Unilateral Linguofacial Trunk of the External Carotid Artery: A Cadaveric Case Report From Myanmar

Introduction

The external carotid artery (ECA) is the principal vascular supply to the head and neck, arising from the common carotid artery at the level of the superior border of the thyroid cartilage and terminating behind the neck of the mandible. The ECA typically branches into the ascending pharyngeal, superior thyroid, lingual, facial, occipital, posterior auricular, superficial temporal, and maxillary arteries [1]. While this arrangement is widely depicted in anatomical texts, branching variability is well established and can significantly alter the vascular supply of the cervical and maxillofacial regions.

Among these variants, the linguofacial trunk (LFT), a common origin of the lingual and facial arteries, is one of the most clinically relevant anomalies. LFT has been reported in 14–24% of cadaveric and imaging-based studies, with variation influenced by population characteristics and methodological differences [2,3]. Failure to recognize this variant can complicate surgical procedures such as maxillofacial reconstruction, radical neck dissections, or emergency control of intraoral hemorrhage, where precise identification and ligation of vessels are essential [2,4]. Inadvertent ligation of an LFT during an attempted LA ligation can compromise perfusion to both the tongue and the face. Similarly, during carotid endarterectomy, unrecognized variant branches can be misleading landmarks and increase operative risk.

The clinical importance of the LFT extends to interventional oncology. Selective intra-arterial chemotherapy is increasingly employed for the management of advanced head and neck cancers, relying on super-selective catheterization of tumor-feeding arteries [5–7]. In the presence of an LFT, super-selection of either the lingual artery (LA) or facial artery (FA) can be technically challenging, and infusion into the trunk itself can result in uneven drug distribution. Such circumstances diminish the therapeutic precision of the procedure and increase the risk of under-treatment or off-target exposure [8–10]. Preoperative imaging, therefore, plays a critical role in identifying these variants and tailoring treatment strategies [11].

Population-based cadaveric studies have reported variable prevalence of the LFT across African, European, and South Asian populations, ranging from 7% to 44.7%, with differences likely influenced by demographic factors, sample size, and dissection protocols [12–14]. However, comparable anatomical data from Myanmar and neighboring regions in Southeast Asia remain limited. Despite extensive documentation of external carotid artery branching variations in diverse populations, data from Myanmar remain scarce. To the best of our knowledge, no cadaveric studies or case reports describing a linguofacial trunk in donors from Myanmar have been reported in the indexed English-language literature. The existing anatomical literature from Southeast Asia is limited and does not include population-specific documentation of this variant from Myanmar. Therefore, the present report aims to contribute region-specific anatomical data and highlight a clinically relevant vascular variation in a local cadaveric specimen. This assessment was based on a focused literature search of PubMed, Scopus, and Google Scholar using combinations of the terms “linguofacial trunk,” “external carotid artery variation,” “cadaveric study,” “Myanmar,” and “Burmese.” In this manuscript, “Burmese” is used to refer to geographic origin (Myanmar) rather than ethnic classification. Moreover, regional data from Southeast Asia remain scarce, and population-specific anatomical documentation is essential because reported prevalence rates differ markedly across ethnic groups. Additionally, the high-resolution cadaveric dissection in this report provides valuable educational material for local surgical training programs, where awareness of ECA branching variations directly impacts maxillofacial, vascular, and interventional procedures.

Case Report

The cadaveric specimen used in this study was obtained through the institutional body donation program of the Department of Anatomy, University of Medicine 1, Yangon, Myanmar. The male donor had provided written informed consent permitting the use of his body for education and research. The specimen was utilized during scheduled undergraduate anatomy dissection sessions. All procedures were conducted in accordance with institutional approval and adhered to local and international ethical standards governing the educational and research use of human cadaveric materials. We examined the carotid triangle during a routine dissection at the University of Medicine 1, Yangon, to assess the ECA branching pattern. The skin, superficial fascia, and infrahyoid muscles were carefully reflected to reveal the carotid sheath and its contents. The common carotid artery was traced to its bifurcation, after which the external carotid artery (ECA) and its branches were systematically dissected. Blunt dissection techniques were employed to preserve adjacent neurovascular structures, including the hypoglossal nerve (HGN), internal jugular vein (IJV), and submandibular gland (SMG). However, certain structures were not clearly visible in the photographic field due to their deeper location or angle of exposure. The ECA branching pattern was examined bilaterally and documented using high-resolution photography.

