This article is on two separate techniques that are taught together in Kihon Kata. The first is ude uke. The translation is of two separate symbols, like many of the other techniques in karate. The first symbol is “ude”, which means “arm” and the second is “uke” which means “to receive” or “block”.
While “arm block” leads some confusion on the inside or outside of the arm, it is meant to be a block coming from the ear to the inside of the body using the bone in the forearm that is closest to the pinky finger.
The second technique is also two symbols, “geidan” and “barrai”. This is most commonly translated as “low” and “block”, but can also be seen as “low sweeping block”.
The arm block technique allows for a handful of applications ranging from a block from a strike, a release, and arm bar or break, and a strike. The primary power for the technique comes from the rotation of the hips. When blocking a strike, a small deflection will cause the attacker to miss completely. When using this technique as a break from a hold you can cause extreme damage to the attackers elbow. Finally, when striking the opponent in the neck, the forearm may not be as hard as the knuckles, but the bones in the forearm can cause large amounts of damage to the neck.
In some styles, such as Shotokan, the low block is used as a strong striking technique to a kick or a low punch. This is a perfectly acceptable application of the movement, but in my style this is mainly a sweeping block, as well as a low block. It is used to redirect a strike or the head of the attacker. It can be used similar to a low tetsui (hammerfist strike). Many more options than just a linear block.