2. Introduction
Anatomy of Mandible
Prenatal Development of Mandible
Mandible at birth
3. Postnatal Development of Mandible
Age changes in mandible
Muscle attachment
Developmental anomalies
Development of mandible in relation
to various theory of growth.
4. INTRODUCTION
• Mandible is
-largest & lowest bone of face.
• Horseshoe shaped body
which is curved horizontally.
• Two ramii vertically with two
processes one condylar & other
is coronoid process.
5. • Two broad rami ascending posteriorly.
• Two surfaces:
- Internal
- External
• Separated by upper and lower border.
- Upper border - bears sockets for teeth
- Lower border - base of mandible
6. LATERAL SURFACE PRESENTS THE FOLLOWING FEATURES
1. Symphisis menti
2. Mental foramen
3. Mental protuberance
4. Mental tubercle
5. The oblique line
6. Condylar process
7. Coronoid process
8. Mandibular notch
9. Alveolar process
7. The Medial surface presents the following features
1. Mental spine
2. Mylohyoid line
3. Submandibular fossa
4. Sublingual fossa
5. Mylohyoid
groove
6. Mandibular foramen
7. Lingula
8.
9. Cartilage and bones of
mandibular skeleton
form from-
Embryonic neural
crest cells in mid and
hind brain region of
neural folds.
11. During 4th week
Thickening develop in lateral & ventral aspect of
cranialmost part of foregut called
pharyngeal/branchial arches.
12. • Later pharyngeal arches grow.
• First Branchial arch called MANDIBULAR ARCH .
13. • Mandibular arch gives off a bud from its dorsal end called
maxillary process.
• It grows ventro-medially cranial to main part of the arch
which is called mandibular process.
14. • Mandibular process of each side grow towards each
other.
• fuse in midline give rise to mandible.
• First structure develop in lower jaw :
- Mandibular division of Trigeminal nerve.
- Neurotrophic factor produced by nerve induce
osteogenesis.
15. Meckel’s cartilage
Primary cartilage of first pharyngeal arch is
Meckel’s cartilage helps in formation of lower jaw.
16. .
• Meckel’s cartilage first appear at 6th week IUL.
• Solid hyaline cartilagenous rod surrounded by fibrocellular
capsule.
• Extending from otic capsule to midsymphysis.
• Symphyseal Cartilage of each side of mandible don’t meet
at midline
- Separates by thin band of mesenchyme.
17. Centre of ossification
Ossification starts
at the division of
mental and incisive
branch of inferior
alveolar nerve
lateral to meckel’s
cartilage around
6th week IUL.
18. .
• 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.
19. • Anteriorly bone extends towards midline and comes in
approximation with similar bone forming on opposite
side.
• These two bones remain separated by fibrous tissue
mental symphysis untill shortly after birth.
• Continued bone formation increases size of mandible
with development of alveolar process to surround the
developing tooth germ.
20. .
Ossification spread
posteriorly to form
ramus of mandible,
turning away from
meckel’s cartilage.
This point of
divergence is
marked by lingula
in adult mandible.
21. Lacks enzyme phosphatase found in ossifying cartilage
thus precluding its ossification.
Greater part of meckel’s cartilage degenerate without
contributing formation of mandible by 24th week.
Most posterior extremity forms ‘incus’ and ‘malleus’ of
inner ear.
22. • Fibrocellular capsule persists as sphenomandibular
ligament
• Small part of its ventral end forms accesory
endochondral ossicles.
• Incorporated in the chin region of the mandible.
23. Further growth until birth influenced by appearance of
secondary cartilage .
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.
24. • Symphyseal cartilage – in the mandibular symphysis
region.
• Mandible develops largely by intramembranous
ossification and by endochondral ossification in
1. Condylar process
2. Coronoid process
3. Mental region
25. Develops from condylar cartilage appear as separate
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.
27. • 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.
• Normally ceases about 20 years of age.
28. 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.
29. 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.
30. 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.
31.
32. Two half of mandible not fused.
Joined by connective tissue at midline of the symphysis.
Condylar development minimal & no articular
eminence in glenoid fossa.