During routine dissection of the carotid triangle in a male donor, a right-sided linguofacial trunk (LFT) was identified as a notable arterial variation. After exposing the common carotid artery and tracing its bifurcation, the external carotid artery (ECA) and its branches were examined systematically. The LFT originated from the anterior surface of the ECA approximately 10 mm superior to the carotid bifurcation and measured 6 mm in length before dividing into the lingual artery (LA) and facial artery (FA). The superior thyroid artery (STA) arose independently below this level. As expected, the LA coursed deep to the hyoglossus muscle to supply the tongue, while the FA passed beneath the posterior belly of the digastric muscle and the submandibular gland, then curved over the inferior border of the mandible anterior to the masseter before ascending across the face to supply its terminal branches (Figures 1B, 2B). All major neurovascular structures, including the hypoglossal nerve and internal jugular vein, were preserved, although some were not visible in the photographic field due to their deeper anatomical position.

There were no major technical challenges encountered during the dissection; however, because the lingual and facial arteries arose from a short linguofacial trunk, the proximal separation between the 2 vessels was less distinct than in the classical pattern. This required more meticulous blunt dissection around the hyoglossus region to preserve nearby structures, particularly the hypoglossal nerve, which remained intact but was not easily visible in the final photographic field due to its deeper course

On the left, the STA, LA, and FA arose independently from the ECA in classical order. The LA originated in the deep submandibular region and coursed medially to the tongue, while the FA was tortuous and prominent, arching over the inferior mandibular border anterior to the masseter before ascending obliquely across the face (Figures 1A, 2A). The branching pattern corresponded with the standard description found in most anatomical references [15,16].

The HGN (Cranial nerve XII) curved anteriorly beneath the posterior belly of the digastric and stylohyoid muscles toward the tongue, typically crossing superficially over both the external carotid and lingual arteries. Within the submandibular triangle, it appeared as a horizontally oriented nerve. The IJV was situated deep to the infrahyoid musculature and lateral to the carotid arteries. To highlight the variation observed, Table 1 contrasts the classical branching pattern of the ECA with our cadaveric findings.

Discussion

The ECA is traditionally described as giving rise to 8 branches in a predictable sequence; however, extensive anatomical research has demonstrated considerable variability in the origin and arrangement of its caudal branches [17]. Among these variations, LFT, a common origin of the lingual and facial arteries, is one of the more frequently encountered patterns, with cadaveric and imaging-based studies (CTA) reporting prevalence rates between 14–24% [2,3]. Fetal studies further demonstrate developmental variability, identifying thyro-lingual (2.5%), thyrolinguo-facial (2.5%), and LFT (20%) patterns [17], underscoring the dynamic embryological remodeling that shapes the final branching configuration of the ECA. Although the LFT is not globally rare, its prevalence appears to differ by ethnicity and study methodology, emphasizing the importance of documenting population-specific patterns. This observation is a documented cadaveric case of a LFT from Myanmar, contributing region-specific anatomical data without implying population-level prevalence.

Embryologically, the LFT is believed to result from persistence and remodeling of a shared vascular channel supplying the developing tongue and face. Such developmental events help explain the diversity of branching patterns observed across populations. Although bilateral LFTs have been documented, unilateral patterns, such as the right-sided LFT observed in the present case, are more commonly reported [15,9–11]. In our case, the LFT originated approximately 10 mm superior to the carotid bifurcation, consistent with previously described ranges for anterior ECA variants [18,19].

