Which vein is located on the outermost side of the upper arm?

The cephalic vein is indeed located on the outermost side of the upper arm. It runs along the lateral aspect of the arm and is typically more visible and accessible than the other veins in that region, making it a common choice for venipuncture.

In context, the basilic vein, although it is a significant vein in the upper arm, is found on the medial side, making it less accessible compared to the cephalic vein. The median cubital vein, primarily located at the elbow, connects the basilic and cephalic veins but does not extend along the outer side of the upper arm. The subclavian vein is located deeper in the body, beneath the clavicle, and is not directly associated with the upper arm's outer anatomy. Understanding the positioning of these veins is crucial for procedures that require venous access.