The external jugular vein is often visible and very easy to locate. However, the presence of valves may hinder cannulation and result in misplacement. Thus, it is not a popular technique.
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The external jugular vein passes posteriorly over the sternomastoid muscle from the angle of the jaw and joins the subclavian vein behind the midpoint of the clavicle.
Place the patient head-down with their arms by the side and head turned away. Introduce the needle well above the clavicle and advance the needle over the vein at about 20 degrees to the frontal plane. When a free flow of blood appears, follow the Seldinger approach, as detailed previously. The valves may make introduction of the j-wire difficult.
As for internal jugular cannulation.