sternum (n.)youdaoicibaDictYouDict
"breastbone," 1660s, from Greek sternon "chest, breast, breastbone" (in Homer, only of males), also "the breast as the seat of affections," related to stornynai "to spread out," from PIE *ster-no- "to stretch, extend," from root *stere-, *ster- "to spread," related to stornynai "to spread out" (see structure (n.)), on the notion of the chest as broad and flat, as opposed to the neck. Related: Sternal.
rhomboid ligamentyoudaoicibaDictYouDict
"The costoclavicular ligament, which extends between the sternal end of the clavicle and the cartilage of the first rib", Early 19th cent..