Abstract:
Careful study of position of terminal branches of inferior thyroid artery
(ITA) in relation to recurrent laryngeal nerve (RLN) is required for safe
thyroid surgery. Generally ITA divides and enters middle or lower portion of
the thyroid. Near the lower pole, RLN is always intimately related or
positioned with ITA. Previous studies have documented possible ethnic and
gender variation with reference to origin and branching pattern of ITA. This
study was conducted to determine anatomical variations in branches of ITA
and its relation with RLN in fresh post-mortems conducted at Judicial
Medical Office, Colombo South Teaching Hospital. Fifty thyroid samples
(36 males and 14 females) without thyroid diseases were taken. Total of 42
left (L) and 38 right (R) were studied for relationship between ITA and RLN
and remaining sides either ITA or RLN was damaged. Three types of
positioning were recognized: RLN passing posterior to ITA or its branches
(Type A: 64%), RLN passing anterior to ITA or its branches (Type B: 16%)
and RLN passing in between branches (Type C: 20%). Total of 34(L) and
31(R) were studied for entering pattern of ITA, 52% entered into middle and
48% into lower portion. Total of 39(L) and 40(R) were studied
microscopically for terminal branches with 2 branches present in 57%, 3
branches in 42% and 4 branches in 1%. This study revealed that Type A was
predominant in both genders and ITA divides into 2 or more branches as
similar with Asians and Americans in other documented studies. Most of
ITA enters into middle lobe and type B was more common in females.
