Establishing a Zonal Anatomic Scheme for the Parapharyngeal Space and Infratemporal Fossa Based on Five Surgical Approaches

Establishing a Zonal Anatomic Scheme for the Parapharyngeal Space and Infratemporal Fossa Based on Five Surgical Approaches | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Establishing a Zonal Anatomic Scheme for the Parapharyngeal Space and Infratemporal Fossa Based on Five Surgical Approaches Xue-Ying Liu, Bing-Huang Zhang, Zhao-hui Shi, Xian-Yang Luo This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6572118/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Objective To develop an anatomical zonal scheme for the parapharyngeal space and infratemporal fossa based on various surgical approaches, including the transnasal posterior maxillary sinus wall approach, the transnasal antrostomy approach, the transoral medial pterygomandibular fold approach, the transoral posterior pharyngeal wall approach, and the transoral retromolar approach. Methods Ten sides from five fresh cadaveric heads were dissected using endoscopic transnasal and transoral approaches to explore the parapharyngeal space and infratemporal fossa. Anatomical landmarks and relationships were observed and recorded for each approach to define the anatomical boundaries of each dissection zone. Results Based on the surgical approaches, the parapharyngeal space and infratemporal fossa were divided into five zones: Zone NO (transnasal posterior maxillary sinus approach), located posterior to the posterolateral wall of the maxillary sinus, laterally to the deep surface of the temporalis muscle, inferiorly to a plane above the maxillary sinus floor, superiorly to the middle cranial fossa floor, medially to the lateral pterygoid plate, medial to the ramus of the mandible and the temporalis muscle attachment, anteriorly to the posterior maxillary sinus fat space, and posteriorly to the styloid process and its associated fascia; Zone NI (transnasal pterygoid approach), encompassing the pterygopalatine fossa (including the medial pterygoid plate), tensor veli palatini muscle, levator veli palatini muscle, cartilaginous portion of the eustachian tube, parapharyngeal muscle group, and nasopharyngeal mucosa; Zone B (transoral infra-pterygomandibular fold medial approach), located inferior to the maxillary sinus floor, inferior to the lateral pterygoid muscle, medial to the medial pterygoid muscle, and medial to the deep lobe of the parotid gland, anterior to the stylomandibular fascia; Zone C (transoral lateral molar approach), located medial to the ascending ramus of the maxilla, lateral to the medial pterygoid muscle, inferior to the lateral pterygoid muscle, and lateral to the deep temporalis muscle group; and Zone D (transoral posterior pharyngeal approach), encompassing the retrostyloid space and part of the jugular foramen area, specifically the area posterior to the styloid process and its associated muscles and stylomandibular fascia (styloid septum), and anterior to the deep cervical fascia (prevertebral fascia). Conclusion This study proposes a revised zonal anatomy of the parapharyngeal space and infratemporal fossa based on different surgical approaches, aiming to provide a reference for preoperative assessment and surgical planning to minimize injury to vital neurovascular structures and muscles. Parapharyngeal space Infratemporal fossa Endoscopic transnasal approach Endoscopic transoral approach Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Introduction The parapharyngeal space and infratemporal fossa are complex regions of the head and neck, characterized by indistinct boundaries and a dense neurovascular network. The anatomical definition of the infratemporal fossa remains inconsistent across literature. In a broad definition, the infratemporal fossa encompasses the parapharyngeal space and masticator space. However, a stricter definition confines it to the region posterior to the body of the maxilla and zygomatic arch, medially bounded by the lateral pterygoid plate, and laterally by the ramus of the mandible. Its inferior and posterior boundaries are open [ 1 ] , while the superior medial boundary is formed by the greater wing of the sphenoid and squamous part of the temporal bone, representing a portion of the middle cranial fossa floor. Recent advances in endoscopic technology and surgical instrumentation have enabled the successful application of transoral endoscopic surgery in the resection of parapharyngeal space and infratemporal fossa tumors, demonstrating favorable clinical outcomes [ 2 – 5 ] . Multiple distinct endoscopic approaches exist for parapharyngeal space and infratemporal fossa surgery, accommodating the varied locations of lesions. Traditional anatomical compartmentalization of the infratemporal fossa primarily relies on anatomical spaces [ 6 ] , limiting its direct applicability to surgical planning. This study employs fresh cadaveric heads to simulate transoral endoscopic approaches, aiming to enhance understanding of infratemporal fossa anatomy and propose a novel infratemporal fossa compartmentalization based on different endoscopic approaches. Materials and Methods 2.1 Study Materials This study utilized ten sides from five fresh adult cadaveric heads. The arterial systems were injected with red latex, and the venous systems with blue latex. Surgical instruments included a Davis mouth gag, a round knife, suction, a tonsil dissector, probes, and standard nasal surgical instruments. The endoscopic system comprised 4 mm 0° and 30° rigid nasal endoscopes (Karl Storz), equipped with a cold light source, high-definition camera system, and high-definition image workstation. 2.2 Treatment This study utilized ten sides from five fresh adult cadaveric heads obtained from the endoscopic anatomy training center of Professor Geng Xu, Qifusheng Hospital, Guangdong Province (gender unspecified). Specimens were injected with red latex into the arterial system and blue latex into the venous system. Subsequently, anatomical observations were performed using simulated transnasal and transoral endoscopic surgical approaches. The results are presented as follows: 1. Transnasal posterior maxillary sinus approach: Initially, the entire ethmoid sinuses and lateral nasal wall were opened to expose the posterior maxillary sinus wall, clearly identifying the location of the infraorbital groove (or notch). The posterior maxillary sinus wall bone was removed using a drill to expose the underlying fascioadipose layer. After resection of this layer, the lateral pterygoid plate, temporalis muscle, maxillary artery and its branches, and lateral pterygoid muscle were sequentially exposed. The lateral pterygoid muscle was dissected along the lateral pterygoid plate to expose the foramen ovale and branches of the mandibular nerve. Finally, portions of the lateral pterygoid muscle were resected to fully expose the temporomandibular joint externally and the pterygomaxillary fascia posteriorly. (2) Transnasal pterygoid approach: Blunt dissection was performed along the palatal mucosa to expose the medial pterygoid plate. Careful dissection along the bone surface allowed for the detachment of the tensor veli palatini and levator veli palatini muscles until the cartilaginous portion of the eustachian tube was exposed, thus gaining access to the parapharyngeal space. After resection of the vertical plate of the palatine bone, the pterygopalatine fossa was exposed. The medial pterygoid plate was then drilled to fully expose the medial aspect of the lateral pterygoid plate. At the base of the pterygoid process, the Vidian nerve was identified and the foramen rotundum and maxillary nerve (V2) precisely located. By inferiorly displacing the eustachian tube and continuing the dissection along the Vidian nerve, the petrous portion of the internal carotid artery was ultimately exposed. (3) the pterygomandibular fold, extending superiorly to the hamulus and inferiorly to the level of the tongue base. The superior pharyngeal constrictor muscle was longitudinally incised to expose the parapharyngeal space fat, laterally bordered by the medial pterygoid muscle. After clearing the fat, the ascending palatine artery was exposed. Inferiorly, the stylopharyngeus and styloglossus muscles were visualized. Superiorly, posterior to the hamulus, the tensor veli palatini muscle was identified, with the levator veli palatini muscle medial to it. The cartilaginous portion of the eustachian tube was visible superior and posterior to the levator veli palatini. The stylopharyngeal fascia was opened posteriorly to enter the retropharyngeal space. Deeper structures required careful dissection. After retracting the stylohyoid muscle group laterally, the carotid sheath was exposed, revealing the ascending pharyngeal artery and longus capitis muscle medial to the carotid sheath. Retropharyngeal lymph nodes were identified between the longus capitis muscle and the carotid sheath. The carotid sheath was opened to expose the internal carotid artery and the posterior cranial nerves. A 0° Storz