The document provides an overview of the mandible, including its anatomy, development, age-related changes, growth, muscle attachments, nerve and blood supply, and developmental anomalies. Key points include: - The mandible develops from intramembranous ossification and has important growth sites at the condylar cartilage, borders of the rami, and alveolar ridge. - Growth and remodeling of the condyle, rami, coronoid process, and angle allow the mandible to increase in length, height and flare with age. - Muscle attachments including the masseter, temporalis, and lateral and medial pterygoids allow movements like elevation, protraction and grinding of the mand

1. MANDIBLE
Presented by:
Dr. Shaimaa
P.G student

2. CONTENTS
1. Introduction
2. Anatomy of Mandible
3. Prenatal Development of Mandible
4. Age changes in mandible
5. Postnatal growth of mandible
6. Muscle attachment
7. Nerve supply to the mandible
8. Arterial supply to the mandible
9. Developmental anomalies

3. Introduction
• The mandible is horseshoe shaped and supports the teeth of the lower dental arch.
• This bone is movable and has no bony articulation with the skull. It is the heaviest and
strongest bone of the head and serves as a framework for the floor of the mouth.
• It is situated immediately below the maxillary and zygomatic bone, its condyles rest in
the mandibular fossa of the temporal bone. This articulation is the temporomandibular
joint.
• The mandible has a horizontal portion, or body, and two vertical portions, or rami. The
rami join the body at an obtuse angle.

4. Anatomy of mandible:
Mandible can be divided into
1. Body of the mandible
2. Rami
3. The alveolar process

5. Body consists of two lateral halves, which are joined at the median shortly after the birth,
marked by a slight ridge known as symphysis.
Two surfaces:
- Internal
- External
Separated by upper and lower border.
- Upper border - bears sockets for teeth
- Lower border - base of mandible

6. Rami:
Ramus ends superiorly into condyloid process, coronoid process and mandibular
notch.

7. Internal surface of the body mandible is roughened by eminences called the superior and
inferior mental spines or genial tubercles. divided into 2 portions by a well defined ridge
the mylohyoid line

8. Alveolar process:
• The border of the alveolar process outlines the alveoli of the teeth and is very thin at
its anterior portion around the roots of the incisor teeth but thicker posteriorly.
• The alveolar process, the superior body of the mandible, differs from the same
process in the maxilla in 1 very important particular: it is not as cancellous, and
instead of the facial plates being relatively thin, it is equally as heavy as the lingual
plate.
• Posterior to the third molar a triangular shallow fossa is outlined, it is called the
retromolar triangle. The cortical plate over this fossa is not as v as the bone
surrounding it, and it is more cancellous under the thin cortical plate.

9. Alveoli- • The central incisor alveolus is flattened
on its mesial surface and is usually
somewhat concave distally to
accommodate the development groove
on the root.
• The canine alveolus is quite large and
oval and, deep accommodate the root
of the mandibular canine. The alveolus
of the first and second premolars are
similar in outline.
• The socket of the first molar is divided
by an inter root septum, which is strong
and regular. The alveolus of the mesial
root is kidney shaped

10. Development of the mandible:
• In human beings, meckel’s cartilage has a close relationship to the developing mandible but
makes no contribution to it.
• At 6 weeks hyaline cartilaginous rod surrounded by a fibro cellular capsule extends from the
developing ear region to the midline of the fused mandibular processes.
• At 7 weeks of development, intramembraneous ossification begins in this condensation,
forming the first bone of the mandible.
• This spread of new bone formation occurs anteriorly along the lateral aspect of meckel’s
cartilage, forming a trough that consists of lateral and medial plates that unite beneath the

11. • The two separate centres of ossification remains separated at the mandibular
symphysis until shortly after birth.
• The ramus of the mandible develops by a rapid spread of ossification posteriorly into
the mesenchyme of the first arch turning away from meckel’s cartilage this point of
divergence is marked by the lingual in the adult mandible, the point at which the
inferior alveolar nerve enters the body of mandible.
• Meckel’s cartilage has the following fate, its most posterior extremity forms the incus
and malleus of the inner ear and the sphenomalleolar ligament.

