2. MANDIBLE IS A UNIQUE BONE BOTH BY ITS
STRUCTURE & FUNCTION.IT IS THE LARGEST
& STRONGEST BONE OF FACE SERVES FOR
THE RECEPTION OF LOWER TEETH.IT
CONSIST OF CURVED HORIZONTAL
PORTION ,THE BODY & TWO
PERPENDICULAR PORTIONS ,THE RAMI
WHICH UNITE WITH THE ENDS OF BODY
NEARLY AT RIGHT ANGLES

10.  It is divided into 3 periods
 1) period of ovum (ferti. to 14th day)
 2)period of embryo (14th day to 56thday)
 3)period of fetus(56th day to birth)

11. EMBRYONIC PERIOD
During 3rd & 8th week of development, a
period known as the embryonic period,
each of the 3 germ layers (endoderm,
ectoderm & mesoderm) give rise to a
number of specific tissues & organs.

12. The pharyngeal
arches appear
between 4th & 5th
weeks of
development

13.  A central cartilage
that forms the
skeleton of the
arch
 A muscular
component
 A vascular
component
 A neural
component

15. SKELETAL
COMPONENTS
MUSCULAR
COMPONENTS
NERVE
Maxillary -
Premaxilla,Maxilla
Zygomatic bone,Part
ofTemporal bone
Mandibular -
Mandible,Malleus,
Incus
Masseter,
Temporalis,Medial &
Lateral Pterygoid
Mylohyoid,Ant. belly
of Digastric
Trigeminal
nerve

16.  The 1st pharyngeal
arch is the
mandibular arch
which contains the
Meckel’s Cartilage.
 It appears at about
6th week of I.U. life.

19.  Makes little
contribution towards
the development of
the mandible
 Provides a Template
for subsequent
development of the
mandible.

20.  meckels cartilage
 it derived from first brachial arch on 41st to 45th
day of IUL .extends from cartilaginous otic
capsule to sysmphysis .it acts as template and
guide for growth of mandible
 a major portion of this disappears and remaining
part develops in to
 mental ossicle
 incus, malleus
 spine of sphenoid
 anterior Ligament of malleus
 sphenomandibular ligament

21.  Proximal or cranial end is
connected to ear capsule &their
distal extremities are joined one
another at the symphysis by
mesodermal tissue

22.  Meckels cartilage has a
close relationship to the
mandibular nerve at
the junction between
middle & posterior third
where mandibular
nerve divides into
lingual & inferior
alveolar nerve

23.  Lingual nerve passes forward on the medial side of
cartilage while the inferior dental nerve lies lateral to
its upper margins & runs forward parallel to it &
terminate by dividing into mental & incisive branches

24.  From the proximal end of each cartilage malleus
& incus bones of middle ear developed.the next
succeeding portion as far as the lingula is
replaced by a fibrous tissue which persist to form
the sphenomandibular ligament.

25.  Between the lingula & canine tooth cartilage
disappears & part of it below & behind the
incisor teeth become ossified & incorporated
with its part of mandible

26.  MANDIBLE FIRST APPEARS AS A BAND OF
FIBROCELLULAR TISSUE WHICH LIES ON
THE LATERAL SIDE OF INFERIOR ALVEOLAR
& INCISIVE NERVES FOR EACH HALF OF
MANDIBLE

27.  OSSIFICATION TAKES PLACE IN THE
MEMBRANE COVERING THE OUTER
SURFACE OF MECKELS CARTILAGE &
EACH HALF OF THE BONE IS FORMED
FROM SINGLE CENTER WHICH APPEARS
IN THE REGION OF BIFURCATION OF
MENTAL& INCISIVE BRANCHES ABOUT 6TH
WEEK OF FETAL LIFE

29.  OSSSIFICATION GROWS MEDIALLY BELOW
THE INCISIVE NERVE & THEN SPREAD
UPWARD BETWEEN THIS NERVE &
MECKELS CARTILAGE SO THE INCISIVE
NERVE CONTAINED IN A TROUGH OR
GROOVE OF BONE FORMED BY THE
MEDIAL & LATERAL PLATE WHICH ARE
UNITED BENEATH THE NERVE

