What word or phrase does your mother always say?
"shoulder blade," 1570s, Modern Latin, from Late Latin scapula "shoulder," from Latin scapulae (plural) "shoulders, shoulder blades," perhaps originally "spades, shovels," on notion of similar shape, but animal shoulder blades might have been used as scraping tools in primitive times, from PIE *skap-, variant of *skep- "to cut, scrape" (see scabies).
scapula scap·u·la (skāp'yə-lə)
n. pl. scap·u·las or scap·u·lae (-lē')
Either of two large, flat, triangular bones forming the back part of the shoulder. Also called shoulder blade.
Plural scapulae (skāp'yə-lē') or scapulas
Either of two flat, triangular bones forming part of the shoulder. In humans and other primates, the scapulae lie on the upper part of the back on either side of the spine. Also called shoulder blade. See more at skeleton.