endoscope was used to photograph the aforementioned anatomical structures and record their spatial relationships. (4) Transoral posterior pharyngeal approach: A mouth gag was placed, and a catheter was inserted through the nasal cavity to retract the contralateral soft palate, providing adequate exposure of the lateral pharyngeal wall. Under 0° endoscopy, a longitudinal mucosal incision was made using a sickle knife posterior to the palatopharyngeal arch, beginning posterior to the torus tubarius and extending vertically downwards to the level of the tongue base. In the direction of the incision, the pharyngeal constrictor muscles were sharply incised, and blunt dissection was performed posterolaterally to expose the longus capitis muscle and its anterior fascia. Further blunt lateral dissection at the lateral border of the prevertebral muscles allowed identification of the stylopharyngeal fascia overlying the carotid sheath. Careful dissection of the stylopharyngeal fascia revealed the ascending pharyngeal artery. Opening the carotid sheath exposed the internal carotid artery (ICA), internal jugular vein, jugular bulb, and posterior cranial nerves. (5) Transoral lateral molar approach: A longitudinal incision was made lateral to the line connecting the maxillary and mandibular molars, incising the buccal mucosa and buccal fat pad. The lateral aspect of the medial pterygoid muscle and the medial aspect of the mandibular ramus were exposed. The anterior extent of the incision reached the buccal nerve. Blunt dissection was performed posteroinferiorly along the medial aspect of the mandibular ramus, exposing the mandibular foramen, inferior alveolar nerve and artery, and a portion of the superior head of the lateral pterygoid muscle. The inferior alveolar artery was traced to the maxillary artery. The inferior alveolar nerve, accompanied by the lingual nerve, was traced to other branches of the mandibular nerve. Superior dissection of the lateral pterygoid muscle, with partial resection, exposed the foramen ovale. Inferior dissection along the maxillary artery exposed the styloid process, the lateral parapharyngeal space, including the trunk of the facial nerve, the stylomastoid foramen, and the external carotid artery. Results The surgical dissection consisted of endoscopic nasal and transoral approaches. The endoscopic nasal approach commenced with either lateral nasal wall resection or a Denker's approach to achieve adequate exposure of the posterior maxillary sinus wall, establishing two surgical corridors: a transnasal posterior maxillary sinus approach and a transantral-infundibular approach. The transoral endoscopic portion utilized a mouth gag to optimize visualization of the oropharynx and tongue base, creating three surgical corridors: a transoral medial pterygomandibular fold approach, a transoral posterior pharyngeal approach, and a transoral lateral molar approach. Based on these distinct surgical approaches, the parapharyngeal space and infratemporal fossa were subdivided into five anatomical regions ( Fig. 1 ). (1) The NO zone is defined anatomically as the region posterior to the posterolateral maxillary sinus wall, extending laterally to the deep surface of the temporalis muscle, inferiorly to a plane above the maxillary sinus floor, superiorly to the floor of the middle cranial fossa, medially to the lateral aspect of the lateral pterygoid plate, the medial aspect of the ascending ramus of the mandible, and the medial aspect of the temporalis muscle attachment, anteriorly to the posterior aspect of the posterior maxillary fat pad, and posteriorly to the styloid process and its fascia. Surgical access involved removal of the posterior maxillary sinus wall to locate the infraorbital canal on the maxillary sinus roof. The maxillary nerve was then identified posteriorly. After locating the lateral pterygoid plate and removing fatty tissue, branches of the maxillary artery, the temporalis muscle, and the buccal nerve were visualized. Resection of the lateral pterygoid muscle and a portion of the temporalis muscle exposed the various branches of the mandibular nerve and the foramen ovale. (Fig. 2 ) (2) Zone NI encompasses the pterygopalatine fossa (including the medial pterygoid plate), tensor veli palatini muscle, levator veli palatini muscle, cartilaginous portion of the Eustachian tube, parapharyngeal muscles, and the nasopharyngeal mucosa. Its superior boundary is defined by the course of the maxillary nerve. Surgical access within this zone primarily centers on the pterygoid bony structures. Identification of the pterygoid canal is crucial; following its course, bone removal allows posterior access to the foramen lacerum. Inferiorly, dissection along the posterior wall of the maxilla provides access to the parapharyngeal space, with posterior identification of the Eustachian tube. ( Fig. 3 ) (3) Zone B is situated inferior to the maxillary sinus floor, inferior to the lateral pterygoid muscle, medial to the medial pterygoid muscle, medial to the deep parotid lobe, and anterior to the stylomandibular fascia, primarily comprising the prestyloid space. A vertical incision medial to the pterygomandibular fold exposes the pterygoid hamulus; the medial pterygoid muscle lies inferolateral to it, and the tensor veli palatini muscle inserts posterior to the hamulus. Incision of the superior pharyngeal constrictor muscle provides access to the parapharyngeal space, revealing its fatty tissue. After dissection of this fat, the ascending palatine artery becomes visible, along with the stylopharyngeus and stylohyoid muscles inferiorly, and the stylomandibular fascia posteriorly. This approach offers excellent visualization of these structures, representing its key advantage. Further dissection through the stylomandibular fascia exposes the retrostyloid space, revealing the internal carotid artery, posterior cranial nerves (IX-XII), retropharyngeal lymph nodes, and the longus capitis muscle. ( Fig. 4 ) (4) Zone C represents the surgical field accessed via a retromolar extraoral approach. This approach offers superior visualization of the medial aspect of the ascending ramus of the maxilla, the lateral aspect of the medial pterygoid muscle, the region inferior to the lateral pterygoid muscle, and the lateral aspect of the deep temporal muscles. A vertical incision is made over the retromolar region, exposing and preserving the buccal nerve. Blunt dissection proceeds along the bony surface of the mandibular ramus. The initial surgical field is relatively confined; however, extending the incision superiorly expands the surgical exposure, allowing identification of the mandibular foramen, inferior alveolar nerve, and inferior alveolar artery posteriorly, and the lateral pterygoid muscle superiorly. This represents the primary surgical space afforded by this approach. Further expansion of the surgical field, with partial resection of the lateral pterygoid muscle, allows for complete visualization of the infratemporal fossa structures of the middle cranial fossa base, including the branches of the mandibular nerve, the foramen ovale, and branches of the maxillary artery. (Fig. 5 ) (5) Region D encompasses the poststyloid space and a portion of the jugular foramen region, specifically the area posterior to the styloid process, its associated musculature, and the stylomandibular ligament (styloid diaphragm), and anterior to the prevertebral fascia (deep cervical fascia). Surgical access is gained via the lateral pharyngeal wall, with a longitudinal incision inferior to the tonsillar pillar. The posterior-lying longus capitis muscle is identified and retracted. Dissection lateral to the longus capitis muscle exposes the stylopharyngeus muscle, ascending pharyngeal artery, internal carotid artery, and the posterior cranial nerves. Medial retraction of the internal carotid artery and surrounding structures exposes the jugular foramen region and the hypoglossal canal. (Fig. 6 ) Discussion The parapharyngeal space and infratemporal fossa (ITF) are complex anatomical regions deeply situated within the neck, containing vital neurovascular structures, making endoscopic approaches via the nasal route challenging. Previous studies have categorized the ITF into five regions based on intercompartmental boundaries [ 6 ] , defined by the muscles of mastication. This regionalization provides guidance for endoscopic surgical planning, facilitating avoidance of neurovascular injury and pterygoid muscle damage. However, this compartmentalization is primarily applicable to transnasal endoscopic approaches; transcervical or transoral approaches are limited, and inadequate maxillary sinus pneumatization can further restrict the endoscopic field of view. Therefore, this study proposes a novel regionalization of the parapharyngeal space and infratemporal fossa based on five surgical approaches, incorporating cadaveric anatomical studies, aiming to optimize surgical access selection and anatomical understanding for lesions within these regions. The first surgical approach, a