Final answer:
The specifics of how far below the AC the skin should be pulled with the non-dominant hand are not provided in the context, and therefore cannot be accurately answered. However, the concept of two-point discrimination is well explained as a measure of sensory nerve function, depending on the density of nerve endings in different body areas.
Step-by-step explanation:
The question seems to relate to a procedure or practice in the medical field, particularly one that involves the position of the arm and the handling of a garment or a bandage, which could relate to the treatment of varicose veins as mentioned in the passage from Quintilian's Institutes of Oratory. However, the instructions regarding the pulling of skin below the antecubital space (AC) with the non-dominant hand are not clear from the context provided. In medical practices, this procedure might refer to something like preparing for a venipuncture, where the skin below the AC is typically anchored with the non-dominant hand to create a good insertion point for the needle. However, without context, providing an accurate measurement or method is not possible.
As for the second part of the provided materials, it relates to the concept of two-point discrimination, which is a test used to measure the sensory nerve function that allows an individual to distinguish between one point and two points when they are simultaneously applied to the skin. The distance at which two points can be discerned as separate is related to the density of nerve endings in different parts of the body, being smallest in areas like the fingertips which have a higher sensory acuity, and larger on areas like the arm or shoulder with lower sensory acuity.