Fig. 1. (  A ) Catheterization site. (  B ) Anatomical structures at the catheterization site:  1 = clavicular head of the claviculosternocleidomastoid muscle;  2 = sternal head of the claviculosternocleidomastoid muscle;  3 = internal jugular vein;  4 = subclavian vein;  5 = point of needle insertion;  6 = clavicle;  7 = sternum;  8 = claviculosternomastoid angle.