Voluntary muscles are skeletal muscles (under somatic control) and involuntary muscles involve the heart, smooth muscles and anything under autonomic control.
Voluntary muscles are consciously moved. Involuntary muscles are not consciously moved, smooth muscles and cardiac muscles are examples of involuntary muscles. When a muscle is both voluntary and...
The rectum is a portion of the end of the colon just before the anus and is controlled by involuntary muscles (smooth muscle). I believe the anal spincter or rear end opening has 2 types of muscles....
The calf muscle is a Skeletal Muscle and is therefore categorized as voluntary.
However, when the calf CRAMPS, it is considered an involuntary muscle contraction.