Clinically, recognition of the LFT is essential because variant branching patterns may influence a wide range of procedures requiring precise vascular identification. These include selective arterial ligation for intraoral hemorrhage, regional flap harvesting, and super-selective intra-arterial chemotherapy (SSIAC) [5–7], where accurate catheterization of tumor-feeding vessels is crucial. In the presence of an LFT, selective catheterization of the lingual or facial artery can be technically challenging, and infusion into the common trunk can result in unpredictable drug distribution. In addition to arterial variants, other anatomical variations in the carotid triangle and parapharyngeal region, such as an elongated styloid process and calcified stylohyoid ligament complex (Eagle syndrome), can alter local neurovascular relationships and contribute to vascular compression or procedural difficulty during head and neck surgery and endovascular interventions [20,21]. The coexistence of vascular variants with osseous or ligamentous anomalies can further increase the risk of misidentification, iatrogenic injury, or incomplete therapeutic targeting [22]. Therefore, comprehensive preoperative imaging and anatomical awareness of both vascular and non-vascular variants are essential for safe surgical planning.

Moreover, Manzato et al (2013) reported a case of delayed, life-threatening post-tonsillectomy hemorrhage in which angiography revealed a pseudoaneurysm originating from a linguofacial trunk; definitive control required emergency endovascular coil embolization [23]. Similarly, in emergency bleeding scenarios, particularly when visualization is compromised, an unrecognized LFT can lead to mistargeted ligation, inadequate hemorrhage control, or inadvertent compromise of both lingual and facial perfusion [16–28]. Thus, while individual clinical scenarios differ, the overarching concern is that unrecognized LFTs increase procedural risk and may adversely affect surgical or interventional outcomes.

Given these implications, preoperative identification of ECA branching variants through high-resolution imaging modalities such as CTA or MRA is recommended. Awareness of such patterns also enhances anatomical education and surgical training, helping to prevent iatrogenic injury and optimize operative planning. This case report contributes valuable regional data, representing, to the best of our knowledge, the first documented cadaveric report of an LFT in Myanmar. Considering that reported prevalence varies across global populations, documentation from Southeast Asia helps fill an important gap in the literature. Expanding anatomical datasets from diverse regions contributes to more precise prevalence estimates, improved anatomical atlases, and better-informed risk stratification for head and neck procedures. For anatomists, systematic documentation of such cases enriches anatomical databases and informs teaching curricula. For clinicians, recognition of the LFT can prevent iatrogenic injury, improve surgical outcomes, and refine interventional strategies. Future population-based studies in diverse regions, including Southeast Asia, may clarify whether the frequency of LFT varies across ethnic groups, thereby contributing to more precise risk stratification.

This report is limited by its reliance on a single cadaveric specimen, which restricts the ability to estimate prevalence or variability within the population. Postmortem changes and dissection techniques may influence the anatomical presentation and do not fully replicate in vivo conditions. Additionally, the absence of radiological correlation, such as CTA or MRA, prevents confirmation of the vascular configuration in living subjects. Future studies combining cadaveric dissection with imaging-based anatomical surveys would provide a more comprehensive understanding of the prevalence of the linguofacial trunk and its clinical relevance.

Conclusions

The ECA is a major extracranial arterial supply to the face, scalp, oral cavity, pharynx, and other superficial structures of the head and neck. The variations in its branching pattern, particularly the LFT, have substantial clinical significance. Recognizing these variants is crucial for accurate diagnostics and safe surgical interventions. Failure to recognize such deviations can increase the risk of intraoperative complications, compromise oncological treatment efficacy, and mislead radiological interpretation. This case report underscores the value of detailed cadaveric investigations and structured dissection-based training in recognizing vascular variability. Systematic reporting of ECA variants, supplemented by preoperative imaging, is critical for optimizing patient safety and improving surgical and interventional outcomes. Ultimately, recognition of the LFT transforms an anatomical observation into a translational insight with direct implications for clinical practice.