Yerks vs Erks - What's the difference?

As a verb yerks

is (yerk).

(head)

(yerk)

(en verb)

(archaic) to stab.

*circa 1603, :

I lack iniquity / Sometimes to do me service: nine or ten times / I had thought to have yerk’d him here, under the ribs.

To throw or thrust with a sudden, smart movement; to kick or strike suddenly; to jerk.

* Drayton

They flirt, they yerk , they backward fling.

* Shakespeare

Their wounded steeds / Yerk out their armed heels at their dead masters.

(obsolete, Scotland) To strike or lash with a whip.

(en noun)

(archaic) A sudden or quick thrust or motion; a jerk.

(head)