The mandible develops through intramembranous and endochondral ossification. Ossification begins around the 6th week in utero near Meckel's cartilage. The body and ramus form through intramembranous ossification spreading from centers of ossification. Secondary cartilages form the condylar process, coronoid process, and mental region which undergo endochondral ossification. Postnatally, the condyle and ramus undergo significant growth through apposition on the lingual surface and resorption on the buccal surface. This drives the mandible downward and forward through childhood and adolescence.

4. Prenatal growth of madible

5. During 4thweek
ventral aspect of cranial
Thickening develop in lateral &
most part of foregut called pharyngeal/branchial arches.

6.  Later pharyngeal arches grow.
 First Branchial arch called MANDIBULAR ARCH .
 It grows ventro-medially cranial to main part of the arch
which is called .


7. Primary cartilage of first
pharyngeal arch is
Meckel’s cartilage helps
in formation of lower
jaw.
Meckel’s cartilage first
appear at 6th week IUL.

8. Ossification starts at
the division of mental
and incisive branch of
inferior alveolar nerve
lateral to meckel’s
cartilage around
6th week IUL.

9. Centre of ossification

 From center of ossification bone formation spreads:
Anteriorly - midline
Posteriorly - where mandibular nerve divided
into lingual and inferior alveolar branch.
 Bone formation spreads rapidly and surrounds the
inferior alveolar nerve to form mandibular canal.
 Intramembranous ossification spreads in anterior
and posterior direction forms the Body & Ramus of
the mandible.

10.  Ossification spread
posteriorly to form
ramus of
mandible, turning
away from
meckel’s cartilage.
 Ossification stops
at site where it
whould be Lingula.
 Major cartilage
disappears .

11. 
 Between 10th and 14th week three secondary
cartilage develops:
I. Condylar cartilage – largest and appear beneath
the fibrous articular layer of future condyle.
II. Coronoid cartilage - seen associated with
coronoid process.

12.  Mandible develops largely by intramembranous
ossification and by endochondral ossification in :

1. Condylar process
2. Coronoid process
3. Mental region

13. CONDYLAR PROCESS
 appear as separate
 Develops from condylar cartilage
area of mesenchymal condensation along
developing mandible around 8th week.
 This area develop in cone-shaped cartilage around
10th week.
 By the 14th week first evidence of endochondral
bone formation appear in condylar region.

14. • Cartilage fuses with mandibular ramus around
4th month.


15.  Cartilage replaced by bone but upper end persists in
adulthood acting as Growth and Articular cartilage.
 Condylar growth rate increases at puberty .
 Peaks between 12 to 14 years of age.

16. 
 Secondary cartilage appears in coronoid process
around 10-14th week.
 Cartilage grow as a response of developing
temporalis muscle.
 Coronoid cartilage become incorporated into
expanding intramembranous bone of ramus and
disappear before birth.

17. MENTAL REGION

 Throughout intrauterine life left and right mandible
are not fused at midline.
 Joined by connective tissue at midline.
 On either side of symphysis, symphyseal cartilage
appear between 10th & 14th week postconception.

18. MENTAL REGION

 Ossify in 7th month to form mental ossicles in
fibrous tissue of symphysis.
 Mental ossicles fuses with mandibular body at the
end of first year after birth.

20. • Mandible undergoes greatest amount of postnatal
growth of all facial bones.

22.  Major site of mandibular growth.
 Growth of condylar cartilage increases
length & height of mandible.
 Interstitial & appositional growth within
plate produce linear movement of condyle
in upward & backward direction towards
temporal bone.

23. .
• Cartilage plate moves by growth on one side & bone
replacement on other side.
• As condylar growth cartilage moves obliquely upward
& posteriorly
- entire head of condyle moves in same direction
by forming new condyle behind moving cartilage.
• This process is continuous & condyle moves by growth.

24. • Formation of bone within condyle causes mandible
rami to grow Upward & Backward
• Displacing entire mandible in Downward & Forward
direction.

25. • As ramus elongates, former level occupied by head
remodeled into upper neck
• Buccal & lingual cortical plates moves inward
towards each other results in reduced transverse
dimension of neck.

26. Inward growth of buccal & lingual
cortices

27. SIGMOID NOTCH
• The height of the ramus increased by :
- addition of new bone along the entire superior
surface of the sigmoid notch only at lingual surface.

28. SIGMOID NOTCH
• Bone deposition –
• post. Border of
• coronoid process
• Bone resorption -
• ant. Face of neck.

29. • To produce backward movement of ramus :
- Ant. Margin of ramus & coronoid process, must
undergo progressive removal.
-Forward facing ant. Border of coronoid process is
resorptive around temporal crest on lingual side.
-Greater portion of lingual surface is depositive
-Entire buccal surface is resorptive.
Light stippling – bone
deposition
Dark stippling – bone
resorption

30. • Coronoid process follows “v” principle.
• Movement of this v towards its wider ends.
• Bone Deposition - inner surface
• Bone Resorption - outer surface
• Which bring about growth in upward & backward
direction.
.

31. • BONE DEPOISITION -
lingual surface (+ +)
• BONE RESORPTION -
buccal surface (- -)

32. • Ramus moves backward in relation to body of mandible
• Post. displacement of ramus converts the formal ramal
bone in post. Part of body of mandible.
• Body of mandible lengthens
& increase in mandibular
arch to accommodate erupting
permanent molars.

33. • Bone deposition (++)
post. border of Ramus
• Bone resorption (--)
ant. border of Ramus
• Leads to AP growth
of mandibe

34. • Growth of chin occurs at puberty .
• Chin become prominent at puberty especially in males, by
selective remodelling.
• Alveolar region growths posteriorly.
• Mental protuberance growths forwardly.
• Which brings increase projection of chin.

35. •Bone deposition - mental protuberance.
•Bone resorption - alveolar region above the
prominence, creating a concavity.

36. • Alveolar growth occurs around tooth buds.
• As teeth develop & begin to erupt, alv. Process
increases in size & height.
• Continued growth of alveolar Bone increases height of
mandibuar body.

37. • Alveolar Process growths upward & outward on expanding
arch.

38. Age changes in mandible


39. • Mental foramen - midway of
upper & lower border.
• Mandibular canal - runs parallel
with mylohyoid line.
• Angle of mandible - 110* - 120*

40. 
Mandibular foramen - near alv. Bone
Mandibular canal - near alv. Bone
Angle of mandible - obtuse 140*