Head and Neck

Question 1

key facts about thyroid embryology

Answer 1

• 1st endocrine organ to develop
• develops day 24
• develops between the 1st &2nd pharnygeal puch
• develops as a proliferation of endodermal cells
• descent is by a pathway outlined by the thyroglossal duct
• by wk 10, thyroid gland lies with its isthmus over tracheal rings 2-4.
• Inferior parathyroid gland & thymus dervied from pharyngeal pouch 3
• superior parathyroid glands from pharyngeal pouch 4

Question 2

What are the disorders of thyroid gland embryology?

Answer 2

lingual thyroid: lump at foramen caecum- causes speech difficulty and dysphagia.
suprahyoid thyroglossal cysts
infrahyoid thryoglossal cyst
retrosternal goitre
thyroglossal fistula- rarely congenital, commonly due to infection/ surgery. Treatment is by surgical excision.