The Great Auricular Nerve (GAN) is the largest sensory branch of the cervical plexus, and is specifically supplied by C2–3. The GAN will branch off the superficial cervical plexus around Erb’s Point and run anteriorly along the sternocleidomastoid (SCM) [1]. The GAN is divided into two branches: the anterior branch and the posterior branch. The anterior (facial) branch provides cutaneous innervation to the parotid gland, and the posterior (mastoid) branch provides cutaneous innervation to the angle of the mandible and posterior surface of the auricle [2].

GAN sacrifice is common in malignant tumor excisions and radical neck dissections. However, preservation is the standard of care in elective procedures like rhytidectomy, platysmaplasty, and the management of benign pathology. GAN complications like paresthesia, anesthesia, or painful neuromas occur 6–7% [3]. Anatomical variation in length and course of the GAN exists as described by Yang et. al where they characterized five branching types [4]. Therefore, during surgical procedures, GAN can be at risk for damage due to anatomical variations and result in sensory deficits. For essential procedures, such as parotidectomies, intraoperative GAN sacrifice is reported, but there is conflicting evidence if GAN preservation can improve postoperative cutaneous sensation [5]. In addition, there will most likely be sensory deficits, regardless of the preservation or sacrifice of GAN. Loss of GAN function does not significantly impact the quality of life [5,6,7]. However, efforts should be made to preserve the GAN if possible, especially in elective procedures. For example, in a rhytidectomy, the GAN is the most likely nerve to be injured, with a complication rate of 6–7% annually [8]. Although GAN injury may be unavoidable in certain cases, inflicting iatrogenic nerve injury in elective cosmetic surgeries falls below the standard of care. A careful understanding of the location and course of the GAN during high risk surgical procedures is essential.

Commonly measured bony landmarks include Erb’s Point, McKinney’s Point, nerve point, and punctum nervosum. Erb’s Point is most commonly used to describe the exit of the cutaneous branches of the cervical plexus, located at the posterior border of SCM [9]. However, Raikos et. al argues all four points are misnomers and identifies the GAN via the Great Auricular Point where the nerves exits at the posterior border of SCM [10]. Aside from named points, there are various landmarks used to identify the GAN, and most studies incorporate both soft tissue and bony anatomical landmarks. Several resources investigated the course of GAN along SCM, where the GAN is reliably found within the middle third of the muscle [3, 10, 11]. Additionally, the external jugular vein is reliably found anterior to the GAN [3, 8]. Rohrich et al focused on the preauricular adipose compartments where the main branch of GAN was reproducibly found in the subauricular membrane [12]. While multiple soft tissue landmarks have been identified, hard tissue landmarks are arguably more reliable due to their fixed positioning and resistance to specimen weight. In terms of bony landmarks, commonly measured points include the mastoid process, angle of the mandible, and external auditory canal [3, 11]. Although these reference points exist, there is not a clear consensus on their reliability. The advantages of fixed bony landmarks include their simple identification and consistent measurements intraoperatively, which makes them advantageous over soft tissue anatomical landmarks. Therefore, a reliable anatomical landmark is advantageous; fixed bony landmarks could potentially provide the surgeon with intraoperative guidance to avoid injury. Specifically, the measurement will focus on the ratio at which the AOM and the tip of the mastoid process bisect GAN.