sternum or breastbone is long flat bone located in central part of chest that connects to ribs via cartilage and forms front of rib cage, thus helping to protect heart, lungs, and major blood vessels from injury
Joe Williams, John Carlson, Damon Hernandez, Don Brutzman
usage examples https://www.web3d.org/x3d/content/examples/HumanoidAnimation/Medical
X3D-Edit 4.0, https://www.web3d.org/x3d/tools/X3D-Edit
X3D Tidy, https://www.web3d.org/x3d/stylesheets/X3dTidy.html