Development of mandible

1. PRE-NATAL
DEVELOPMENT
OF MANDIBLE
Dr. Prerana A Suryawanshi
Dept. of Orthodontics
PG II

2. • There is a marked acceleration of mandibular growth between the eighth and
twelfth weeks of fetal life. As a result of the mandibular length increase, the
external auditory meatus appears to move posteriorly
• Mandible is the 2nd bone in the body to ossify
• 1st structure to form in primordium of lower jaw- mandibular division ofTrigeminal
nerve
• Appears at 2/3rd length of Meckel’s cartilage

3. • Mandible is derived from the 1st arch- grows ventromedially

4. • 5th week IUL- bilateral rod like hyaline cartilaginous condensation (future ear to
midline) surrounded by fibrocellular capsule
MECKEL’S CARTILAGE- close positional relation
• Intramembranous ossification- mesenchymal condensations develop lateral to
Meckel’s cartilage at 36-38 days IUL
• Ossification starts at 6th week IUL- future mental foramen
• Proceeds towards midline– disappearance of cartilage
The part of Meckel cartilage that has been encapsulated with bone appears to
have served its purpose as a splint for the intramembranous ossification, and it
largely deteriorate

5. Derivatives of Meckel’s cartilage (MISASG)
Malleus
Incus
Spine of sphenoid
Anterior ligament of malleus
Sphenomandibular ligament
Genial tubercle

6. • 1ST structure to form from
mesenchymal condensation- INFERIOR
ALVEOLAR NERVE
• Ossification starts lateral to region-
nerve bifurcation into incisive and
mental branches ( 7th week )
• Anteriorly to midline
• Posteriorly – mandibular nerve division
to lingual & inferior alveolar nerve
• Ramus- spread of ossification
backward into mesenchyme

7. • Rudimentary mandible soley from Intramembranous ossification by 10th week

8. • Endochondral ossification- 14th week IUL
Coronoid cartilage- appears at 10-14 weeks, grows and fuses with ramal portion,
transient- disappears before birth
Condylar cartilage- develops initially 5th week; 10th to 12th week IUL- cone/carrot
shaped projection (Interstitial & appositional growth)(FGF 2) (fibrous)
20th week- ossifies –Superior end persists
Symphyseal cartilage- at 7th month of life start to ossify; fuses at 1st yr. of life

9. • Right & left sides are separate at birth
• Ramus- short & low
• Coronoid & condylar process at occlusal level(fetal)
• Even though the lateral halves of the mandible have fused by the time the embryo
is 18 mm long, the mandible is still relatively short. It is recognizable in shape by
the end of the eighth week of intrauterine life

11. Syndromes associated

13. REFERENCES
• Enlow DH, Hans MG. Essentials of facial growth. WB Saunders
Company; 1996.
• Premkumar S. Textbook of craniofacial growth. JP Medical Ltd; 2011
• S Gowrishankar. Textbook of Orthodontics. Paras Medical Publisher
2011

14. THANKYOU