The medial confluence of stress lines on the medial surface of the ramus that represents the arcial growth of surface of the mandible is known as:

Ricketts noticed that in the dried mandible, the stress lines run on the medial aspect parallel to the external oblique ridge and ascend up the ramus. The stress lines fork into two at a particular point. Ricketts named this point Eva to honor his mother. So Eva is the confluence or the point of the forking of the stress lines at the terminus of the oblique ridge on the medial surface of the ramus.