Jugular notch

Also called the suprasternal notch, a u-shaped depression at the superior border of the manubrium in the midline.

From Kungfuonline.com

“The hollow at the base of the throat. Also called the jugular notch, it is found as a small notch at the top of the sternum. In self-defense, a person may thrust their fingers into the suprasternal notch, using straight and downward pressure. This maneuver induces choking and/or unconsciousness through blockage/crushing of the windpipe.

Fun Fact: A thrusting attack to the suprasternal notch was choreographed into the subway station fight scene in the movie The Matrix.”