The external carotid artery (ECA) is a major artery of the head and neck. Although numerous studies describe the variability of ECA branches, the course variation of the ECA was seemingly overlooked. It was aimed to study the morphological possibilities of the retromandibular segment of the ECA. A retrospective study was performed on 60 computed tomography angiograms of 26 male and 31 female adult patients. Three types of retromandibular ECA were defined: type 1 – the ECA has a straight course deep to the anatomical plane of the ramus of the mandible; type 2 – the ECA makes a retromandibular loop directed laterally, extending externally to the anatomical plane of the ramus of the mandible; and type 3 – the retromandibular loop directed laterally reaches just behind the posterior margin of the ramus of the mandible. Type 1 was found in just 43.33%, type 2 in 18.33%, and type 3 in 38.33% of 120 sides cases. On the right, type 1 was significantly associated with the male gender, and type 3 with the female gender (Pearson Chi2=10.9, p=0.004). On the left, there were no statistically significant associations (Pearson Chi2=3.5, p=0.153). In 20 cases, the retromandibular course of the ECA was asymmetrical; in 21 cases, type 1 was recorded bilaterally; in 5 cases, type 2 was bilaterally symmetrical; and in 14 cases, type 3 was found bilaterally. These previously undocumented types of ECA are relevant during parotid surgery and should be investigated preoperatively on a case-by-case basis.

中文翻译：

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颈外动脉下颌后环

颈外动脉（ECA）是头颈部的主要动脉。尽管大量研究描述了 ECA 分支的变异性，但 ECA 的路线变异似乎被忽视了。目的是研究 ECA 下颌后段的形态可能性。对 26 名男性和 31 名女性成年患者的 60 例计算机断层扫描血管造影进行了回顾性研究。下颌后 ECA 被定义为三种类型： 1 型 – ECA 具有直达下颌升支解剖平面的深度；类型 2 – ECA 形成一个横向的下颌后环，向外延伸至下颌升支的解剖平面；类型 3 – 下颌后环横向延伸至下颌升支后缘后方。在 120 例病例中，1 型仅占 43.33%，2 型占 18.33%，3 型占 38.33%。右侧，1 型与男性显着相关，3 型与女性显着相关（Pearson Chi2=10.9，p=0.004）。左侧，没有统计学上显着的关联（Pearson Chi2=3.5，p=0.153）。 20例中，ECA下颌后走行不对称； 21例为双侧1型； 2型双侧对称5例； 14例为双侧3型。这些以前未记录的 ECA 类型与腮腺手术相关，应在术前根据具体情况进行调查。