The popular Facebook group “Aikido” shares well-written content about the traditional martial art, and the technical notebook.
Yokomenuchi is a strike to the side of the head. In aikido, this is often a weaponless simulation of the sword strike with the same name. You use the ridge of your hand instead of a sword. The strike can also be done with a knife. Whether armed or unarmed, sankyo against this attack looks pretty much the same.
Basically, there are two ways of doing sankyo. One can be called sotokaiten, outer rotation – that is, on the outside of uke’s arm. The other way is uchikaiten, inner rotation, where you pass under uke’s arm.
You start with a taisabaki entrance on the inner side of the attack. Don’t step to the front of uke, but to the other side of him or her, seen from the attacking arm. Your blocking movement is quite the same as the initial movement on gyakuhanmi.
Control uke’s elbow with one hand, and grab uke’s hand with the other. When you have grabbed uke’s hand, you can pass under the arm and turn toward uke. By this movement, you easily turn your hand grip into the sankyo position. It happens all by itself.
After you have passed under uke’s arm and turned toward him or her, you can apply the sankyo wrist twist, and lead uke by it – just about any direction you want. Usually just continue with the spiral movement, where uke lands on the floor, and immediately apply the end pinning.