3.2.7 Zone 7

The greater auricular nerve arises from the anterior primary rami of the second and third cervical nerves. It provides sensory innervation to the lower two-thirds of the auricle, the skin underneath the ear, and the posterior two-thirds of the jawline. The nerve pierces the deep cervical fascia at the posterior border of sternocleidomastoid and runs on the muscle, superficial and posterior to platysma toward the angle of the jaw. At a point 6.5 cm inferior to the external auditory canal, the nerve can be found halfway between the posterior and anterior borders of the sternocleidomastoid [16]. Below the ear it divides into anterior and posterior branches. This danger zone can be considered as an oblong, 2 cm wide and 6 cm long, with its center on a point 6.5 cm below the external auditory meatus oriented parallel to the external jugular vein (Fig. 3.7). The greater auricular nerve is prone to injury during neck dissections and suture plication of platysma to the mastoid fascia.

Great care should be taken as dissections proceed forward from the postauricular incision toward the nerve. It is identifiable about 1 cm posterior to the external jugular vein and runs parallel to it. The dissection in this zone should be in the subcutaneous plane, superficial to the nerve. When platysma is mobilized, it should be redraped over the nerve, and care should be taken not to compress or include the nerve or its branches in the suture. Injury to the greater auricular nerve may result in numbness, dysesthesia, or chronic hypesthesia in the skin of the inferior part of the ear, and skin anterior and inferior to this area.

3.3 Conclusions

No surgical procedure is without risks and potential complications. In the face, although there are several risks associated with surgery, such as infection, bleeding, and hematoma, the most serious complication is injury to one of the cranial nerves. Injury to one of the facial nerve branches, such as transection, traction, thermal injury, or blunt trauma, may present as weakness, asymmetry, or total paralysis of the brow, eye, lips, and mouth. There are several, welldefined areas or zones in the face where the important motor and sensory nerves have a predictable path. Mapping these danger zones out before surgical intervention, using bony landmarks where possible, helps orient the surgeon during dissections of the face and neck and may reduce the incidence of significant complications.

Fig. 3.7 Danger zone 7. This lies 6.5 cm below the external auditory meatus, in the middle of sternocleidomastoid, parallel to the external jugular vein. The greater auricular nerve is prone to injury as it passes through this danger zone behind the border of platysma

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