Anatomy of the localization and segmentation of the parapharyngeal segment of the internal carotid artery with an endoscopic transoral medial pterygomandibular fold approach

doi:10.16098/j.issn.0529-1356.2025.03.007

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Acta Anatomica Sinica ›› 2025, Vol. 56 ›› Issue (3) : 301-306. DOI: 10.16098/j.issn.0529-1356.2025.03.007

Anatomy

Anatomy of the localization and segmentation of the parapharyngeal segment of the internal carotid artery with an endoscopic transoral medial pterygomandibular fold approach

WANG Lei^1,2 XUE Kai^1,3 ZHANG Huan-kang^1,3 LIU Quan^1,3 SUN Xi-cai^1,3* YU Hong-meng^1,3*

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Abstract

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.

Key words

Internal carotid artery

/ Pterygomandibular fold / Parapharyngeal space / Transoral approach / Anatomy / Endoscopy / Human

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WANG Lei XUE Kai ZHANG Huan-kang LIU Quan SUN Xi-cai YU Hong-meng. Anatomy of the localization and segmentation of the parapharyngeal segment of the internal carotid artery with an endoscopic transoral medial pterygomandibular fold approach[J]. Acta Anatomica Sinica. 2025, 56(3): 301-306 https://doi.org/10.16098/j.issn.0529-1356.2025.03.007

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