clavicle

Sternum which is composed of manubrium, gladiolus, and xiphoid process.

Ribs

Costal cartilage

Thoracic vertebrae

You have xipoid process, costal carilages, medial ends of two clavicle and xipisternum attached to the sternum bone.

I presume it is the Sternum. It is the breast bone which is joined by the two collar bones called clavicle, and it is joined by the costal cartilages of the ribs to form the chest cavity

clavicle or collarbone Cheek Chin Chest Calf Clitoris Cerebellum Cerebral Cortex Cervix Cells Cartilage Carpus Clavicle Cranial Nerves Cranium Costal Cartilages Coccygeal Vertabrae Cervical Vertibrae