Bilateral Pentafurcation of the Common Carotid Arteries: A New Anatomic Variant

Bilateral Pentafurcation of the Common Carotid Arteries: A New Anatomic Variant | 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 Bilateral Pentafurcation of the Common Carotid Arteries: A New Anatomic Variant Thornton Mardis, Kayla Crawford, Delaney Koontz, Sara Sloan This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9247653/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 15 You are reading this latest preprint version Abstract Purpose The Common Carotid Artery (CCA) is understood to bifurcate at the level of the upper border of the thyroid cartilage into the internal carotid artery (ICA) and external carotid artery (ECA). Variations on these branching patterns have been reported and several classification systems have been proposed. Pentafurcations at the carotid sinus are very rare, with no previous mention of bilateral occurrences found in the literature. The clinical importance of understanding the variability in carotid vasculature is paramount in both radiologic and surgical specialties, and for predicting the impact of carotid artery anomalies on the pathophysiology of carotid atherosclerosis. Methods During the first-year medical student anatomy course at Kansas City University, dissection of the deep anterior neck region was performed on an 84-year-old male formalin fixed cadaver with limited past medical history. Results A bilateral carotid artery pentafurcation was identified. In addition to typical ICA and ECA branches, the carotid sinus bilaterally produces the superior thyroid artery (STA), anterior pharyngeal artery (APA) and occipital artery (OA). Conclusions This case presents a previously unreported bilateral carotid artery pentafurcation. Understanding the variability possible in head and neck anatomy is paramount in critical during surgical and radiologic procedures, and explaining the pathogenesis of certain vasculopathies. carotid anatomic variation pentafurcation bilateral cadaveric study Figures Figure 1 Figure 2 Introduction and Clinical Significance An appreciation of functional anatomical relationships is typically essential most medical procedure, whether diagnostic or interventional, clinical or surgical. This is especially true for regions with multiple closely related vital neurovascular structures, such as the anterior neck. The common carotid artery (CCA) branches are the predominant blood supply to the face, anterior neck, and anterior cerebral circulation. The CCA traditionally bifurcates at the level of the upper border of the thyroid cartilage, forming the internal carotid artery (ICA) and external carotid artery (ECA). The ICA continues without branching until it enters the neurocranium where it produces the ophthalmic artery, supplying the eye, and continues to provide the brain's anterior circulation. The ECA has eight branches, traditionally following the ascending order of superior thyroid artery (STA), ascending pharyngeal artery (APA), lingual artery (LA), facial artery (FA), occipital artery (OA), posterior auricular artery (PAA), maxillary artery (MA), and superficial temporal artery (TA). Most of these vessels produce additional branches, those of significance here are the APA’s pharyngeal branch, inferior tympanic artery, and posterior meningeal artery. Numerous variations have been described in the literature, and several ECA branching pattern classification systems have been proposed, underscoring the degree of variability possible in the ECA alone. This report describes a rare bilateral pentafurcation of the CCAs in which the STA, APA, OA arise from the carotid sinus before its typical bifurcation into ICA and ECA. Because of the wide range of surgical and radiologic procedures performed in such a small, critical region, documentation of such a rare variation may prove essential to avoid complications and iatrogenic injuries. Case Presentation A rare variation of the carotid vasculature was observed bilaterally in an 84-year-old male formalin-fixed cadaver during routine dissection of the anterior neck at Kansas City University. Clinical history was limited to what was provided by family members, including a past medical history of polypoidal cyst, pacemaker, prostate cancer, dysphagia, diabetes and atrial fibrillation. Cause of death was reported as Parkinson disease 2.2. Dissection and Anatomical Findings The left carotid system exhibits anomalous branching beginning with the STA, branching from the carotid sinus 5.17 mm distal to the base of the ECA. With a diameter of 2.23 mm, the STA takes an inferomedial course to supply the thyroid. Further dissection revealed two additional vessels exiting between the ICA and ECA, identified as the OA and APA. The left OA branched superolaterally from the CS and continued posteriorly to supply the occiput without further branching; its diameter was 3.74 mm. The APA branched superomedially from the CS with a diameter of 1.88 mm. 29.42 mm from the CS the left APA bifurcated into the inferior tympanic artery and posterior meningeal artery. The pharyngeal branch did not originate from the APA, as is the common branching pattern, but instead branched directly off of the ECA. The left ECA exhibited a sigmoidal course at the level of the carotid sinus, which was notably wide, measuring 17.98 mm at the carotid bifurcation. At this level, the ECA formed a four-branch trunk consisting of the lingual artery, facial artery (3.98 mm), what would be the APA’s pharyngeal branch (9.66 mm), and the continuation of the ECA. The origins of the lingual and facial arteries branched 1.64 mm apart, and distally the ECA continuation measured 3.03 mm. The remainder of the left ECA and