Venstre arteria subclavia er more deeply placed than the høyre in the first part of its course, and, as a rule, does not reach quite as high a level in nakken. The posterior border of the Sternocleidomastoideus corresponds pretty closely to the lateral border of the Scalenus anterior, so that the tredje portion of arterien, the part most accessible for operation, lies immediately lateral to the posterior border of the Sternocleidomastoideus.