30.  AT THE SAME TIME NOTCH CONTAINING
INCISIVE NERVE EXTEND VENTRALLY
AROUND THE MENTAL NERVE TO FORM
MENTAL FORAMEN.THIS BONY TROUGH
GROWS MEDIALLY TO THE MIDLINE
WHERE IT COME IN CLOSE RELATIONSHIP
WITH THE OPPOSITE BONE BUT WHICH IS
SEPERATED BY A CONNECTIVE TISSUE

31.  SIMILAR SPREAD OF OSSIFICATION
SPREAD ALONG THE BACKWARD
DIRECTION PRODUCES TROUGH OF BONE
IN WHICH LIES THE INFERIOR DENTAL
NERVE & LATER MANDIBULAR CANAL IS
FORMED.

32.  From this centre, bone formation spreads
rapidly backwards, forwards & upwards
around inferior alveolar nerve & its
terminal branches

33.  BY THESE PROCESS OF GROWTH OF
PRIMARY CENTER OSSIFICATION
PRODUCES BODY OF MANDIBLE

34.  Appears between
10th & 14th week of
I.U. life.
 Forms the head of
condyle, part of
coronoid process &
mental
protruberances

35.  Endochondral bone formation in mandible .
Seen in3 areas
 condylar process
 mental region
 coronoid process

36.  condylar process;
at 5th week of intrauterine life
mesenchymal condensation seen
above ventral part of mandible. By
10th week it develops into cone
shaped cartilage. by 14th week it starts
ossifying. it then migrates inferiorly
and fuse with mandibular ramus by
4th months . by 6-7 th month of IUL
much of cartilage ossifies except
upper end which ossifies at adulthood

38.  mental region
 on either of symphysis 2 small cartilage
appears in 7th month of Intrauterine life .it then
incorporates into body . symphysis ossifies
after 1yr after birth
 coronoid process
 it is formed by secondary cartilage. appears
at 10-14th week of Intrauterine life. it grows as
response to temporalis muscle. it then join
with ramus

39. Of all the facial bones mandible
undergoes the largest amount of growth
postnatally.

40.  BY THE 1ST YEAR THE
SYMPHYSEAL
CARTILAGE IS
REPLACED BY BONE.

41.  THE PRINCIPLE
GROWTH VECTORS
ARE IN POSTERIOR &
SUPERIOR DIRECTION

42.  To accommodate & provide an attachment base
for the increasing mass of masticatory muscles.
 To accommodate the enlarged breadth of the
pharyngeal space.
 To accommodate the vertical lengthening of the
nasomaxillary part of the growing face.
 To facilitate the lengthening of the corpus which in
turn accommodate the erupting molars.

43.  THE RAMUS IS
STRUCTURAL
COUNTERPART OF
THE MIDDLE CRANIAL
FOSSA.

44.  Greater amounts of
bone deposition takes
inferiorly than
superiorly on the
posterior border of
ramus.
 Correspondingly
greater amounts of
resorption on anterior
Border takes places
inferiorly than
superiorly resulting in in
drift of mandible in
posterior direction

45.  FLARING OF ANGLE
OF MANDIBLE
 Lingual side of
angle of mandible
resorption takes
place in
posteroinferior
aspect &
deposition occurs
on anterosuperior
aspect

48.  Maintains constant
position midway
between the anterior
& posterior borders of
the ramus

51.  In infancy chin is under
developed.
 As age advances the
growth of chin becomes
significant
 Males are seen to have
prominent chin compared
to females.
 The prominence is
accentuated by bone
resorption in the alveolar
region below it, creating a
concavity

52.  IT DEVELOPS IN RESPONSE TO THE PRESENCE OF
TOOTH BUDS .
 ITS FORMATION IS CONTROLLED BY DENTAL
ERUPTION & IT RESORBS WHERE TEETH ARE
EXFOLIATED / EXTRACTED.
 ADAPTIVE REMODELLING OF ALVEOLAR PROCESS
MAKES ORTHODONTC TOOTH MOVEMENT POSSIBLE.

