Question

question 48
the contractile unit of a muscle is the:
○ sarcolemma
○ motor unit
○ muscle fiber
○ sarcomere

Explanation:

• Sarcolemma is the muscle cell membrane, not the contractile unit.
• A motor unit consists of a motor neuron and muscle fibers it innervates, not the contractile unit.
• A muscle fiber is a muscle cell, and the contractile unit is within it.
• The sarcomere is the basic contractile unit of a muscle, made of actin and myosin filaments that slide during contraction.

Answer:

D. sarcomere