12. The further growth of the mandible until birth is influenced strongly by the appearance of
3 secondary cartilages and the development of muscular attachments. These secondary
cartilages include:
• Condylar cartilage-most important
• Coronoid cartilage
• Symphyseal cartilage

13. • Develops from condylar cartilage appear as separate area of mesenchymal
condensation along developing mandible around 8th week.
• Cartilage fuses with mandibular ramus around 4th month. 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. • Coronoid cartilage-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.
• Symphyseal cartilage- 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.
• Thus the mandible is membrane bone, developed in relation to the nerve of the first
arch and almost entirely independent of meckel’s cartilage.

15. Age changes in the mandible
At birth
• The body of the bone is a mere shell, containing the sockets of the two incisor, the
canine, and the two deciduous molar teeth, imperfectly partitioned off from one
another.
• The mandibular canal is of large size, and runs near the lower border of the bone; the
mental foramen opens beneath the socket of the first deciduous molar tooth
• The angle is obtuse (175°), and the
condyloid portion is nearly in line with
the body.
• The coronoid process is of
comparatively large size, and projects
above the level of the condyle.

16. Childhood
The two segments of the bone become joined at the symphysis, from below upward, in the first
year; but a trace of separation may be visible in the beginning of the second year, near the
alveolar margin. The body becomes elongated in its whole length, but more especially behind
the mental foramen, to provide space for the three additional teeth developed in this part
• thickening of the subdental portion which
enables the jaw to withstand the
powerful action of the masticatory
muscles;
• The mandibular canal, after the second
dentition, is situated just above the level
of the mylohyoid line; and the mental
foramen occupies the position usual to it
in the adult.
• The angle becomes less obtuse, owing to
the separation of the jaws by the teeth;
about the fourth year it is 140°.

17. Adulthood
• The alveolar and subdental portions of the body are usually of equal depth.
• The mental foramen opens midway between the upper and lower borders of the
bone, and the mandibular canal runs nearly parallel with the mylohyoid line.
• The ramus is almost vertical in direction, the angle measuring from 110° to 120°.

18. Old age
• The bone becomes greatly reduced in size, for with the loss of the teeth the alveolar
process is absorbed, and, consequently, the chief part of the bone is below the
oblique line.
• The mandibular canal, with the mental foramen opening from it, is close to the
alveolar border.
• The ramus is oblique in direction, the angle measures about 140°, and the neck of the
condyle is more or less bent backward.

19. Postnatal growth of mandible
• 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. 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.

20. The main site of postnatal mandibular growth:
• Condylar cartilage
• Ant. & Post. Border of rami
• Alveolar ridge
Red arrows-bone resorption
Blue arrows-bone deposition

21. Growth at condyle:
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.
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.
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.
Formation of bone within condyle causes
mandible rami to grow upward & backward.
Displacing entire mandible in Downward &

22. • 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
• Buccal & lingual cortical plates moves inward towards each other results in reduced
transverse dimension of neck.

23. 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.

24. Sigmoid notch:
Bone deposition - post. Border of coronoid process
Bone resorption - ant. Face of neck.
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.

25. Coronoid process:
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). Forward facing ant. Border of coronoid process is resorptive around temporal
crest on lingual side
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.

26. Growth at ramus:
Bone deposition-post. border of Ramus
Bone resorption-ant. border of ramus leads to AP growth of mandible
• Ramus moves backward in relation to body of
mandible
• Buccal side-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.
• Lingual side- 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

27. Angle of mandible- Selective bone remodelling causes flaring of angle of mandible on age
advancement.
Buccal surface
Bone deposition - posteroinferior surface
Bone resorption - anterosuperior surface
Lingual surface
Bone deposition - anterosuperior surface
Bone resorption - posteroinferior surface
Causes flaring of angle of mandible.

28. Chin-
• Growth of chin occurs at puberty as age advances. Chin become prominent at puberty
especially in males, by selective remodelling.
• Bone deposition at the mental protuberance. Cortex is thick, dense composed of slow
growing type of lamellar bone.

29. 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.
• Alveolar Process grows upward & outward on expanding arch.
• This permits dental arch to accommodate larger permanent teeth

30. Muscle attachement
The muscles of mastication are a group of muscles associated with movements of the jaw
Embryologically, the muscles of mastication develop from the first pharyngeal arch.
Consequently they are innervated by a branch of the trigeminal nerve (CN V),mandibular
nerve.