33. Coronoid process – relatively large & projects well above
condyle.
• Two ramii are quite short.
• Body is merely an open shell –
containing buds of deciduous teeth.
34. Mandibular canal runs low in the body
Angle of mandible is obtuse around 172* & more.
Mental foramen near to lower border.
35.
36. Right & left mandibular body fuses at midline symphysis
one year after birth.
Mandible appears as single bone.
37. Growth of mandible in relation to various
theory of growth
Genetic theory - BRODIE (1941)
Cartilagenous theory - JAMES SCOTT
Expanding V principle – ENLOW
Enlow counterpart theory
38. Van limborgh’s theory – (1970)
Servosystem theory - PETROVIC &
STUTZMAN (1980)
Functional matrix theory – MELVIN MOSS
39. Functional matrix for
skeletal units
All growth changes in size, shape & spatial position of
skeletal units are secondary to temporal primary
changes in their specific functional matrix.
Growth of skeletal units
-influenced by functional matrix
40. FUNCTIONAL MATRIX - carries out
functions.
ex : muscle, nerve , gland , vessels
- There is periosteal capsule and capsular matrices.
SKELETAL UNITS - supports & protects the
relative functional matrices
- divided in to macroskeletal & microskeletal units.
42. Teeth – Alveolar microskeletal unit.
Temporalis muscle - Coronoid microskeletal unit.
Masseter and Medial pterygoid - Angular microskeletal
unit.
Lateral pterygoid - Condylar process
43. MANDIBULAR GROWTH
Mandibular condylar cartilage not
primary site of mandibular growth.
Lociat which secondary
compensatory periosteal growth
occurs.
44. Bil.
Removal of condylar cartilage in
growing man
- doesn’t inhibit spatial
translation of now acondylar complex
of mand. Functional cranial
component
45. - also doesn’t inhibit change in microskeletal unit.
Mandibular growth is combination of morphologic
effect of both capsular & periosteal matrices.
Capsular matrices growth causes expansion of
orofacial capsule.
Enclose macroskeletal unit (mandible) passively &
secondarily
translated in new position.
46. Periosteal matrices related to mandibular
microskeletal units responds to this volumetric
expansion.
Such alterations in their spatial position causes
them to grow.
Both translation & change in form comprises totality
of mandibular growth.
47. • Two points are implicit :
- periosteal matrices not capable of functioning
normally –spatial related skeletal unit alter their
spatial position without changes in their size &
shape.
- such changes in size & shape of themselves are
insufficient biological cause of translation.
48. Difference in mand. Position & form due to both
periosteal & capsular matrices.
Growth of mandible is accomplished by both spatial
translation & change in form.
49. • Mandible undergoes greatest amount of postnatal
growth of all facial bones.
• Limited growth at symphysis menti untill fusion.
• The main site of postnatal mandibular growth:
- Condylar cartilage
- Ant. & Post. Border of rami
- Alveolar ridge
50. •In general, the downward and forward
mandibular growth follows the expanding
“v” principle.
52. Major site of mandibular growth.
Growth of condylar cartilage increases length & height
of mandible.
Condylar cartilage serves as both :
Articular cartilage : characterised by fibrocartilage
surface.
53. • Growth cartilage : analogous to epiphyseal plate in
long bone.
• Interstitial & appositional growth within plate produce
linear movement of condyle in upward & backward
direction towards temporal bone.
54. • As it grows, deeper portion of proliferating cartilage
replaced by endochondral bone.
• Which adds to medullary bone in condyle & its neck.
• Endochondral bone formation results - medullary core of
fine cancellous bone.
• Cortex formed by activity of the periosteum &
endosteum.
55. .
• 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.
56. • Formation of bone within condyle causes mandible rami
to grow upward & backward
• Displacing entire mandible in Downward & forward
direction.
57. Former condyle simultaneously converted into
elongated neck by sequential series of remodelling.
As ramus elongates, former level occupied by head
remodeled into upper neck.
Former upper part of neck remodeled into new lower
part.
Entire process is continuous & repetitive .
58. .