its branches exhibited traditional routing. The lingual artery originated from the ECA trunk and was situated between the STA and FA. It was located 7.23 mm from the STA with a diameter of 3.27 mm at its origin. The facial artery likewise originated from the ECA trunk with a diameter of 3.98 mm. Table 1 External Diameters of bilateral carotid systems Vessel Right Side (mm) Left Side (mm) CCA, STA level 11.48 8.91 CCA, CB level 12.01 17.98 Internal Carotid Artery (ICA) 1 5.36 × 7.36 8.53 × 7.22 ECA, CB level 1 5.28 × 4.98 9.66 x 6.56 ECA, post-LA, FA branching 3.65 3.03 Superior Thyroid Artery (STA) 3.05 2.23 Lingual Artery (LA) 2.92 3.27 Facial Artery (FA) 3.98 3.49 LA-FA distance 4.13 1.64 Ascending Pharyngeal Artery (APA) 2.35 1.88 Occipital Artery (OA) 2.81 3.74 1 ICA and ECA measurements at the carotid sinus were taken in two planes to account for their irregular lumen shapes. Discussion Development of the carotid arteries and their branches begin with the formation of the ventral aortas, dorsal aortas, and arterial arches between 21–28 days of gestation, which is considered the “pre-Padget” stage. During Padget stage 1, the primitive ICA begins developing from the dorsal aorta, near the third arterial arch, around day 30. By day 31, the ICA is clearly delineated, and the primitive ECA begins development from the ventral pharyngeal artery (VPA), which originates from the ventral aorta between the first two aortic arches. The VPA is in the median part of the embryo and extends from the aortic bulb towards the mandibular root of the fifth cranial nerve. Once these arches have regressed, the VPA is considered the ECA [2]. The ECA and ICA remain separated by the ventral and dorsal aortic systems throughout the duration of Padget stage 3 while the VPA continues elongation and the ICA develops its cerebral branches. By Padget stage 4 the ventral aortas have regressed, leaving behind the CCA. The VPA is now considered the ECA [2]. The separate origins of the ECA and ICA could lead to more variations in bifurcation location and angle. By arising from two completely separate aortic systems, rather than branching from one common location, there is additional chance for variation. Furthermore, their late unification allows more time for a variation to arise. The branches do not fully unify until typically day 36, a full five days after the ICA has been established. This allows for more time for variations to occur in bifurcation location and angle. During Padget stage 5, the CCA continues elongation and the ECA begins angiogenesis of its branches, including STA, LA, OA, and MA [2]. The branching in later stages of arterial development could, again, lead to more branching variations. The APA develops independently from the ECA, and is typically considered a remnant of the hypoglossal artery, which appears distal to the 6th pharyngeal arch during Padget stage 1 and supplies the two longitudinal neural arteries, which go on to form the basilar artery during Padget stage 3. Between Padget stages 3 and 5 the origin of the hypoglossal artery shifts from the ICA to the ECA. The separate development of the APA from the ECA and its branches lends itself to the increased possibility of variations developing [6]. Previous literature has described branching of the OA, APA, and STA from the carotid bifurcation with various incidences. While highly variable, the most common of these variations is the STA, with incidences reported to range from 30% to 76.7% of cases [1]. Al Rafiah et al. observed an incidence of 3.3% of the APA branching off the carotid bifurcation [1]. The rarest of these branch origins would be the OA, as demonstrated in a study by Uchino et al., who found a single OA branching from the carotid bifurcation unilaterally in sample size of 2,866 patients [7]. Very few carotid artery pentafurcations have been documented in prior literature, with various branching patterns. Of these pentafurcations, one demonstrated a branching pattern where the STA, LA, and FA detached from the CCA before the carotid bifurcation [10], and another found three pentafurcations comprising of ECA, ICA, STA, OA, and PAA [5]. While some of these atypical branching patterns, especially STA, are not uncommon, it is notable that this case had three branches originating at the carotid bifurcation, and this branching was observed bilaterally. These two publications describe either a unilateral pentafurcation [10] or do not explicitly discuss laterality [5]. These documented pentafurcations do not follow the same branching pattern that was observed in the current study. The STA is potentially encountered in thyroidectomy, tracheostomy, and carotid endarterectomy. In carotid endarterectomy, duplex ultrasonography is the imaging modality most commonly utilized. However this is a small region where ultrasound provides relatively less anatomical detail. Early STA origin may conceal the true carotid bifurcation site or be confused for the ECA, complicating vessel identification. Additional surgical risk exists due to the external branch of the superior laryngeal nerve’s close proximity to the STA. Variability in one structure can lead to unpredictable variations in the other. Accurate localization of these structures is critically important, as accidental injury of STA during surgical procedures or jugular venipuncture can result in hematoma and critical bleeding. In addition to potential injuries of the STA, the localization of the STA becomes important in occlusion of the CCA, as it can form a supra-isthmic anastomosis that shuttles blood to the brain. The APA supplies the pharynx, auricular mucosa, skull base and cranial nerves IX, X, XI, and XII. A relatively common aberration of the APA