Behind Knee Compared To Prepatellarbursitis Which Is

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First Aid USMLE Step 1: MSK Questions with Detailed

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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

tibia due to MCL injury

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

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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

Ans: Supraspinatous (innervated by suprascapular nerve) assessed by

empty/full can test

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

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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

Name the carpal bones

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)

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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

Ans: Deltoid (arm abduction)

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

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Ans: Musculocutaneous nerve injury

What branches of brachial plexus compose musculocutaneous nerve?

Ans: C5–C7

What branches of brachial plexus compose radial nerve?

Ans: C5–T1

What nerve can midshaft fracture of humerus or compression of axilla

injure?

Ans: Radial nerve injury

Wrist drop (loss of elbow, wrist, and finger extension), decreased grip

strength (no wrist extension, so no maximal strength of flexors), and loss of

sensation over posterior arm/forearm and dorsal hand

Ans: Radial nerve injury

Saturday night palsy is due to injury of what nerve

Ans: Radial

Supracondylar fracture of humerus (proximal), carpal tunnel syndrome and

wrist laceraction injure what nerve

Ans: Median (C5-T1)

What branches of brachial plexus make up median nerve?

Ans: C5–T1

Pope’s blessing/Ape’s hand, loss of wrist flexion, flexion of lateral fingers,

thumb opposition, lumbricals of 2nd and 3rd digits; loss of sensation over

thenar eminence and dorsal and palmar aspects of lateral 3.5 fingers; tinel

sign (tingling on percussion) in carpal tunnel syndrome

Ans: Median nerve injury