Muscular System Practice Questions

50 multiple-choice questions on Muscular system for paramedic and EMT students, from Chapter 8 (Anatomy and Physiology). Read each question, pick your answer, then tap Show answer to check it and read the explanation.

50 practice questions

1. Which muscle type is under voluntary control?

   1. A. Visceral
   2. B. Smooth
   3. C. Cardiac
   4. D. Skeletal
   Show answer

   Answer: D. Skeletal

   Skeletal muscle is striated and voluntary.

2. Which muscle type has automaticity and is found only in the heart?

   1. A. Skeletal
   2. B. Striated voluntary
   3. C. Cardiac
   4. D. Smooth
   Show answer

   Answer: C. Cardiac

   Cardiac muscle can generate its own electrical impulses.

3. After a fall, a patient cannot straighten his elbow, and the triceps attachment to the ulna is torn. Which structure is injured?

   1. A. Ligament
   2. B. Cartilage
   3. C. Bursa
   4. D. Tendon
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   Answer: D. Tendon

   Tendons connect muscle to bone, so a torn triceps attachment is a tendon injury (a strain). Ligaments connect bone to bone, and their injuries are sprains. Cartilage covers joint surfaces, and a bursa is a fluid sac that reduces friction.

4. Which ion released from the sarcoplasmic reticulum triggers muscle contraction?

   1. A. Calcium
   2. B. Chloride
   3. C. Potassium
   4. D. Sodium
   Show answer

   Answer: A. Calcium

   Calcium lets actin and myosin bind so the muscle fiber shortens.

5. Which neurotransmitter is released at the neuromuscular junction?

   1. A. Dopamine
   2. B. Acetylcholine
   3. C. Serotonin
   4. D. Norepinephrine
   Show answer

   Answer: B. Acetylcholine

   Acetylcholine triggers skeletal muscle contraction. Paralytics used in RSI block it.

6. The less movable attachment point of a muscle is called the:

   1. A. Origin
   2. B. Fascia
   3. C. Insertion
   4. D. Belly
   Show answer

   Answer: A. Origin

   The origin stays fixed and the insertion moves.

7. Smooth muscle is found in the:

   1. A. Walls of the heart chambers
   2. B. Biceps and the other limb flexors
   3. C. Diaphragm and intercostal muscles
   4. D. Vessel and GI tract walls
   Show answer

   Answer: D. Vessel and GI tract walls

   Smooth muscle is involuntary and lines hollow organs, vessels, and the airways.

8. Muscle tone is:

   1. A. A state of partial contraction at rest
   2. B. Complete relaxation of fibers at rest
   3. C. The overall size and bulk of the muscle
   4. D. Maximum sustained contraction of fibers
   Show answer

   Answer: A. A state of partial contraction at rest

   Tone keeps posture and readiness. Loss of tone can be a sign of neurologic injury.

9. Which compound gives muscle a rapid backup supply for regenerating ATP?

   1. A. Lactic acid
   2. B. Stored triglyceride
   3. C. Creatine phosphate
   4. D. Muscle glycogen
   Show answer

   Answer: C. Creatine phosphate

   Creatine phosphate regenerates ATP within seconds, before glycolysis and aerobic pathways catch up.

10. A motor unit consists of:

    1. A. One sensory neuron and its receptors
    2. B. One motor neuron and its muscle fibers
    3. C. Two opposing muscles acting on a joint
    4. D. One muscle and the tendon it pulls on
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    Answer: B. One motor neuron and its muscle fibers

    It includes all the muscle fibers that neuron controls. Fine-control muscles, like those of the eye, have small motor units. Large muscles have big ones.

11. The three types of muscle tissue are:

    1. A. Fast-twitch, slow-twitch, and mixed
    2. B. Skeletal, smooth, and cardiac
    3. C. Voluntary, involuntary, mixed
    4. D. Skeletal, cardiac, and elastic
    Show answer

    Answer: B. Skeletal, smooth, and cardiac

    Only skeletal muscle is voluntary. Elastic tissue is a connective tissue fiber, not a muscle type.

12. Skeletal muscle appears striated because of:

    1. A. Dense blood supply between fibers
    2. B. Orderly actin and myosin filaments
    3. C. Fat deposited between the fibers
    4. D. Nerve endings spaced along the fiber
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    Answer: B. Orderly actin and myosin filaments

    The banding pattern reflects sarcomere structure.

13. The functional contractile unit of skeletal muscle is the:

    1. A. Myofibril
    2. B. Sarcolemma
    3. C. Motor unit
    4. D. Sarcomere
    Show answer

    Answer: D. Sarcomere

    Sarcomeres shorten during contraction.

