Vena Taka.

The lateral fragment is depressed by the weight of the arm and is pulled medially and forward by the strong adductor muscles of the shoulder joint, especially the pectoralis major.

The guy on the right had a knife with a 10 inch blade, and he went in under my elbow, and it went up and cut my inferior vena cava.

The superior vena cava (also known as the cava or cva) is a large diameter, yet short, vein that carries deoxygenated blood from the upper half of the body to the heart's right atrium.