posterior maxillary sinus wall approach, corresponds to zone N0. This region encompasses adipose tissue enveloped by the maxillary artery and its branches (with the pterygoid muscles located posteriorly), and includes the pterygopalatine fossa, foramen ovale, mandibular nerve (V3), and the superior head of the lateral pterygoid muscle. Neurogenic tumors, such as schwannomas, are relatively common in this region [ 7 ] . In addition to addressing lesions originating from the mandibular nerve (V3), endoscopic access to zone N0 can extend to the middle cranial fossa and Meckel's cave. The second surgical approach, a transnasal-pterygoid approach, corresponds to zone N1, encompassing the parapharyngeal space, including the pterygoid plates, specifically involving the tensor veli palatini, levator veli palatini muscles, the cartilaginous portion of the Eustachian tube, prevertebral muscles, and the nasopharyngeal mucosa. The extended transpterygoid approach (ETPA) provides access in a non-midline coronal plane, effectively reaching the pterygopalatine fossa (PPF) and upper parapharyngeal space (UPPS) [ 8 ] . Important anatomical landmarks for this approach include the infraorbital canal (IOC), sphenopalatine foramen (SPF), vidian nerve (VN), and Eustachian tube, with the infraorbital canal serving as an anatomical boundary between the pterygopalatine fossa (PPF) and infratemporal fossa (ITF) [ 9 ] . The transnasal-pterygoid approach encompasses the pterygopalatine fossa, Eustachian tube region, and parts of the upper parapharyngeal space, including common locations for retropharyngeal lymph nodes and nasopharyngeal carcinoma recurrence. The third surgical approach, the endoscopic transoral-medial pterygomandibular fold approach (ETO-MPF), corresponds to zone B and is used to address lesions in the pre-parapharyngeal space. Nasocranial base lesions often involve multiple anatomical regions, making complete resection challenging with a single approach. For example, when a skull base lesion extends into the parapharyngeal space inferior to the hard palate, complete resection is difficult using solely a transnasal or anterior maxillary sinus wall approach [ 10 ] . This approach begins with the dissection of the soft palate; the incision is made in the soft palatal mucosa medial to the pterygomandibular fold. The pterygomandibular fold serves as an incision landmark; its submucosal counterpart is the pterygomandibular raphe (a non-constant structure, and thus not an ideal anatomical landmark), which demarcates the buccinator and superior pharyngeal constrictor muscles [ 11 ] . After incising the superior pharyngeal constrictor, access is gained to the prestyloid compartment of the lower parapharyngeal space, requiring precise identification and preservation of the internal carotid artery (ICA). The superior pharyngeal constrictor muscle, serving as the medial boundary of the parapharyngeal space and the anterior boundary of the retropharyngeal space, provides a reliable landmark for anterior-posterior dissection; the medial pterygoid muscle, a thick and consistently located structure, forms the lateral boundary of the lower parapharyngeal space. The stylohyoid and styloglossus muscles are important landmarks for the ETO-MPF approach; the carotid sheath lies posterior to them, aiding in ICA localization. The levator veli palatini muscle, located superiorly in the surgical field, with its superior attachment point located anterolateral to the ICA, also serves as a landmark for ICA localization [ 11 ] . In summary, this approach offers the advantages of relatively stable anatomical landmarks, avoiding extensive resection of normal tissue. The soft palate incision can be adjusted according to lesion size and location, and bony resection is unnecessary, resulting in minimal trauma, reduced bleeding, shorter operative time, and high safety. The endoscopic ETO-MPF approach allows for the safe and effective management of benign and malignant lesions involving the parapharyngeal space, retropharyngeal space, infratemporal fossa, and skull base, holding significant clinical importance and broad application prospects. The fourth surgical approach, the transoral retropharyngeal approach, corresponds to zone D and is utilized for managing lesions in the posterior parapharyngeal space. The endoscopic transoral retropharyngeal approach extends laterally towards the mandibular ramus and superolaterally towards the jugular bulb. Except when posterior superior extension towards the petrous bone is required, this corridor lacks consistent bony anatomical landmarks. The incision begins posterior to the torus tubarius and extends vertically inferiorly to the base of the tongue. The mucosa is dissected in an anteroposterior direction, sequentially exposing the pharyngeal constrictors, the longus capitis muscle and its overlying prevertebral fascia, and the stylopharyngeal fascia covering the carotid sheath. Some authors describe further dissection superolaterally to expose the cartilaginous portion of the Eustachian tube, the third division of the trigeminal nerve, the chorda tympani, and the styloid process and its associated muscles [ 12 ] . However, this approach offers a relatively limited surgical field; tumor compression can cause parapharyngeal tissue displacement and alteration of anatomical relationships. Intraoperative bleeding can also reduce the brightness and clarity of the endoscopic image. Therefore, intraoperative ultrasound-guided fine-needle aspiration may be necessary to precisely locate the internal carotid artery (ICA). The fifth surgical approach, the transoral molar buccal approach, corresponds to zone C and primarily involves the area lateral to the medial pterygoid muscle in the infratemporal fossa, medial to the ascending ramus of the mandible, and inferior to the lateral pterygoid muscle. Compared to the transnasal posterior maxillary sinus wall approach, this approach avoids bony resection and injury to crucial neurovascular structures, offering relative simplicity. A longitudinal incision is made in the buccal mucosa lateral to the molar teeth, exposing the medial surface of the mandible. To accurately locate the infratemporal fossa (ITF), mucosal dissection should closely follow the medial mandibular surface to create a pathway into the ITF. Key anatomical structures in this region include the medial pterygoid muscle, inferior alveolar nerve, maxillary artery, lateral pterygoid muscle, styloid process, and facial nerve. Superior dissection of the lateral pterygoid muscle allows exposure of the foramen ovale; this area partially overlaps with the NO region. The advantage of this approach lies primarily in its exposure of lesions located lateral to the medial pterygoid muscle and inferior to the lateral pterygoid muscle. The endoscopic transoral molar buccal approach allows direct visualization of the ITF without requiring resection of nasal or maxillary structures. However, this approach has a narrow surgical field, lacks clear bony anatomical landmarks, and is rich in soft tissue and neural structures. The medial surface of the posterior mandible serves as an important reference point; studies show an average distance of 26.72 mm between the lateral aspect of the second molar and the medial mandibular surface, which can aid in inferior alveolar nerve localization [ 13 ] . Although studies suggest that the transoral molar buccal approach provides safer ITF access compared to the transnasal endoscopic approach, it still carries potential risks of intraoperative bleeding and limited surgical space, requiring particularly cautious handling of the maxillary artery. Therefore, careful preoperative assessment of lesion location and extent is essential. Conclusion This study proposes a revised zonal anatomy of the parapharyngeal space and infratemporal fossa based on different surgical approaches, aiming to provide guidance for preoperative assessment and surgical planning. Clinically, tumors often involve multiple anatomical regions, potentially necessitating combined approaches or intraoperative conversion to open surgery. Ensuring surgical safety remains the paramount consideration. Therefore, preoperative assessment, including tumor histology, extent of local invasion, and the degree of adhesion to surrounding structures, is crucial for selecting the optimal surgical approach. Declarations Ethical approval The research was conducted ethically following the Code of Ethics of the World Medical Association (Declaration of Hel sinki). Competing interests The authors declare no competing interests. Funding This research received no specific grant from public, com mercial, or not-for-profit funding agencies. Data availability No datasets were generated or analysed during the current study. Author Contribution Conceptualization, L.X.Y.; methodology, B.H.Z. and L.X.Y.; data curation, B.H.Z. and Z.H.S.; writing—original draft preparation, B.H.Z. and L.X.Y.; writing—review and editing, L.X.Y. and Z.H.S. All authors have read and agreed to the published version of the manuscript. 