1. Development of the Face, Palate & Nasal Cavity
Donna Forbes, Ph.D.
University of Minnesota
Medical School Duluth
Applied Anatomy: Med 6505
Fall, 2007

2. Pg. 12

3. Facial Prominences Frontonasal Maxillary (2) Mandibular (2) Pg. 12
~ 4 wks
Frontonasal
Maxillary (2)
Mandibular (2)
First Arch

4. Frontonasal prominence Mandibular prominence
Pg. 12
Facial prominences
Frontonasal prominence
Maxillary prominence 2 1 3
Mandibular prominence

5. Placodes Pg. 12 = Localized thickenings of surface ectoderm
Lens of Eye
Inner Ear
Note locations of the lens and otic placodes on the SIDE of the head. The eyes will move to the front of the head as development proceeds.
Eye and ear development will be covered in the Nervous System course.

6. Placodes & Stomodeum Nasal Placodes Stomodeum Pg. 12
Nasal placodes will form the nose and part of the upper lip.
Stomodeum: Floor forms the ectodermal surface of the buccopharyngeal membrane. This membrane breaks down around day 24.
Note that you cannot see the lens and otic placodes in this view.

7. Transformation of “Prominences” to “Face”Pg
Transformation of “Prominences” to “Face”
Week 5
Week 6
Intermaxillary segment
Philtrum
Primary palate
Premaxilla C D
--Medial nasal prominences >>midline of nose, nasal septum part, intermaxillary segment.
--Lateral nasal prominences >> sides of the nose
--Rest of frontonasal prominence >> forehead & dorsal part of nose
--Mandibular prominences merge in wk 4 >> lower lip, jaw, inferior face
--Maxillary prominences fuse with medial nasal prominences, lateral nasal prominences & mandibular prominences to form >> cheek, lateral lip, secondary palate
Week 7
Week 10
Growth
Migration
Fusion
Similar to M&P fig 9-26 [10-26]

8. Transformation of “Prominences” to “Face”Pg
Transformation of “Prominences” to “Face”
1st
2nd
Images #1 and #3 are human; #2 is mouse
~ 4.5 wks
~ 6 wks
~ 7 wks

9. Eyes and Ears Pg. 13 ~ 4.5 wks ~ 6 wks ~ 7 wks 1st 1st 2nd 1st 2nd 2nd
--Eyes move from lateral aspect of head to the front of the face as the medial migration of structures takes place.
--Ears: external ear develops from mesenchyme of the 1st and 2nd arches >>> six auricular hillocks form around the first pharyngeal cleft.
1st
2nd
2nd
~ 4.5 wks
~ 6 wks
~ 7 wks

10. Eyes and Ears, cont. 4 - 5 weeks 9 weeks 13 weeks Pg. 13
--Eyes move from lateral aspect of head to the front of the face as the medial migration of structures takes place.
--Ears:
---external ear develops from mesenchyme of the 1st and 2nd arches >>> six auricular hillocks form around the first pharyngeal cleft.
--ears start out low on side of neck and migrate up to their final position.
9 weeks
13 weeks
Details of Eye and Ear Development
in the Nervous System Course

11. Pg. 13
Palate Development
Critical period of development from week 6 to beginning of week 9.
Palate forms between wks 5 and but wks are most critical.
Primary palate develops from the intermaxillary segment.
Secondary palate forms from the palatine shelves of the maxillary prominences.
of the secondary palate
Frontonasal prominence  Medial nasal prominence  Intermaxillary segment

12. Pg. 13
Palate Development
Critical period of development from week 6 to beginning of week 9.
of the secondary palate
Palate forms between wks 5 and but wks are most critical.
Primary palate develops from the intermaxillary segment.
Secondary palate forms from the palatine shelves of the maxillary prominences.
Intermaxillary segment forms the philtrum of the lip, four incisor teeth & primary palate.
Secondary palate formed from the palatine shelves of the maxillary prominences/processes.

13. Palate Development
Secondary palate forms from medial outgrowths of the maxillary prominences known as the palatine shelves. These shelves elevate, grow & fuse in the midline. The primary & secondary palates fuse with one another at the incisive foramen to form the definitive palate.
***Palatine shelves aka palatine processes aka lateral palatine processes
--initially oriented downward
--move to horizontal probably due to hydration of hyaluronic acid in the mesenchymal cells of the palatine shelves.
***Region of uvula is the last to fuse at about 12 wks
***Incisive foramen:
--marks point of fusion of primary and secondary portions of the palate
--nasopalatine n + term brs of sphenopalatine artery
HARD PALATE: Primary palate and rostral secondary palate: intramembranous bone
SOFT PALATE: Caudal secondary palate: skeletal muscle
NASAL SEPTUM from the medial nasal prominences grows down and fuses with the palate -- forming the perpendicular plate of the ETHMOID plus the VOMER.
Bone develops in the primary palate & anterior part of secondary palate to form the hard palate. Posterior secondary palate has no bone & forms the soft palate + uvula.
Pg. 13

14. Nostrils & Nasal Cavities
Pg. 14
Nostrils & Nasal Cavities
As the medial and lateral nasal prominences enlarge, the nasal pits deepen to form blind pits = the primitive nasal cavities.
Nasal placodes
Nasal pits
Nasal sacs
~ 4.5 wks
~ 6 wks
~ 7 wks

