Question 1

Which of the following best describes the difference between skeletal and cardiac muscle fibers?

Accepted Answer

Skeletal muscle fibers are multinucleated and unbranched, while cardiac muscle fibers are single-nucleated and branched.

Question 2

A patient presents with an inability to abduct their arm beyond 15 degrees but can initiate the movement. Which muscle is most likely injured?

Accepted Answer

Supraspinatus

Question 3

Which connective tissue layer directly surrounds individual muscle fibers?

Accepted Answer

Endomysium

Question 4

A 35-year-old male suffers a sudden, forceful contraction of the biceps brachii while lifting a heavy object, resulting in a 'Popeye' deformity. Which of the following is most likely true?

Accepted Answer

He will lose approximately 20% of forearm flexion strength but a greater loss of supination strength.

Question 5

Which muscle is primarily responsible for protracting the scapula and preventing 'winged scapula'?

Accepted Answer

Serratus anterior

Question 6

A patient with facial nerve (CN VII) paralysis is unable to close their eyelid gently but can forcefully squint. Which part of the orbicularis oculi is most likely affected?

Accepted Answer

Palpebral part

Question 7

Which of the following muscle arrangements allows for the greatest power generation due to the angle of fiber attachment?

Accepted Answer

Pennate

Question 8

During a physical exam, a patient is unable to dorsiflex their foot and exhibits 'foot drop.' Which nerve is most likely damaged?

Accepted Answer

Deep fibular (peroneal) nerve

Question 9

Which muscle is the chief extensor of the thigh and is only briefly used during walking?

Accepted Answer

Gluteus maximus

Question 10

A patient presents with a drooping shoulder and difficulty elevating the arm above the head. Injury to which nerve is most likely responsible?

Accepted Answer

Spinal accessory nerve (CN XI)

Question 11

Which of the following best describes the action of the triceps brachii muscle?

Accepted Answer

Extension at the elbow and shoulder

Question 12

A surgeon makes a vertical incision along the linea alba for abdominal surgery. What is the main advantage of this approach?

Accepted Answer

Minimal bleeding and easy access to abdominal organs

Question 13

Which muscle acts as a fixator to stabilize the shoulder joint during arm movement?

Accepted Answer

Supraspinatus

Question 14

Which of the following is the correct order of connective tissue layers from innermost to outermost in a skeletal muscle?

Accepted Answer

Endomysium, perimysium, epimysium

Question 15

A patient with a history of fluoroquinolone antibiotic use presents with sudden pain and inability to plantarflex the foot after a sporting event. Which structure is most likely ruptured?

Accepted Answer

Calcaneal (Achilles) tendon

Question 16

Which muscle is the main abductor of the shoulder joint and is a common site for intramuscular injections?

Accepted Answer

Deltoid

Question 17

Which muscle is responsible for flexion at the hip and is formed by the union of the iliacus and psoas major muscles?

Accepted Answer

Iliopsoas

Question 18

A patient is unable to adduct their thigh and has weakness in medial rotation. Which muscle group is most likely affected?

Accepted Answer

Medial compartment of the thigh

Question 19

Which muscle is primarily responsible for dorsiflexion of the ankle and extension of the toes?

Accepted Answer

Tibialis anterior

Question 20

A violent inversion injury of the foot results in an avulsion fracture at the base of the 5th metatarsal. Which muscle's tendon is most likely responsible?

Accepted Answer

Peroneus (fibularis) brevis

Muscular System: Structure, Function, and Clinical Relevance

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