31. 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.

32. 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.

33. 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
NERVE SUPPLY:
- Branch of ant. division of mabdibular nerve.
ACTIONS: Depresses the mandible to open mouth.
Protract the mandible. Helps in grinding movement.
Medial pterygoid
ORIGIN:
SUPERFICIAL HEAD – Tuberosity of maxilla.
DEEP HEAD - Medial surface of lat. Pterygoid plate.
INSERTION: postero-inferiorly to medial surface of
ramus.
NERVE SUPPLY- nerve to medial pterygoid.
ACTIONS – Elevates mandible
Protraction of the mandible. Side to side movement.

34. Buccinator
ORIGIN: From alv. Process of maxilla
& mandible, TMJ
INSERTION: in the fibres of orbicularis
oris
NERVE SUPPLY: buccal branch of
facial nerve.
ACTIONS: Flattens cheek against gums
&teeth. Prevents accumulatiom of
food in the vestibule. aids whistling &
smiling. neonates helps in suckle.

35. Platysma
ORIGIN : subcutaneous tissue of
infraclavicular & supraclavicular.
INSERTION : Base of the
mandible,skin of cheek & lower lip,
angle of mouth.
NERVE SUPPLY : Cervical branch of
facial nerve.
ACTIONS :- depresses mandible
-Pulls angle of mouth downwards.

36. Mentalis
ORIGIN: Incisive fossa of mandible
INSERTION: skin of chin.
ACTIONS: - elevates & wrinkles skin of
chin.
-protrude lower lip.
NERVE SUPPLY:
Mandibular branch of facial nerve

37. Mylohyoid muscle
ORIGIN: Mylohyoid line of mandible.
INSERTION: Post. Fibres – hyoid bone.
Middle & Ant. Fibres - median raphe
between mandible & hyoid bone
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

38. Nerve supply of the mandible:

39. Arterial supply

40. ANOMALIES OF DEVELOPMENT
• Agnathia
• Micrognathia
• Macrognathia
• Hemifacial macrosomia
• Mandibular dyostosis

41. Agnathia: Agnathia (also termed hypognathous] is absence of a portion or the entirety of
one or both jaws.It is a very rare condition. deficiency of neural crest tissue in lower
part of face.

42. Micrognathia is a condition in which the jaw is undersized. It is a symptom of a variety of
craniofacial conditions. Sometimes called mandibular hypoplasia, micrognathia may interfere
with your child’s feeding and breathing.
Micrognathia is somewhat common in infants, but often corrects itself as your child grows.
In some children, micrognathia can cause abnormal tooth alignment because there is not
enough room in your child’s mouth for the teeth to grow.
Micrognathia can present as a birth defect in numerous syndromes, including cleft lip, cleft
palate, Pierre Robin sequence or syndrome, Stickler’s syndrome, Beckwith-Wiedemann
syndrome, hemifacial microsomia, Teacher Collins syndrome and others.
Micrognathia can be inherited (passed on through genes)or caused by a genetic mutation.

43. Macrognathia
Macrognathia: An abnormally large jaw. Macrognathia can be associated with pituitary
gigantism, tumors, and other disorders. Macrognathia can often be corrected with
surgery.

44. Hemifacial microsomia
Hemifacial microsomia is a congenital disorder that affects the development of the lower
half of the face, most commonly the ears, the mouth and the mandible.
It can occur on one side of the face or both.
If severe it can lead to difficulties in breathing, obstructing the trachea and requiring a
tracheotomy. It is the second most common facial birth defect after clefts, with an
incidence in the range of 1 in 3500 to 4500.
Hemifacial microsomia shares many similarities with Treacher Collins syndrome.

45. Mandibular dyostosis
Treacher Collins syndrome (TCS), also known as Treacher Collins–Franceschetti
syndrome,[1] or mandibulofacial dysostosis,[2] is a rare autosomal dominant congenital
disorder characterized by craniofacial deformities, such as absent cheekbones.
Treacher Collins syndrome is found in about one in 50,000[4] births. The typical physical
features include downward-slanting eyes, micrognathia (a small lower jaw), conductive
hearing loss, underdeveloped zygoma, drooping part of the lateral lower eyelids, and
malformed or absent ears.