Alias · Triangle system
Arm-in triangle choke
Also known as Arm-In Triangle — the canonical term used on this site.
Training background: descriptive
Descriptive — triangle with the arm trapped inside
Arm-in triangle choke is a descriptive name for the arm-in triangle — naming the version where the opponent’s arm is trapped inside the triangle alongside the head.
Etymology. “Arm-in” specifies that one arm is caught inside the legs with the head; “triangle choke” names the strangle. The label distinguishes it from the arm-out triangle, where the arm is cleared outside.
Mechanics. With the arm inside, the strangle applies force less directly and must compensate: the trapped arm fills space the legs would otherwise close, so the attacker drives the knee across and angles off to make the legs and the opponent’s own shoulder press both sides of the neck despite the arm being in the way.
Cross-reference. “Head and arm triangle (leg variant)” is a sibling alias. Full mechanical coverage on Arm-In Triangle.