Fig. 3

Cervical emphysema in a 63-year-old man with tracheal rupture after endotracheal intubation (respiratory failure in CPOD patient complicated by lung infection). Contrast-enhanced CT scan at supra–hyoid (a and b) and infra-hyoid (c and d) cervical levels, illustrate the cervical fascia and its layers. The superficial or investing layer (green line) is superiorly attached to the superior nuchal line of the occipital, the mastoid process of the temporal bone and the inferior border of the mandible, and inferiorly to the manubrium, clavicles and scapula; laterally it merges with subcutaneous tissues of the neck. The middle fascia (pink line) runs, anteriorly, from the hyoid downwards in front of the trachea and large vessels, ultimately blending with the fibrous pericardium; and posteriorly from the skull base, attaches to the prevertebral fascia, and merges with the investing fascia at the lateral borders of the infrahyoid muscles. The deep or prevertebral layer (blue line) encircles the paraspinous and perivertebral muscles; it runs from the skull base downwards to the coccyx; its more anterior layer contribute to the posterior and lateral wall of the retropharyngeal space and insert on the diaphragm; it gives off a thin lamina, the alar layer, attached to the prevertebral layer by loose connective tissue, creating a potential space between mediastinum and neck, the dangerous space (orange shaded area)—for free movement of air/gas between mediastinum and neck