can occur when it originates from the ICA, seen in up to 8% of cases [8]. The APA is also the major blood supply for numerous skull base tumors including menangiomas, tumors of the jugular foramen, and primary adenomatous tumors of the middle ear [3]. The APA has also been indicated in post-tonsillectomy hemorrhage, making it an important surgical consideration. Though not seen in this case, these changes stress the increased risk incurred when origins of such crucial vessels are located closer to carotid endarterectomy sites than anticipated; embolization of the aberrant APA could impact any of its dependents [3]. Though significantly less common, the OA can also originate from the ICA reported at less than 0.1% [8]. The OA and APA can be utilized for microcatheter embolization of certain head and neck cancers. The OA can also be used as a bypass for a PICA aneurysm [9], in which case the origin of the OA from the carotid bifurcation would need to be recognized prior to attempting such a procedure. The gradual ECA branching angle demonstrates potential for decreased wall shear stress, which can have indications with atherosclerosis [4]. Wall shear stress decreases with branching angle, which would increase the potential for atherosclerosis, thus demonstrating the importance of the clinical significance of the branching angle noted in this case. Conclusions This case report documents a heretofore unreported bilateral variation of the CCAs in which the carotid sinus produces three of the ECA’s traditional branches in addition to the expected ICA and ECA bifurcation. An extensive array of radiologic and surgical procedures are performed in this densely populated space, highlighting the clinical relevance of variations of these vascular structures. Documentation and classified variations of the carotid system is critical to anticipate for preoperative planning, medical management, and explaining some cases of vasculopathic pathogenesis. Declarations Additional Findings No additional muscular, vascular, or neural variations were identified in the anterior cervical region. The carotid sheath and the remainder of its contents followed expected anatomical relationships. Compliance with Ethical Standards Conflicts of Interest : The authors declare no conflicts of interest. Funding : No funds, grants, or other support was received for this study. Ethical Statement and Data Availability The study was conducted according to the guidelines of the Declaration of Helsinki, and approved by the Institutional Biosafety Committee at Kansas City University (protocol #2359680, approved 25 September 2025) Competing Interests : The authors have no relevant financial or non-financial interests or disclosures to declare. Informed Consent Statement : Informed consent, including permission to publish images for research and/or educational purposes, was obtained from all subjects involved in the study through their participation in the Gift Body Program at Kansas City University. All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee and with the tenets of the Declaration of Helsinki and its later amendments. Data Availability Statement : The raw data supporting the conclusions of this article will be made available by the authors on request. Author Contributions TA Mardis: Project development, Data collection, Data analysis, Manuscript writing KE Crawford: Data collection, Manuscript editing DR Koontz: Manuscript writing SS Sloan: Manuscript editing All authors read and approved the final manuscript. References Al-Rafiah A, EL-Haggagy AA, Aal IHA, Zaki AI. Anatomical study of the carotid bifurcation and origin variations of the ascending pharyngeal and superior thyroid arteries. Folia Morphol . 2011;70(1). Bertulli L, Robert T. Embryological development of the human cranio-facial arterial system: a pictorial review. Surg Radiol Anat . 2021;43(6):961–973. doi: 10.1007/s00276-021-02684-y Hacein-Bey L, Daniels DL, Ulmer JL, et al. The ascending pharyngeal artery: branches, anastomoses, and clinical significance. AJNR Am J Neuroradiol . 2002;23(7):1246–1256. Nguyen KT, Clark CD, Chancellor TJ, Papavassiliou DV. Carotid geometry effects on blood flow and on risk for vascular disease. Journal of Biomechanics . 2008;41(1):11–19. doi: 10.1016/j.jbiomech.2007.08.012 Ogeng’o, J., Misiani, M., Malek, A., Inyimili, M., Murunga, A., & Ongeti, K. (2024 Variant Termination of the Common Carotid Artery: Cases of Quadrifurcation and Pentafurcation. Anatomy Journal of Africa , 3 (3). 2014. Retrieved from https://anatomyafrica.com/index.php/aja/article/view/132 Robert T, Bonasia S. Embryology and Variations of the Ascending Pharyngeal Artery. In: Robert T, Bonasia S, Bojanowski MW, eds. Anatomy of Cranial Arteries, Embryology and Variants . Springer International Publishing; 2023:385–395. doi: 10.1007/978-3-031-32913-5_38 Uchino A, Saito N, Mizukoshi W, Okada Y. Anomalous origin of the occipital artery diagnosed by magnetic resonance angiography. Neuroradiology . 2011;53(11):853–857. doi: 10.1007/s00234-010-0825-z Wacker F, Lippert H, Pabst R, eds. Arterial Variations in Humans: Key Reference for Radiologists and Surgeons: Classification and Frequency . 1st edition. Thieme; 2018. doi: 10.1055/b-004-138012 Wang AC, Peeters SM, Samarage HM, Martin NA. Revascularization techniques for complex aneurysms and skull base tumors. In: Youmans and Winn Neurological Surgery. 8th ed. Vols 1–4. Elsevier; 2023:3623–3635.e3. Zaccheo F, Mariotti F, Guttadauro A, et al. A Rare Configuration origin of the Superior Thyroid, Lingual and Facial Arteries in a Pentafurcated Common Carotid Artery. Anatomia . 