|Year : 2020 | Volume
| Issue : 4 | Page : 184-187
Variation in the branching pattern of the anterior branches of the external carotid artery
Mohamed Elsllabi1, Sabri Garoushi2, Khaled Aneiba3, Osama A Tashani4
1 Department of Anatomy, Faculty of Medicine, University of Benghazi, Benghazi, Libya; Centre for Anatomy and Human Identification, University of Dundee; Department of General Surgery, Ninewells Hospital, Dundee, UK
2 Department of Anatomy, Faculty of Medicine, University of Benghazi, Benghazi, Libya; Biomedical Sciences, MENA Research Group, School of Clinical and Applied Sciences, Leeds, Beckett University; Department of Outpatients, St James University Hospital, Leeds, UK
3 Biomedical Sciences, MENA Research Group, School of Clinical and Applied Sciences, Leeds, Beckett University, Leeds; Department of Trauma and Orthopaedics, University Hospitals of Coventry and Warwick, Coventry, UK
4 Department of Anatomy, Faculty of Medicine, University of Benghazi, Benghazi, Libya; Biomedical Sciences, MENA Research Group, School of Clinical and Applied Sciences, Leeds, Beckett University, Leeds, UK
|Date of Submission||24-Jun-2020|
|Date of Acceptance||25-Nov-2020|
|Date of Web Publication||28-Dec-2020|
Dr. Osama A Tashani
Centre for Pain Research, MENA Research Group, Portland PD609, City Campus, Leeds LS1 3HE, England
Source of Support: None, Conflict of Interest: None
Background/Aim: External carotid artery (ECA) shows a variable branching pattern of its stemming vessels. The aim of this study was to investigate the variations in the origin of the three primary anterior branches of the ECA: superior thyroid artery (STA), lingual artery (LA), and facial artery (FA). Methods: The branching pattern of the ECA was studied on 15 Thiel embalmed cadavers of Scottish population (7 males and 8 females). The carotid triangle was dissected bilaterally to uncover the common carotid artery (CCA), internal carotid artery and ECA. The level of carotid artery bifurcation (CB) was located. Variation of the branching patterns of the ECA was assessed. Moreover, the distances between the origin sites of these vessels and the site of the CB were measured. Results: The STA was found to arise more frequently from the ECA (60%) than from the CCA (40%), with no differences in distribution between sexes or sides. Regarding the assessment of the branching patterns of the ECA, the specimens where the STA, LA, and FA emerged as individual branches were 90% of cases, linguofacial trunk cases were 6.7%, and thyrolinguofacial trunk cases were 3.3%. The distances from the vessel origin site to the CB were found to be 8.11 ± 2.77 mm, 19.38 ± 8.85 mm, and 27.95 ± 10.15 mm, for the STA, LA, and FA, respectively. Conclusions: The current findings have confirmed that the ECA branching pattern is highly variable in Thiel embalmed cadavers of Scottish population. Therefore, considering some radiological imaging before conducting any invasive procedure in the neck region could be vital to prevent iatrogenic injuries.
Keywords: Anatomical variation, carotid bifurcation, common carotid artery, external carotid artery
|How to cite this article:|
Elsllabi M, Garoushi S, Aneiba K, Tashani OA. Variation in the branching pattern of the anterior branches of the external carotid artery. Libyan J Med Sci 2020;4:184-7
|How to cite this URL:|
Elsllabi M, Garoushi S, Aneiba K, Tashani OA. Variation in the branching pattern of the anterior branches of the external carotid artery. Libyan J Med Sci [serial online] 2020 [cited 2021 Apr 12];4:184-7. Available from: https://www.ljmsonline.com/text.asp?2020/4/4/184/305243
| Introduction|| |
At its origin, the external carotid artery (ECA) lies anteromedial to the internal carotid artery in the carotid triangle. It gives off eight branches to supply the head and neck; three of them usually emerge from the anterior aspect of the ECA, namely the superior thyroid artery (STA), lingual artery (LA), and facial artery (FA). The ECA also gives rise to two posterior branches – the occipital artery and posterior auricular artery – and one medial branch – the ascending pharyngeal artery. The ECA is then related to the posterior surface of the neck of the mandible, where it eventually divides into its two terminal branches, the superficial temporal and maxillary arteries within the parotid gland. The branching pattern of the ECA, however, has shown considerable variation.
Several anatomic studies have defined the arterial supply of the neck region in detail;,, however, thorough explanation of their topo-anatomic relations with the neck region is restricted. Unnoticed vascular anomalies in the head and neck raise the risk of perioperative complications, for instance, accidental damage or ligature of the anomalous vessel, leading to undesirable ischemic or bleeding consequences., The aim of this study is to assess the anatomic variations of the origins of the anterior branches of the ECA.
| Methods|| |
A total of 15 Thiel embalmed cadavers (7 males and 8 females) were obtained from the Centre for Anatomy and Human Identification (CAHID), University of Dundee, Scotland. All cadavers in CAHID are under license of Human Tissue Act (Scotland). Permission was granted by the Thiel Advisory Committee and the CAHID Ethics Committee. Samples were studied to examine individual differences in the ECA branching pattern variations with regard to sex and side. The age of cadavers was between 64 and 94 years. All the cadavers were of adult native white Scottish population.
