Tate-Shiho-Gatame (縦四方固) is one of the seven mat holds, Osaekomi-waza, of Kodokan Judo.

You sit astride your opponent knees up high under armpits to avoid being bucked or alternatively lying on top of your opponent grapevining their legs with your own whilst your arms act as stabilisers and your chest smothering their airways.

The high armpit position allows transition to armbars the other to various choke holds.

It is also part of the movement described as the cross lock (juji-jime) defense method in the book The Canon of Judo.

"The elbow escape from the mounted position" is described in the book Brazilian Jiu-Jitsu, Theory and Technique, and demonstrated in the video Gracie_Jiu-Jitsu_Basics_Vol.1.