What are the main muscles in the structure and function of the major muscular system?

The major muscular system primarily consists of three types of muscles: skeletal, smooth, and cardiac muscles. Skeletal muscles are responsible for voluntary movements and are attached to bones, enabling locomotion and posture. Smooth muscles control involuntary movements in organs like the intestines and blood vessels, while cardiac muscle makes up the heart, facilitating its rhythmic contractions. Together, these muscles play crucial roles in movement, stability, and vital bodily functions.