What Part of the Cow Is Prime Rib?
The prime rib steak comes from the rib part of the cow. The rib portion is located just behind the shoulder blades, up by the back of the cow. Rib eye, prime rib, and regular rib meat all come from the rib portion of the animal.
A prime rib comes from the bottom of the rib cage of the cow. You can view more about cuts of beef here: http://www.cooksillustrated.com/images/document/howto/ND02_BeefRoasts.pdf.
The most prominent parts that are used as aprime cut are usually found in the lower end of the rib cage. Some of the prime cuts are the Tenderloin Steak, or the Filet Mignon.