Venous cannulation sites in the arm, illustration. Arm veins are often chosen as a site to insert catheters to deliver drugs or draw blood samples. This illustration shows the anatomy of the veins of the arms. The upper arm contains the cephalic and basilic veins, which are superficial veins. Below these, the pattern of the veins various from patient to patient. Here, a typical anatomy is shown where the intermediate veins (deeper than the superficial veins) merge in the cubital fossa (elbow pit) to form a vein in the forearm.