USMLE STEP 1-MSK |ACTUAL QUESTIONS AND
VERIFIED ANSWERS|BRAND NEW 2026-2027
UPDATE|GRADED A+
Question 1
Old lady with severe right hip pain after a fall.
Current meds - low dose prenisone.
40 pack year history of smoking.
Injury to what artery is most likely to lead to osteonecrosis?
CORRECT ANSWER
*Medial circumflex femoral*
Medial circumflex supplies blood to the head of the femur.
*CAST Bent LEGS*
Question 2
What are the causes of avascular necrosis of the femoral head?
CORRECT ANSWER
CAST Bent LEGS
Corticosteroids
Alcoholism
Sickle cell disease
Trauma
1
,the Bends
LEggs-Calves-Perthes (childhood disorder of blood flow to the hip)
Gaucher's Disease (cerebroside metabolism)
Slipped Femoral Capital Epiphysis
Question 3
Fractures of the surgical neck of the humerus damage what nerve?
CORRECT ANSWER
axillary
Question 4
Fractures of the midshaft of the humerus damage what nerve and potentially what artery?
Name one other fracture that could potentially damage this nerve?
CORRECT ANSWER
Radial, deep brachial
Anterolateral displacement of a supracondylar ridge humerus fracture could also damage
radial
Question 5
1st line treatment for osteoporosis is?
CORRECT ANSWER
Bisphosphonates
2
,(-dronates; Risedronate)
Question 6
What is a classic difference in the presentation of Myasthenia Gravis and Lambert-Eaton
myasthenic syndrome?
CORRECT ANSWER
MG - strength *decreases* with repetition
- autoantibodies to the ACh post-synaptic receptor, so more repetition = less and less ACh
available to be released from the synapse --> weakness
LEMS - strength *increases* with repetition
- autoantibodies to the pre-synaptic Ca++ channel, (less release of ACh). More repetition
leads to increased calcium in the pre-neuron --> more release of ACh --> strength
Question 7
Patient is being treated for a Pseudomonas infection and complains of weakness and
vision deficits that occur later in the day. What is occuring?
CORRECT ANSWER
Pt is being tx with Aminoglycosides
SE of Aminoglycosides - neuromuscular blockade (+ nephrotoxicity, + ototoxicity, +
teratogenicity)
Question 8
Two main "classes" of muscle relaxers are what?
3
, Which would be used for outpatient tx? for surgery?
CORRECT ANSWER
1. centrally acting - outpatient
2. peripherally acting - surgery
Question 9
What are the two main peripherally acting muscle relaxers and how do their MOAs differ?
CORRECT ANSWER
Succinylcholine
"Curiums" and "Curonium"
Succinyl - DEPOLARIZING (binds to receptor, causes prolonged depolarization and eventually
relaxation)
Curiums - NON-DEPOLARIZING (competitive antagonist of ACh receptors)
Question 10
What do/are the A-band, I-band, H-zone, and Z-line contain/made of?
CORRECT ANSWER
A-band = full length of myosin aka thick filament (dark on EM)
I-band = only actin aka thin filaments and structural elements (light on EM)
Z-line = structural support proteins aka the anchoring point for actin filaments
4
VERIFIED ANSWERS|BRAND NEW 2026-2027
UPDATE|GRADED A+
Question 1
Old lady with severe right hip pain after a fall.
Current meds - low dose prenisone.
40 pack year history of smoking.
Injury to what artery is most likely to lead to osteonecrosis?
CORRECT ANSWER
*Medial circumflex femoral*
Medial circumflex supplies blood to the head of the femur.
*CAST Bent LEGS*
Question 2
What are the causes of avascular necrosis of the femoral head?
CORRECT ANSWER
CAST Bent LEGS
Corticosteroids
Alcoholism
Sickle cell disease
Trauma
1
,the Bends
LEggs-Calves-Perthes (childhood disorder of blood flow to the hip)
Gaucher's Disease (cerebroside metabolism)
Slipped Femoral Capital Epiphysis
Question 3
Fractures of the surgical neck of the humerus damage what nerve?
CORRECT ANSWER
axillary
Question 4
Fractures of the midshaft of the humerus damage what nerve and potentially what artery?
Name one other fracture that could potentially damage this nerve?
CORRECT ANSWER
Radial, deep brachial
Anterolateral displacement of a supracondylar ridge humerus fracture could also damage
radial
Question 5
1st line treatment for osteoporosis is?
CORRECT ANSWER
Bisphosphonates
2
,(-dronates; Risedronate)
Question 6
What is a classic difference in the presentation of Myasthenia Gravis and Lambert-Eaton
myasthenic syndrome?
CORRECT ANSWER
MG - strength *decreases* with repetition
- autoantibodies to the ACh post-synaptic receptor, so more repetition = less and less ACh
available to be released from the synapse --> weakness
LEMS - strength *increases* with repetition
- autoantibodies to the pre-synaptic Ca++ channel, (less release of ACh). More repetition
leads to increased calcium in the pre-neuron --> more release of ACh --> strength
Question 7
Patient is being treated for a Pseudomonas infection and complains of weakness and
vision deficits that occur later in the day. What is occuring?
CORRECT ANSWER
Pt is being tx with Aminoglycosides
SE of Aminoglycosides - neuromuscular blockade (+ nephrotoxicity, + ototoxicity, +
teratogenicity)
Question 8
Two main "classes" of muscle relaxers are what?
3
, Which would be used for outpatient tx? for surgery?
CORRECT ANSWER
1. centrally acting - outpatient
2. peripherally acting - surgery
Question 9
What are the two main peripherally acting muscle relaxers and how do their MOAs differ?
CORRECT ANSWER
Succinylcholine
"Curiums" and "Curonium"
Succinyl - DEPOLARIZING (binds to receptor, causes prolonged depolarization and eventually
relaxation)
Curiums - NON-DEPOLARIZING (competitive antagonist of ACh receptors)
Question 10
What do/are the A-band, I-band, H-zone, and Z-line contain/made of?
CORRECT ANSWER
A-band = full length of myosin aka thick filament (dark on EM)
I-band = only actin aka thin filaments and structural elements (light on EM)
Z-line = structural support proteins aka the anchoring point for actin filaments
4
