Dev"t Of The Tongue And Thyroid Gland

Question 1

What are the three initial swellings that form the tongue?

Answer 1

Two lateral lingual swellings

One median swelling (Tuberculum impar)
All from the 1st branchial arch.

Question 2

Which structure forms the anterior 2/3 of the tongue, and what is its sensory innervation?

Answer 2

Formation: The two lateral swellings outgrow the tuberculum impar and merge.

Sensory innervation: Mandibular branch of the trigeminal nerve (CN V3) for general sensation; taste is supplied by the facial nerve (CN VII).

Question 3

Which pharyngeal arches contribute to the posterior 1/3 of the tongue?

Answer 3

Primarily the 3rd branchial arch (with minor contributions from the 4th arch for the root near the epiglottis).

Innervation: Glossopharyngeal nerve (CN IX) for both general and taste sensation.

Question 3

What marks the boundary between the anterior 2/3 and posterior 1/3 of the tongue?

Answer 3

V-shaped groove: Terminal sulcus.

Landmark: Foramen cecum (origin of the thyroid gland).

Question 4

What is the origin of the thyroid gland in tongue development

Answer 4

The thyroid gland originates from the foramen cecum, a midline pit at the junction of the anterior 2/3 and posterior 1/3 of the tongue.

Question 5

Which nerve innervates the muscles of the tongue, and what is their embryological origin?

Answer 5

Motor innervation: Hypoglossal nerve (CN XII).

Embryological origin: Occipital myotomes.

Question 6

What is ankyloglossia (tongue-tie), and how does it occur?

Answer 6

Definition: Restricted tongue movement due to a short or tight frenulum.

Cause: Incomplete degeneration of tissue under the tongue during development, leaving the frenulum as the primary attachment.

Question 7

hat causes bifid tongue?

Answer 7

Failure of fusion of the two lateral lingual swellings during development.

Question 8

What is macroglossia?

Answer 8

Abnormal enlargement of the tongue, often due to genetic conditions (e.g., Down syndrome) or tumors.