3. Is theIs the largestlargest andand strongeststrongest bone of thebone of the
face, serves for the reception of theface, serves for the reception of the
lower teeth. It consists of a curved,lower teeth. It consists of a curved,
horizontal portion, thehorizontal portion, the bodybody,, and twoand two
perpendicular portions, theperpendicular portions, the ramirami,, whichwhich
unite with the ends of the body nearly atunite with the ends of the body nearly at
right angles.right angles.
The Mandible
8. Do u remember the
development of the body of
the mandible?
9. Prenatal development ofPrenatal development of
mandiblemandible
First thing to develop in primodrium ofFirst thing to develop in primodrium of
mandible of lower jaw is themandible of lower jaw is the mandibularmandibular
division of trigiminal nerve.division of trigiminal nerve.
…………..
Starting at theStarting at the 44thth
weekweek of intrauterine life,theof intrauterine life,the
brain and pericardium form two prominentbrain and pericardium form two prominent
pulges on the ventral aspect of the embryopulges on the ventral aspect of the embryo
which are seprated bywhich are seprated by the primitive oral cavitythe primitive oral cavity
or stomodeum.or stomodeum.
10.
11. The floor of stomodeum is formed byThe floor of stomodeum is formed by
buccopharyngeal membrane.buccopharyngeal membrane.
…………..
Pharengeal arches are laid down on the lateralPharengeal arches are laid down on the lateral
and ventral aspects of the cranial most part ofand ventral aspects of the cranial most part of
the foregut which are lies in close with thethe foregut which are lies in close with the
stomodeumstomodeum..
…………....
Phryngeal arches:Phryngeal arches:
First we have 6 pharyngeal archesFirst we have 6 pharyngeal arches
12. The 5The 5thth
arch after it is formation it willarch after it is formation it will
disappear…so that the remaining only five.disappear…so that the remaining only five.
…………....
They are seprated by 4 branchial grooves.They are seprated by 4 branchial grooves.
…………..
First ArchFirst Arch:mandibular arch:mandibular arch
…………
Second archSecond arch:hyoid Arch:hyoid Arch
13.
14. Arches Contents:Arches Contents:
1.1.A central cartilage rod that forms theA central cartilage rod that forms the
2.2.skeleton of the arch.skeleton of the arch.
3.3.A muscular componenet calledA muscular componenet called
4.4.branchiomerebranchiomere
5.5.A vascular componentA vascular component
6.6.A neural element.A neural element.
17. It is come from theIt is come from the 11stst
branchial arch atbranchial arch at
5_65_6week of intrauterine life.week of intrauterine life.
…………
it is extending fromit is extending from cartilaginous otic capsulecartilaginous otic capsule
toto the midline or symphesisthe midline or symphesis..
…………
It act as a guiding for growth of mandible.It act as a guiding for growth of mandible.
A major portion of this cartilage disappearA major portion of this cartilage disappear
during growth.during growth.
18. The remaining part developsThe remaining part develops
into the following:into the following:
1.1. The mental ossiclesThe mental ossicles
2.2. Incus and malleusIncus and malleus
3.3. Spine of sphenoid boneSpine of sphenoid bone
4.4. Ant. Ligament of malleusAnt. Ligament of malleus
5.5. Spheno mandibular ligamentSpheno mandibular ligament
19. At each half of mandible asingle ossificationAt each half of mandible asingle ossification
start atstart at the 6the 6thth
weekweek of untra uterine life, in theof untra uterine life, in the
region of the bifurcation of the inferior alveolarregion of the bifurcation of the inferior alveolar
nerve and artery into the mental and incisivenerve and artery into the mental and incisive
branches.branches.
…………
The ossyfing membrane located laterl to theThe ossyfing membrane located laterl to the
meckles` cartilagemeckles` cartilage and it acompanyingand it acompanying
neuro_vascular bundleneuro_vascular bundle..
……....
20. there is marked acceleration of the mandibularthere is marked acceleration of the mandibular
growth betweengrowth between 88thth
andand 1212thth
week. As aresultweek. As aresult
of mandibular length increaseof mandibular length increase, the external, the external
auditory meatusauditory meatus appear to move posteriorely .appear to move posteriorely .
bone begin to develop lateral to meckles`bone begin to develop lateral to meckles`
cartilage during thecartilage during the 77thth
week and continuesweek and continues
until the posterior aspect is covered with bone.until the posterior aspect is covered with bone.
21. Ossification stops at this point,which will laterOssification stops at this point,which will later
become thebecome the “mandibular lingula”“mandibular lingula” and theand the
remaining part of meckels` cartilage continuesremaining part of meckels` cartilage continues
on it is own to formon it is own to form the sphenomandibularthe sphenomandibular
ligamentligament and theand the spinous process of thespinous process of the
sphenoidsphenoid(meckels`caritlage lacks enzyme(meckels`caritlage lacks enzyme
phosphate) found in ossifying cartilage,thusphosphate) found in ossifying cartilage,thus
precluding ossification.precluding ossification.
Meckels` cartilage does,however persist untilMeckels` cartilage does,however persist until
as long as theas long as the 2424thth
week IU before it disappear.week IU before it disappear.
22. Secondary ”accessorySecondary ”accessory
cartilage”cartilage”
appear between theappear between the 1010thth
andand 1414thth
weeks Iu toweeks Iu to
formform the head of condylethe head of condyle ,, part of thepart of the
coronoid processcoronoid process ,and,and the mentalthe mental
protuberance.protuberance.‘‘
23. The mandibular processThe mandibular process
It come fromIt come from mandiblemandible and theand the temporaltemporal
bone(tympanic ring)bone(tympanic ring)
……..
Type of ossificationType of ossification:Intramembranous:Intramembranous
……..
TimingTiming: 6: 6thth
week of intrauterine lifeweek of intrauterine life
No. of ossification:No. of ossification:
2(on the right and left)2(on the right and left)
