hamate, capitate, trapezoid,
triapezium
Characteristics of scaphoid carpal bone (3)
Ans: Palpate in anatomic snuffbox
Most frequently fractured carpal bone
Prone to AVN due to retrograde blood supply
Dislocation of what carpal bone can cause acute carpal tunnel syndrome
Ans: lunate
FOOSH can damage which carpal bone and cause what nerve injury
Ans: Can damage hamate and cause ulnar nerve injury
What nerve is affected in carpal tunnel syndrome?
Ans: Median (entrapped in carpal tunnel)
, 4 Exampromax - Stuvia US 2025/2026
Pain, paresthesia, numbness in distribution of median nerve often
associated with RF, pregnancy, hypothyroidism, and may be associated
with repetitive use
Ans: Carpal tunnel syndrome
Injury classically seen in cyclists
Ans: Guyon canal syndrome, which is compression of ulnar nerve at wrist
or hand
What nerve is affected in Guyon canal syndrome
Ans: Ulnar
Two muscles axillary nerve innervates
Exampromax - Stuvia US
Ans: Deltoid (arm abduction)
Approved By:
Terres minor (arm adduction; lateral rotation)
Fracture or anterior dislocation of humerus can injury what nerve
Ans: Axillary
Flattened deltoid, loss of arm abduction at shoulder (over 15 degrees), and
loss of sensation over deltoid muscle and lateral arm
Ans: Axillary
What branches of brachial plexus make up axillary nerve?
Ans: C5-C6
Upper trunk compression injures what nerve?
Ans: Musculocutaneous (C5-C7)
Loss of forearm flexion and supination; loss of sensation over lateral
forearm
First Aid USMLE Step 1: MSK Questions with Detailed
Verified Answers (100% Correct Answers) /Already
Graded A+
Anterior drawer sign
Ans: Movement of tibia anterior relative to femur due to ACL injury
Posterior drawer sign
Ans: Movement of tibia posterior relative to femur due to PCL injury
Abnormal passive abduction
Ans: Movement of knee laterally (valgus) causes medial space widening of
Exampromax - Stuvia US
tibia due to MCL injury
Approved By:
Abnormal passive adduction
Ans: Movement of knee medially (varus) causes lateral space widening of
tibia (LCL injury)
McMurray Test
Ans: Knee externally rotated with pain/popping: medial meniscal tear
Knee internally rotated with pain/popping: lateral meniscal tear
Unhappy triad
Ans: ACL, MCL, and medial meniscus injuries (although lateral meniscus
injury is more common)
Prepatellar bursitis
Ans: Caused from repeated trauma or kneeling, otherwise known as
"housemaid's knee" (in front of knee, compared to Baker's cyst, which is
behind the knee)
Baker Cyst
, 2 Exampromax - Stuvia US 2025/2026
Ans: Popliteal fluid collection commonly related to chronic joint disease
(behind knee, compared to prepatellar bursitis, which is in front of knee)
Name the rotator cuff muscles and nerves that innervate them
Ans: Supraspinatus (suprascapular nerve), infraspinatus (suprascapular
nerve), terres minor (axillary nerve), subscapularis (upper and lower
subscapular nerves)
What branches of brachial plexus innervate rotator cuff muscles
(supraspinatous, infraspinatous, terres minor, subscapularis)
Ans: C5-C6
Most common rotator cuff injury? How is it assessed
Exampromax - Stuvia US
Ans: Supraspinatous (innervated by suprascapular nerve) assessed by
empty/full can test
Approved By:
Action of supraspinatous (rotator cuff innervated by suprascapular nerve)
Ans: Abducts arm (before deltoid action)
Action of infraspinatous (rotator cuff innervated by suprascapular nerve)
Ans: Laterally rotates the arm
Rotator cuff injury commonly hurt while pitching
Ans: Infraspinatous (suprascapular nerve)
Action of terres minor (rotator cuff innervated by axillary nerve)
Ans: Adducts and laterally rotates arm
Action of subscapularis (rotator cuff innervated by upper and lower
subscapular nerve)
Ans: Adducts and medially rotates arm
Golfer's elbow
, 3 Exampromax - Stuvia US 2025/2026
Ans: Medial epicondylitis due to repetitive flexion or idiopathic; pain near
medial epicondyle
Pain near medial epicondyle
Ans: Medial epicondylitis
Pain near lateral epicondyle
Ans: Lateral epicondylitis- tennis elbow due to repetitive extension
Tennis elbow
Ans: Lateral epicondylitis due to repetitive extension or idiopathic; pain
near lateral epicondyle
Exampromax - Stuvia US
Name the carpal bones
Approved By:
Ans: Scaphoid, lunate, triquetrium, pisiform, hamate, capitate, trapezoid,
triapezium
Characteristics of scaphoid carpal bone (3)
Ans: Palpate in anatomic snuffbox
Most frequently fractured carpal bone
Prone to AVN due to retrograde blood supply
Dislocation of what carpal bone can cause acute carpal tunnel syndrome
Ans: lunate
FOOSH can damage which carpal bone and cause what nerve injury
Ans: Can damage hamate and cause ulnar nerve injury
What nerve is affected in carpal tunnel syndrome?
Ans: Median (entrapped in carpal tunnel)
, 4 Exampromax - Stuvia US 2025/2026
Pain, paresthesia, numbness in distribution of median nerve often
associated with RF, pregnancy, hypothyroidism, and may be associated
with repetitive use
Ans: Carpal tunnel syndrome
Injury classically seen in cyclists
Ans: Guyon canal syndrome, which is compression of ulnar nerve at wrist
or hand
What nerve is affected in Guyon canal syndrome
Ans: Ulnar
Two muscles axillary nerve innervates
Exampromax - Stuvia US
Ans: Deltoid (arm abduction)
Approved By:
Terres minor (arm adduction; lateral rotation)
Fracture or anterior dislocation of humerus can injury what nerve
Ans: Axillary
Flattened deltoid, loss of arm abduction at shoulder (over 15 degrees), and
loss of sensation over deltoid muscle and lateral arm
Ans: Axillary
What branches of brachial plexus make up axillary nerve?
Ans: C5-C6
Upper trunk compression injures what nerve?
Ans: Musculocutaneous (C5-C7)
Loss of forearm flexion and supination; loss of sensation over lateral
forearm