14. The sliding filament theory describes:

    1. A. Impulses sliding along the nerve axon
    2. B. Actin and myosin sliding past each other
    3. C. Muscle fibers sliding along their tendons
    4. D. Bones sliding against each other at joints
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    Answer: B. Actin and myosin sliding past each other

    The sliding shortens each sarcomere and the muscle. Calcium and ATP are both required.

15. ATP is required in muscle contraction for:

    1. A. Conducting the impulse along the sarcolemma
    2. B. The power stroke and cross-bridge release
    3. C. Calcium release from the reticulum only
    4. D. Muscle relaxation only, not the power stroke
    Show answer

    Answer: B. The power stroke and cross-bridge release

    ATP powers the stroke and detaches the cross-bridges. Rigor mortis reflects ATP depletion.

16. The sarcolemma is the:

    1. A. Calcium storage network
    2. B. Main contractile protein
    3. C. Muscle cell membrane
    4. D. Muscle cell nucleus
    Show answer

    Answer: C. Muscle cell membrane

    Impulses travel along it into the fiber.

17. A calcium channel blocker overdose weakens cardiac contraction mainly because:

    1. A. Less calcium enters cells to trigger actin-myosin binding
    2. B. Sodium can no longer leave the myocardial cells
    3. C. Acetylcholine release at the heart increases sharply
    4. D. Myoglobin can no longer store oxygen in the muscle
    Show answer

    Answer: A. Less calcium enters cells to trigger actin-myosin binding

    Calcium entering the cell and released from the sarcoplasmic reticulum exposes binding sites on actin so myosin can pull. Blocking calcium entry weakens contraction and slows conduction, which causes hypotension and bradycardia. The sodium-potassium pump, acetylcholine, and myoglobin are not the drug's target.

18. Paralytics such as succinylcholine and rocuronium cause paralysis for intubation by acting at the:

    1. A. Sarcoplasmic reticulum's calcium stores
    2. B. Neuromuscular junction's acetylcholine receptors
    3. C. Spinal cord's motor neurons
    4. D. Cerebral motor cortex
    Show answer

    Answer: B. Neuromuscular junction's acetylcholine receptors

    Skeletal muscle contracts when acetylcholine released at the neuromuscular junction binds receptors on the motor end plate. Neuromuscular blockers act at these receptors. They do not act on calcium stores, the cord, or the brain, so the patient is not sedated by them and needs separate sedation.

19. Muscles can only:

    1. A. Pull on their attachments
    2. B. Expand to push against bones
    3. C. Push bones away from each other
    4. D. Twist bones around their axis
    Show answer

    Answer: A. Pull on their attachments

    Because muscles only pull, they work in opposing pairs. Flexors and extensors oppose each other.

20. An antagonist muscle is one that:

    1. A. Produces the main movement at a joint
    2. B. Assists the prime mover's action
    3. C. Opposes the action of the prime mover
    4. D. Stabilizes the joint during movement
    Show answer

    Answer: C. Opposes the action of the prime mover

    The biceps and triceps are antagonists.

21. The prime mover in a movement is also called the:

    1. A. Agonist
    2. B. Synergist
    3. C. Antagonist
    4. D. Fixator
    Show answer

    Answer: A. Agonist

    Synergists assist it.

22. Isotonic contraction means the muscle:

    1. A. Lengthens without producing force
    2. B. Stays the same length under tension
    3. C. Relaxes completely without tension
    4. D. Shortens while producing movement
    Show answer

    Answer: D. Shortens while producing movement

    Lifting an object is isotonic.

23. Isometric contraction means the muscle:

    1. A. Builds tension without changing length
    2. B. Lengthens rapidly while under a heavy load
    3. C. Relaxes completely between impulses
    4. D. Shortens while moving the joint
    Show answer

    Answer: A. Builds tension without changing length

    Pushing against a wall is isometric.

24. Muscle fatigue is associated with:

    1. A. Excess ATP accumulating in the fibers
    2. B. Depleted energy stores and metabolic waste
    3. C. Increased calcium stored in the reticulum
    4. D. Increased oxygen delivery to the muscle
    Show answer

    Answer: B. Depleted energy stores and metabolic waste

    Rest and oxygen restore function.

25. Oxygen debt refers to:

    1. A. Oxygen lost through hyperventilation
    2. B. Extra oxygen needed after exercise
    3. C. Excess oxygen stored in myoglobin
    4. D. Reduced breathing after heavy exertion
    Show answer

    Answer: B. Extra oxygen needed after exercise

    The extra oxygen restores normal metabolism. Rapid breathing after exertion reflects it.

26. Myoglobin functions in muscle to:

    1. A. Produce ATP without using oxygen
    2. B. Bind actin to shorten the fiber
    3. C. Store oxygen in muscle cells
    4. D. Conduct impulses along the fiber
    Show answer

    Answer: C. Store oxygen in muscle cells

    Released myoglobin can damage the kidneys after crush injury.

