ATI RN
Muscular System Test Questions Questions
Question 1 of 5
Which disease results in muscle weakness due to a lack of neurotransmitter receptors?
Correct Answer: C
Rationale: Myasthenia gravis causes muscle weakness by reducing acetylcholine receptors at the neuromuscular junction. Autoantibodies attack these receptors, impairing signal transmission from motor neurons to skeletal muscle, leading to fatigue, especially in facial and limb muscles. Muscle dystrophy involves progressive fiber degeneration, not receptor loss. Intermittent claudication stems from vascular insufficiency, weakening muscles via oxygen deprivation, not neurotransmission. Tetanus, from bacterial toxin, causes rigid contractions, not weakness, by overstimulating neurons. Fibromyositis (likely fibromyalgia) involves pain and stiffness, not receptor deficits. In myasthenia gravis, the postsynaptic membrane's receptor scarcity confirmed by immunological and electromyographic studies disrupts voluntary movement, often relieved by acetylcholinesterase inhibitors boosting acetylcholine. This autoimmune mechanism contrasts with structural or infectious muscle disorders, highlighting a specific synaptic failure. Clinical data show receptor density dropping 70-90% in affected junctions, underscoring its unique pathophysiology among neuromuscular diseases.
Question 2 of 5
The nurse is assessing the patient s cane for appropriate length. The nurse affirms that the appropriate cane has been selected when the:
Correct Answer: A
Rationale: A properly fitted cane supports posture and balance, with the hand grip ideally at hip level (greater trochanter height). This allows a natural 20-30 degree elbow bend when leaning on it, optimizing weight distribution and comfort. An elbow flexed at 45 degrees would be excessive, straining the arm. The cane tip touching outside the good foot relates to positioning during use, not length assessment. Removing the rubber tip during measurement is impractical and unsafe, as it's part of the cane's function. Hip-level grip ensures the cane aligns with the body's center of gravity, reducing fatigue and enhancing stability during ambulation, making it the standard for fitting.
Question 3 of 5
The nurse is assessing the patient s crutches. The nurse recognizes that correctly sized crutches are:
Correct Answer: C
Rationale: Crutches must fit to support posture and arm movement, typically measured as 16-18 inches below the patient's height or 2-3 finger-widths below the axilla when standing. This allows a 20-30 degree elbow bend for comfort and leverage. Shoulder height would be too tall, risking nerve damage under the arms. Twelve inches below shoulders is imprecise and often too short. Fully extended arms would overstretch, reducing control. The height-based measure ensures the crutches align with the torso and arms, providing stability and preventing strain, making it the standard for correct sizing across diverse body types.
Question 4 of 5
The patient with mild discomfort from carpal tunnel syndrome delightedly reports amazing relief from taking a daily dose of vitamin:
Correct Answer: B
Rationale: Mild carpal tunnel syndrome can benefit from vitamin B6 (pyridoxine), which supports nerve health and may reduce inflammation or nerve sensitivity, offering relief for some patients. Studies suggest it helps in early stages, though evidence varies. Vitamin A aids vision and skin, not nerves directly. B12 supports nerve repair in deficiencies but isn't standard for carpal tunnel. Vitamin C boosts collagen but doesn't target nerve compression symptoms. B6's reported efficacy in this case aligns with its use as a conservative treatment, explaining the patient's relief without implying it's a universal cure.
Question 5 of 5
A muscle that has an action opposite that of the prime mover (agonist) and yields to the movement of the prime mover.
Correct Answer: C
Rationale: An antagonist is a muscle that opposes the action of the prime mover (agonist) and relaxes or yields to allow the intended movement to occur. For instance, when the biceps brachii (agonist) flexes the elbow, the triceps brachii (antagonist) extends it, working in opposition. This relationship ensures smooth, controlled motion and prevents overstretching. Compartment refers to a group of muscles, not an individual muscle's action. Anal triangle is a pelvic region, unrelated to muscle function in this context. Synergists assist the prime mover, not oppose it. The antagonist's role in opposing and yielding to the prime mover is a fundamental concept in muscle dynamics, making it the correct answer here, as it directly contrasts with the agonist's action while facilitating coordinated movement.