In Aikido, a Shomenuchi (overhead strike) is not redirected over your head, but rather in the direction that the attack travels, downward.
I apologize if I was too general in my original post. Jim, I added the English language conversions just for you
Are you talking about Shomenuchi or Shomenkiri? The difference?
Shomenuchi - head strike, which is usually delivered in a slightly UPWARD direction to the forehead knocking the head back (used to expose the throat for a cut) this is delivered more like a punch (with edge of hand) , to the forehead. This actually causes an UPWARD feel/direction to nage when doing technique, not downward.
Shomenkiri - head cut, which is usually delivered in a DOWNWARD direction starting at the top of the forehead cutting downward through the head. This actually causes a DOWNWARD feel/direction to nage when doing technique.
Sorry, as a swordsman I tend to get rather technical about these things. In Aikido, these are really two separate attacks and technique for these are different as well. I don't believe this difference is emphasized enough in practice as a lot of visitors only seem to know of the shomenkiri attack.
I have been taught that shomenuchi was used in swordsmenship when the enemy had a helment on that also had a piece that covered the throat. It was not wise to try and cut through the helment because your sword could get stuck or break. If the helment was knocked back however (striking the forehead area back) the throat was then exposed for a cut.
Also, depending on who you talk to, the shomenuchi strike was also done with the mune or back of the blade. This was to prevent cutting or sticking the blade into the helment.
Dan P. - Mongo