Final answer:
The deep fascia of the arm is called the interosseous membrane of the forearm, which connects the radius and ulna bones.
Step-by-step explanation:
The deep fascia of the arm, which is thick, is called the interosseous membrane of the forearm. It is a sheet of dense connective tissue that connects the radius and ulna bones. This membrane provides support and stability to the forearm, allowing for coordinated movements of the wrist and hand.