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

Smooth muscle is the involuntary muscle type located in the walls of internal organs, such as the intestines, blood vessels, and the bladder. Its primary function is to facilitate movements within the body that are not consciously controlled, such as digestion and regulating blood flow. This muscle type operates automatically, responding to the autonomic nervous system without the need for conscious effort from individuals.

In contrast, skeletal muscle, which is voluntary, is attached to bones and allows for movement of the skeleton, and cardiac muscle, while also involuntary, is specific to the heart's walls. Striated muscle refers to the appearance of both cardiac and skeletal muscle under a microscope, characterized by light and dark bands. However, smooth muscle does not have this striated appearance and is distinctly different in function and location within the body.