Final answer:
The subclavian vein divides down the arm into the cephalic vein and the basilic vein, which are responsible for returning blood from the upper limbs to the heart.
Step-by-step explanation:
The subclavian vein divides down the arm into two main veins: the cephalic vein and the basilic vein. The cephalic vein runs along the lateral aspect of the arm and drains into the axillary vein, while the basilic vein runs on the medial aspect of the arm and also drains into the axillary vein. Together, these veins are essential for returning deoxygenated blood from the upper limbs back to the heart, where it then enters the superior vena cava.