Pectoral, from the Latin pectus, breast. It's been suggested that pectus in turn comes from the Latin word for comb, pecten, because the ribs look like the teeth of a comb.
Pecten is the source of pectineus, a muscle originating from the pubic bone, either because the muscle's parallel fascicles resemble a comb or because pecten was once the name of the pubic bone. (Why the pubic bone should call to mind a comb is anybody's guess: one suggestion is that pubic hair was somehow reminiscent of wispy tufts of hair left on a comb.)
The comb-like parallel ridges of myocardial tissue seen within the right atrium and both auricles of the heart is called the pectinate muscle.