Development of tongue

Question 1

What marks the anterior 2/3 from the posterior 1/3 of the tongue?

Answer 1

Sulcus terminalis

Question 2

What shape is the sulcus terminalis?

Answer 2

V shape

Question 3

What is the point of the sulcus terminalis?

Answer 3

Foramen caecum

Question 4

What embryonic tissue does the tongue develop from?

Answer 4

Parts of each of the pharyngeal arches

Question 5

What is the structure of the developing tongue?

Answer 5

Lateral lingual swellings x2

Median lingual swellings x3

Question 6

How are the lingual swellings of the developing tongue arrached?

Answer 6

Lateral lingual swellings are antero-lateral on each side

Median lingual swellings are posterior to the lateral lingual swellings and in the midline

Question 7

What are the three median swellings?

Answer 7

Tuberculum impar

Cupola

Epiglottal swelling

Question 8

Which pharyngeal arch do the lateral lingual swellings develop from?

Answer 8

1st pharyngeal arch

Question 9

Which pharyngeal arch does the tuberculum impar develop from?

Answer 9

1st pharyngeal arch

Question 10

Which pharyngeal arch does the cupola develop from?

Answer 10

2nd, 3rd and 4th pharyngeal arches from anterior to posterior

Question 11

Which pharyngeal arch does the epiglottal swelling develop from?

Answer 11

4th pharyngeal arch

Question 12

What happens to the lateral and medial swellings of the tongue as it develops?

Answer 12

Lateral lingual swellings overgrow tuberculum impar

The 3rd pharyngeal arch part overgrows the 2nd pharyngeal arch part of the cupola

Question 13

What is the structure of the developed tongue?

Answer 13

Anterior 2/3 made up of lateral lingual swellings

Posterior 1/3 made up of 3rd and 4th pharyngeal arches

Question 14

How does the lingual frenulum develop?

Answer 14

Degeneration of inferior surface of tongue
freeing it from the floor of the oral cavity

only the lingual frenulum remains

Question 15

How does the development of the tongue explain the sensory innervation of the tongue?

Answer 15

Anterior 2/3 derived from 1st pharyngeal arch
general sensory innervation by CN5 trigeminal nerve

Posterior 1/3 from 3rd pharyngeal arch
sensory innervation by CN9 glossopharyngeal nerve

Question 16

How do the muscles of the tongue develop?

Answer 16

Occipital somites
myogenic precursors migrate from here into developing tongue
develop into intrinsic and extrinsic muscles of tongue

Question 17

Which nerve corresponds to the occipital somites?

Answer 17

CN12 hypoglossal nerve

Question 18

How does the development of the muscles of the tongue explain the motor innervation of the tongue?

Answer 18

Myogenic precursors from occipital somites take their innervation with them
hence intrinsic and extrinsic muscles of tongue innervated by CN12 hypoglossal nerve