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J Neurol Surg B Skull Base 79(3):229–240 Shimada K, Gasser RF (1989) Morphology of the pterygomandibular raphe in human fetuses and adults. Anat Rec 224(1):117–122 Zhang Q, Lv H, Wang Z, Guo H, Li M (2011) Endoscopic transoral approach for extracranial hypoglossal schwannoma. ORL J Otorhinolaryngol Relat Spec 73(5):282–286 Cai WW, Zou Y, Kang Z, Liang JG, He HY, Yang QT (2019) Endoscopic anatomical study of the trans-lateral molar approach to the infratemporal fossa. Eur Arch Otorhinolaryngol 276(6):1783–1791 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-6572118","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":453965808,"identity":"e9165a23-9e38-41cb-bafd-14212d86c0a9","order_by":0,"name":"Xue-Ying Liu","email":"","orcid":"","institution":"The First Affiliated Hospital of Xiamen University, Xiamen University","correspondingAuthor":false,"prefix":"","firstName":"Xue-Ying","middleName":"","lastName":"Liu","suffix":""},{"id":453965809,"identity":"ff022e33-81e0-4d65-b520-fced928511de","order_by":1,"name":"Bing-Huang Zhang","email":"","orcid":"","institution":"The First Affiliated Hospital of Xiamen University, Xiamen University","correspondingAuthor":false,"prefix":"","firstName":"Bing-Huang","middleName":"","lastName":"Zhang","suffix":""},{"id":453965810,"identity":"ea6874c5-50be-4740-b410-dd6187afe175","order_by":2,"name":"Zhao-hui Shi","email":"","orcid":"","institution":"The Third Affiliated Hospital of Sun Yat-sen University","correspondingAuthor":false,"prefix":"","firstName":"Zhao-hui","middleName":"","lastName":"Shi","suffix":""},{"id":453965811,"identity":"60cb15f7-0a2f-4ccc-88a6-f4936d61b6c8","order_by":3,"name":"Xian-Yang Luo","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA/0lEQVRIiWNgGAWjYDACCSB+YABmMj74UGHDwEaUlgQDMMVsOONMGrFaIBSbNG/bYcLu4p/dfOxBQsGdOn7p9stAW84n9kk3MN54w2Anp9uAw5I7x9INEgyeSUjOOVMI9MvtxDaZA8yWcxiSjc0OYNdiIJFjJpFgcFjC4EZOMtCW28ZsEgls0jwMBxK34dSS/w2sxf5GThrQL+eI0ZLDBrFFIv0YUMsBOYJaJG6kgR0mOeNGDiiQk+XYZA42W84xwO0X/hnJzyQ+/DnMzz8j/SHQ+3Y88rObD954U2Enh0sLEuAxgFrM2CABYxMA7A+gWoCIhygdo2AUjIJRMEIAAGdCW6V3DSnvAAAAAElFTkSuQmCC","orcid":"","institution":"The First Affiliated Hospital of Xiamen University, Xiamen University","correspondingAuthor":true,"prefix":"","firstName":"Xian-Yang","middleName":"","lastName":"Luo","suffix":""}],"badges":[],"createdAt":"2025-05-01 13:23:06","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6572118/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6572118/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":82583125,"identity":"71588e58-2585-4901-ad7e-046dcd3ac20a","added_by":"auto","created_at":"2025-05-13 06:48:32","extension":"jpeg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":260441,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eSchematic illustration of the imaging-based anatomical subdivisions of the parapharyngeal space and infratemporal fossa\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"floatimage1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-6572118/v1/0c46d898552a915c5ecf2cbf.jpeg"},{"id":82583129,"identity":"722943fe-3c94-4a19-b698-c450228d3767","added_by":"auto","created_at":"2025-05-13 06:48:32","extension":"jpeg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":1107933,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eAnatomical illustration of the transnasal approach to the posterior wall of the maxillary sinus\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eION\u003c/strong\u003e: Infraorbital nerve; \u003cstrong\u003ePWMS\u003c/strong\u003e: Posterior wall of maxillary sinus; \u003cstrong\u003eSPF\u003c/strong\u003e: Sphenopalatine foramen; \u003cstrong\u003eDPA\u003c/strong\u003e: Descending palatine artery; \u003cstrong\u003epIMA\u003c/strong\u003e: Pterygopalatine segment of internal maxillary artery; \u003cstrong\u003eV2\u003c/strong\u003e: Maxillary nerve;\u003cstrong\u003eV3\u003c/strong\u003e:Mandibular nerve; \u003cstrong\u003eBN\u003c/strong\u003e:Buccal nerve; \u003cstrong\u003eVN\u003c/strong\u003e:Vidian nerve; \u003cstrong\u003eDPN\u003c/strong\u003e:Descending Palatine Nerve; \u003cstrong\u003ePPG\u003c/strong\u003e:\u003cstrong\u003e \u003c/strong\u003ePterygopalatine Ganglion; \u003cstrong\u003eLBR\u003c/strong\u003e: Lacrimal branch; \u003cstrong\u003eSTM\u003c/strong\u003e: \u003cstrong\u003eSuperficial Temporalis Muscle\u003c/strong\u003e; \u003cstrong\u003eDTM\u003c/strong\u003e:\u003cstrong\u003e \u003c/strong\u003eDeep Temporalis Muscle; \u003cstrong\u003eZTM\u003c/strong\u003e: Zygomatic part of the temporalis muscle; \u003cstrong\u003eiIMA\u003c/strong\u003e: Infratemporal part of internal maxillary artery; \u003cstrong\u003eBP\u003c/strong\u003e: base of the pterygoid process; \u003cstrong\u003eLPP\u003c/strong\u003e: Lateral pterygoid plate; \u003cstrong\u003eDTN\u003c/strong\u003e: Deep Temporal Nerve; \u003cstrong\u003eGW\u003c/strong\u003e:\u003cstrong\u003e Greater Wing of the Sphenoid; MyN: \u003c/strong\u003eMylohyoid nerve; \u003cstrong\u003eMMA\u003c/strong\u003e: Middle Meningeal Artery; \u003cstrong\u003eTM\u003c/strong\u003e: Temporal muscle; \u003cstrong\u003eLPM\u003c/strong\u003e: Lateral Pterygoid Muscle;\u003cstrong\u003e IAN\u003c/strong\u003e: Inferior alveolar nerve; \u003cstrong\u003ecIMA\u003c/strong\u003e: condylar segment of internal maxillary artery; \u003cstrong\u003eLN\u003c/strong\u003e: Lingual nerve\u003c/p\u003e","description":"","filename":"floatimage2.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-6572118/v1/161c5af67bcd926a6ff62438.jpeg"},{"id":82584803,"identity":"4c5273cc-0d90-4428-9ddf-4240fd01124b","added_by":"auto","created_at":"2025-05-13 06:56:32","extension":"jpeg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":444243,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eAnatomical illustration of the transnasal transpterygoid approach\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eBP\u003c/strong\u003e: base of pterygoid plates; \u003cstrong\u003eVN\u003c/strong\u003e: Vidian nerve;\u003cstrong\u003e LPP\u003c/strong\u003e: Lateral pterygoid plate; \u003cstrong\u003ePP\u003c/strong\u003e: Perpendicular plate of palatine bone; \u003cstrong\u003eET\u003c/strong\u003e: Eustachian tube; \u003cstrong\u003eMPP\u003c/strong\u003e: Medial pterygoid plate; \u003cstrong\u003ePPS\u003c/strong\u003e: Parapharyngeal space; \u003cstrong\u003eMPM\u003c/strong\u003e: Medial pterygoid muscle;\u003cstrong\u003e TVPM\u003c/strong\u003e: Tensor veli palati muscle; \u003cstrong\u003eSPF\u003c/strong\u003e: Sphenopalatine foramen;\u003cstrong\u003e V1\u003c/strong\u003e: Optic nerve; \u003cstrong\u003eV2\u003c/strong\u003e: Maxillary nerve; \u003cstrong\u003eV3\u003c/strong\u003e: Mandibular nerve; \u003cstrong\u003epICA\u003c/strong\u003e:\u003cstrong\u003e \u003c/strong\u003ePetrous segment of the internal carotid artery\u003c/p\u003e","description":"","filename":"floatimage3.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-6572118/v1/f2d6735a5a2f5e5f1d96d163.jpeg"},{"id":82584802,"identity":"a982cb87-940a-442a-9713-e4dc83bc4e34","added_by":"auto","created_at":"2025-05-13 06:56:32","extension":"jpeg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":360492,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eAnatomical illustration of the transoral approach medial to the pterygomandibular fold\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eUVU\u003c/strong\u003e:Uvula; Mol:Molar; \u003cstrong\u003ePML\u003c/strong\u003e:Pterygomandibular ligament; \u003cstrong\u003eMPM\u003c/strong\u003e:Medial pterygoid muscle; \u003cstrong\u003eTVP\u003c/strong\u003e:Tensor Veli Palatini; \u003cstrong\u003eSCM\u003c/strong\u003e: Superior constrictor muscle of pharynx; \u003cstrong\u003eSpM\u003c/strong\u003e:Styloid pharyngeal muscle; \u003cstrong\u003eSgM\u003c/strong\u003e:\u003cstrong\u003e \u003c/strong\u003eStyloglossus muscles; \u003cstrong\u003eATP\u003c/strong\u003e: Ascending palatine artery; \u003cstrong\u003eAPA\u003c/strong\u003e:Ascending pharyngeal artery; \u003cstrong\u003eRLN\u003c/strong\u003e:Retropharyngeal lymph nodes;\u003cstrong\u003e phICA\u003c/strong\u003e:Parapharyngeal Internal Carotid Artery;\u003cstrong\u003e LC\u003c/strong\u003e: Longus capitis; \u003cstrong\u003eIX\u003c/strong\u003e:\u003cstrong\u003e \u003c/strong\u003eGlossopharyngeal nerve; \u003cstrong\u003eET\u003c/strong\u003e: Eustachian tube; \u003cstrong\u003eLVP\u003c/strong\u003e: Levator Veli Palatini; \u003cstrong\u003eX\u003c/strong\u003e:Vagus Nerve;\u003cstrong\u003e XI\u003c/strong\u003e:Accessory Nerve;\u003cstrong\u003e XII\u003c/strong\u003e:Hypoglossal Nerve\u003c/p\u003e","description":"","filename":"floatimage6.