2022;1(2):204–209. doi: 10.3390/anatomia1020020 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 07 Apr, 2026 Reviews received at journal 07 Apr, 2026 Reviews received at journal 04 Apr, 2026 Reviewers agreed at journal 04 Apr, 2026 Reviews received at journal 02 Apr, 2026 Reviewers agreed at journal 01 Apr, 2026 Reviews received at journal 01 Apr, 2026 Reviewers agreed at journal 01 Apr, 2026 Reviewers agreed at journal 31 Mar, 2026 Reviewers agreed at journal 30 Mar, 2026 Reviewers agreed at journal 30 Mar, 2026 Reviewers invited by journal 30 Mar, 2026 Editor assigned by journal 30 Mar, 2026 Submission checks completed at journal 27 Mar, 2026 First submitted to journal 27 Mar, 2026 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. 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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-9247653","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":614609403,"identity":"0e8eb5e7-2347-4bf0-91ea-d4ba6314b733","order_by":0,"name":"Thornton Mardis","email":"data:image/png;base64,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","orcid":"","institution":"Kansas City University","correspondingAuthor":true,"prefix":"","firstName":"Thornton","middleName":"","lastName":"Mardis","suffix":""},{"id":614609404,"identity":"fb35a866-6052-4eba-816c-f775fdd1f43c","order_by":1,"name":"Kayla Crawford","email":"","orcid":"","institution":"Kansas City University","correspondingAuthor":false,"prefix":"","firstName":"Kayla","middleName":"","lastName":"Crawford","suffix":""},{"id":614609405,"identity":"dff08d9d-a3c9-4d3e-b33e-8ea0452bd6ae","order_by":2,"name":"Delaney Koontz","email":"","orcid":"","institution":"Kansas City University","correspondingAuthor":false,"prefix":"","firstName":"Delaney","middleName":"","lastName":"Koontz","suffix":""},{"id":614609406,"identity":"ed49b169-f53d-4311-a07a-3ed6ed9c2b63","order_by":3,"name":"Sara Sloan","email":"","orcid":"","institution":"Kansas City University","correspondingAuthor":false,"prefix":"","firstName":"Sara","middleName":"","lastName":"Sloan","suffix":""}],"badges":[],"createdAt":"2026-03-27 18:38:19","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9247653/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9247653/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":105886493,"identity":"321b6681-22dc-4b1e-a797-d0d09d56df56","added_by":"auto","created_at":"2026-04-01 07:29:46","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":344428,"visible":true,"origin":"","legend":"\u003cp\u003eLeft carotid system before reflecting the stylohyoid, stylopharyngeus, and styloglossus muscles (unlabeled)\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-9247653/v1/abe1c47ccd1f582b7cc8ceda.png"},{"id":105886486,"identity":"0b77f374-4517-4fb7-8333-91e1d3b06ffa","added_by":"auto","created_at":"2026-04-01 07:29:44","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":832697,"visible":true,"origin":"","legend":"\u003cp\u003elabeled views of the left and right carotid arteries and their branches: (a) Left carotid sinus, lateral view. APA (superior) and STA (inferior) selected. (b) Right carotid sinus, lateral view. APA selected with inferior tympanic artery (ITA) and neuromeningeal trunk (NMT) shown. (c) Left carotid sinus, medial view. APA exiting superomedially. (d) Right carotid sinus, medial view. APA selected.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-9247653/v1/81592fca989db5904c9a50d5.png"},{"id":105886545,"identity":"a1814ec9-6a40-4834-9153-520caadfbcad","added_by":"auto","created_at":"2026-04-01 07:29:52","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1953788,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9247653/v1/7a654def-847e-4e3a-8f72-d665f7e12305.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Bilateral Pentafurcation of the Common Carotid Arteries: A New Anatomic Variant","fulltext":[{"header":"Introduction and Clinical Significance","content":"\u003cp\u003eAn appreciation of functional anatomical relationships is typically essential most medical procedure, whether diagnostic or interventional, clinical or surgical. This is especially true for regions with multiple closely related vital neurovascular structures, such as the anterior neck. The common carotid artery (CCA) branches are the predominant blood supply to the face, anterior neck, and anterior cerebral circulation. The CCA traditionally bifurcates at the level of the upper border of the thyroid cartilage, forming the internal carotid artery (ICA) and external carotid artery (ECA). The ICA continues without branching until it enters the neurocranium where it produces the ophthalmic artery, supplying the eye, and continues to provide the brain's anterior circulation. The ECA has eight branches, traditionally following the ascending order of superior thyroid artery (STA), ascending pharyngeal artery (APA), lingual artery (LA), facial artery (FA), occipital artery (OA), posterior auricular artery (PAA), maxillary artery (MA), and superficial temporal artery (TA). Most of these vessels produce additional branches, those of significance here are the APA\u0026rsquo;s pharyngeal branch, inferior tympanic artery, and posterior meningeal artery.\u003c/p\u003e \u003cp\u003eNumerous variations have been described in the literature, and several ECA branching pattern classification systems have been proposed, underscoring the degree of variability possible in the ECA alone. This report describes a rare bilateral pentafurcation of the CCAs in which the STA, APA, OA arise from the carotid sinus before its typical bifurcation into ICA and ECA. Because of the wide range of surgical and radiologic procedures performed in such a small, critical region, documentation of such a rare variation may prove essential to avoid complications and iatrogenic injuries.