27. Rhabdomyolysis involves:

    1. A. Damage to peripheral motor nerves
    2. B. Rapid growth of new muscle fibers
    3. C. Inflammation of the joint lining
    4. D. Muscle breakdown releasing myoglobin
    Show answer

    Answer: D. Muscle breakdown releasing myoglobin

    Potassium is released too. Crush injuries and prolonged immobility cause it.

28. Skeletal muscle makes up approximately what proportion of body weight?

    1. A. About 10 to 15 percent
    2. B. About 40 to 50 percent
    3. C. About 20 to 25 percent
    4. D. About 70 to 80 percent
    Show answer

    Answer: B. About 40 to 50 percent

    It is the largest tissue mass in the body.

29. The diaphragm is which type of muscle?

    1. A. Mixed smooth and skeletal
    2. B. Skeletal muscle
    3. C. Smooth muscle
    4. D. Cardiac muscle
    Show answer

    Answer: B. Skeletal muscle

    It is skeletal muscle that functions largely involuntarily. It can be consciously controlled during breath holding.

30. Cardiac muscle differs from skeletal muscle because it:

    1. A. Is under voluntary, conscious control
    2. B. Needs no calcium to contract
    3. C. Lacks striations and visible sarcomeres
    4. D. Has automaticity and intercalated discs
    Show answer

    Answer: D. Has automaticity and intercalated discs

    Intercalated discs connect the cells. This allows coordinated contraction.

31. Smooth muscle in the GI tract produces:

    1. A. Gastric acid secretion
    2. B. Nutrient absorption
    3. C. Peristalsis
    4. D. Voluntary chewing
    Show answer

    Answer: C. Peristalsis

    It is controlled by the autonomic nervous system. Smooth muscle in the gut wall contracts in waves that push contents along. Acid is secreted by gastric glands, absorption is done by the intestinal lining, and chewing uses voluntary skeletal muscle.

32. Smooth muscle in blood vessels controls:

    1. A. Heart rate and contractility
    2. B. Vessel diameter and resistance
    3. C. Clotting and platelet activation
    4. D. Respiratory rate and depth
    Show answer

    Answer: B. Vessel diameter and resistance

    Vessel diameter sets resistance and blood flow distribution. Sympathetic stimulation constricts most vessels.

33. An unresponsive patient after cardiac arrest is limp with no muscle tone. Why does this increase airway obstruction?

    1. A. The epiglottis becomes rigid and stays open over the larynx
    2. B. The cartilage rings of the trachea collapse inward
    3. C. The vocal cords go into spasm and stay shut
    4. D. The relaxed tongue and soft tissue fall back into the pharynx
    Show answer

    Answer: D. The relaxed tongue and soft tissue fall back into the pharynx

    Normal muscle tone holds the tongue and pharyngeal tissues forward. In a limp, unresponsive patient they fall back and block the airway, which is why the head-tilt/chin-lift, jaw thrust, and airway adjuncts are used. The trachea is held open by cartilage rings. Laryngospasm is a reflex that usually occurs with stimulation, not flaccidity.

34. Muscle atrophy results from:

    1. A. Disuse, denervation, or malnutrition
    2. B. Good perfusion and adequate nutrition
    3. C. Regular aerobic and resistance exercise
    4. D. Increased use and strength training
    Show answer

    Answer: A. Disuse, denervation, or malnutrition

    It develops quickly with immobilization.

35. Muscle hypertrophy results from:

    1. A. Severe protein starvation
    2. B. Prolonged disuse of the limb
    3. C. Repeated heavy resistance training
    4. D. Injury to the motor nerve
    Show answer

    Answer: C. Repeated heavy resistance training

    It increases fiber size. The number of fibers changes little.

36. When the biceps bends the elbow, its attachment on the radius moves while its shoulder attachment stays fixed. The radial attachment is the:

    1. A. Origin
    2. B. Belly
    3. C. Insertion
    4. D. Fascia
    Show answer

    Answer: C. Insertion

    The insertion is the more movable attachment, pulled toward the origin. The origin is the fixed end (here, at the shoulder). The belly is the thick contractile middle of the muscle, and fascia is the connective sheet around it.

37. The belly of a muscle is:

    1. A. The thick central contractile portion
    2. B. The fixed attachment point on bone
    3. C. The nerve and blood supply entry point
    4. D. The tendon joining it to bone
    Show answer

    Answer: A. The thick central contractile portion

    Contraction shortens the belly.

