Final answer:
The Brachial Plexus Tie-In Nerve Motor Point is the point where the brachial plexus connects with the motor nerves controlling the neck muscles. It is specifically associated with the spinal accessory nerve, which innervates the sternocleidomastoid and trapezius muscles. The function of this plexus and nerve can be assessed by testing the movement and strength of these muscles.
Step-by-step explanation:
The Brachial Plexus Tie-In Nerve Motor Point refers to a specific point where the brachial plexus, a nerve plexus associated with the lower cervical spinal nerves and the first thoracic spinal nerve, connects with the motor nerves that control the muscles in the neck. Specifically, it is the point where the spinal accessory nerve, also known as the eleventh cranial nerve, innervates the sternocleidomastoid and trapezius muscles. These muscles are involved in various movements of the head and neck and can be assessed for function and strength by testing the function of the spinal accessory nerve.