Anatomy of the cervicothoracic junction: a study of cadaveric dissection, cryomicrotomy, and magnetic resonance imaging.

The morphologic characteristics of the cervicothoracic junction from C6 to T2 were examined. Gross dissection and cryomicrotomy was performed on 13 fresh cadavers. Four healthy volunteers underwent magnetic resonance imaging. Results indicated that vertebral body dimensions do not change appreciably, except for vertebral body heights and medial pedicular angulation, both of which increase from C6 to T2. Based on the findings of gross dissection and cryomicrotomy, the mediolateral width of the spinal canal was largest at C6 to accommodate the larger spinal cord at C6. The cross-sectional area ratios of the spinal cord to spinal canal were 1:2.3 at C6, 1:3.7 at C7, 1:4 at T1, and 1:3.7 at T2. The foraminal height and width were greater at C7-T1 and T1-T2 than at C6-C7. The thinnest lamina was at C7. The anatomy of the pedicles showed that the outer mediolateral diameter averaged 6.78 mm at C6, 7.5 mm at C7, 9.23 mm at T1, and 7.9 mm at T2. The superior-inferior diameter of the pedicle increased from 7.58 mm at C6 to 12.43 mm at T2. Medial angulations decreased from 44.5 at C6 to 23.35 at T2. The coronal angulation of the exiting nerve was 64.83 for C7, 79.83 for C8, and 90.33 for T1 nerve roots based on coronal magnetic resonance imaging. Finally, gross dissection during the anterior approach to the cervicothoracic junction revealed that this approach was extensible, allowing access to the anterior aspect of the cervicothoracic spine. Associated vital structures must be protected, such as the arch of aorta, common carotid artery, innominate vein, thoracic duct, recurrent laryngeal nerve, stellate ganglion, trachea, and esophagus.