The Sympathetic Trunk

The cervical sympathetic chain consists of several ganglia, between two and four, and the trunk connecting them. The sympathetic trunk lies medial to the phrenic nerve and posterior to the carotid sheath. It may be found during the dissection of the carotid sheath, when the surgeon carries the dissection too far medially over the deep muscles (Figs. 5-24 and 5-25). In these cases it may be mistaken for the vagus nerve when, in reality, the vagus nerve runs more anteriorly within the carotid sheath, not posterior to it, between the carotid artery and the internal jugular vein. Precise knowledge of the anatomy of this area is important to prevent injury to the sympathetic trunk.

Figure 5-24 Lateral view of the contents of the carotid sheath on the right side. IJ, internal jugular vein; vn, vagus nerve; st, sympathetic trunk; ac, ansa cervicalis.

The basic references for identifying the sympathetic trunk are its close relation to the posterior wall of the carotid artery and its medial situation with respect to other neural neck structures. Unlike the phrenic nerve, the sympathetic trunk does not lie upon the anterior scalene muscle, but medial to it.

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