Thiel embalming which was used is a soft embalming method which permits the cadaver to preserve its flexibility and life-like tissue quality. Some dissection of the carotid arterial system was already performed bilaterally, so further cleaning was done to remove any remaining fascia or other tissue to permit measurement and photography. The origin and course of each ECA anterior branch were noted.
| Results|| |
Superior thyroid artery
In 18 of 30 specimens (60%), the STA originated from the ECA with an equal distribution between both sides in 5 females and 4 males [Table 1] and [Figure 1]. The STA most commonly arose as a separate branch; however, in one specimen, an aberrant thyrolinguofacial trunk was noted on the right side of a female cadaver. In 12 of 30 specimens (40%), the STA arose from the common carotid artery (CCA) bilaterally with an equal distribution between sexes. The mean distance of the STA origin site from the carotid artery bifurcation (CB) was 8.11 ± 2.77 mm. The male cadavers exhibited a significantly larger distance from the STA to CB (P = 0.03). No significant difference was noted for the STA origin to CB distance between right and left sides for the whole sample (P = 0.25). Moreover, while comparing the values between right and left sides within male and female cadavers separately, there was no significant difference between both sides for males or females (P = 0.15 and 0.98 for males and females, respectively).
|Figure 1: STA originated from the CCA, whereas LA and FA arose from the ECA as a common linguofacial trunk. CCA: Common carotid artery, ICA: Internal carotid artery, ECA: External carotid artery, STA: Superior thyroid artery, LFT: Linguofacial trunk, LA: Lingual artery, FA: Facial artery, DM: Digastric muscle|
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The LA originated from the ECA in 27 of the 30 specimens (90%) as a separate branch [Table 2]. In two specimens (6.7%), the LA shared origin with FA and arose from the ECA as a common linguofacial trunk. In one case (3.3%), the LA originated from the ECA as a common thyrolinguofacial trunk. The mean distance of LA origin site from the CB was 19.38 ± 8.85 mm. The female cadavers showed a considerably larger distance from the LA origin to CB (P = 0.03). There was no significant difference in distances from LA origin site to CB between right and left sides for the whole sample (P = 0.47). No significant difference between the sides within the male cadavers (P = 0.86) or the female cadavers (P = 0.41) was observed.
The FA was noted to arise from the ECA in 27 of the 30 specimens (90%) as a separate branch. Linguofacial and thyrolinguofacial trunks were also seen in 6.7% and 3.3%, respectively. The mean distance of FA origin site from the CB was 27.95 ± 10.15 mm. There was no significant difference in distances from the FA origin site to CB between sexes (P = 0.15). No significant difference was noted for the FA origin site to CB distance between right and left sides for the entire sample (P = 0.67). Furthermore, there was no considerable difference between sides within male or female samples (P = 0.84 and 0.42, respectively).
| Discussion|| |
The usual branching pattern of the ECA is giving rise to separate formation of the STA, LA, and FA, which was noted in 69%–89% of the cases investigated elsewhere.,, This proportion was between 8% and 31% for the common linguofacial trunk variant and 1% and 18% for the common thyrolingual trunk variant.,, Rare thyrolingual trunk cases originating from the CCA have been reported by some authors with an incidence of 0.1%.,
In the current study, the percentage of samples where the STA, LA, and FA arose as individual branches from the ECA was found to be 90%, while it was 6.7% for the linguofacial trunk and only 3.3% for the thyrolinguofacial trunk variants. Moreover, a case of a thyrolinguofacial trunk arising from the right ECA was noted, while none originating from the CCA was encountered.
The STA usually emerges from the anterior aspect of the ECA immediately inferior to the level of the greater cornua of the hyoid bone.,, In the current study, 12 STA samples (40%) arising from the CCA were found; however, no cases of STA arising from the CB level were observed. In the literature, the distance between the STA origin site and the CB showed extensive variations between studies with a wide range between 1 and 21 mm.,, The current study showed a value of 8.11 ± 2.77 mm. It was also found that the distance between the STA origin site and the CB varied significantly between sexes (but not between sides).
According to the literature, the LA most commonly originates from the anteromedial surface of the ECA, at a level ranging between 1.3 mm and 40 mm from the CB.,, The LA usually arises as an individual branch from the ECA; however, there were occasional cases of LA arising from the CCA and linguofacial, thyrolingual, or thyrolinguofacial trunk cases from the ECA.,, In this study, the LA was commonly found to arise as a separate branch from the ECA at a distance of 19.38 ± 8.85 mm from the CB. However, a significant difference was found for the same distance with regard to sex (but not with regard to side).
The FA was found by most researchers to arise as an individual branch from the ECA; nevertheless, anomalous trunks including linguofacial and thyrolinguofacial cases have been reported.,,, Occasionally, the FA shared origin with the maxillary artery and emerged from the ECA by means of a common maxillofacial trunk. According to the literature, there were cases, though seldom, where no FA found. In this situation, the maxillary, ophthalmic, or transverse FAs compensate by giving some branches to supply the areas normally served by the FA.,, Studies showed variations in terms of the distance between the FA origin site and the CB between 8 and 50 mm., The current study has found the FA most commonly (90%) arising as a separate branch from the ECA at a distance of 27.95 ± 10.15 mm from the CB. It has also been noted that there was no significant difference for the distance from the FA origin site to the CB based on the sex or side.
| Conclusions|| |
Our results revealed that the vessels investigated display great variability. These branches are important landmarks for the proper dissection of the carotid triangle and must be recognized before placing cross-clamps and performing arteriotomy. Therefore, during invasive radiological or surgical procedures, including tracheostomy, thyroid surgeries, laryngeal surgeries, and microvascular surgeries, surgeons need to be very careful to avoid serious complications in this area.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2]