The middle portion of a muscle is commonly called the what?

• A. Belly
• B. Insertion
• C. Origin
• D. Fascia

Answer: (A)

The middle portion of a muscle is called the belly. This is the fleshy, contractile part where most of the muscle fibers are concentrated and generate force when they shorten. The ends of a muscle attach to bone: the fixed end is called the origin, and the end that moves toward the origin during contraction is the insertion. Fascia is the connective tissue that surrounds and separates muscles, not the central part of the muscle itself. So the term that best fits the middle, contractile section is the belly, distinguishing it from the tendinous attachments at the ends and from the surrounding connective tissue.