\u003c/p\u003e"},{"header":"Case Presentation","content":"\u003cp\u003eA rare variation of the carotid vasculature was observed bilaterally in an 84-year-old male formalin-fixed cadaver during routine dissection of the anterior neck at Kansas City University. Clinical history was limited to what was provided by family members, including a past medical history of polypoidal cyst, pacemaker, prostate cancer, dysphagia, diabetes and atrial fibrillation. Cause of death was reported as Parkinson disease\u003c/p\u003e \u003cp\u003e2.2. Dissection and Anatomical Findings\u003c/p\u003e \u003cp\u003eThe left carotid system exhibits anomalous branching beginning with the STA, branching from the carotid sinus 5.17 mm distal to the base of the ECA. With a diameter of 2.23 mm, the STA takes an inferomedial course to supply the thyroid. Further dissection revealed two additional vessels exiting between the ICA and ECA, identified as the OA and APA. The left OA branched superolaterally from the CS and continued posteriorly to supply the occiput without further branching; its diameter was 3.74 mm. The APA branched superomedially from the CS with a diameter of 1.88 mm. 29.42 mm from the CS the left APA bifurcated into the inferior tympanic artery and posterior meningeal artery. The pharyngeal branch did not originate from the APA, as is the common branching pattern, but instead branched directly off of the ECA.\u003c/p\u003e \u003cp\u003eThe left ECA exhibited a sigmoidal course at the level of the carotid sinus, which was notably wide, measuring 17.98 mm at the carotid bifurcation. At this level, the ECA formed a four-branch trunk consisting of the lingual artery, facial artery (3.98 mm), what would be the APA\u0026rsquo;s pharyngeal branch (9.66 mm), and the continuation of the ECA. The origins of the lingual and facial arteries branched 1.64 mm apart, and distally the ECA continuation measured 3.03 mm. The remainder of the left ECA and its branches exhibited traditional routing.\u003c/p\u003e \u003cp\u003eThe lingual artery originated from the ECA trunk and was situated between the STA and FA. It was located 7.23 mm from the STA with a diameter of 3.27 mm at its origin. The facial artery likewise originated from the ECA trunk with a diameter of 3.98 mm.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eExternal Diameters of bilateral carotid systems\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVessel\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eRight Side (mm)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eLeft Side (mm)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCCA, STA level\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e11.48\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e8.91\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCCA, CB level\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e12.01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e17.98\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eInternal Carotid Artery (ICA)\u003csup\u003e1\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e5.36 \u0026times; 7.36\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e8.53 \u0026times; 7.22\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eECA, CB level\u003csup\u003e1\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e5.28 \u0026times; 4.98\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e9.66 x 6.56\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eECA, post-LA, FA branching\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e3.65\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3.03\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSuperior Thyroid Artery (STA)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e3.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2.23\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLingual Artery (LA)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2.92\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3.27\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFacial Artery (FA)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e3.98\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3.49\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLA-FA distance\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e4.13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.64\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAscending Pharyngeal Artery (APA)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2.35\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.88\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOccipital Artery (OA)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2.81\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3.74\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003csup\u003e1\u003c/sup\u003e ICA and ECA measurements at the carotid sinus were taken in two planes to account for their irregular lumen shapes.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eDevelopment of the carotid arteries and their branches begin with the formation of the ventral aortas, dorsal aortas, and arterial arches between 21\u0026ndash;28 days of gestation, which is considered the \u0026ldquo;pre-Padget\u0026rdquo; stage. During Padget stage 1, the primitive ICA begins developing from the dorsal aorta, near the third arterial arch, around day 30. By day 31, the ICA is clearly delineated, and the primitive ECA begins development from the ventral pharyngeal artery (VPA), which originates from the ventral aorta between the first two aortic arches. The VPA is in the median part of the embryo and extends from the aortic bulb towards the mandibular root of the fifth cranial nerve. Once these arches have regressed, the VPA is considered the ECA [2].