38. Which muscle group is primarily responsible for quiet inspiration?

    1. A. Sternocleidomastoid and scalenes
    2. B. Abdominal and internal intercostals
    3. C. Diaphragm and external intercostals
    4. D. Latissimus dorsi and pectorals
    Show answer

    Answer: C. Diaphragm and external intercostals

    Accessory muscles join during distress.

39. Accessory muscle use during breathing indicates:

    1. A. Improved alveolar ventilation
    2. B. Increased work of breathing
    3. C. Normal, relaxed breathing
    4. D. Reduced respiratory effort
    Show answer

    Answer: B. Increased work of breathing

    Look at the neck, chest wall, and abdomen.

40. Muscle contraction generates:

    1. A. Movement and body heat
    2. B. Heat only, with no movement
    3. C. Movement, but it absorbs body heat
    4. D. Movement only, with no heat
    Show answer

    Answer: A. Movement and body heat

    Contraction produces a significant amount of body heat. Shivering exploits this heat production. Contraction releases heat rather than absorbing it, which is why exertion warms the body.

41. The neuromuscular junction is the point where:

    1. A. Two muscles meet at a tendon
    2. B. A motor neuron meets a muscle
    3. C. A tendon attaches muscle to bone
    4. D. Two neurons meet at a synapse
    Show answer

    Answer: B. A motor neuron meets a muscle

    Paralytic drugs act here.

42. Calcium's role in contraction is to:

    1. A. Supply energy for the power stroke
    2. B. Relax the muscle after contraction
    3. C. Break down ATP for the cross-bridge
    4. D. Expose myosin-binding sites on actin
    Show answer

    Answer: D. Expose myosin-binding sites on actin

    Exposed binding sites let actin and myosin interact. Contraction stops when calcium is pumped back.

43. Fast-twitch muscle fibers are suited for:

    1. A. Rapid, powerful bursts of activity
    2. B. Maintaining posture for long periods
    3. C. Long-duration endurance activity
    4. D. Involuntary contraction of organs
    Show answer

    Answer: A. Rapid, powerful bursts of activity

    They fatigue quickly.

44. Slow-twitch fibers are suited for:

    1. A. Explosive, powerful lifting
    2. B. Involuntary visceral contraction
    3. C. Short sprints at maximum speed
    4. D. Sustained activity and posture
    Show answer

    Answer: D. Sustained activity and posture

    They resist fatigue and use aerobic metabolism.

45. A strain is an injury to:

    1. A. Cartilage or meniscus
    2. B. Bone or periosteum
    3. C. Muscle or tendon
    4. D. Ligament or joint capsule
    Show answer

    Answer: C. Muscle or tendon

    A sprain involves ligaments.

46. Compartment syndrome develops when:

    1. A. A muscle is cut through by a laceration
    2. B. A tendon ruptures away from the bone
    3. C. A joint dislocates and tears its capsule
    4. D. Compartment pressure impairs circulation
    Show answer

    Answer: D. Compartment pressure impairs circulation

    Pressure within a fascial compartment impairs circulation to the tissues. Pain out of proportion is an early sign.

47. Cramping is commonly associated with:

    1. A. Electrolyte loss and dehydration
    2. B. Excess ATP stored in the fibers
    3. C. Overhydration as the only cause
    4. D. Cold exposure as the only cause
    Show answer

    Answer: A. Electrolyte loss and dehydration

    Overuse also contributes. Heat cramps are the classic example.

48. Muscle mass changes with aging by:

    1. A. Increasing as fat converts to muscle
    2. B. Remaining unchanged throughout life
    3. C. Increasing steadily with age
    4. D. Declining, reducing strength
    Show answer

    Answer: D. Declining, reducing strength

    Declining mass also lowers metabolic rate. Resistance activity slows the decline.

49. The energy sources available to a contracting muscle include:

    1. A. Fatty acids as the sole fuel
    2. B. Myoglobin and hemoglobin broken down for fuel
    3. C. Stored ATP only, with no backup
    4. D. ATP, creatine phosphate, and glycogen
    Show answer

    Answer: D. ATP, creatine phosphate, and glycogen

    Muscle uses stored ATP first, then creatine phosphate, then glycogen, with blood glucose and fat supplying aerobic metabolism over longer periods. Each supplies energy over a different time frame. Myoglobin and hemoglobin carry and store oxygen; they are not broken down for fuel.

50. Which describes the sequence of skeletal muscle contraction?

    1. A. Impulse, ACh release, calcium, sliding
    2. B. Impulse, sliding, ACh release, calcium
    3. C. Sliding, calcium release, impulse, ACh
    4. D. Calcium release, impulse, ACh, sliding
    Show answer

    Answer: A. Impulse, ACh release, calcium, sliding

    Nerve impulse, then acetylcholine release, then calcium release, then filament sliding. Relaxation requires calcium to be pumped back.