ATI RN
Muscular System Exam Questions Questions
Question 1 of 5
Calcium is stored and released in skeletal muscle by the
Correct Answer: B
Rationale: The sarcoplasmic reticulum (SR), a specialized endoplasmic reticulum in skeletal muscle, stores and releases calcium to trigger contraction. Surrounding myofibrils, it sequesters calcium via calsequestrin, maintaining low cytosolic levels (10^-7 M) at rest. Upon T-tubule-transmitted action potentials, SR terminal cisternae release calcium (rising to 10^-5 M) through ryanodine receptors, binding troponin to initiate actin-myosin interaction. The sarcolemma conducts the initial depolarization, not storage. T-tubules relay signals inward but lack storage capacity. Caveoli (likely a typo for caveolae) are membrane invaginations, irrelevant here. Myofilaments use calcium but don't store it. The SR's role, detailed in muscle physiology, is critical: its ATPase pumps reuptake calcium post-contraction, relaxing the fiber. Electron microscopy reveals its extensive network, ensuring rapid, uniform calcium spread, distinguishing it from signal-conducting or contractile structures in excitation-contraction coupling.
Question 2 of 5
The nurse is caring for a patient who has had an arthrocentesis. The nurse has completed discharge instructions. Which statement by the patient indicates the need for further instruction?
Correct Answer: A
Rationale: Arthrocentesis, removing fluid from a joint, aims to relieve pressure and improve mobility. Saying the knee mustn't move for 1-2 weeks suggests misunderstanding, as gentle movement is typically encouraged soon after to prevent stiffness, with rest limited to a day or two unless specified otherwise. Steroids reducing inflammation is accurate, as they're often injected post-procedure. Expecting some pain aligns with recovery, as does wearing a bandage for 2-3 days for support. The prolonged immobility statement requires correction, as it contradicts the goal of restoring function, risking complications like adhesions further teaching ensures the patient balances rest and activity correctly.
Question 3 of 5
The patient, who is a legal secretary, asks the nurse how she can avoid developing carpal tunnel syndrome. The nurse suggests:
Correct Answer: C
Rationale: Carpal tunnel syndrome arises from median nerve compression in the wrist, often from repetitive typing without support. A wrist pad maintains a neutral position, reducing strain on the tunnel during prolonged work, a proactive ergonomic fix. Repetitive flexion exercises could worsen pressure on the nerve, increasing risk. Elastic bandages might restrict movement but don't address posture and could impair circulation. Warm compresses soothe but don't prevent the underlying mechanical stress. The pad targets the root cause poor wrist alignment making it the most effective suggestion for a secretary's daily typing demands.
Question 4 of 5
A muscle that stabilizes the origin of the prime mover so that the prime mover can act more efficiently.
Correct Answer: C
Rationale: Fixators are muscles that stabilize the origin of a prime mover, allowing it to move more effectively by preventing unwanted movement at the point of attachment. This stabilization ensures that the force generated by the prime mover is directed toward the intended action, such as lifting or rotating a limb. For example, in shoulder abduction, fixator muscles stabilize the scapula so the deltoid can efficiently lift the arm. Superficial describes muscle location, not function. Synergists assist the prime mover by reducing unnecessary movement or enhancing its action, but they do not specifically stabilize the origin. Aponeurosis is a structural term for a tendon-like sheet, not a muscle type or function. The role of stabilizing the origin is a distinct characteristic of fixators, making it the correct choice here, as it directly supports the prime mover's efficiency in movement.
Question 5 of 5
The region of the pelvic floor that contains the anus.
Correct Answer: A
Rationale: The anal triangle is the posterior region of the pelvic floor, containing the anus and bounded by the coccyx and ischial tuberosities. It's distinct from the anterior urogenital triangle and is key in understanding perineal anatomy, especially in procedures like episiotomies. Fixators are muscles, not regions. Origin and insertion are muscle attachment points, not pelvic areas. The anal triangle precisely fits the description, making it the correct answer, as it identifies the specific anatomical zone housing the anus, critical for both structural and clinical contexts in the pelvic floor.