Thyroid gland

Question 1

Describe the development of the thyroid gland (5)

Answer 1

Dvelops initially from pouch 4 and arches 4 and 5.
It descends through the foramen caecum (hole in the tongue at the border of the nerve innervations) and bifurcates in its descent.
It remains connected to the tongue by the thyroglossal duct.

Question 2

Describe two pathologies relating to the descent of the thyroid gland. (2)

Answer 2

Ectopic thyroid tissue along the descent.

Thyroglossal duct cyst from failure of the duct to close. Will move on tongue protrusion.

Question 3

Describe the vascular supply to the thyroid gland. (6)

Answer 3

Supplied by the superior and inferior thyroid arteries (branches of the brachiocephalic trunk).
Drained by the superior, middle and inferior thyroid veins (drain into the L subclavian vein).
The thyroid IMA is a tiny artery present in 10% of the population that is a major cause of haemorrhage during neck surgery.

Question 4

Describe the relationship between the thyroid gland and the recurrent laryngeal nerves (2)

Answer 4

The nerves sit behind the thyroid gland, so are at risk of paralysis durin gthyroid surgery.

Question 5

Describe the endocrine role of the thyroid. (2)

Answer 5

Produce T3 and T4 under the influence of TSH.