The great auricular nerve (GAN) is the largest branch of the superficial cervical plexus (see Chapter 60, Fig. 60-1). It provides cutaneous innervation to the periauricular region.¹ The GAN wraps around the posterior border of the sternocleidomastoid muscle (SCM) and then courses superiorly and anteriorly, dividing into anterior and posterior branches.² Because of its superficial location, the GAN can be damaged during surgical procedures in the neck.³ The nerves of the superficial cervical plexus lie deep to the platysma when first emerging from the plexus, but superficial to the prevertebral fascia.

The GAN lies superficial to the lateral border of the SCM and can be traced to the preauricular area or back to the superficial cervical plexus. The lesser occipital nerve has similar anatomy, except that it can be followed behind the ear.

Suggested Technique

The GAN has a characteristic monofascicular or bifascicular appearance on ultrasound scans where it courses over the SCM. The GAN flattens in shape slightly as it lies over the SCM. The nerve becomes difficult to image at the lateral corner of the SCM. This point is about the level of the cricoid cartilage. Isolated GAN blocks are possible, but its large size and characteristic ultrasound appearance make the GAN a convenient way of identifying the position of the remainder of the superficial cervical plexus.

Because the GAN is very superficial, an out-of-plane approach to GAN block is usually used with the nerve viewed in short axis. The GAN lies near the external jugular vein, so vascular puncture and minor bleeding are possible.

Clinical Pearls

• The GAN consists of contributions from the second and third cervical nerves. The GAN divides into anterior and posterior branches.

• The GAN often can be seen both superficial and deep to the sternocleidomastoid muscle within one plane of imaging because the nerve loops around the posterolateral border of this muscle.

• Dominance patterns of cutaneous innervation of the external ear have been examined.⁴ Most patterns are either lesser occipital or great auricular dominant.

FIGURE 59-1 Above, left, In 11 of 19 hemifaces (58%), the lesser occipital nerve innervated the superior one third of the ear. Above, right, In 3 of 19 hemifaces (16%), the great auricular nerve provided sensory supply to the entire ear. Below, left, In 4 of 19 hemifaces (21%), the lesser occipital nerve supplied the superior two thirds of the ear. Below, right, In 1 of 19 hemifaces (5%), the lesser occipital nerve innervated the majority of the ear, and the great auricular nerve supplied the earlobe.

(From Pantaloni M, Sullivan P. Relevance of the lesser occipital nerve in facial rejuvenation surgery. Plast Reconstr Surg 2000;105(7):2594–9.)

FIGURE 59-2 External photograph showing an out-of-plane approach to great auricular nerve block (A). The corresponding sonogram is shown before needle placement (B).

FIGURE 59-3 Short-axis view of the great auricular nerve near the posterolateral border of the sternocleidomastoid muscle (A). The great auricular nerve divides into anterior and posterior branches (B).

FIGURE 59-4 Short-axis view of the great auricular nerve before (A) and after (B) injection of local anesthetic. Local anesthetic is seen to distribute around the nerve.

FIGURE 59-5 The great auricular nerve descends to loop around the posterolateral edge of the sternocleidomastoid muscle, and therefore can be visible both above and below this muscle within one transverse plane of imaging. Sliding the transducer caudally verifies that these two nerves join at the muscle border. The great auricular nerve can be blocked deep to the sternocleidomastoid muscle for more complete anesthesia.