ATI RN
Muscular System Multiple Choice Questions Questions
Question 1 of 5
Thick myofilaments are composed of
Correct Answer: A
Rationale: Thick myofilaments in sarcomeres are primarily myosin, a motor protein with a tail forming the filament backbone and heads projecting outward for actin binding. This structure, assembled from hundreds of myosin molecules, drives contraction via ATP-powered cross-bridge cycling. Thin filaments, conversely, comprise actin (a globular protein polymerized into strands), troponin (calcium-binding regulator), and tropomyosin (actin-covering modulator), not thick filaments. Combining myosin with troponin and tropomyosin lacks biochemical basis, as these regulate thin filaments. Actin alone forms thin filaments, not thick ones, and pairing myosin with actin misrepresents filament distinction. Myosin's unique tail-head configuration, detailed in structural biology, enables its role in force generation, distinct from thin filaments' regulatory proteins. Electron microscopy and X-ray diffraction reveal thick filaments as myosin aggregates, with heads engaging actin during contraction. This composition underpins muscle mechanics, ensuring thick filaments' contractile power, a fundamental concept in physiology distinguishing filament types.
Question 2 of 5
The nurse encourages the patient to use the four-point crutch gait technique. This technique is most likely indicated because it:
Correct Answer: B
Rationale: The four-point crutch gait involves alternating crutch and leg movements (right crutch, left leg, left crutch, right leg), providing maximum stability due to three points of support on the ground at all times. This is ideal for patients needing balance and safety, such as those with weakness or partial weight-bearing restrictions. Non-weight bearing typically uses a swing-through gait, not four-point. Mimicking normal walking is closer to a two-point gait, which is less stable. Rapid pace aligns with swing gaits, not the deliberate four-point method. Stability is the key advantage here, making it suitable for patients recovering from lower limb injuries or neurological conditions, ensuring safe mobility over speed or normalcy.
Question 3 of 5
A patient is learning to use crutches on the stairs. When evaluating this patient, which action indicates that the patient needs further instruction?
Correct Answer: B
Rationale: When ascending stairs with crutches, the correct technique is to lead with the good leg, using it to bear weight and lift the body, followed by the crutches and affected leg together. Placing the affected leg first risks instability and injury, as it can't support the climb reliably, indicating a need for reteaching. Leading with the good leg is proper, as is placing crutches on the next step with the affected leg in some methods. The swing-through method applies more to flat surfaces, not stairs, but isn't the focus here. The error in leading with the affected leg shows misunderstanding of weight-bearing sequence, critical for safety and efficiency on stairs.
Question 4 of 5
The nurse explains that carpal tunnel syndrome is caused when the carpal tunnel compresses the:
Correct Answer: C
Rationale: Carpal tunnel syndrome results from compression within the wrist's carpal tunnel, a narrow passage housing tendons and the median nerve. This nerve, when squeezed by swelling or repetitive strain, causes numbness, tingling, and pain in the thumb and fingers. The radial artery supplies the hand but isn't in the tunnel. The brachial artery is in the upper arm, unrelated to wrist issues. The ulnar nerve runs outside the tunnel, affecting different fingers when compressed. The median nerve's location and symptoms align with the condition's hallmark, making it the clear cause, distinct from vascular or other nerve involvement.
Question 5 of 5
In oblique passageway in the anterior abdominal wall just superior and parallel to the medial half of the inguinal ligament that transmits the spermatic cord and ilioinguinal nerve in the male and round ligament of the uterus and ilioinguinal nerve in the female.
Correct Answer: A
Rationale: The inguinal canal is an anatomical structure in the anterior abdominal wall, running obliquely just above and parallel to the medial half of the inguinal ligament. In males, it transmits the spermatic cord (containing the vas deferens, blood vessels, and nerves) and the ilioinguinal nerve, while in females, it carries the round ligament of the uterus and the same nerve. This canal is clinically significant due to its association with inguinal hernias. Insertion refers to the movable attachment point of a muscle, not a passageway. Deep is a positional term, not a structure. Origin is the stationary attachment of a muscle, also unrelated to this definition. The inguinal canal's specific location and contents match the description perfectly, making it the correct answer, as it is a well-defined feature in abdominal anatomy distinct from muscle attachment points.