Which of the following points is specifically related to the upper arm position?

The point related to the upper arm position is the brachial plexus tie-in. This area is significant in defensive tactics as it involves the brachial plexus, which is a network of nerves that supply the upper limb.

Targeting the brachial plexus can incapacitate an opponent temporarily, due to the disruption of nerve signaling that controls movement and sensation in the arm. When applied appropriately, it can create a momentary weakness or loss of control, allowing an individual to gain an advantage in a defensive situation.

In contrast, the other options pertain to different anatomical structures or areas that are not specifically focused on upper arm positioning. The jugular notch and clavicle notch are related to the neck region, while the radial artery is associated with the forearm and wrist. These do not play a direct role in techniques pertaining to the upper arm's positioning in a physical confrontation.