ATI RN
Muscular System Questions Questions
Question 1 of 5
What is the primary function of the sternum?
Correct Answer: B
Rationale: The sternum connects ribs via costal cartilage, supporting the thoracic cavity and protecting heart/lungs. Spinal cord is vertebral, breathing is secondary (diaphragm-driven), skull support is cranial. Sternum's thoracic role, per anatomy, makes 'b' correct.
Question 2 of 5
After you eat lunch, nerve cells in your stomach respond to the distension (the stimulus) resulting from the food. They relay this information to
Correct Answer: A
Rationale: Nerve cells (sensors) detect stomach distension and relay it to a control center (e.g., brainstem) in a feedback loop to process and respond (e.g., digestion adjustment). A set point is a target value, not a receiver. Effectors act (e.g., muscles), not receive. Sensors detect, not receive relayed data. Control center's role, per homeostasis, makes 'a' correct.
Question 3 of 5
What are two major disadvantages of MRI scans?
Correct Answer: B
Rationale: MRI disadvantages include high cost (expensive machines) and need for shielding from strong magnetic fields, protecting nearby devices/patients. It doesn't release radiation (a, d), images are high-quality (not a), views all tissues (not c), and confinement is a minor issue. Cost and shielding, per imaging tech, make 'b' correct.
Question 4 of 5
Which choice below indicates the proper order in decreasing size?
Correct Answer: A
Rationale: Muscle structure follows a hierarchy from largest to smallest: the whole muscle (e.g., biceps), encased by epimysium, contains fascicles bundles of fibers wrapped in perimysium. Each fascicle holds muscle fibers, single elongated cells in endomysium, visible under light microscopy. Within fibers, myofibrils, rod-like organelles, house sarcomeres, the contractile units. This sequence muscle (centimeters), fascicle (millimeters), fiber (micrometers), myofibril (nanometers) reflects anatomical nesting. Reversing fascicle and fiber misaligns bundles with cells, while placing myofibrils before fibers ignores their intracellular role. A whole muscle, spanning bone to bone, dwarfs fascicles (10-100 fibers), which outsize fibers (10-100 micrometers wide), containing hundreds of myofibrils. Dissection and electron microscopy confirm this descending scale, critical for understanding force transmission from sarcomeres to gross movement, distinguishing organizational levels in muscle physiology.
Question 5 of 5
The nurse explains that, if muscles are not regularly stretched and contracted, the muscles will become:
Correct Answer: C
Rationale: Muscles require regular movement to maintain their length and elasticity. Without stretching and contraction, they adapt to a shortened position due to immobility, losing their ability to elongate fully over time. This results in reduced elasticity, making them prone to stiffness and contractures. Longer and flexed muscles would imply active stretching, which doesn't occur without intervention. Fibrosis and spasticity suggest scarring or neurological overactivity, more common in specific conditions like cerebral palsy, not general immobility. Shorter and painful could occur, but pain isn't a universal outcome of disuse shortening and loss of elasticity are the primary physiological changes. This explanation underscores the need for exercise to preserve muscle function, aligning with the natural response of tissues to prolonged inactivity.