Final answer:
The superficial region located between the brachium and the antebrachium is known as the antecubital fossa, which contains the brachial artery and the median cubital vein.
Step-by-step explanation:
The superficial region located between the brachium (upper arm) and the antebrachium (forearm) is commonly referred to as the antecubital fossa or elbow pit. This region is clinically significant as it contains several important structures including the brachial artery, which provides blood supply to the upper limb and eventually bifurcates into radial and ulnar arteries that supply the forearm. The antecubital fossa is also known for the presence of the median cubital vein, a superficial vessel that is often used for venipuncture procedures such as drawing blood.