Development of the Face

Dr.Dashrath Kafle

FaceAt the end of the 4th week, facial prominences consisting

primarily of neural crest-derived mesenchyme appearMaxillary prominences- lateral to the stomodeum mandibular prominences- caudal to stomodeum

2

Face contd...Frontonasal prominence - proliferation of mesenchyme

ventral to the brain vesicles

On both sides, local thickenings of the surface ectoderm, the nasal placodes originate

3

Face contd...During the 5th week, the nasal placodes invaginate to

form nasal pits

Lateral nasal prominences

Medial nasal prominences

5

Face contd...

7

8

Formation of lipThe maxillary prominences grow medially,

compressing medial nasal prominences towards midline, two fuse forming upper lip by two medial nasal prominences and two maxillary prominences

10

Development of noseMaxillary prominences enlarge to form the cheeks and

maxillaNose is formed from five facial prominences:

- frontal prominence gives rise to bridge

- merged medial nasal prominences provide the crest and tip

- lateral nasal prominences form the alae

11

Intermaxillary SegmentTwo medial nasal prominences merge at a deeper level

forming the intermaxillary segment Composed of

(a) philtrum of the upper lip

(b) upper jaw component- carries the four incisor teeth

(c) primary palate

12

Intermaxillary Segment contd...

13

Secondary PalateFormed by two palatine shelves (6th week of

development) –maxillary processDirected obliquely downward on each side of the tongue In the 7th week, the palatine shelves ascend to attain a

horizontal position above the tongue and fuse, forming the secondary palate

14

Secondary Palate contd...

Nasal septum: derivative of Frontonasal process

15

Secondary Palate contd...Anteriorly, the palatine shelves fuse with the primary

palate

18

Development of TongueAppear at 4 weeks As two lateral lingual swellings and one medial swelling,

the tuberculum impar (all originate from the first pharyngeal arch)

A second median swelling, the copula, formed by mesoderm of the second, third, and part of the fourth arch

19

Tongue contd...

20

Tongue contd...Lateral lingual swellings increase in size, overgrow the

tuberculum impar and merge, forming the anterior two-thirds, or body, of the tongue

The body of the tongue is separated from the posterior third by a V-shaped groove, the terminal sulcus

22

Tongue contd...A third median swelling, formed by the posterior part of

the fourth arch, marks development of the epiglottis

23

Development contd....

24

Tongue contd...The mucosa covering the body of the tongue originates

from the first pharyngeal arch Sensory innervation to the posterior part, or root part of

the tongue is supplied by the glossopharyngeal nerve

25

Tongue contd...The epiglottis and the extreme posterior part of the tongue

are innervated by the superior laryngeal nerve, reflecting their development from the fourth arch

Most tongue muscles are derived from myoblasts originating in occipital somites. So innervated by the hypoglossal nerve

26

Tongue contd...Special sensory innervation (taste) to the anterior two

thirds of the tongue is provided by the chorda tympani branch of the facial nerve, while the posterior third is supplied by the glossopharyngeal nerve

27

Development contd.......

•Circumvallate papilla- 2-5 months• Fungiform - 11 weeks•Filliform – after birth•Gustatory cells- starts 7th week•All taste bud present at birth except- taste bud (circumvallate papilla)