The structures within the muscle fiber that shorten to cause skeletal muscle fiber contraction are (the)

Question

Quizplus · Accepted Answer

Myofibrils are the structures within the muscle fiber that contain the contractile proteins (actin and myosin) and are responsible for skeletal muscle fiber contraction.

Answer A is incorrect because the myoneural junction is where the motor neuron meets the muscle fiber, and is involved in initiating the contraction, but does not directly cause the contraction.

Answer C is incorrect because sarcoplasm refers to the cytoplasm of the muscle fiber, which contains various organelles and molecules involved in muscle metabolism, but not directly involved in contraction.

Answer D is incorrect because not all of the answers are correct, as explained above.

Answer E is incorrect because there is a correct answer (B).

The Structures Within the Muscle Fiber That Shorten to Cause