The Auriculotemporal Nerve: A Comprehensive Review of Its Anatomical Variation and Clinical Manifestations.

Objectives: Various studies have described anatomical variations of the auriculotemporal nerve (ATN), starting with its initial nerve roots and relationship to the middle meningeal artery (MMA). Despite its crucial role in innervating various regions, the precise anatomical course of ATN and its variants remains uncertain. This study aims to provide a comprehensive review of the ATN, including its anatomical course, variations, and clinical significance, particularly in relation to head and neck surgery. Methods: A systematic literature review was conducted using Medline, Embase, and PubMed databases to identify all articles describing the clinical anatomy of ATN. This search strategy adhered to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) guidelines. English-language and human studies were selected. Additionally, dissections were performed on three human cadavers to obtain representative images. Results: ATN exhibited 1-5 roots, most commonly two (52%), relevant to surgical planning and perineural tumor spread. An inferior alveolar root origination was present in 32.6% of specimens, potentially contributing to unexpected anesthesia or neuralgia. ATN enclosed the MMA in 72.2%, often forming a triangle/V-shaped (61.4%) or "buttonhole" (1.7%) configuration. TMJ innervation was present in all specimens, with 5.8% of branches penetrating the lateral pterygoid, implicating TMJ pain. ATN branches crossed the superficial temporal artery in 73% of cases, relevant to migraine decompression. Parotid branches originated 2-16 mm from the tragus, impacting Frey's syndrome and tumor tracking. Facial nerve communication (> 90%) and greater auricular nerve connection (up to 30%) may underlie atypical facial pain and extended anesthesia fields. Conclusions: Our review reveals considerable diversity in ATN origins, branching patterns, and relationships with adjacent vessels, challenging traditional anatomical depictions. Understanding these variations is crucial for managing compression and entrapment syndromes like temporomandibular disorder and surgical procedures such as parotidectomy, where iatrogenic damage can lead to complications such as Frey Syndrome.