• All changes takes place simultaneously.
• Condylar head is broad & neck derived from head by
remodeling with marked reduction in width.
• Reduction brought about by surface resorption on
outer(periosteum) surface & deposition on
inner(endosteum) surface.
59. • Buccal & lingual cortical plates moves inward towards
each other results in reduced transverse dimension of
neck.
Inward growth of buccal & lingual cortices
60. Growth remodeling process in condylar bone
follows “v” principle.
Bone deposition -
inner surface.
Bone resorption -
outer surface of
V shaped neck
Results in growth
movement of entire
V in post. & sup.
direction.
61. SIGMOID NOTCH
• Bone deposition -
post. Border of
coronoid process
• Bone resorption -
ant. Face of neck.
62. • Periosteal bone added - lingual surface of ramus just
below sigmoid notch continue down from condylar head
around lingual side of sigmoid notch , then extends up to
apex of coronoid process.
Light stippling – bone deposition
Dark stippling – bone resorption
63. • Periosteal bone deposition - lingual surface
• Periosteal bone resorption - buccal surface of sigmoid
notch.
• Results in shift of ant. Base of neck in lingual direction.
64. • The height of the ramus increased by
- addition of new bone along the entire superior
surface of the sigmoid notch only at lingual surface.
• Continued bone deposition results in growth in lingual &
cephalic direction.
65. To produce backward movement of ramus :
- Ant. Margin of ramus & coronoid process, must
undergo progressive removal.
This growth change first recognized by JOHN HUNTER
& later verified by HUMPHRY (1864).
66. -Forward facing ant. Border of coronoid process is
resorptive around temporal crest on lingual side.
-Greater portion of lingual surface is depository
-Entire buccal surface is resorptive.
Light stippling – bone deposition
Dark stippling – bone resorption
67. • 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.
.
68. 4’ – bone addition
on lingual surface.
4 – bone removal
on buccal surface
Growth sequence of coronoid process by “v” principle
69. BONE DEPOISITION -
lingual surface (+ +)
BONE RESORPTION -
buccal surface (- -)
70. GROWTH AT RAMUS
• Bone deposition (++)
post. border of Ramus
• Bone resorption (--)
ant. border of Ramus
• Leads to AP growth
of mandibe
71. 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.
72.
73. BUCCAL SIDE OF RAMUS
• Upper part of mand. Ramus possesses a resorptive surface.
• Resorptive surface continuous down from neck on to upper
part of ramus.
• Below this area deposition occur.
Dark stippling - resorption
Light stippling - deposition
74. LINGUAL SIDE OF RAMUS
• Bone deposition - part of ramus located ant. & sup. to
oblique ridge extending down from neck on to ramus.
• Producing growth in sup. as well as in post. direction.
Dark stippling - resorption
Light stippling - deposition
75. Selective bone remodelling causes flaring of angle of
mandible on age advancement.
Buccal surface
Bone deposition - posteroinferior surface
Bone resorption - anterosuperior surface
76. Lingual surface
Bone deposition - anterosuperior surface
Bone resorption - posteroinferior surface
Causes flaring of angle of mandible.
77. Growth of chin occurs at puberty as age advances.
Chin become prominent at puberty especially in males,
by selective remodelling.
Bone deposition - mental protuberance.
Cortex is :
thick, dense
composed of slow growing type of
lamellar bone.
78. •Bone resorption - alveolar region above the
prominence, creating a concavity.
79. Cortex is made of - typical endosteal bone.
Alveolar region grows posteriorly.
Mental protuberance grows forwardly.
Which brings increase projection of chin.
80. 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.
81. • Alveolar Process grows upward & outward on expanding
arch.
• This permits dental arch to accommodate larger
permanent teeth.
82. INFANTS –
Mental foramen - near lower border
Mandibular canal - lower border of body of mandible
Angle of mandible - obtuse around 140* or more
83. ADULTS-
• Mental foramen -
midway of upper & lower
border.
• Mandibular canal - runs
parallel with mylohyoid line.
