English

Abstract

The variations in the distribution pattern of superior thyroid artery are of great importance for head and neck surgeons because of its vital relationship to the external laryngeal nerve. In this case an unusual unilateral variation in the arterial supply of thyroid gland was found during routine dissection of an elderly male cadaver in the Department of Anatomy, GGS Medical College, Faridkot, Punjab. The left superior thyroid artery took origin from the anterior aspect of left common carotid artery and it exhibited a usual relationship with the left external laryngeal nerve. The inferior thyroid arteries did not show any unusual distribution. Knowledge of such arterial variations related to the thyroid gland is immensely helpful for surgeons in order to put ligature on anomalous artery and to avoid damage to vital structures in this area. It is also helpful to the INTRODUCTION: The Superior Thyroid Artery (STA) is the main source of arterial blood to the thyroid gland, upper part of the larynx and neck region. It is a branch of external carotid artery (ECA) and arises from its anterior surface, just below the level of greater cornu of the hyoid bone. It runs downwards from its origin and gives a branch i.e. superior laryngeal artery (SLA) which pierces the thyrohyoid membrane along with the internal laryngeal nerve. It also gives an infrahyoid branch, a branch to the sternocleidomastoid muscle and a crico-thyroid branch. 1 The relationship of the superior thyroid artery to the external laryngeal nerve is important to the surgeon during thyroid surgery. The artery and nerve are close to each other higher up but diverge near the gland. Thus in order to avoid injury to the external laryngeal nerve, the superior thyroid artery is ligated as near to the gland as possible. The STA is frequently used as a recipient vessel for microvascular free tissue transfer in head and neck surgery, for selective embolization of thyroid and head and neck tumors, and as a landmark for identifying the external laryngeal nerve in thyroid surgery. 2 Surgical procedures involving the thyroid gland require a thorough knowledge not only of the normal gross anatomy of the structures within the region but also of the anatomical variations of the structures located within it. Thyroid surgery being a major surgery and quite often performed, a thorough knowledge of variations in arterial supply is very essential for surgeons to prevent alarming number of table deaths in patients with thyroid disease due to excessive and uncontrollable bleeding. It is also of help to the radiologists and physicians for proper physical examination and treatment of the patient and to the anatomists for learning the variant patterns.