"Baby" refers to the small size of the ribs. "Back" refers to the fact
that the ribs come from along the backbone of the hog.
"Where Do Baby Back Ribs Come From?
Baby Back Ribs are located on the loin of the hog. They are
basically the spine and part of the ribs. They are cut when you
"take" the loin off of the backbone.
The name comes not from the age of the hog, but because of the small
size of the "ribs" compared to the larger pork spareribs. Pork
Spareribs are the actual ribs of a hog."
"Pork Loin Ribs (Baby Backs)
Back ribs shall consist of at least 8 ribs and as many as 14 ribs.
Generally, a rack of ribs will be 12 to 13 ribs. The back rib is the
vertebrae section of the pork loin."
From Sunset Magazine:
"Imagine an X-ray view of a cow, pig, or lamb to see where ribs come
from. From the shoulder back to the rump or leg is the rib-loin
section. These ribs attach to the backbone and fall to the stomach
area. Ribs along the upper back section of the loin are lean and
tender. Those cut from the center of this section (back or prime ribs
are best known) have the leanest meat and most uniform size. In pork,
they are a by-product of center-cut loin roasts and commonly called
baby back pork ribs."
" No, baby back ribs don't come from baby pigs! Smoked baby back ribs
are very popular. That's why they are one of the most expensive cuts
of meat from the hog...
Also called "back ribs", they come from the upper part of the pork rib
cage, next to the loin along the back. Hence, back ribs."
Here's a page with pictures and diagrams of the porkloin:
"baby back ribs" vertebrae
"baby back ribs" backbone
I hope this helps.