TO STUDY THE TERMINAL DEVISION OF RECURRENT LARYNGEAL NERVE AND ITS VARIATION IN COMPARISION OF INFERIOR THYROID ARTERY

The vagus nerve, which supplies the larynx with motor, sensory, and parasympathetic bers, branches into the recurrent laryngeal nerve (RLN) and Superior Laryngeal nerve. Before ascending behind the inferior constrictor to the nerve's entry location into the larynx, the RLN is regularly seen in close relation to the inferior thyroid artery and its branches. This association is a signicant turning point in its identication in thyroid surgery patients. However, one wellknown risk factor for RLN injury after thyroid surgery is anatomic abnormalities of the RLN. Acute airway obstruction and stridor in cases of bilateral damage are two signs of RLN paralysis, which can result from injury to the RLN and range [1,2] from nearly undetectable hoarseness in unilateral lesions. About 3-8% of cases result in transient post-operative RLN [3-5] paralysis, while 0.3–3% of cases result in chronic paralysis. Therefore, in order to protect the nerve and its function during surgery, it is critical to recognize the anatomical variations of the RLN. While advancements in monitoring have made it possible to lower the incidence of RLN injury with intraoperative neuromonitoring, visual identication of the [6] RLN remains the gold standard for RLN injury avoidance . In order to do thyroid surgery, it is crucial to ascertain the RLN's anatomical location. The recurrent laryngeal nerves innervate the majority of the muscles involved in vocal cord movement. any lesion along the vagal nerves' route above the recurrent laryngeal nerves' branching or along the recurrent laryngeal nerves themselves can result in vocal cord paralysis (VCP). Due to the vagal nerve's close relationship to other cranial nerves at this level, an adverse lesion located in the brainstem or skull base typically results in several cranial nerve impairments. Isolated laryngeal complaints are often caused by pathology involving the recurrent laryngeal nerves and/or the extracranial vagal nerves. Numerous pathological conditions might result in VCP because of the vagal and recurrent laryngeal nerves' lengthy anatomical courses. VCP can be brought on by surgery, cancer, trauma, infection, and inammation. The most common cause of VCP, according to a survey of over 800 patients, is iatrogenic damage during [7] mediastinal and neck surgery. laryngoscopy can be used to evaluate vocal cord function. During this procedure, a stroboscopic light can be used to conrm that the aficted side is immobile. Hoarseness, vocal tiredness, loss of voice pitch, dyspnea, and aspiration are among the signs and symptoms [8] of VCP. Nonetheless, between 30 and 40 percent of patients [9, 10] with unilateral VCP have no symptoms. While the recurrent laryngeal nerve is the main efferent branch of the vagus nerve, the external branch of the superior laryngeal nerve is particularly signicant because it can sustain damage from post-operative inammation, tethering, or scarring, or from [11, 12] surgical injury during thyroid or carotid endarterectomy. Due to the loss of efferent bers to the cricothyroid muscle (CT), iatrogenic injury to the external branch of the superior laryngeal nerve (EBSLN) typically causes hoarseness, poor [13] sound, and vocal fatigue. The frequency of EBSLN injury varies from 0% to 58% as a result of differing postoperative [14] assessments and surgical procedures. Furthermore, there [15] aren't many trustworthy anatomical landmarks in the area.