So, in school I was taught that spiral staircases in castles are pretty much always anticlockwise so that soldiers could easily run up the stairs easily wielding their sword in there right hand since most people are right-handed.
I have thought about this again recently and disagree. Surely the people running up these staircases wielding swords would be attackers of the castle and thus this would aid the attacker? Possibly it's to carry a bow up the stairs to fire down on the enemy?
Just a thought
Check out the comprehensive answer from /u/mormengil to an older version of this question - https://www.reddit.com/r/AskHistorians/comments/406sa5/were_castle_stairs_designed_to_impede_sword_use/
To answer you directly, if we accept that this design was intentional (which seems pretty reasonable), your original reasoning was correct, but a spiral staircase will be both clockwise and anti-clockwise depending on whether you are climbing or descending it. They were almost always clockwise when going up, which restricted the motion of attackers’ right/sword arms, and anti-clockwise when going down, giving defenders’ sword/right arms room to swing.
The Stairwells If you have ever visited a medieval castle, you might have noticed that the stairwells are designed as a clockwise spiral. There is a very good reason why medieval castle designers chose to build them this way, and again it is all about defense.
According to Will Kalif of All Things Medieval, “this meant that any attackers coming up the stairs had their sword hands (right hand) against the interior curve of the wall and this made it very difficult for them to swing their swords.” On the other hand, the defenders could easily swing their swords and additionally, thanks to this specific design, their bodies were exposed much less than the bodies of their enemies.