ATI RN
Questions for Muscular System Questions
Question 1 of 5
Which part of the sarcomere in a contracted muscle decreases in size (or may disappear completely)?
Correct Answer: B
Rationale: In a sarcomere, the functional unit of skeletal muscle, contraction occurs via the sliding filament theory, where actin (thin) and myosin (thick) filaments slide past each other. During this process, the H zone the central region of the A band with only thick filaments shortens or vanishes as thin filaments overlap it. Similarly, the I band, containing only thin filaments on either side of the Z line, narrows as actin slides toward the sarcomere's center. The A band, spanning the thick filaments' full length, remains constant because myosin doesn't shorten, while Z lines, anchoring actin, move closer together but don't disappear. This dynamic reflects muscle shortening without altering filament lengths, driven by ATP-powered cross-bridge cycling. Electron microscopy and physiological studies confirm that contraction compresses these zones, distinguishing them from static structures like the A band. Misinterpreting these changes could confuse the sarcomere's architecture, but the consistent reduction of H zones and I bands aligns with observed muscle mechanics, critical for understanding force generation.
Question 2 of 5
The nurse uses a visual aid to show the pathologic muscle tone changes that result in footdrop. Those changes are:
Correct Answer: B
Rationale: Footdrop occurs when the ankle dorsiflexors, responsible for lifting the foot, weaken or become overstretched, often due to immobility or nerve damage. This allows the plantar flexors (calf muscles) to dominate, pulling the foot downward. The flexor muscles, including dorsiflexors like the tibialis anterior, stretch and lose tone, leading to the characteristic drooping posture. Calf muscles stretching would imply the opposite, raising the foot, which doesn't fit footdrop. Toes curling downward suggests a different condition, like claw toes, not the flaccid drop of this issue. Thigh muscle contraction is unrelated, as footdrop stems from lower leg dynamics. The visual aid highlights this imbalance, showing how flexor overstretching results in the inability to lift the foot, a key feature of the condition.
Question 3 of 5
When preparing a patient for electromyography (EMG), the nurse will instruct the patient to:
Correct Answer: B
Rationale: EMG assesses muscle and nerve function by recording electrical activity, requiring clear signals. Caffeine, a stimulant, can increase muscle tension or jitteriness, potentially skewing results, so avoiding it for 3 hours prior is standard. Smoking cessation for 12 hours isn't typically required, as its effect on EMG is less direct. Muscle relaxants would dampen activity, defeating the test's purpose of measuring natural responses. While EMG can take time, 2 hours isn't standard for all cases, and preparation focuses more on accuracy than duration. Refraining from caffeine ensures the test reflects true neuromuscular status, making it the key instruction for reliable outcomes.
Question 4 of 5
The nurse explains that the major advantage of the external fixation device is that the patient:
Correct Answer: C
Rationale: External fixation stabilizes fractures with pins and a frame outside the skin, allowing precise alignment. Its major advantage is greater freedom of movement, as the limb isn't encased like in a cast, permitting easier access for wound care and some mobility, depending on the injury. Healing speed depends on the fracture, not the device alone. Weight-bearing varies by case and isn't immediate. Pain levels aren't inherently lower than other methods. Movement freedom stands out, enhancing patient comfort and care flexibility, distinguishing external fixation from more restrictive options like casts or traction.
Question 5 of 5
While the nurse is giving morning care to a patient who sustained a fractured pelvis and bilateral fractures of the femur in a motorcycle accident yesterday, the patient complains of shortness of breath and is audibly wheezing. An assessment of the oxygen saturation reveals 76%. The initial intervention by the nurse should be to:
Correct Answer: C
Rationale: Sudden shortness of breath, wheezing, and 76% oxygen saturation post-fracture suggest a fat embolism, a life-threatening complication from long bone trauma. Administering oxygen at 4-5 L/min via nasal cannula is the initial step to boost oxygenation, stabilizing the patient while further help is sought. Alerting the code team is premature without first aiding breathing. Informing the charge nurse follows oxygen delivery, as does raising to high Fowler's to ease breathing but oxygen comes first. This rapid response addresses hypoxia directly, critical in trauma where respiratory decline can escalate fast, buying time for diagnosis and treatment.