 It descends in front of the longus colli muscles.The prevertebral fascia is prolonged downward and laterally behind the carotid vessels and in front of the scalene muscles.It forms a sheath for the brachial nerves, subclavian artery, and subclavian vein in the posterior triangle of the neck; it is continued under the clavicle as the axillary sheath and is attached to the deep surface of the coracoclavicular fascia.