\u003c/p\u003e \u003cp\u003eThe ECA and ICA remain separated by the ventral and dorsal aortic systems throughout the duration of Padget stage 3 while the VPA continues elongation and the ICA develops its cerebral branches. By Padget stage 4 the ventral aortas have regressed, leaving behind the CCA. The VPA is now considered the ECA [2]. The separate origins of the ECA and ICA could lead to more variations in bifurcation location and angle. By arising from two completely separate aortic systems, rather than branching from one common location, there is additional chance for variation. Furthermore, their late unification allows more time for a variation to arise. The branches do not fully unify until typically day 36, a full five days after the ICA has been established. This allows for more time for variations to occur in bifurcation location and angle.\u003c/p\u003e \u003cp\u003eDuring Padget stage 5, the CCA continues elongation and the ECA begins angiogenesis of its branches, including STA, LA, OA, and MA [2]. The branching in later stages of arterial development could, again, lead to more branching variations.\u003c/p\u003e \u003cp\u003eThe APA develops independently from the ECA, and is typically considered a remnant of the hypoglossal artery, which appears distal to the 6th pharyngeal arch during Padget stage 1 and supplies the two longitudinal neural arteries, which go on to form the basilar artery during Padget stage 3. Between Padget stages 3 and 5 the origin of the hypoglossal artery shifts from the ICA to the ECA. The separate development of the APA from the ECA and its branches lends itself to the increased possibility of variations developing [6].\u003c/p\u003e \u003cp\u003ePrevious literature has described branching of the OA, APA, and STA from the carotid bifurcation with various incidences. While highly variable, the most common of these variations is the STA, with incidences reported to range from 30% to 76.7% of cases [1]. Al Rafiah et al. observed an incidence of 3.3% of the APA branching off the carotid bifurcation [1]. The rarest of these branch origins would be the OA, as demonstrated in a study by Uchino et al., who found a single OA branching from the carotid bifurcation unilaterally in sample size of 2,866 patients [7].\u003c/p\u003e \u003cp\u003eVery few carotid artery pentafurcations have been documented in prior literature, with various branching patterns. Of these pentafurcations, one demonstrated a branching pattern where the STA, LA, and FA detached from the CCA before the carotid bifurcation [10], and another found three pentafurcations comprising of ECA, ICA, STA, OA, and PAA [5].\u003c/p\u003e \u003cp\u003eWhile some of these atypical branching patterns, especially STA, are not uncommon, it is notable that this case had three branches originating at the carotid bifurcation, and this branching was observed bilaterally. These two publications describe either a unilateral pentafurcation [10] or do not explicitly discuss laterality [5]. These documented pentafurcations do not follow the same branching pattern that was observed in the current study.\u003c/p\u003e \u003cp\u003eThe STA is potentially encountered in thyroidectomy, tracheostomy, and carotid endarterectomy. In carotid endarterectomy, duplex ultrasonography is the imaging modality most commonly utilized. However this is a small region where ultrasound provides relatively less anatomical detail. Early STA origin may conceal the true carotid bifurcation site or be confused for the ECA, complicating vessel identification. Additional surgical risk exists due to the external branch of the superior laryngeal nerve\u0026rsquo;s close proximity to the STA. Variability in one structure can lead to unpredictable variations in the other. Accurate localization of these structures is critically important, as accidental injury of STA during surgical procedures or jugular venipuncture can result in hematoma and critical bleeding. In addition to potential injuries of the STA, the localization of the STA becomes important in occlusion of the CCA, as it can form a supra-isthmic anastomosis that shuttles blood to the brain.\u003c/p\u003e \u003cp\u003eThe APA supplies the pharynx, auricular mucosa, skull base and cranial nerves IX, X, XI, and XII. A relatively common aberration of the APA can occur when it originates from the ICA, seen in up to 8% of cases [8]. The APA is also the major blood supply for numerous skull base tumors including menangiomas, tumors of the jugular foramen, and primary adenomatous tumors of the middle ear [3]. The APA has also been indicated in post-tonsillectomy hemorrhage, making it an important surgical consideration. Though not seen in this case, these changes stress the increased risk incurred when origins of such crucial vessels are located closer to carotid endarterectomy sites than anticipated; embolization of the aberrant APA could impact any of its dependents [3].\u003c/p\u003e \u003cp\u003eThough significantly less common, the OA can also originate from the ICA reported at less than 0.1% [8]. The OA and APA can be utilized for microcatheter embolization of certain head and neck cancers. The OA can also be used as a bypass for a PICA aneurysm [9], in which case the origin of the OA from the carotid bifurcation would need to be recognized prior to attempting such a procedure.\u003c/p\u003e \u003cp\u003eThe gradual ECA branching angle demonstrates potential for decreased wall shear stress, which can have indications with atherosclerosis [4]. Wall shear stress decreases with branching angle, which would increase the potential for atherosclerosis, thus demonstrating the importance of the clinical significance of the branching angle noted in this case.