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-6572118/v1/7e0ba154d5d1383c965079f3.jpeg"},{"id":82584804,"identity":"76fdcf8b-6b56-4e53-ac01-a20a898a889e","added_by":"auto","created_at":"2025-05-13 06:56:32","extension":"jpeg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":786343,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eAnatomical illustration of the transoral approach lateral to the molar\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMOL\u003c/strong\u003e: Molar; \u003cstrong\u003eBN\u003c/strong\u003e: Buccal nerve;\u003cstrong\u003e MPM\u003c/strong\u003e: Medial pterygoid muscle; \u003cstrong\u003eIMA\u003c/strong\u003e: Internal maxillary artery;\u003cstrong\u003e IAA\u003c/strong\u003e: Inferior alveolar artery; \u003cstrong\u003eIAN\u003c/strong\u003e: Inferior alveolar nerve; \u003cstrong\u003eLPM\u003c/strong\u003e: Lateral Pterygoid Muscle; \u003cstrong\u003eLN\u003c/strong\u003e: Lingual nerve; \u003cstrong\u003eTM\u003c/strong\u003e: Temporal muscle; \u003cstrong\u003eDTA\u003c/strong\u003e: Deep Temporal Artery; \u003cstrong\u003eDTN\u003c/strong\u003e: Deep Temporal Nerve; \u003cstrong\u003eV3\u003c/strong\u003e: Mandibular nerve; \u003cstrong\u003eAMA\u003c/strong\u003e: Accessory Meningeal Artery; \u003cstrong\u003eMMA\u003c/strong\u003e: Middle Meningeal Artery;\u003cstrong\u003e LPP\u003c/strong\u003e: Lateral pterygoid plate; \u003cstrong\u003eVII\u003c/strong\u003e: Facial Nerve;\u003cstrong\u003e PG\u003c/strong\u003e: Parotid Gland; \u003cstrong\u003eSP\u003c/strong\u003e: Styloid Process\u003c/p\u003e","description":"","filename":"floatimage5.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-6572118/v1/cd8a191bb16fe0740eece2c1.jpeg"},{"id":82583133,"identity":"7e19aaf2-d6d3-4d9e-9482-1a912cd9808c","added_by":"auto","created_at":"2025-05-13 06:48:32","extension":"jpeg","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":756686,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eAnatomical illustration of the transoral retropharyngeal approach\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eSCM\u003c/strong\u003e: Superior constrictor muscle of pharynx; \u003cstrong\u003eLC\u003c/strong\u003e: Longus capitis; \u003cstrong\u003ephICA\u003c/strong\u003e: Parapharyngeal Internal Carotid Artery; \u003cstrong\u003eAPA\u003c/strong\u003e: Ascending pharyngeal artery; \u003cstrong\u003eIX\u003c/strong\u003e:\u003cstrong\u003e \u003c/strong\u003eGlossopharyngeal Nerve; \u003cstrong\u003eX\u003c/strong\u003e: Vagus Nerve; \u003cstrong\u003eXI\u003c/strong\u003e: Accessory Nerve; \u003cstrong\u003eJF\u003c/strong\u003e: Jugular foramen; \u003cstrong\u003eIJV\u003c/strong\u003e: Internal jugular vein; \u003cstrong\u003eHyc\u003c/strong\u003e: Hypoglossal canal;\u003c/p\u003e","description":"","filename":"floatimage4.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-6572118/v1/90430e71523189b4bc49cd73.jpeg"},{"id":100371479,"identity":"d2803826-86f2-4cd4-a39d-44012402944a","added_by":"auto","created_at":"2026-01-16 08:10:20","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":4447813,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6572118/v1/c0c20170-757a-466c-87e3-12f56d7c2a67.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Establishing a Zonal Anatomic Scheme for the Parapharyngeal Space and Infratemporal Fossa Based on Five Surgical Approaches","fulltext":[{"header":"Introduction","content":"\u003cp\u003eThe parapharyngeal space and infratemporal fossa are complex regions of the head and neck, characterized by indistinct boundaries and a dense neurovascular network. The anatomical definition of the infratemporal fossa remains inconsistent across literature. In a broad definition, the infratemporal fossa encompasses the parapharyngeal space and masticator space. However, a stricter definition confines it to the region posterior to the body of the maxilla and zygomatic arch, medially bounded by the lateral pterygoid plate, and laterally by the ramus of the mandible. Its inferior and posterior boundaries are open\u003csup\u003e[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]\u003c/sup\u003e, while the superior medial boundary is formed by the greater wing of the sphenoid and squamous part of the temporal bone, representing a portion of the middle cranial fossa floor. Recent advances in endoscopic technology and surgical instrumentation have enabled the successful application of transoral endoscopic surgery in the resection of parapharyngeal space and infratemporal fossa tumors, demonstrating favorable clinical outcomes \u003csup\u003e[\u003cspan additionalcitationids=\"CR3 CR4\" citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]\u003c/sup\u003e. Multiple distinct endoscopic approaches exist for parapharyngeal space and infratemporal fossa surgery, accommodating the varied locations of lesions. Traditional anatomical compartmentalization of the infratemporal fossa primarily relies on anatomical spaces\u003csup\u003e[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]\u003c/sup\u003e, limiting its direct applicability to surgical planning. This study employs fresh cadaveric heads to simulate transoral endoscopic approaches, aiming to enhance understanding of infratemporal fossa anatomy and propose a novel infratemporal fossa compartmentalization based on different endoscopic approaches.\u003c/p\u003e"},{"header":"Materials and Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1 Study Materials\u003c/h2\u003e \u003cp\u003eThis study utilized ten sides from five fresh adult cadaveric heads. The arterial systems were injected with red latex, and the venous systems with blue latex. Surgical instruments included a Davis mouth gag, a round knife, suction, a tonsil dissector, probes, and standard nasal surgical instruments. The endoscopic system comprised 4 mm 0° and 30° rigid nasal endoscopes (Karl Storz), equipped with a cold light source, high-definition camera system, and high-definition image workstation.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2 Treatment\u003c/h2\u003e \u003cp\u003e This study utilized ten sides from five fresh adult cadaveric heads obtained from the endoscopic anatomy training center of Professor Geng Xu, Qifusheng Hospital, Guangdong Province (gender unspecified). Specimens were injected with red latex into the arterial system and blue latex into the venous system. Subsequently, anatomical observations were performed using simulated transnasal and transoral endoscopic surgical approaches. The results are presented as follows:\u003c/p\u003e \u003cp\u003e1. Transnasal posterior maxillary sinus approach: Initially, the entire ethmoid sinuses and lateral nasal\u003c/p\u003e \u003cp\u003ewall were opened to expose the posterior maxillary sinus wall, clearly identifying the location of the infraorbital groove (or notch). The posterior maxillary sinus wall bone was removed using a drill to expose the underlying fascioadipose layer. After resection of this layer, the lateral pterygoid plate, temporalis muscle, maxillary artery and its branches, and lateral pterygoid muscle were sequentially exposed. The lateral pterygoid muscle was dissected along the lateral pterygoid plate to expose the foramen ovale and branches of the mandibular nerve. Finally, portions of the lateral pterygoid muscle were resected to fully expose the temporomandibular joint externally and the pterygomaxillary fascia posteriorly.\u003c/p\u003e \u003cp\u003e(2) Transnasal pterygoid approach: Blunt dissection was performed along the palatal mucosa to expose the medial pterygoid plate. Careful dissection along the bone surface allowed for the detachment of the tensor veli palatini and levator veli palatini muscles until the cartilaginous portion of the eustachian tube was exposed, thus gaining access to the parapharyngeal space. After resection of the vertical plate of the palatine bone, the pterygopalatine fossa was exposed. The medial pterygoid plate was then drilled to fully expose the medial aspect of the lateral pterygoid plate. At the base of the pterygoid process, the Vidian nerve was identified and the foramen rotundum and maxillary nerve (V2) precisely located. By inferiorly displacing the eustachian tube and continuing the dissection along the Vidian nerve, the petrous portion of the internal carotid artery was ultimately exposed.\u003c/p\u003e \u003cp\u003e(3) the pterygomandibular fold, extending superiorly to the hamulus and inferiorly to the level of the tongue base. The superior pharyngeal constrictor muscle was longitudinally incised to expose the parapharyngeal space fat, laterally bordered by the medial pterygoid muscle. After clearing the fat, the ascending palatine artery was exposed. Inferiorly, the stylopharyngeus and styloglossus muscles were visualized. Superiorly, posterior to the hamulus, the tensor veli palatini muscle was identified, with the levator veli palatini muscle medial to it. The cartilaginous portion of the eustachian tube was visible superior and posterior to the levator veli palatini. The stylopharyngeal fascia was opened posteriorly to enter the retropharyngeal space. Deeper structures required careful dissection. After retracting the stylohyoid muscle group laterally, the carotid sheath was exposed, revealing the ascending pharyngeal artery and longus capitis muscle medial to the carotid sheath. Retropharyngeal lymph nodes were identified between the longus capitis muscle and the carotid sheath. The carotid sheath was opened to expose the internal carotid artery and the posterior cranial nerves. A 0° Storz endoscope was used to photograph the aforementioned anatomical structures and record their spatial relationships.