ATI RN
Multiple Choice Questions on Muscular System Questions
Question 1 of 5
The attachment of a muscle s tendon to the stationary bone is called the
Correct Answer: A
Rationale: The origin is the tendon's attachment to a stationary bone, providing a fixed point for muscle contraction, like the scapula for the biceps brachii. The insertion attaches to the movable bone (e.g., radius), belly is the muscle's fleshy part, and aponeurosis is a broad tendon sheet. Origin is the correct answer, as it defines the stable anchor in muscle anatomy, essential for understanding how contraction produces motion by pulling the insertion toward it.
Question 2 of 5
This is a major energy source in a hurdle race to the leg muscles
Correct Answer: D
Rationale: In a hurdle race, a high-intensity, endurance-based activity lasting over a minute, leg muscles primarily rely on oxidative metabolism for energy. This process uses oxygen to break down glucose, fats, and proteins in mitochondria, producing ATP efficiently via the aerobic pathway, sustaining prolonged effort. Glycolysis provides quick ATP anaerobically but fatigues muscles due to lactate buildup, insufficient for a race's duration. Lactate and pyruvate are intermediates, not primary sources. Preformed ATP is limited, depleting in seconds. Oxidative metabolism dominates in events requiring sustained power, like hurdling, where oxygen delivery supports muscle contraction over time, distinguishing it from short-burst energy systems and aligning with the aerobic demands of such races.
Question 3 of 5
The thin filaments of a sarcomere are made up of
Correct Answer: D
Rationale: Thin filaments in a sarcomere consist of actin, troponin, and tropomyosin, forming a complex that interacts with myosin for contraction. Actin provides the structural backbone, tropomyosin covers binding sites in rest, and troponin binds calcium to shift tropomyosin, exposing sites for myosin. Only actin oversimplifies, ignoring regulatory proteins. Only myosin misplaces it myosin forms thick filaments. Actin and myosin together suggest a mix, but they're separate filaments. The trio of actin, troponin, and tropomyosin defines thin filaments, enabling controlled contraction, distinct from incomplete or incorrect combinations, critical for the sliding filament theory and muscle movement precision.
Question 4 of 5
The latent period, the contraction period, and the relaxation period are the three stages of a:
Correct Answer: A
Rationale: A muscle twitch, a single contraction-relaxation cycle from one stimulus, has three phases: latent (signal delay to contraction start), contraction (cross-bridge activity shortens muscle), and relaxation (calcium removal, filament separation). A myogram records this, not the event itself. Summation is multiple twitches overlapping, not a single cycle. A motor unit is a neuron and fibers, not a phase sequence. The twitch's distinct stages define its mechanics, distinguishing it from recordings, cumulative effects, or anatomical units, fundamental to muscle response analysis.
Question 5 of 5
Identify a muscle that promotes smiling.
Correct Answer: D
Rationale: Zygomaticus (major and minor) lifts the mouth's corners upward and laterally, forming a smile. Buccinator compresses cheeks, not smiling. Frontalis raises the brow, unrelated to lips. Orbicularis oris purses lips, as in kissing, not smiling. Zygomaticus' specific pull on the mouth defines smiling, distinct from cheek, brow, or lip-closing actions, central to happy expressions.