Prevertebral fascia
The prevertebral fascia extends medially behind the carotid vessels, where it assists in forming their sheath, and passes in front of the prevertebral muscles.
The prevertebral fascia is fixed above to the base of the skull, and below it extends behind the esophagus into the posterior mediastinal cavity of the thorax. 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