part of ends during starts during death vertebra process rib ribs XAO:0004500 xenopus_anatomy Any of the bony lateral projections from the presacral veterebrae of the anterior trunk region, enabling the lungs to expand and thus facilitate breathing by expanding the chest cavity. They serve to protect the lungs, heart, and other internal organs of the thorax. 2013-04-10T19:32:29Z vertebral rib eriksegerdell NF stage 52