ATI RN
Multiple Choice Questions Muscular System Questions
Question 1 of 5
What is the protein of thick myofilaments in a skeletal muscle cell?
Correct Answer: B
Rationale: Thick myofilaments in sarcomeres are composed of myosin, a motor protein with heads forming cross-bridges to actin during contraction. Actin forms thin myofilaments with tropomyosin and troponin, while acetylcholine is a neurotransmitter, not a filament component. Myosin's bundled structure, comprising about 300 molecules per filament, drives the sliding filament mechanism, distinguishing it as the thick filament's core protein, critical for muscle force generation and movement.
Question 2 of 5
What is the source of the ATP used by muscles for vigorous activity that may last for 10 to 15 seconds?
Correct Answer: D
Rationale: For 10-15 seconds of vigorous activity, creatine phosphate rapidly phosphorylates ADP to ATP, sustaining high-intensity effort beyond stored ATP (seconds). Glycolysis (minutes) and aerobic respiration (long-term) are slower. This quick energy buffer distinguishes creatine phosphate's role, vital for short bursts like sprinting.
Question 3 of 5
Which of the following statements is correct about what happens during flexion?
Correct Answer: B
Rationale: Flexion decreases the angle between bones, as when bending the elbow (humerus and radius/ulna angle shrinks), a fundamental joint movement in kinesiology. Increasing the angle describes extension, not flexion. Moving away from the body aligns with abduction, not flexion, which typically occurs in a sagittal plane. Moving toward the body's center might suggest adduction, but flexion is about angle reduction, not midline proximity (e.g., knee flexion doesn't necessarily approach the midline). The angle decrease precisely defines flexion's action, making it correct.
Question 4 of 5
Where is the inferior oblique muscle located?
Correct Answer: B
Rationale: The inferior oblique, one of six extraocular muscles, is in the eye socket (orbit), originating near the nasal bone and inserting on the eyeball's posterior, elevating and abducting the eye. The abdomen has obliques (external/internal) for trunk movement, not eyes. The anterior neck includes muscles like SCM, not ocular. The face has expression muscles, not eye movers. Its orbital location, controlling gaze, distinguishes it, making 'b' correct.
Question 5 of 5
The large muscle group that attaches the leg to the pelvic girdle and produces extension of the hip joint is the group.
Correct Answer: A
Rationale: The gluteal group (gluteus maximus, medius, minimus) attaches the femur to the pelvic girdle, with gluteus maximus primarily extending the hip (e.g., standing from sitting). Obturator muscles rotate the thigh, not extend. Adductors pull the leg inward. Abductors move it outward (e.g., gluteus medius), not extend. Gluteals' size and hip extension role, per lower limb mechanics, make 'a' the correct group.