\u003c/p\u003e \u003cp\u003e(4) Transoral posterior pharyngeal approach: A mouth gag was placed, and a catheter was inserted through the nasal cavity to retract the contralateral soft palate, providing adequate exposure of the lateral pharyngeal wall. Under 0° endoscopy, a longitudinal mucosal incision was made using a sickle knife posterior to the palatopharyngeal arch, beginning posterior to the torus tubarius and extending vertically downwards to the level of the tongue base. In the direction of the incision, the pharyngeal constrictor muscles were sharply incised, and blunt dissection was performed posterolaterally to expose the longus capitis muscle and its anterior fascia. Further blunt lateral dissection at the lateral border of the prevertebral muscles allowed identification of the stylopharyngeal fascia overlying the carotid sheath. Careful dissection of the stylopharyngeal fascia revealed the ascending pharyngeal artery. Opening the carotid sheath exposed the internal carotid artery (ICA), internal jugular vein, jugular bulb, and posterior cranial nerves.\u003c/p\u003e \u003cp\u003e(5) Transoral lateral molar approach: A longitudinal incision was made lateral to the line connecting the maxillary and mandibular molars, incising the buccal mucosa and buccal fat pad. The lateral aspect of the medial pterygoid muscle and the medial aspect of the mandibular ramus were exposed. The anterior extent of the incision reached the buccal nerve. Blunt dissection was performed posteroinferiorly along the medial aspect of the mandibular ramus, exposing the mandibular foramen, inferior alveolar nerve and artery, and a portion of the superior head of the lateral pterygoid muscle. The inferior alveolar artery was traced to the maxillary artery. The inferior alveolar nerve, accompanied by the lingual nerve, was traced to other branches of the mandibular nerve. Superior dissection of the lateral pterygoid muscle, with partial resection, exposed the foramen ovale. Inferior dissection along the maxillary artery exposed the styloid process, the lateral parapharyngeal space, including the trunk of the facial nerve, the stylomastoid foramen, and the external carotid artery.\u003c/p\u003e "},{"header":"Results","content":"\u003cp\u003eThe surgical dissection consisted of endoscopic nasal and transoral approaches. The endoscopic nasal approach commenced with either lateral nasal wall resection or a Denker's approach to achieve adequate exposure of the posterior maxillary sinus wall, establishing two surgical corridors: a transnasal posterior maxillary sinus approach and a transantral-infundibular approach. The transoral endoscopic portion utilized a mouth gag to optimize visualization of the oropharynx and tongue base, creating three surgical corridors: a transoral medial pterygomandibular fold approach, a transoral posterior pharyngeal approach, and a transoral lateral molar approach. Based on these distinct surgical approaches, the parapharyngeal space and infratemporal fossa were subdivided into five anatomical regions ( Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e(1) The NO zone is defined anatomically as the region posterior to the posterolateral maxillary sinus\u003c/p\u003e\u003cp\u003ewall, extending laterally to the deep surface of the temporalis muscle, inferiorly to a plane above the maxillary sinus floor, superiorly to the floor of the middle cranial fossa, medially to the lateral aspect of the lateral pterygoid plate, the medial aspect of the ascending ramus of the mandible, and the medial aspect of the temporalis muscle attachment, anteriorly to the posterior aspect of the posterior maxillary fat pad, and posteriorly to the styloid process and its fascia. Surgical access involved removal of the posterior maxillary sinus wall to locate the infraorbital canal on the maxillary sinus roof. The maxillary nerve was then identified posteriorly. After locating the lateral pterygoid plate and removing fatty tissue, branches of the maxillary artery, the temporalis muscle, and the buccal nerve were visualized. Resection of the lateral pterygoid muscle and a portion of the temporalis muscle exposed the various branches of the mandibular nerve and the foramen ovale. (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e)\u003c/p\u003e\u003cp\u003e(2) Zone NI encompasses the pterygopalatine fossa (including the medial pterygoid plate), tensor\u003c/p\u003e\u003cp\u003eveli palatini muscle, levator veli palatini muscle, cartilaginous portion of the Eustachian tube, parapharyngeal muscles, and the nasopharyngeal mucosa. Its superior boundary is defined by the course of the maxillary nerve. Surgical access within this zone primarily centers on the pterygoid bony structures. Identification of the pterygoid canal is crucial; following its course, bone removal allows posterior access to the foramen lacerum. Inferiorly, dissection along the posterior wall of the maxilla provides access to the parapharyngeal space, with posterior identification of the Eustachian tube. ( Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e)\u003c/p\u003e\u003cp\u003e(3) Zone B is situated inferior to the maxillary sinus floor, inferior to the lateral pterygoid muscle,\u003c/p\u003e\u003cp\u003emedial to the medial pterygoid muscle, medial to the deep parotid lobe, and anterior to the stylomandibular fascia, primarily comprising the prestyloid space. A vertical incision medial to the pterygomandibular fold exposes the pterygoid hamulus; the medial pterygoid muscle lies inferolateral to it, and the tensor veli palatini muscle inserts posterior to the hamulus. Incision of the superior pharyngeal constrictor muscle provides access to the parapharyngeal space, revealing its fatty tissue. After dissection of this fat, the ascending palatine artery becomes visible, along with the stylopharyngeus and stylohyoid muscles inferiorly, and the stylomandibular fascia posteriorly. This approach offers excellent visualization of these structures, representing its key advantage. Further\u003c/p\u003e\u003cp\u003edissection through the stylomandibular fascia exposes the retrostyloid space, revealing the internal carotid artery, posterior cranial nerves (IX-XII), retropharyngeal lymph nodes, and the longus capitis muscle. ( Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e)\u003c/p\u003e\u003cp\u003e(4) Zone C represents the surgical field accessed via a retromolar extraoral approach. This approach\u003c/p\u003e\u003cp\u003eoffers superior visualization of the medial aspect of the ascending ramus of the maxilla, the lateral aspect of the medial pterygoid muscle, the region inferior to the lateral pterygoid muscle, and the lateral aspect of the deep temporal muscles. A vertical incision is made over the retromolar region, exposing and preserving the buccal nerve. Blunt dissection proceeds along the bony surface of the mandibular ramus. The initial surgical field is relatively confined; however, extending the incision superiorly expands the surgical exposure, allowing identification of the mandibular foramen, inferior alveolar nerve, and inferior alveolar artery posteriorly, and the lateral pterygoid muscle superiorly. This represents the primary surgical space afforded by this approach. Further expansion of the surgical field, with partial resection of the lateral pterygoid muscle, allows for complete visualization of the infratemporal fossa structures of the middle cranial fossa base, including the branches of the mandibular nerve, the foramen ovale, and branches of the maxillary artery. (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e)\u003c/p\u003e\u003cp\u003e(5) Region D encompasses the poststyloid space and a portion of the jugular foramen region, specifically the area posterior to the styloid process, its associated musculature, and the stylomandibular ligament (styloid diaphragm), and anterior to the prevertebral fascia (deep cervical fascia). Surgical access is gained via the lateral pharyngeal wall, with a longitudinal incision inferior to the tonsillar pillar. The posterior-lying longus capitis muscle is identified and retracted. Dissection lateral to the longus capitis muscle exposes the stylopharyngeus muscle, ascending pharyngeal artery, internal carotid artery, and the posterior cranial nerves. Medial retraction of the internal carotid artery and surrounding structures exposes the jugular foramen region and the hypoglossal canal. (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e)\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThe parapharyngeal space and infratemporal fossa (ITF) are complex anatomical regions deeply situated within the neck, containing vital neurovascular structures, making endoscopic approaches via the nasal route challenging. Previous studies have categorized the ITF into five regions based on intercompartmental boundaries \u003csup\u003e[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]\u003c/sup\u003e, defined by the muscles of mastication. This regionalization provides guidance for endoscopic surgical planning, facilitating avoidance of neurovascular injury and pterygoid muscle damage. However, this compartmentalization is primarily applicable to transnasal endoscopic approaches; transcervical or transoral approaches are limited, and inadequate maxillary sinus pneumatization can further restrict the endoscopic field of view. Therefore, this study proposes a novel regionalization of the parapharyngeal space and infratemporal fossa based on five surgical approaches, incorporating cadaveric anatomical studies, aiming to optimize surgical access selection and anatomical understanding for lesions within these regions.