目的  通过尸头解剖探索内镜经口翼下颌皱襞内侧入路咽旁段颈内动脉（ppICA）的定位标志和分段方法，并探讨其临床意义。   方法  于复旦大学附属眼耳鼻喉科医院鼻颅底肿瘤外科治疗技术创新单元解剖实验室对5例（10侧）新鲜冷冻尸头标本进行解剖，通过内镜下经翼下颌皱襞内侧入路对咽旁间隙进行分层解剖，对ppICA的定位标志及其毗邻结构进行解剖学研究。观察并描述ppICA相关的解剖定位标志并根据ppICA的毗邻结构对其进行解剖学分段，测量每1段ppICA的长度。   结果  肌肉结构是内镜经口翼下颌皱襞内侧入路的重要解剖标志。第1层肌肉包括咽上缩肌、腭帆张肌及翼内肌，第2层肌肉包括茎突咽肌、茎突舌肌、头长肌及腭帆提肌。茎突咽肌和腭帆提肌紧邻ppICA，是定位ppICA的可靠标志，并根据两者与ppICA的位置关系将ppICA分为3段：第1段ppICA（P1ICA）位于舌骨大角水平面和茎突咽肌上缘与ppICA交点水平面之间；第2段ppICA（P2ICA）位于茎突咽肌上缘与ppICA交点水平面和腭帆提肌下缘投影与ppICA交点水平面之间；ppICA第3段（P3ICA）位于腭帆提肌下缘投影与ppICA交点水平面至颈动脉管外口之间。P2ICA位于头长肌、茎突咽肌和腭帆提肌围成的解剖区域内，本文中我们将此区域命名为“动脉之窗”。在尸头标本下测量P1ICA长度为（36.5±7.3）mm，P2ICA长度为（15.5±1.6）mm，P3ICA长度为：（7.4±1.7）mm。   结论  肌肉结构是内镜经口翼下颌皱襞内侧入路中相对恒定的解剖参考标志，其中茎突咽肌和腭帆提肌是ppICA可靠的定位和分段标志，具有重要的临床意义。

Objective  To explore the anatomical landmarks and segmentation method  for the intraoperative identification of the cervical segment of the internal carotid artery by studying cadaveric dissections with an endoscopic transoral medial pterygomandibular fold approach and to investigate its clinical significance.   Methods  The head specimens of five fresh frozen cadavers were dissected in the anatomical laboratory of the Surgical Treatment Technology Innovation Unit of Nasal Skull Base Tumor in Eye & ENT Hospital of Fudan University. The parapharyngeal space was dissected layer by layer through the endoscopic transoral medial pterygomandibular fold approach, and the location marks of parapharyngeal internal carotid artery (ppICA) and adjacent structures of ppICA were anatomically studied. The anatomical landmarks associated with ppICA were observed and characterized, and the ppICA was segmented anatomically according to its adjacent structures. Then, the length of each ppICA segment was measured.  Results  Muscle structures were essential anatomical landmarks for an endoscopic transoral pterygoid medial approach that identifies mandibular folds. The first layer of muscles included the superior pharyngeal constrictor, tensor veli palatini, and medial pterygoid muscles. The second layer includes the stylopharyngeus, styloglossus, longus capitis, and levator veli palatini muscles. The stylopharyngeal and levator veli palatini muscles were close to the ppICA and were reliable landmarks for locating the ppICA. Furthermore, the ppICA was divided into three segments according to their positional relationship with the ppICA. The first segment of ppICA(P1ICA) was located between the greater horn plane of the hyoid bone and the intersection plane between the upper margin of stylopharyngeal muscle and ppICA. The second segment of ppICA (P2ICA) was between the plane where the upper edge of the stylopharyngeal muscle intersected with the ppICA and the plane where the projection of inferior edge of the levator veli palatini muscle intersected with the ppICA. The third segment of ppICA (P3ICA) was between the intersection of the lower margin projection of the levator veli palatini muscle and ppICA and the external orifice of the carotid canal. The P2ICA was within an anatomical region bounded by the levator veli palatini muscle, longus capitis muscle, and stylopharyngeus muscle. This region was termed “ICA window” in this paper measured under the cadaver head specimen, the lengths of P1ICA, P2ICA, and P3ICA were (36.5±7.3) mm, (15.5±1.6) mm, (7.4±1.7) mm respectively.   Conclusion  The muscular structure refers to the relatively constant anatomical reference landmarks within the endoscopic transoral medial pterygomandibular fold. The stylopharyngeus and levator veli palatini muscles are reliable landmarks for precisely locating and segmenting the ppICA, thus having essential clinical implications.