53. GENETIC THEORY:-
This theory states that all growth is compelled by
genetic influence ie: genetic encoding of
mandible determines its growth.

54.  THIS THEORY STATES THAT GENETIC
CONTROL IS EXPRESSED DIRECTY AT THE
LEVEL OF THE BONE & ITS LOCUS IS THE
PERIOSTEUM.

56.  This theory states that the cartilage is the
primary determinant of skeletal growth
while bone responds secondarily &
passively.
 According to this theory, the condyle by
means of endochondral ossification
deposits bone, which tends to the growth of
the mandible.

58.  According to this theory, the soft tissue matrix in
which the skeletal elements are embedded is the
primary determinant of growth & both bone &
carilage are secondary followers.
 Which means the muscles, connective tisses etc.
carries the entire mandible away from the cranial
base . The bone follows secondarily at the condyle
to maintain constant contact with the glenoid
fossa.

59.  The best statement appeared in 1981:
“…in summary form, the functional matrix
hypothesis explicitly claims that the origin,
growth & maintenance of all skeletal tissues &
organs are always secondary, compensatory &
obligatory responses to temporally &
operationally prior events or processes that
occur in specifically related non skeletal tissues,
organs or functioning spaces.”

61.  This theory states that many facial bones or a part
of the bone follows a ‘v’ pattern of enlargement.
> Due to differential deposition & selective
resorption
> Deposition is in the inner surface of wide ends of
‘v’ & along the ends of ‘v’. Resorptionis seen along
the outer surface of ‘v’.
CORONOID: Deposition –lingualsurface, Resorption-
buccal
CONDYLE: Deposition-anterior & posterior Margins,
Resorption- buccal & lingual surfaces.

63.  This principle states that growth of any given facial
or cranial part relates specifically to other structural
& geometric counterpart in the face & cranium
Eg;- The maxillary arch is the counter part of the
mandibular arch.

64.  PETROVIC attributes the control of growth &
development to cybernetics
 Growth of the condyle is mainly attributed to the
quantitative response to the growth of the maxilla
ie: the maxilla is the constantly changing reference
input & mandible is the controlled variable
 This means the mandible grows in response to
feedback mechanism that occurs as a result of
maxillary growth.

65.  AGNATHIA: Grossly deficient or absent mandible
 MICROGNATHIA: small jaw
 BIFID OR DOUBLE CONDYLE: Results from the
persistence of septa dividing the foetal condylar
cartilage

67.  HEMIFACIAL
HYPERTROPHY:
Unilateral enlargement
of mandible, the
mandibular fossae &
the teeth of unknown
aetiology.
 MANDIBULAR CLEFTS:
Occasionally both lip
& jaw may be involved

68.  Severe
micrognathia
 Cleft palate
 Periodic
dyspnoea
 Congenital
cardiac
annomalies
 Mentally
handicap
 glossoptosis

69.  Abnormally large
size
 Associated with
paget’s disease
 Associated with
acromegaly

70.  Failure of the
development of
the condyle
 can be unilateral or
bilateral
 if unilateral there is
facial asymmetry
and shift is present

71.  Could be due to
Abnormal
development, Birth
injury, Congenital
syphillis
 can be fiberous or
bony
 bilateral leads to
under
development of
lower face

72.  CONTEMPORARY ORTHODONTICS –
PROFFIT
 ORTHODONTICS PRINCIPLES AND
PRACTICE- GRABER
 TEXT BOOK OF CRANIOFACIAL GROWTH
-SRIDHAR PREMKUMAR

73.  ESSENTIALS OF FACIAL GROWTH-DONALD H
ENLOW
 TEXT BOOK OF ORTHODONTICS-SAMIR E
BISHARA
 HUMAN EMBRYOLOGY-INDERBIR SINGH
 HUMAN ANATOMY-B D CHAURASIA