A thoroughly-marbled boneless ribeye steak. The ribeye cap lines the steak in the top of the photo, the longissimus dorsi comprises the middle, …..
Ribeyes are truly the beefiest steak on the animal, and their reputation (and price) reflect it. Cut from the back ribs (as opposed to the short ribs) within the rib primal, this mess of muscles lining the spinal column is one part tender muscles and one part intra- and inter-muscular fat, with little bits of other rich muscles thrown on to round things out.
Which muscles form the ribeye?
The ribeye steak is comprised of bits of a few different muscles, but the true “ribeye muscle” would be the longissimus dorsi, a long, round tube muscle that runs from the hip (all the way back in the round primal), to the shoulder (in the chuck primal). As it runs through the loin primal, it forms the greater part of the New York strip, and as it continues into the chuck, it forms the chuck eye, naturally (we have a whole article on that here). This is one of those “lazy” muscles that spends the majority of the animal’s life relaxing, without much weight to carry. It’s therefore quite tender, but this section of the rib benefits from pockets of intramuscular fat, or “marbling.
Note this, however: along with intramusucular fat that forms marbling, the ribeye steak contains bits of several other muscles, which means it also has a heavy dose of intermuscular fat: those big, chewy deposits you might associate with a prime rib roast. In the photo on the right, you’ll notice big white globs of this type of fat, which cushions the muscles from each other. The muscle that runs along the rib bone (at the top of the photo on the right) is called the ribeye cap or spinalis, and has a reputation all its own as a prized steak. Often, the ribeye cap roll (the whole muscle before it’s sliced into steaks, removed as a sheet from the whole rib roast), is rolled into pinwheels. It’s a secret favorite of many butchers and chefs.
Unlike the tenderest muscles which require additional flavor agents like sauces (primarily the tenderloin), the ribeye contains enough fat to present big, beefy flavors with just a kiss of salt and pepper. (Read a pan-sear recipe here). Get that cast-iron pan screaming hot, make sure the steak is as dry as possible (to ensure tons of browning in the short cooking time), and cook up some potatoes or greens to go along.
Fun fact for meat nerds: while the ribeye and a slice of prime rib are the exact same cut of beef, a ribeye is truly a steak because it is cooked after being sliced, while a prime rib “steak” is technically a slice of roast. The same would go for a filet mignon (a steak) vs. a “slice of cooked tenderloin” (a slice of roast).