Answer: sternums

AnswerCrossword Clue
STERNUMSBreastbones
STERNUMSChest protectors
STERNUMSParts of some cages
sternumsSTERNUM, a long, flat supporting bone of most vertebrates
sternumsA thickened ventral plate on each segment of the body of an arthropod
sternumsThe breastbone