Wiktionary
suprasternal notch
n. (context anatomy English) The conspicuous dip visible at the top of the human chest where the neck joins the sternum.
Wikipedia
Suprasternal notch
The suprasternal notch (fossa jugularis sternalis), also known as the jugular notch, is part of human anatomy. It is a large, visible dip in between the neck and the collarbone.