C2 At least one cm lateral to the occipital protuberance at the base of the skull. Alternately, it can be located at least 3 cm behind the ear. C3 In the supraclavicular fossa, at the midclavicular line. C4 Over the acromioclavicular joint. C5 On the lateral (radial) side of the antecubital fossa just proximal to the elbow (see image below). C6 On the dorsal surface of the proximal phalanx of th..