Thyroid Gland Flashcards

Explore thyroid gland anatomy, including its lobes, microscopic follicles, embryological development, vascular supply, and surgical relationships.

Card 1 of 30Question

Where is the thyroid gland located?

In the anterior neck, immediately inferior to the larynx and anterolateral to the upper trachea.

In This Section

1. Where is the thyroid gland located?

In the anterior neck, immediately inferior to the larynx and anterolateral to the upper trachea.

2. What are the principal anatomical parts of the thyroid gland?

Right and left lateral lobes connected by a central isthmus.

3. Which tracheal rings are typically crossed by the thyroid isthmus?

The second to fourth tracheal rings, although its position varies.

4. What is the pyramidal lobe of the thyroid gland?

A variable superior extension of thyroid tissue, usually arising from the isthmus or adjacent left lobe.

5. What embryological structure gives rise to the pyramidal lobe?

A persistent portion of the thyroglossal duct.

6. Where does the thyroid gland originate during embryological development?

From an endodermal thickening in the floor of the primitive pharynx near the future foramen cecum.

7. What is the thyroglossal duct?

A transient embryonic channel connecting the developing thyroid gland to its origin at the tongue base.

8. What is the anatomical relationship between the thyroid gland and the larynx during swallowing?

The thyroid gland moves superiorly with the larynx because of its fascial attachments.

9. What are the two connective tissue coverings of the thyroid gland?

A true fibrous capsule and an outer fascial sheath derived from the pretracheal layer of deep cervical fascia.

10. What is Berry's ligament?

A thickening of fascia anchoring the posteromedial thyroid gland to the cricoid cartilage and upper trachea.

11. Which muscles cover the anterior and lateral surfaces of the thyroid gland?

Primarily the sternothyroid and sternohyoid muscles, with overlapping omohyoid and sternocleidomastoid.

12. What is the relationship of the thyroid gland to the carotid sheath?

The carotid sheath lies posterolateral to each thyroid lobe.

13. Which nerve lies close to the posteromedial thyroid gland near Berry's ligament?

The recurrent laryngeal nerve, usually approaching the larynx near the tracheoesophageal groove.

14. Which endocrine glands are commonly located near the posterior thyroid surface?

The superior and inferior parathyroid glands.

15. Which artery supplies the superior portion of each thyroid lobe?

The superior thyroid artery, usually the first anterior branch of the external carotid artery.

16. What is the usual origin of the inferior thyroid artery?

The thyrocervical trunk of the subclavian artery.

17. What is the thyroid ima artery?

An occasional additional artery ascending anterior to the trachea to supply the thyroid isthmus or lower gland.

18. Where do the superior and middle thyroid veins drain?

Into the internal jugular veins.

19. Where do the inferior thyroid veins typically drain?

Into the brachiocephalic veins, often through a venous plexus anterior to the trachea.

20. Which lymph nodes receive drainage from the thyroid gland?

Primarily prelaryngeal, pretracheal, paratracheal, and deep cervical lymph nodes.

21. What autonomic nerves supply the thyroid gland?

Predominantly sympathetic vasomotor fibers from the superior, middle, and inferior cervical sympathetic ganglia.

22. What is the basic structural and functional unit of the thyroid gland?

The thyroid follicle, a spherical epithelial structure surrounding a colloid-filled lumen.

23. What type of epithelial cells line normal thyroid follicles?

Simple cuboidal follicular cells, varying from flattened to columnar according to functional activity.

24. What is the principal component of thyroid follicular colloid?

Thyroglobulin, a protein used for the synthesis and storage of thyroid hormone precursors.

25. Which hormones are produced by thyroid follicular cells?

Thyroxine (T4) and triiodothyronine (T3).

26. Which thyroid cells secrete calcitonin?

Parafollicular cells, also called C cells.

27. Which pituitary hormone primarily regulates thyroid follicular cell activity?

Thyroid-stimulating hormone (TSH) from the anterior pituitary gland.

28. Why is the external branch of the superior laryngeal nerve vulnerable during thyroid surgery?

It courses near the superior thyroid vessels and may be injured during ligation near the superior thyroid pole.

29. What vocal abnormality may follow recurrent laryngeal nerve injury during thyroidectomy?

Ipsilateral vocal fold weakness or paralysis, often causing hoarseness and impaired voice projection.

30. Why can a thyroglossal duct cyst move upward during tongue protrusion?

Its persistent attachments to the tongue base and hyoid region transmit movement to the cyst.