Comparative anatomical and ultrasonographic analysis of the accessory parotid gland in cadaveric specimens

The accessory parotid gland (APG) is a salivary tissue separated from the parotid gland (PG). Despite its higher malignancy risk than the PG, detailed anatomical data remain limited. This study aimed to characterize the prevalence, morphometry, and structural relationships of the APG through cadaveric dissection with direct ultrasonography (US) comparison. Twenty-eight hemifaces (mean age, 81.21 years, 7 females and 7 males) were analyzed. Pre-dissection US, cadaveric dissection, and post-dissection US were performed. APG prevalence was higher on dissection (35.7%) than on US (21.4%). All APGs were located superior to the parotid duct (PD), inferior to the Frankfort horizontal plane, and within the middle third of the cheek. The mean length and width were 22.1 ± 5.7 mm and 14.4 ± 2.7 mm, respectively, at a mean distance of 6.5 ± 4.2 mm from the PG. An accessory parotid duct draining into the PD was identified in 30.0% of cases. The buccal branches of the facial nerve showed three spatial patterns relative to the APG, namely superficial (66.7%), marginal (22.2%), and penetrating (11.1%). This study provides dissection-based anatomical reference data for the APG with direct US comparison that may serve as a practical reference for radiological evaluation and surgical planning.