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eThis case report documents a heretofore unreported bilateral variation of the CCAs in which the carotid sinus produces three of the ECA\u0026rsquo;s traditional branches in addition to the expected ICA and ECA bifurcation. An extensive array of radiologic and surgical procedures are performed in this densely populated space, highlighting the clinical relevance of variations of these vascular structures. Documentation and classified variations of the carotid system is critical to anticipate for preoperative planning, medical management, and explaining some cases of vasculopathic pathogenesis.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAdditional Findings\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNo additional muscular, vascular, or neural variations were identified in the anterior cervical region. The carotid sheath and the remainder of its contents followed expected anatomical relationships. \u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompliance with Ethical Standards\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflicts of Interest\u003c/strong\u003e: The authors declare no conflicts of interest.\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e:\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003eNo funds, grants, or other support was received for this study.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthical Statement and Data Availability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe study was conducted according to the guidelines of the Declaration of Helsinki, and approved by the Institutional Biosafety Committee at Kansas City University (protocol #2359680, approved 25 September 2025)\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting Interests\u003c/strong\u003e: The authors have no relevant financial or non-financial interests or disclosures to declare.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eInformed Consent Statement\u003c/strong\u003e: Informed consent, including permission to publish images for research and/or educational purposes, was obtained from all subjects involved in the study through their participation in the Gift Body Program at Kansas City University. All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee and with the tenets of the Declaration of Helsinki and its later amendments.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData Availability Statement\u003c/strong\u003e: The raw data supporting the conclusions of this article will be made available by the authors on request.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor Contributions\u003c/strong\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eTA Mardis: Project development, Data collection, Data analysis, Manuscript writing\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eKE Crawford: Data collection, Manuscript editing\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eDR Koontz: Manuscript writing\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eSS Sloan: Manuscript editing\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAll authors read and approved the final manuscript.\u0026nbsp;\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003e\u003cspan\u003eAl-Rafiah A, EL-Haggagy AA, Aal IHA, Zaki AI. Anatomical study of the carotid bifurcation and origin variations of the ascending pharyngeal and superior thyroid arteries. \u003cem\u003eFolia Morphol\u003c/em\u003e. 2011;70(1).\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eBertulli L, Robert T. Embryological development of the human cranio-facial arterial system: a pictorial review. \u003cem\u003eSurg Radiol Anat\u003c/em\u003e. 2021;43(6):961\u0026ndash;973. doi:\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/s00276-021-02684-y\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eHacein-Bey L, Daniels DL, Ulmer JL, et al. The ascending pharyngeal artery: branches, anastomoses, and clinical significance.\u0026nbsp;\u003cem\u003eAJNR Am J Neuroradiol\u003c/em\u003e. 2002;23(7):1246\u0026ndash;1256.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eNguyen KT, Clark CD, Chancellor TJ, Papavassiliou DV. Carotid geometry effects on blood flow and on risk for vascular disease. \u003cem\u003eJournal of Biomechanics\u003c/em\u003e. 2008;41(1):11\u0026ndash;19. doi:\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.jbiomech.2007.08.012\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eOgeng\u0026rsquo;o, J., Misiani, M., Malek, A., Inyimili, M., Murunga, A., \u0026amp; Ongeti, K. (2024 Variant Termination of the Common Carotid Artery: Cases of Quadrifurcation and Pentafurcation. \u003cem\u003eAnatomy Journal of Africa\u003c/em\u003e, \u003cem\u003e3\u003c/em\u003e(3). 2014. Retrieved from \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://anatomyafrica.com/index.php/aja/article/view/132\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eRobert T, Bonasia S. Embryology and Variations of the Ascending Pharyngeal Artery. In: Robert T, Bonasia S, Bojanowski MW, eds. \u003cem\u003eAnatomy of Cranial Arteries, Embryology and Variants\u003c/em\u003e. Springer International Publishing; 2023:385\u0026ndash;395. doi:\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/978-3-031-32913-5_38\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eUchino A, Saito N, Mizukoshi W, Okada Y. Anomalous origin of the occipital artery diagnosed by magnetic resonance angiography. \u003cem\u003eNeuroradiology\u003c/em\u003e. 2011;53(11):853\u0026ndash;857. doi:\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/s00234-010-0825-z\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eWacker F, Lippert H, Pabst R, eds. \u003cem\u003eArterial Variations in Humans: Key Reference for Radiologists and Surgeons: Classification and Frequency\u003c/em\u003e. 1st edition. Thieme; 2018. doi:\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1055/b-004-138012\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eWang AC, Peeters SM, Samarage HM, Martin NA. Revascularization techniques for complex aneurysms and skull base tumors. In: Youmans and Winn Neurological Surgery. 