Question 1

Which structure is the smallest contractile unit within a skeletal muscle fiber, responsible for muscle contraction?

Accepted Answer

Sarcomere

Question 2

During muscle contraction, which ion is released from the sarcoplasmic reticulum and is essential for the cross-bridge cycle?

Accepted Answer

Calcium ($$Ca^{2+})$$

Question 3

A patient presents with a complete separation of a tendon from its bony attachment site after a sports injury. What is this type of injury called?

Accepted Answer

Avulsion

Question 4

Which protein directly binds to calcium ions during skeletal muscle contraction, leading to exposure of binding sites on actin?

Accepted Answer

Troponin

Question 5

Which of the following best describes the pathophysiology of osteoarthritis (OA)?

Accepted Answer

Degeneration of articular cartilage and formation of bone spurs

Question 6

A patient with rheumatoid arthritis is likely to present with which of the following laboratory findings?

Accepted Answer

Elevated serum rheumatoid factor ($$RF)$$

Question 7

Which connective tissue wrapping surrounds individual muscle fibers?

Accepted Answer

Endomysium

Question 8

What is the primary difference between a strain and a sprain?

Accepted Answer

A strain involves a tendon, while a sprain involves a ligament.

Question 9

Which of the following is a factor that can delay bone healing after a fracture?

Accepted Answer

Poor nutrition

Question 10

At the neuromuscular junction, which neurotransmitter is released to stimulate muscle contraction?

Accepted Answer

Acetylcholine

Question 11

Which of the following best describes the sequence of events leading to muscle contraction after an action potential arrives at the axon terminal?

Accepted Answer

Release of acetylcholine, opening of sodium channels, depolarization of sarcolemma

Question 12

A patient presents with morning joint stiffness lasting more than one hour, symmetric arthritis, and rheumatoid nodules. Which condition is most likely?

Accepted Answer

Rheumatoid arthritis

Question 13

Which of the following is a manifestation of a bone fracture?

Accepted Answer

Unnatural alignment and muscle spasm

Question 14

Which structure is responsible for storing and releasing calcium ions in skeletal muscle fibers?

Accepted Answer

Sarcoplasmic reticulum

Question 15

Which of the following is a risk factor for developing osteoarthritis?

Accepted Answer

Obesity

Question 16

Which of the following best describes the role of acetylcholinesterase at the neuromuscular junction?

Accepted Answer

It degrades acetylcholine, terminating the signal.

Question 17

A patient with osteoarthritis is most likely to have which of the following findings on imaging studies?

Accepted Answer

Bone spurs (osteophytes)

Question 18

Which of the following is true regarding the organization of skeletal muscle from largest to smallest structure?

Accepted Answer

Muscle → Fascicle → Muscle fiber → Myofibril → Myofilament

Question 19

Which of the following is a characteristic feature of rheumatoid arthritis but NOT osteoarthritis?

Accepted Answer

Systemic autoimmune damage to synovial membrane

Question 20

A patient is taking medications that impair blood clotting and has poor nutrition. After sustaining a bone fracture, which equation best represents the relationship between healing time ($$T) $$and these risk factors ($$R$$), assuming all other factors are constant?

Accepted Answer

$$T \propto R$$

Musculoskeletal System: Structure, Function, and Pathophysiology

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