\u003c/p\u003e\u003cp\u003eThe first surgical approach, a posterior maxillary sinus wall approach, corresponds to zone N0. This region encompasses adipose tissue enveloped by the maxillary artery and its branches (with the pterygoid muscles located posteriorly), and includes the pterygopalatine fossa, foramen ovale, mandibular nerve (V3), and the superior head of the lateral pterygoid muscle. Neurogenic tumors, such as schwannomas, are relatively common in this region\u003csup\u003e[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]\u003c/sup\u003e. In addition to addressing lesions originating from the mandibular nerve (V3), endoscopic access to zone N0 can extend to the middle cranial fossa and Meckel's cave.\u003c/p\u003e\u003cp\u003eThe second surgical approach, a transnasal-pterygoid approach, corresponds to zone N1, encompassing the parapharyngeal space, including the pterygoid plates, specifically involving the tensor veli palatini, levator veli palatini muscles, the cartilaginous portion of the Eustachian tube, prevertebral muscles, and the nasopharyngeal mucosa. The extended transpterygoid approach (ETPA) provides access in a non-midline coronal plane, effectively reaching the pterygopalatine fossa (PPF) and upper parapharyngeal space (UPPS)\u003csup\u003e[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]\u003c/sup\u003e. Important anatomical landmarks for this approach include the infraorbital canal (IOC), sphenopalatine foramen (SPF), vidian nerve (VN), and Eustachian tube, with the infraorbital canal serving as an anatomical boundary between the pterygopalatine fossa (PPF) and infratemporal fossa (ITF)\u003csup\u003e[\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]\u003c/sup\u003e. The transnasal-pterygoid approach encompasses the pterygopalatine fossa, Eustachian tube region, and parts of the upper parapharyngeal space, including common locations for retropharyngeal lymph nodes and nasopharyngeal carcinoma recurrence.\u003c/p\u003e\u003cp\u003eThe third surgical approach, the endoscopic transoral-medial pterygomandibular fold approach (ETO-MPF), corresponds to zone B and is used to address lesions in the pre-parapharyngeal space. Nasocranial base lesions often involve multiple anatomical regions, making complete resection challenging with a single approach. For example, when a skull base lesion extends into the parapharyngeal space inferior to the hard palate, complete resection is difficult using solely a transnasal or anterior maxillary sinus wall approach\u003csup\u003e[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]\u003c/sup\u003e. This approach begins with the dissection of the soft palate; the incision is made in the soft palatal mucosa medial to the pterygomandibular fold. The pterygomandibular fold serves as an incision landmark; its submucosal counterpart is the pterygomandibular raphe (a non-constant structure, and thus not an ideal anatomical landmark), which demarcates the buccinator and superior pharyngeal constrictor muscles\u003csup\u003e[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]\u003c/sup\u003e. After incising the superior pharyngeal constrictor, access is gained to the prestyloid compartment of the lower parapharyngeal space, requiring precise identification and preservation of the internal carotid artery (ICA). The superior pharyngeal constrictor muscle, serving as the medial boundary of the parapharyngeal space and the anterior boundary of the retropharyngeal space, provides a reliable landmark for anterior-posterior dissection; the medial pterygoid muscle, a thick and consistently located structure, forms the lateral boundary of the lower parapharyngeal space. The stylohyoid and styloglossus muscles are important landmarks for the ETO-MPF approach; the carotid sheath lies posterior to them, aiding in ICA localization. The levator veli palatini muscle, located superiorly in the surgical field, with its superior attachment point located anterolateral to the ICA, also serves as a landmark for ICA localization\u003csup\u003e[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]\u003c/sup\u003e. In summary, this approach offers the advantages of relatively stable anatomical landmarks, avoiding extensive resection of normal tissue. The soft palate incision can be adjusted according to lesion size and location, and bony resection is unnecessary, resulting in minimal trauma, reduced bleeding, shorter operative time, and high safety. The endoscopic ETO-MPF approach allows for the safe and effective management of benign and malignant lesions involving the parapharyngeal space, retropharyngeal space, infratemporal fossa, and skull base, holding significant clinical importance and broad application prospects.\u003c/p\u003e\u003cp\u003eThe fourth surgical approach, the transoral retropharyngeal approach, corresponds to zone D and is utilized for managing lesions in the posterior parapharyngeal space. The endoscopic transoral retropharyngeal approach extends laterally towards the mandibular ramus and superolaterally towards the jugular bulb. Except when posterior superior extension towards the petrous bone is required, this corridor lacks consistent bony anatomical landmarks. The incision begins posterior to the torus tubarius and extends vertically inferiorly to the base of the tongue. The mucosa is dissected in an anteroposterior direction, sequentially exposing the pharyngeal constrictors, the longus capitis muscle and its overlying prevertebral fascia, and the stylopharyngeal fascia covering the carotid sheath. Some authors describe further dissection superolaterally to expose the cartilaginous portion of the Eustachian tube, the third division of the trigeminal nerve, the chorda tympani, and the styloid process and its associated muscles\u003csup\u003e[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]\u003c/sup\u003e. However, this approach offers a relatively limited surgical field; tumor compression can cause parapharyngeal tissue displacement and alteration of anatomical relationships. Intraoperative bleeding can also reduce the brightness and clarity of the endoscopic image. Therefore, intraoperative ultrasound-guided fine-needle aspiration may be necessary to precisely locate the internal carotid artery (ICA).\u003c/p\u003e\u003cp\u003eThe fifth surgical approach, the transoral molar buccal approach, corresponds to zone C and primarily involves the area lateral to the medial pterygoid muscle in the infratemporal fossa, medial to the ascending ramus of the mandible, and inferior to the lateral pterygoid muscle. Compared to the transnasal posterior maxillary sinus wall approach, this approach avoids bony resection and injury to crucial neurovascular structures, offering relative simplicity. A longitudinal incision is made in the buccal mucosa lateral to the molar teeth, exposing the medial surface of the mandible. To accurately locate the infratemporal fossa (ITF), mucosal dissection should closely follow the medial mandibular surface to create a pathway into the ITF. Key anatomical structures in this region include the medial pterygoid muscle, inferior alveolar nerve, maxillary artery, lateral pterygoid muscle, styloid process, and facial nerve. Superior dissection of the lateral pterygoid muscle allows exposure of the foramen ovale; this area partially overlaps with the NO region. The advantage of this approach lies primarily in its exposure of lesions located lateral to the medial pterygoid muscle and inferior to the lateral pterygoid muscle. The endoscopic transoral molar buccal approach allows direct visualization of the ITF without requiring resection of nasal or maxillary structures. However, this approach has a narrow surgical field, lacks clear bony anatomical landmarks, and is rich in soft tissue and neural structures. The medial surface of the posterior mandible serves as an important reference point; studies show an average distance of 26.72 mm between the lateral aspect of the second molar and the medial mandibular surface, which can aid in inferior alveolar nerve localization\u003csup\u003e[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]\u003c/sup\u003e. Although studies suggest that the transoral molar buccal approach provides safer ITF access compared to the transnasal endoscopic approach, it still carries potential risks of intraoperative bleeding and limited surgical space, requiring particularly cautious handling of the maxillary artery. Therefore, careful preoperative assessment of lesion location and extent is essential.