Which type of muscle is involuntary and found in the walls of organs?

• A. Skeletal muscle
• B. Cardiac muscle
• C. Smooth muscle
• D. Striated muscle

Answer: (C)

Smooth muscle is the correct answer because it is characterized as involuntary muscle and is specifically located in the walls of various organs such as the intestines, blood vessels, and the bladder. This type of muscle functions autonomously and is not under conscious control, allowing organs to perform their functions without needing direct input from the nervous system.

Skeletal muscle, on the other hand, is voluntary and is attached to the bones, which allows for conscious movement and is responsible for locomotion. Cardiac muscle, while also involuntary, is specifically found in the heart and is responsible for pumping blood. Striated muscle refers to a classification based on the appearance of the muscle under a microscope, which includes both skeletal and cardiac muscle, but not smooth muscle. Hence, the defining attributes of smooth muscle align perfectly with the question's criteria.