What is an expansive tendinous sheet that projects from a muscle called?

The term for an expansive tendinous sheet that projects from a muscle is aponeurosis. An aponeurosis is a type of connective tissue that is broader and flatter than a typical tendon, serving to attach muscles to the parts they move or to connect muscular structures to one another. This structure plays a critical role in distributing the force generated by the muscle over a larger area, facilitating coordinated movement and stability.

In contrast, fascia generally refers to a sheet of connective tissue that surrounds muscles, vessels, and nerves, providing support and structure but not necessarily connecting directly to muscle action like an aponeurosis does. A tendon is a more narrow, cord-like structure that directly connects muscle to bone, while a ligament connects bone to bone, providing joint stability rather than muscle attachment. Understanding the distinction between these connective tissues helps in recognizing their specific functions within the musculoskeletal system.