Loin

The loin sits along the upper back of the steer, directly behind the rib primal. It's divided into two sub-sections: the short loin (closer to the rib) and the sirloin (closer to the round).

This is where tenderness reaches its peak. The longissimus dorsi muscle continues from the rib into the short loin, becoming what we know as the New York strip. And running beneath it is the tenderloin (psoas major) — the most tender muscle on the entire animal because it does virtually zero work.

Key Cuts from the Loin: - New York strip (boneless) / Shell steak (bone-in) - Tenderloin / Filet mignon - T-bone steak (strip + small tenderloin, separated by T-shaped bone) - Porterhouse (like a T-bone but with a larger tenderloin section — minimum 1.25" across) - Top sirloin - Tri-tip (from the bottom sirloin)

The T-Bone vs Porterhouse Question: I get asked this constantly. Both are cross-cut from the short loin with a T-shaped vertebral bone. The difference is where along the loin it's cut. The porterhouse comes from the rear, where the tenderloin is wider — USDA requires at least 1.25 inches of tenderloin measured from the bone. Anything less is technically a T-bone.

Buying Tip: The tenderloin as a whole muscle (PSMO — peeled, side muscle on) is one of the best bulk purchases for a home cook. You can fabricate it yourself into filet mignon steaks, tips, and chain meat for grinding. Expect to pay $20–$35/lb for Prime.