What type of muscle is found within the "walls" of hollow organs?

The type of muscle found within the "walls" of hollow organs is smooth muscle. This muscle tissue is responsible for involuntary movements and is predominantly located in the walls of hollow structures such as the digestive tract, blood vessels, and respiratory passages. Smooth muscle fibers are non-striated, which distinguishes them from skeletal and cardiac muscle. Their contraction is regulated by the autonomic nervous system and various hormones, allowing for functions like peristalsis in the gastrointestinal tract and regulating blood vessel diameter.

Skeletal muscle, on the other hand, is under voluntary control and is attached to the skeleton, enabling movement of bones. Cardiac muscle is specialized tissue found only in the heart, where it facilitates the pumping of blood. Striated muscle refers to any muscle tissue that contains stripes (or striations) and includes both skeletal and cardiac muscle, but it does not encompass the smooth muscle that lines hollow organs. Thus, smooth muscle is the most accurate answer regarding the muscle type found specifically within the walls of hollow organs.