The traditional ribeye is a cross-section of the entire ribeye roll which has three major muscles. These are the longissimus dorsi, or large center eye, the complexus, a smaller side muscle which is not always present depending on where the steak is cut, and the spinalis dorsi, also called the cap of ribyeye or deckle. The muscles of the ribeye are held together with tender sinew with large swaths of rich fat between them.
These steaks are cut from the rib primal which covers ribs six through twelve and is located between the chuck and loin primals. This section has a high amount of natural marbling which is a key to the amount of flavor and juiciness of a cut.
Fast fact: The ribeye is known by many different names, including Delmonico, beauty steak and market steak. In Australia, ask for a Scotch steak.