Step-by-Step Endonasal Endoscopic Dissection to the Pterygopalatine Fossa, Parapharyngeal Space, and Infratemporal Fossa

Objectives: Anatomical dissection to illustrate the step-by-step endoscopic endonasal approach to the pterygopalatine (PPF), parapharyngeal space (PS) and infratemporal fossa (ITF), emphasizing the landmarks and the complex anatomy of those areas. Methods: Three embalmed and latex-injected human head specimens were used for dissection. The procedures were documented with high-quality 2D and 3D images. All data were obtained in accordance with the Committee for Cadaveric use in Research. Initially, a total ethmoidectomy, sphenoidotomy, and wide maxillary antrostomy were performed. A great exposure of the posterior wall of the maxillary sinus (MS) was achieved. Subsequently, the posterior wall of the MS was removed to expose the PPF contents and pterygoid musculature of the ITF. Then, the pterygoid plates were removed with exposure of the eustachian tube (ET) and parapharyngeal space, including the internal carotid artery (ICA). Finally, part of the pterygoid base was drilled to expose the lateral recess of the sphenoid and the lacerum ICA. Results: [ Figs. 1 ], [ 2 ], and [ 3 ] illustrate the step-by-step anatomical dissection and relevant anatomical landmarks. The sphenopalatine foramen was an important landmark to start the removal of the posterior wall of the MS and exposure of the PPF. The proximal segment of the vidian nerve runs lateral to the lacerum ICA and superior to petrous ICA. Careful drilling of the pterygoid base should be taken when drilling inferior and medial to the proximal segment of the vidian nerve. The ET is anterior and “protects” the parapharyngeal ICA. Care should be taken during resection of the posterior and lateral attachments of the ET due to the proximity to the ICA. Conclusion: This study described a detailed step-by-step approach to guide the endonasal endoscopic access to the PPF, parapharyngeal space and ITF. It is highlighted the importance of mastering the surgical landmarks of each step and the deep anatomical knowledge of those areas. Fig. 1 ( A–D, F ) Antrostomy and exposure of the posterior wall of the maxillary sinus; ( E ) anteroposterior ethmoidectomy and sphenoidectomy. Fig. 2 Removal of the posterior wall of the maxillary sinus to reach the pterygopalatine fossa contents. Fig. 3 ( A ) Detachment of the pterygoid muscles and view of the ITF with the maxillary nerve (V3). ( B–E ) removal of the pterygoid plates with exposure of the ET and parapharyngeal space with ICA. ( F–H ) removal of the ET and part of the pterygoid base to expose the lateral recess of the sphenoid and the lacerum ICA. ITF, infratemporal fossa; ICA, internal carotid artery; ET, eustachian tube. Publication History Article published online: 15 February 2022 © 2022. Thieme. All rights reserved. Georg Thieme Verlag KG Rüdigerstraße 14, 70469 Stuttgart, Germany