15. Nasal Cavities Pg. 14 6 weeks 5 weeks 7weeks 12 weeks
***Oronasal membrane:
--separates the nasal pits from the primitive oral cavity.
--ruptures during wk 6 to form PRIMITIVE CHOANAE -- so communication established between nasal and oral cavities.
***Formation of the SECONDARY PALATE partially separates the nasal and oral cavities.-- leading to formation of the DEFINITIVE CHOANAE.
***SUPERIOR, MIDDLE & INFERIOR CONCHAE form from swellings in the lateral wall of each nasal cavity.
***OLFACTORY EPITHELIUM develops in the roof of each nasal cavity. Some of these cells differentiate into olfactory receptors that extend their axons through the cribriform plate to terminate in the olfactory bulb.
***NASAL SEPTUM from the medial nasal prominences grows down and fuses with the palate -- forming the perpendicular plate of the ETHMOID plus the VOMER.
7weeks
12 weeks

16. Nasal Septum & Palate Pg. 14
NASAL SEPTUM from the medial nasal prominences grows down and fuses with the palate -- forming the perpendicular plate of the ETHMOID plus the VOMER.
The nasal septum fuses with the midline region of the definitive palate.

17. Changes in shape of face
Pg. 14
Changes in shape of face
Paranasal air sinuses
Nasal conchae
Tooth development
***Size and shape of face changes dramatically throughout development toward adulthood.
*** Paranasal sinuses: most are formed after birth as outgrowths of the walls of the nasal cavities (only maxillary and part of ethmoid are present at birth)
*** Nasal conchae develop as elevations of the lateral wall of each nasal cavity.
*** Maxilla and mandible grow and change shape along with tooth development.

18. Congenital Abnormalities
Pg. 15
Congenital Abnormalities
Anterior defects
Involve upper lip, alveolar part of maxilla & anterior or primary palate
Posterior defects
Involve hard and soft palate (secondary palate)
Combination anterior & posterior defects

19. Cleft 2° palate + unilateral
Cleft Lip & Palate
Pg. 15
Anterior defect: B
Posterior defect: E
Combination defects: C, D, F
Unilateral cleft lip
& nose
Unilateral cleft lip,
jaw, 1° palate
Normal
Complete anterior defect runs between lateral incisor and canine tooth.
Bilateral cleft lip,
jaw, 1° palate
Cleft 2° palate + unilateral
cleft lip, jaw, 1° palate
Cleft 2° palate

20. Congenital Abnormalities of Lip and Palate
Pg. 15
Anterior defects
Due to failure of fusion of maxillary prominences with the fused medial nasal prominences.
Know this!
Posterior defects
Due to failure of fusion of the palatine shelves with one another, with the nasal septum & with the posterior margin of the primary palate.
***CLEFT LIP:
--1/1000 births
% males
--Increases with increasing maternal age
*** CLEFT PALATE:
--1/2500 births
--Twice as common in females: might be related to the fact that palatal shelves close about 1 wk later in girls -- thus separating further in time the palatal fusion from the lip fusion.
--no association with maternal age

21. Congenital Abnormalities: Etiology is Multifactorial
Pg. 15
Teratogens interfere with migration of neural crest so that there is too little mesenchyme to work with. Examples include:
Anticonvulsants such as Dilantin
Vitamin A; isotretinoin (Accutane)
Genetic
Chromosomal syndromes (e.g. Trisomy 13)
Single gene mutations
Other:
Excessive cell death during the formation of the maxillary & nasal prominences
Failure of palatal shelves to elevate at the proper time
Excessively wide head

22. Cleft Lip & Palate Pg. 15 Incomplete unilateral cleft lip
Incomplete Unilateral Cleft lip [anterior defect]
Bilateral cleft lip involving the lip, jaw & primary palate [anterior defect]
Unilateral Cleft lip, cleft jaw, primary palate plus cleft secondary palate [combined anterior + posterior defect]
Incomplete unilateral cleft lip
Bilateral cleft lip involving lip, jaw & 1° palate
Unilateral cleft lip cleft jaw, 1° palate + cleft of 2° palate

23. Movies Face Development Front view 3/4 view Side view
You have to be patient for this movies to load. Very slow!!
Source is the University of Illinois at Chicago.
Front view
3/4 view
Side view
Click on an image or its title & wait for the movie to load. They are slow to appear.

24. Movies Face Development Click on the words “Face Development”
& wait for the movie to load.

25. Pg. 16
“Cases to Consider”
Discussion of these cases will be sent out as an after you have some time to consider them.

26. Now for the “T-Quiz”! Origin: Thymus  Thyroid  Tongue  Tonsil 
Trachea 
Trigeminal nerve 
Tympanic cavity 
Tympanic membrane 

27. “T-Quiz” are on the last slide.
Answers to this
“T-Quiz” are on the last slide.

28. Questions?

29. Answers to the “T’s”! Origin: Thymus  3rd Pharyngeal Pouch
Thyroid  Floor of pharynx between arches 1 & parafollicular cells from the 4th pouch
Tongue  Floor of pharynx including arches 1 thru 4
Tonsil  2nd Pharyngeal Pouch + Mesenchyme
Trachea  Laryngotracheal diverticulum
Trigeminal nerve  Trigeminal Ganglion & Brain Stem
Tympanic cavity  1st Pharyngeal Pouch
Tympanic membrane  Ectoderm of external auditory meatus, Mesoderm, Endoderm of tympanic cavity