As the sternal ribs degenerate into the "false" asternal or incomplete ribs from before, obliquely backward down to the last dorsal vertebra, so the thoracic space takes form.
"Surgical Anatomy"
Joseph Maclise
In animals, as in man, the ribs which articulate with the sternum by their cartilages are called true, or sternal ribs; those whose cartilages do not articulate with the sternum are called false, or asternal.
"Artistic Anatomy of Animals"
Édouard Cuyer