8th ed. Vols 1\u0026ndash;4. Elsevier; 2023:3623\u0026ndash;3635.e3.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eZaccheo F, Mariotti F, Guttadauro A, et al. A Rare Configuration origin of the Superior Thyroid, Lingual and Facial Arteries in a Pentafurcated Common Carotid Artery. \u003cem\u003eAnatomia\u003c/em\u003e. 2022;1(2):204\u0026ndash;209. doi:\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.3390/anatomia1020020\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"surgical-and-radiologic-anatomy","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"sara","sideBox":"Learn more about [Surgical and Radiologic Anatomy](http://link.springer.com/journal/276)","snPcode":"276","submissionUrl":"https://submission.nature.com/new-submission/276/3","title":"Surgical and Radiologic Anatomy","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"carotid, anatomic variation, pentafurcation, bilateral, cadaveric study","lastPublishedDoi":"10.21203/rs.3.rs-9247653/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9247653/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cb\u003ePurpose\u003c/b\u003e\u003c/p\u003e \u003cp\u003eThe Common Carotid Artery (CCA) is understood to bifurcate at the level of the upper border of the thyroid cartilage into the internal carotid artery (ICA) and external carotid artery (ECA). Variations on these branching patterns have been reported and several classification systems have been proposed. Pentafurcations at the carotid sinus are very rare, with no previous mention of bilateral occurrences found in the literature. The clinical importance of understanding the variability in carotid vasculature is paramount in both radiologic and surgical specialties, and for predicting the impact of carotid artery anomalies on the pathophysiology of carotid atherosclerosis.\u003c/p\u003e\u003cp\u003e\u003cb\u003eMethods\u003c/b\u003e\u003c/p\u003e \u003cp\u003eDuring the first-year medical student anatomy course at Kansas City University, dissection of the deep anterior neck region was performed on an 84-year-old male formalin fixed cadaver with limited past medical history.\u003c/p\u003e\u003cp\u003e\u003cb\u003eResults\u003c/b\u003e\u003c/p\u003e \u003cp\u003eA bilateral carotid artery pentafurcation was identified. In addition to typical ICA and ECA branches, the carotid sinus bilaterally produces the superior thyroid artery (STA), anterior pharyngeal artery (APA) and occipital artery (OA).\u003c/p\u003e\u003cp\u003e\u003cb\u003eConclusions\u003c/b\u003e\u003c/p\u003e \u003cp\u003eThis case presents a previously unreported bilateral carotid artery pentafurcation. Understanding the variability possible in head and neck anatomy is paramount in critical during surgical and radiologic procedures, and explaining the pathogenesis of certain vasculopathies.\u003c/p\u003e","manuscriptTitle":"Bilateral Pentafurcation of the Common Carotid Arteries: A New Anatomic Variant","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-04-01 07:28:54","doi":"10.21203/rs.3.rs-9247653/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-04-07T08:14:37+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-07T07:40:35+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-04T22:44:23+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"311534618529317434510093646465532287176","date":"2026-04-04T18:26:19+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-02T17:34:39+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"54953892555579546283016604987156615511","date":"2026-04-01T14:30:49+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-01T10:23:33+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"207869078553910534170272658781262140002","date":"2026-04-01T10:11:44+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"325431254300381786902605266633707880041","date":"2026-03-31T19:19:40+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"50153346350017934174613494021532145156","date":"2026-03-30T13:12:20+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"190719830874664149909447650546342256567","date":"2026-03-30T12:41:06+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-03-30T08:50:27+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-03-30T08:42:30+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-03-28T02:38:49+00:00","index":"","fulltext":""},{"type":"submitted","content":"Surgical and Radiologic Anatomy","date":"2026-03-27T18:22:16+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"surgical-and-radiologic-anatomy","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"sara","sideBox":"Learn more about [Surgical and Radiologic Anatomy](http://link.springer.com/journal/276)","snPcode":"276","submissionUrl":"https://submission.nature.com/new-submission/276/3","title":"Surgical and Radiologic Anatomy","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"c113df29-277e-4024-b5df-e4ccdf29eea0","owner":[],"postedDate":"April 1st, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-05-04T09:23:40+00:00","versionOfRecord":[],"versionCreatedAt":"2026-04-01 07:28:54","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9247653","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9247653","identity":"rs-9247653","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}