ATI RN
Muscular System Exam Questions Questions
Question 1 of 5
Which of the following best describes the biceps brachii?
Correct Answer: C
Rationale: The biceps brachii has two origins (long and short heads) on the scapula and is located in the upper arm, inserting on the radius to flex the elbow. It's not in the forearm (that's brachioradialis), nor deep to the brachialis (it's superficial). It doesn't have two insertions or reside in the leg. Two origins and upper arm location define the biceps brachii, making it the correct answer, reflecting its anatomical structure and function as a prominent arm flexor.
Question 2 of 5
Elastic bundles of tissue which perform various functions is termed as
Correct Answer: D
Rationale: Muscles are elastic tissue bundles with diverse roles movement, posture, heat production stretching and contracting to function. Skeletal muscles move bones, smooth muscles regulate organs, and cardiac muscles pump blood, showcasing versatility. Tendons, though fibrous, primarily transmit force, not perform varied tasks themselves. Ligaments stabilize joints, limiting motion, not acting broadly. Joints are bone junctions, not tissues. Muscles' elasticity and multifunctional nature contracting for strength, relaxing for flexibility define them, distinguishing their dynamic, active contributions from tendons' and ligaments' supportive, static roles or joints' structural purpose, making them the clear fit for this description.
Question 3 of 5
This event occurs during muscular contraction L. H-zone disappears I. A band widens I. I band shortens IV. Width of $A$ band is unaffected V. $M$ line and $Z$ line get closer
Correct Answer: B
Rationale: During muscular contraction, the sliding filament theory explains sarcomere changes: actin filaments slide over myosin, shortening the sarcomere. The H-zone (myosin-only region) disappears as actin overlaps it. The I band (actin-only) shortens as Z lines approach each other. The A band (myosin length) remains constant, unaffected by sliding. The M line and Z lines get closer due to overall shortening. The A band widening doesn't occur, as its width is fixed by myosin filament length. The correct combination includes the H-zone vanishing, I band shortening, A band staying unchanged, and Z lines nearing the M line, reflecting the mechanics of contraction where filament overlap drives muscle shortening without altering myosin's span, a key principle in muscle physiology.
Question 4 of 5
The dark region of a sarcomere is called the
Correct Answer: C
Rationale: The A band, the dark region of a sarcomere, spans the thick myosin filaments, appearing dark under a microscope due to overlapping actin and myosin in most areas. It remains constant in length during contraction, reflecting myosin's extent. The H-zone, within the A band, is lighter, showing only myosin, narrowing as actin slides in. The Z-line anchors actin, defining sarcomere boundaries, not dark. The I band, light, contains only actin, shortening during contraction. The A band's darkness and myosin content distinguish it, central to sarcomere structure, unlike the lighter, shifting H-zone, structural Z-line, or actin-only I band, key to understanding muscle striation.
Question 5 of 5
In a muscle twitch, the time period from stimulation until the start of the contraction is the period.
Correct Answer: D
Rationale: The latent period in a muscle twitch spans from stimulus to contraction onset, covering action potential travel, T-tubule signaling, and calcium release about 2 milliseconds. Contraction is the active shortening phase, post-latent. Relaxation follows, as muscle returns to rest. Fatigue is a state, not a twitch phase. The latent period's pre-contraction delay is unique, ensuring calcium reaches troponin before movement, distinct from active or recovery phases, critical for timing muscle activation in physiological studies.