This protection is important during venipuncture (taking blood) from the median cubital vein.

There exists a fair amount of variation of the median cubital vein.

The blood is drawn from a large arm vein close to the skin, usually the median cubital vein on the inside of the elbow.

Blood is most commonly obtained from the median cubital vein, which lies within the cubital fossa anterior to the elbow.

The preferred injection site is the crook of the elbow (i.e., the Median cubital vein), on the user's non-writing hand.

In human anatomy, the median cubital vein (or median basilic vein) is a superficial vein of the upper limb.

There is a connecting vein between the two, the median cubital vein, which passes through the cubital fossa and is clinically important for venepuncture (withdrawing blood).

Typically, a prominent vein in the forearm such as the median cubital vein would suffice, although the Keidel vacuum can take blood for any prominent peripheral vein.

The most convenient site is often the arm, especially the veins on the back of the hand, or the median cubital vein at the elbow, but any identifiable vein can be used.

It communicates with the basilic vein via the median cubital vein at the elbow and is located in the superficial fascia along the anterolateral surface of the biceps brachii muscle.

Several veins are also in the area (for example, the median cubital vein, cephalic vein, and basilic vein) but these are usually considered superficial to the cubital fossa, and not part of its contents.

Near the region anterior to the cubital fossa, in the bend of the elbow joint, the basilic vein usually connects with the other large superficial vein of the upper extremity, the cephalic vein, via the median cubital vein (or median basilic vein).