**Question:** During thyroidectomy, inferior thyroid artery is ligated at:

**Core Concept:** The inferior thyroid artery is one of the two main branches of the external carotid artery and supplies blood to the lower part of the thyroid gland. In a thyroidectomy, ligation refers to tying the artery to prevent blood flow to the affected part of the thyroid gland.

**Why the Correct Answer is Right:** In a thyroidectomy, the inferior thyroid artery should be ligated at the level of the lower border of the thyroid gland. This ensures that blood supply to the lower part of the gland is interrupted, preventing injury to the recurrent laryngeal nerve, which runs close to the inferior thyroid artery at this level.

**Why Each Wrong Option is Incorrect:**
A. Ligating the artery too high (superior) to the lower border of the thyroid gland would not effectively interrupt the blood supply to the lower part of the gland.
B. Ligating the artery too low (inferior) to the lower border of the thyroid gland would still allow blood flow to the lower part of the gland, potentially damaging the recurrent laryngeal nerve.
C. Ligating the artery at the level of the isthmus would only affect the middle part of the gland, leaving the lower part unaffected and potentially damaging the nerve.
D. Ligating the artery too far above the thyroid gland (supraglottic level) would not target the lower part of the gland and could be unnecessary if the artery is already bifurcating into the internal and external carotid arteries.

**Clinical Pearl:** In thyroidectomy, it is crucial to ligate the inferior thyroid artery at the level of the lower border of the thyroid gland to effectively interrupt blood supply to the lower part of the gland and minimize the risk of damaging the adjacent recurrent laryngeal nerve.

**Correct Answer:** C. Ligating the inferior thyroid artery at the level of the isthmus

In thyroidectomy, ligating the inferior thyroid artery at the level of the isthmus ensures that the artery is divided near its origin, effectively interrupting blood supply to the middle and lower parts of the thyroid gland, while leaving the upper part unaffected. This approach helps minimize the risk of damaging the adjacent recurrent laryngeal nerve during the surgery.