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThis study proposes a revised zonal anatomy of the parapharyngeal space and infratemporal fossa based on different surgical approaches, aiming to provide guidance for preoperative assessment and surgical planning. Clinically, tumors often involve multiple anatomical regions, potentially necessitating combined approaches or intraoperative conversion to open surgery. Ensuring surgical safety remains the paramount consideration. Therefore, preoperative assessment, including tumor histology, extent of local invasion, and the degree of adhesion to surrounding structures, is crucial for selecting the optimal surgical approach.\u003c/p\u003e"},{"header":"Declarations","content":" \u003cp\u003e \u003cstrong\u003eEthical approval\u003c/strong\u003e \u003cp\u003e The research was conducted ethically following the Code of Ethics of the World Medical Association (Declaration of Hel sinki).\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eCompeting interests\u003c/strong\u003e \u003cp\u003eThe authors declare no competing interests.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eFunding\u003c/h2\u003e \u003cp\u003eThis research received no specific grant from public, com mercial, or not-for-profit funding agencies.\u003c/p\u003e \u003cp\u003e \u003cb\u003eData availability\u003c/b\u003e No datasets were generated or analysed during the current study.\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eConceptualization, L.X.Y.; methodology, B.H.Z. and L.X.Y.; data curation, B.H.Z. and Z.H.S.; writing\u0026mdash;original draft preparation, B.H.Z. and L.X.Y.; writing\u0026mdash;review and editing, L.X.Y. and Z.H.S. All authors have read and agreed to the published version of the manuscript.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eFalcon RT, Rivera-Serrano CM, Miranda JF, Prevedello DM, Snyderman CH, Kassam AB et al (2011) Endoscopic endonasal dissection of the infratemporal fossa: Anatomic relationships and importance of eustachian tube in the endoscopic skull base surgery. Laryngoscope 121(1):31\u0026ndash;41\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSalzano G, Togo G, Maglitto F, Borriello G, Perri F, Audino G et al (2022) Trans-Oral Robotic Surgery: 14 Cases of Pleomorphic Adenoma of the Parapharyngeal Space. J Craniofac Surg 33(5):1587\u0026ndash;1590\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMiller JE, Sajed DP, Mendelsohn AH (2023) Transoral Robotic Surgery for a Parapharyngeal Space Tumor. JAMA Otolaryngol Head Neck Surg 149(7):645\u0026ndash;646\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eOakley GM, Harvey RJ (2017) Endoscopic Resection of Pterygopalatine Fossa and Infratemporal Fossa Malignancies. Otolaryngol Clin North Am 50(2):301\u0026ndash;313\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLarson AR, Ryan WR (2021) Transoral Excision of Parapharyngeal Space Tumors. Otolaryngol Clin North Am 54(3):531\u0026ndash;541\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLi L, London NR Jr., Prevedello DM, Carrau RL (2020) Anatomy based corridors to the infratemporal fossa: Implications for endoscopic approaches. Head Neck 42(5):846\u0026ndash;853\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYang L, Hu L, Zhao W, Zhang H, Liu Q, Wang D (2018) Endoscopic endonasal approach for trigeminal schwannomas: our experience of 39 patients in 10 years. Eur Arch Otorhinolaryngol 275(3):735\u0026ndash;741\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHardesty DA, Montaser AS, Carrau RL, Prevedello DM (2018) Limits of endoscopic endonasal transpterygoid approach to cavernous sinus and Meckel's cave. J Neurosurg Sci 62(3):332\u0026ndash;338\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eIsaacs SJ, Goyal P (2007) Endoscopic anatomy of the pterygopalatine fossa. Am J Rhinol 21(5):644\u0026ndash;647\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSun X, Yan B, Truong HQ, Borghei-Razavi H, Snyderman CH, Fernandez-Miranda JC (2018) A Comparative Analysis of Endoscopic-Assisted Transoral and Transnasal Approaches to Parapharyngeal Space: A Cadaveric Study. J Neurol Surg B Skull Base 79(3):229\u0026ndash;240\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eShimada K, Gasser RF (1989) Morphology of the pterygomandibular raphe in human fetuses and adults. Anat Rec 224(1):117\u0026ndash;122\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhang Q, Lv H, Wang Z, Guo H, Li M (2011) Endoscopic transoral approach for extracranial hypoglossal schwannoma. ORL J Otorhinolaryngol Relat Spec 73(5):282\u0026ndash;286\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCai WW, Zou Y, Kang Z, Liang JG, He HY, Yang QT (2019) Endoscopic anatomical study of the trans-lateral molar approach to the infratemporal fossa. Eur Arch Otorhinolaryngol 276(6):1783\u0026ndash;1791\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Parapharyngeal space, Infratemporal fossa, Endoscopic transnasal approach, Endoscopic transoral approach","lastPublishedDoi":"10.21203/rs.3.rs-6572118/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6572118/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eObjective\u003c/h2\u003e \u003cp\u003eTo develop an anatomical zonal scheme for the parapharyngeal space and infratemporal fossa based on various surgical approaches, including the transnasal posterior maxillary sinus wall approach, the transnasal antrostomy approach, the transoral medial pterygomandibular fold approach, the transoral posterior pharyngeal wall approach, and the transoral retromolar approach.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eTen sides from five fresh cadaveric heads were dissected using endoscopic transnasal and transoral approaches to explore the parapharyngeal space and infratemporal fossa. Anatomical landmarks and relationships were observed and recorded for each approach to define the anatomical boundaries of each dissection zone.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eBased on the surgical approaches, the parapharyngeal space and infratemporal fossa were divided into five zones: Zone NO (transnasal posterior maxillary sinus approach), located posterior to the posterolateral wall of the maxillary sinus, laterally to the deep surface of the temporalis muscle, inferiorly to a plane above the maxillary sinus floor, superiorly to the middle cranial fossa floor, medially to the lateral pterygoid plate, medial to the ramus of the mandible and the temporalis muscle attachment, anteriorly to the posterior maxillary sinus fat space, and posteriorly to the styloid process and its associated fascia; Zone NI (transnasal pterygoid approach), encompassing the pterygopalatine fossa (including the medial pterygoid plate), tensor veli palatini muscle, levator veli palatini muscle, cartilaginous portion of the eustachian tube, parapharyngeal muscle group, and nasopharyngeal mucosa; Zone B (transoral infra-pterygomandibular fold medial approach), located inferior to the maxillary sinus floor, inferior to the lateral pterygoid muscle, medial to the medial pterygoid muscle, and medial to the deep lobe of the parotid gland, anterior to the stylomandibular fascia; Zone C (transoral lateral molar approach), located medial to the ascending ramus of the maxilla, lateral to the medial pterygoid muscle, inferior to the lateral pterygoid muscle, and lateral to the deep temporalis muscle group; and Zone D (transoral posterior pharyngeal approach), encompassing the retrostyloid space and part of the jugular foramen area, specifically the area posterior to the styloid process and its associated muscles and stylomandibular fascia (styloid septum), and anterior to the deep cervical fascia (prevertebral fascia).\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eThis study proposes a revised zonal anatomy of the parapharyngeal space and infratemporal fossa based on different surgical approaches, aiming to provide a reference for preoperative assessment and surgical planning to minimize injury to vital neurovascular structures and muscles.\u003c/p\u003e","manuscriptTitle":"Establishing a Zonal Anatomic Scheme for the Parapharyngeal Space and Infratemporal Fossa Based on Five Surgical Approaches","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-05-13 06:48:27","doi":"10.21203/rs.3.rs-6572118/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"5f280a3e-01af-45d5-be45-8cd864ce07d7","owner":[],"postedDate":"May 13th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-01-14T13:54:45+00:00","versionOfRecord":[],"versionCreatedAt":"2025-05-13 06:48:27","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6572118","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6572118","identity":"rs-6572118","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}