Thyroid gland morphology with special considerations of the recurrent laryngeal nerves variations

Abstract

Background: Various anatomical positions of the recurrent laryngeal nerves were reported in relation to
the inferior thyroid artery. Knowledge of these variations is especially important in thyroid surgery.
Objectives: This study aimed to explore the anatomical relationship between the inferior thyroid artery
(ITA) and the recurrent laryngeal nerve (RLN) in Sudanese cadavers. Moreover, it aimed at detecting
any other morphological findings e.g. the presence of non-recurrent laryngeal nerve, the presence of a
pyramidal lobe and/or a thyroidea ima artery.
Methods: The gross anatomy of the thyroid gland and recurrent laryngeal nerves were studied by direct
dissection in fifty Sudanese cadavers in Khartoum State.
Results: On the right side the RLN was detected between the branches of the ITA in 16 cadavers (32%),
behind the artery in 12 cadavers (24%) and in front of the artery in 22 (44%). On the left side, the nerve
passed between the branches of the artery in13 cadavers (26%), behind the artery in 30 cadavers (60%)
and in front of the artery in 7 cadavers (14%). The pyramidal lobe was present in five cadavers (10%) and
the thyroidea ima artery in one cadaver (2%). Congenital abnormalities and non-recurrent laryngeal nerve
were not detected.
Conclusion: location of the right RLN was significantly detected in front of the ITA while the left nerve
was detected more commonly behind the artery. The surgeon’s knowledge about these variations helps in
identification and preservation of the RLN and prevention of some complications in thyroid surgery.