Sonographic anatomy and imaging of the great auricular nerve.

PURPOSE: The great auricular nerve (GAN) provides sensory innervation to the region of the parotid gland, angle of mandible, external ear and mastoid process. Sonographic imaging can allow lesions, injury and entrapment of the superficial GAN to be diagnosed. To sonographically image the GAN, its detailed relative anatomy, how and where it can be demonstrated with ultrasound, and its sonographic appearance should be appreciated.

METHODS

A review of the literature was conducted to unpack the path and course of the GAN, its areas of sensory innervation and how it should be clinically and sonographically assessed. Practical scanning workshops have informed the technique to sonographically image the GAN.

RESULTS

Magnetic resonance imaging is best used to demonstrate the proximal path of the GAN deep to the sternocleidomastoid muscle. Ultrasound imaging can be used for imaging the superficial portion of the GAN and guiding therapeutic injections. The superficial GAN can be easily sonographically located overlying the sternocleidomastoid muscle (SCM) in the mid neck and tracked inferiorly (proximally) and superiorly (distally) from this point including to its branches.

CONCLUSION

Sonographic imaging of the GAN and ultrasound guided injections around it, require an appreciation of the GAN path, its detailed relative anatomy, sonographic appearance and technique to image it, as well as common structural and clinical conditions that can impact it.