Three major veins used for venipuncture in the antecubital fossa?

1. Median cubital vein: This is the most common vein used for venipuncture. It is located in the middle of the antecubital fossa, between the biceps brachii and triceps brachii muscles.

2. Cephalic vein: This vein is located on the lateral (outer) side of the antecubital fossa. It runs from the wrist to the shoulder.

3. Basilic vein: This vein is located on the medial (inner) side of the antecubital fossa. It runs from the wrist to the shoulder.