Superior Thyroid Artery Lab Report

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Anatomical variation of the superior thyroid artery and its relation to the external laryngeal nerve.

The thyroid gland is the largest endocrine gland located in the anterior triangle of the neck. It consists of two lobes, right and left, connected by an isthmus in the middle.
The thyroid gland is mainly supplied by the superior thyroid artery, the first branch of the external carotid artery, and the inferior thyroid artery, a branch of the thyrocervical trunk of the subclavian artery; and occasionally by the thyroidea ima artery, an infrequent branch of the arch of the aorta.
The venous drainage of the thyroid gland is into the internal jugular vein through the superior and the middle thyroid vein; and by the inferior thyroid
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An evaluation of the origin of the superior thyroid artery in 64 cases has shown that it is most frequently originated from the external carotid artery, in 53.12% of cases; compared with 28.12% had their origin in the common carotid trunk. In 18.75 % of cases, the thyroid artery originated from the carotid bifurcation ending up by trifurcation (Gavrilidou et al., 2013).
The superior laryngeal nerve (SLN) is a branch of the vagus nerve (cranial nerve X). It arises from the skull base, it then descends as far as the proximity of the horn of the hyoid bone, and terminates into two branches: the internal superior (ISLN) and the external superior laryngeal (ESLN). The ISLN perforates the thyroid membrane and then enters the larynx to give sensory innervation of the supraglottic region.
The ESLN passes over or pierces the inferior pharyngeal constrictor muscle aiming to innervate the cricothyroid muscle. The main function of this muscle is to keep the vocal folds under tension (Botelho et al., 2009). Therefore, damaging the ESLN leads to paralysis of cricothyroid muscle with subsequent loss of high pitch
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After conducting a metanalysis of STA variations in 3453 Caucasians and 931 East Asian, the majority of the superior thyroid arteries originated from the external carotid artery in Caucasian and from the common carotid artery in East Asian. There was also no significant difference in gender with more asymmetry in Caucasians (Toni et al., 2004). Moreover, there is no consensus on the most common relationship between the STA and ELN. Taking previous studies in consideration this study will try to prove whether the STA more commonly originates from the ECA in Caucasians and to investigate any gender differences. Furthermore, the relationship between the STA and ELN will be studied and results will be compared with the current

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