Embryological Development (Tongue And Thyroid)

Question 1

What are the 2 parts of the tongue?

Answer 1

Anterior 2/3s (Oral part)
Posterior 1/3 (Pharyngeal part)

Question 2

What is the line that marks the 2 different parts of the tongue called?

Answer 2

Sulcus terminalis

Question 3

What is the name of the hole where the thyroid develops in the part between the 2 parts of the tongue?

Answer 3

Foramen caecum

Question 4

What 2 nerves does the anterior 2/3s of the tongue receive sensory innervation from?

Answer 4

Trigeminal nerve (nerve tot first pharyngeal arch)

Taste from facial nerve

Question 5

What nerve does the posterior 1/3 part of the tongue receive sensory innervation from?

Answer 5

Sense and taste from the Glossopharyngeal nerve

Question 6

What pharyngeal arch’s lead to the development of the posterior 1/3 of the tongue?

Answer 6

2nd + 3rd pharyngeal arch

Question 7

What do the muscles of the tongue arise from?

Answer 7

Occipital somites at the level of the hypoglossal nerve

Question 8

What does the 4th and 6th pharyngeal arch contribute to the formation of around the tongue?

Answer 8

Epiglottis and glottis of airway

Question 9

What is the Foramen caecum?

Answer 9

The hole between the anterior 2/3s and posterior 1/33 of the tongue from which thyroid diverticulum originates from

Question 10

Briefly describe the development of the thyroid gland:

Answer 10

Thyroid diverticulum originates from the Foramen caecum
As the thyroid diverticulum descends down it forms the Thyroglossal duct

The Thyroglossal duct connects the thyroid gland to the tongue

Question 11

What normally happens to the Thyroglossal duct?

Answer 11

Usually gets obliterated as the thyroid gland descends

Question 12

What can occur as a result of the Thyroglossal duct failing to obliterate?

Answer 12

Can get Thyroglossal cysts and Thyroglossal fistulae opening at the foramen caecum

Question 13

How can asking a patient to move their tongue help you determine if a neck lump is a Thyroglossal cyst?

Answer 13

The remaining fibrous band of the old Thyroglossal duct connects the Thyroglossal cyst to the base of the tongue

So when patient moves their tongue the fibrous band will be pulled up pulling the cyst

Question 14

Where is ectopic thyroid tissue usually found?

Answer 14

The pathway by which the thyroid gland descends

Question 15

What is a Thyroglossal fistulae?

Answer 15

When the Thyroglossal duct completely persists connecting the thyroid cyst to the tongue