Anterior glandular branch of the superior thyroid artery

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The superior thyroid artery is classically described as the fist branch of the external carotid artery [1, 2]. • It courses inferiormedially, lateral to the thyrohyoid ...
Anterior glandular branch of the superior thyroid artery Ourania-Thaleia Syminelaki 1,2, Ana C. Valenzuela G. 1,3, Mohamed Elajnaf 1, David Stellon 1, Abduelmenem Alashkham 1 Anatomy, Medical School: Biomedical Sciences, University of Edinburgh, Edinburgh, United Kingdom 2 The Alexander S. Onassis Public Benefit Foundation, Department of Scholarships for Hellenes, Athens, Greece 3 Chevening Scholarships, Foreign and Commonwealth Office, London, United Kingdom 1

Background

Common facial vein

• The superior thyroid artery is classically described as the fist branch of the external carotid artery [1, 2].

• Although it is the main thyroid gland blood supply, its variation is seldom reported [3].

Anterior glandular vessels

Superior thyroid vessels

• It courses inferiormedially, lateral to the thyrohyoid muscle and then posterior to the infrahyoid muscles reaching the thyroid gland [1, 2]. • It gives glandular (anterior, posterior and lateral) branches supplying the thyroid gland, muscular branches to the sternocleidomastoid, cricothyroid and infrahyoid muscles, and cutaneous branches to the neck [1, 2].

Thyrohyoid muscle

Common carotid artery

Sternothyroid muscle

Internal jugular vein

Thyroid gland

Aim Sternohyoid muscle

Carotid sheath

• This study aimed to report a variation of the anterior glandular branch of the superior thyroid artery.

Figure 1: Lateral view of the right superior thyroid vessels. The sternohyoid muscle has been reflected inferiorly. The anterior glandular vessels course over the sternothyroid muscle. Notice that the common carotid artery lies outside (medial) of the carotid sheath.

Methods Superior laryngeal artery

• Five Genelyn-fixed bodies (3 male, 2 female: mean age 66.8 years) from Anatomy, University of Edinburgh were examined. All cadavers had been obtained in accordance with the Human Tissue Act 2006.

Thyrohyoid muscle Superior thyroid artery

• Dissection of the neck region was accomplished according to Grant’s Dissector, 15th edition [2]. • Observations were analysed and compared with the literature.

Results

• As it lies superficial to the sternothyroid muscle, it could be liable to inadvertent laceration during surgery such as thyroidectomy, parathyroidectomy, or neck lymph node dissection.

Thyroid gland

Carotid sheath

Thyrohyoid muscle

Anterior glandular branch

Laryngeal prominence

Superior thyroid artery

• The current study reports that the anterior glandular branch of the superior thyroid artery was found to run anterior to the sternothyroid muscle.

Common carotid artery

• Surgeons should be aware of this variation in order to avoid unexpected complications.

Internal jugular vein

The authors express their thanks to donors and their families; without them this study would not have been possible. Special thanks to Centre for Anatomy, School of Biomedical Sciences, University of Edinburgh, Edinburgh, United Kingdom.

Sternohyoid muscle

Figure 2: Lateral view of the right superior thyroid artery after removal of the veins.

Conclusion

Acknowledgment

Anterior glandular artery

Common carotid artery

Posterior glandular branch

• Further study is recommended to determine if there is a correlation between sex and side of this variation in a larger cohort.

Thyroid cartilage

Sternothyroid muscle

• The anterior glandular branch of the superior thyroid artery was found coursing anteriorly to the sternothyroid muscle on the right side of a 46year old female cadaver (n=1, 10%) (Figures 1 and 2). • It was observed to supply the cricothyroid, isthmus, and anterior surface of the thyroid gland (Figure 3).

Internal laryngeal nerve

Thyroid cartilage

Cricothyroid artery Isthmic branch

Carotid sheath

Sternothyroid muscle

Thyroid gland

Figure 3: Anterior view of the anterior glandular branch of the right superior thyroid artery. The branch crossed over the sternothyroid muscle to supply the cricothyroid, isthmus and the anterior surface of the thyroid gland.

References 1 Gray, Standring S (2016). Gray's anatomy: the anatomical basis of clinical practice. 41st edition. Edinburgh: Elsevier Churchill Livingstone. p.453 2 Tank, P., & Grant, J. (2013). Grant's dissector Patrick W. Tank. (Fifteenth ed.). 3 Dover, K., Howdieshell, T., & Colborn, G. (1996). The dimensions and vascular anatomy of the cricothyroid membrane: Relevance to emergent surgical airway access. Clinical Anatomy, 9(5), 291-295.