Emergency Medical Technician (EMT) Intermediate Practice Exam

Which of the following is NOT a voluntary muscle?

1. Skeletal muscle

2. Cardiac muscle

3. Smooth muscle

4. All of the above are voluntary

The correct answer is: Smooth muscle

Smooth muscle is not classified as a voluntary muscle. This type of muscle operates involuntarily, meaning its contractions are not consciously controlled. Smooth muscle is found in various structures within the body, such as the walls of hollow organs like blood vessels, the intestines, and the bladder. It facilitates automatic processes, such as peristalsis in the digestive system and the regulation of blood flow through vascular structures. In contrast, skeletal muscle is voluntary and can be controlled by the individual, allowing for deliberate movements such as walking or lifting. Cardiac muscle, which makes up the heart, is also not under voluntary control; instead, it contracts rhythmically and autonomously to pump blood throughout the body. Hence, smooth muscle distinguishes itself from skeletal and cardiac muscle due to its involuntary nature.