 Immediately above and behind the clavicle an areolar space exists between the investing layer and the sheath of the subclavian vessels, and in this space are found the lower part of the external jugular vein, the descending clavicular nerves, the transverse scapular and transverse cervical vessels, and the inferior belly of the omohyoid muscle.This space is limited below by the fusion of the coracoclavicular fascia with the anterior wall of the axillary sheath.Inferiorly, the prevertebral layer blends with the endothoracic fascia peripherally and fuses with the anterior longitudinal ligament centrally at approximately the level of the T3 vertebra.