• Angle of mandible - 110* -
120*
84. • OLD AGE
Mandibular foramen - near alv. Bone
Mandibular canal - near alv. Bone
Angle of mandible - obtuse 140*
85. Timing of Growth in Width Length
and Height:
Growth in width is completed 1st then growth in
length and finally growth in height (W>L>H).
Mandibular intercanine width is more likely to
decrease than increase after age 12.
Intercanine width is essentially completed by the
end of ninth year in girls and the tenth year in boys.
Both molar and bicondylar widths show small
increases until the end of growth in length .
86. Growth of mandible continues at a relatively steady
rate before puberty.
On the average, ramus height increases 1-2
mm/year.
body length increases 2-3 mm/year.
In girls growth in length of the jaw has caused by
age 14-15 years.
In boys, it does not decline to the basal adult level
until 18 years.
88. MASSETER
ORIGIN: Ant. 2/3rd of lower
border of zygomatic arch &
zygomatic process of maxilla.
INSERTION: Ramus & coronoid
process of mandible.
NERVE SUPPLY: Masseteric
branch from ant. Division of
mandibular nerve.
ACTIONS:- Elevates mandible
to close mouth.
- Superficial fibres Protract the
mandible.
89. TEMPORALIS
ORIGIN: Temporal fossa
INSERTION: Coronoid
process & ant. Border of
ramus.
NERVE SUPPLY:
Temporal branch from
ant. Division of
mandibular nerve.
ACTIONS: -Elevates
mandible.
-Side to side grinding
movement.
-Post. Fibres Retract the
protracted mandible.
95. LATERAL PTERYGOID
ORIGIN:
UPPER HEAD - crest of
greater wing of
sphenoid
LOWER HEAD - lat.
surface of lat. pterygoid
plate
INSERTION:
-Pterygoid fovea on ant.
Surface of neck of
mandible
-Ant. Margin of articular
disc & capsule of TMJ
96. LATERAL PTERYGOID
• NERVE SUPPLY:
- Branch of ant. division of mabdibular nerve.
• ACTIONS:
- Depresses the mandible to open mouth.
- Protract the mandible.
- Helps in grinding movement.
97. MEDIAL PTERYGOID
ORIGIN:
SUPERFICIAL HEAD
– Tuberosity of
maxilla.
DEEP HEAD - Medial
surface of lat.
Pterygoid plate.
INSERTION:
postero-inferiorly to
medial surface of
ramus.
98. MEDIAL PTERYGOID
NERVE SUPPLY-
- nerve to medial pterygoid.
ACTIONS –
- Elevates mandible.
- Protraction of the mandible.
- Side to side movement.
99. MYLOHYOID MUSCLE
ORIGIN: Mylohyoid
line of mandible.
INSERTION:
Post. Fibres – hyoid
bone.
Middle & Ant. Fibres -
median raphe
between mandible &
hyoid bone
100. MYLOHYOID MUSCLE
• NERVE SUPPLY :
- Mylohyoid nerve , from inf. Alveolar branch of
mandibular nerve.
• ACTIONS :
- Elevate floor of mouth at first stage of deglutition.
- depression of mandible
.
- Elevation of hyoid bone.
102. - Mandible grossly deficient or absent.
- deficiency of neural crest tissue in lower
part of face.
103. Hemifacial Microsomia
Also called goldenhar syndrome
Due to lack of mesenchymal tissue or neural
crest cells
Underdeveloped mandible
Unilateral and asymmetrical
104. Mandibular Dysostosis
also called Treacher-collins syndrome
Due to disturbance in origins, migration &
interaction of neural crest cells.
Prevelance 1:25000
Hypoplasia of mandible
105. Prevelance 1: 8500
Mandible is underdeveloped
Small body
Obtuse antigonial angle
Posteriorly placed condyle
Cleft palate
106. Produce prognathism
usually inherited
Abnormal growth
phenomenon –
hyperpituitarism.
107. BIBLIOGRAPHY
Gray’s anatomy
Craniofacial development - Steven M Sperber
Human embryology - Inderbir Singh
Contemporary orthodontics - William R Proffit
The human face - Donald H Enlow
Shafer’s textbook of oral pathology
