It contains following subheadings: -maxilla and mandible anatomy -TMJ(Temporo mandibular joint) -Muscles of mastication By: Dr. Syed Irfan Qadeer Prof. and HOD Department of Anatomy SPIDMS,Lucknow

1. The Mastication
Apparatus

2. Mastication Apparatus
• The Mastication apparatus consist of a centre
core or a framework consisting of the
bones, the temporomandibular joint and the
muscles of mastication.

3. Maxilla
• It is the second largest bone of the face
• It forms the upper jaw with the fellow of the
opposite side
• It also contributes to the formation of
1. Floor of the nose and the orbit
2. Roof of the mouth
3. Lateral wall of the nose
4. Pterigopalatine and infratemporal fossae
5. Pterigomaxillary and infraorbital fissures

4. Anatomy of the maxilla
• The anatomy of the maxilla has two main
parts:
1. Body(pyramidal shape)
– Anterior surface
– Posterior surface
– Orbital surface
– Nasal surface
2. Processes
– Zygomatic
– Frontal
– Alveolar
– Palatine

6. Anterior Surface:
• Incisive Fossa:
– Depressor septi nasi
– Orbicularis oris
• Canine fossa:
– Levator anguli oris
• Infraorbital foramen (above canine fossa)
– Infraorbital nerves and vessels
• Above sharp border between anterior and orbital
surface:
– Levator labi superioris
• Nasal notch: Dilator Naris
• Ant Nasal Spine

8. Posterior Surface
• It is directed backwards and laterally
• It forms anterior wall of the infratemporal fossa
• Anterior and posterior surfaces are seperated by ridge
which leads to the socket of 1st molar tooth
• Near the centre of posterior surface 2 to 3 openings of
dental canal for posterior superior alveolar vessels and
nerves
• At the lower end there is a raised maxillary tubrosity which
is rough in the upper part of its medial end for tubercle of
the palatine bone which has the attachment of superficial
fibres of themedial pterigoid muscles
• Above this smooth surface which forms the boundry of the
ptrigopalatine fossa is grooved for the maxillary nerve, this
groove is contineous with the infra orbital groove

9. Orbital surface
Smooth and triangular
• Medial border
– Notch: lacrimal notch
– Behind this it articulates with the
• Lacrimal
• Orbital plate of ethmoid
• Orbital process of palatine
• Posterior border: Smooth, rounded and it forms greater part of
infraorbital fissure in middle infraorbital groove
• Anterior border: forms orbital margin ,infraorbital groove and
canal; a little lateral to this is canalis sinuosus which passes in the
anterior wall of the maxillary sinus and reaches in the nasal cavity
and opens in the side of the nasal septum in front of incisive canal
• A little lateral to the lacrimal groove there is attachment of inferior
oblique muscle of eveball

10. Nasal Surface
• In its upper posterior part there is a large
maxillary hiatus which leads into the maxillary
sinus
In articulated skull this hiatus is completed by
ethmoid and lacrimal bones
• Behind this there is a rough impression for the
perpendicular plate of palatine bone
• Infront of maxillary hiatus there is a lacrimal
groove
• More anteriorly concal crest for articulation with
inferior nasal concha

12. Maxillary Sinus
• Large pyramidal cavity with its apex directed laterally
towards the zygomatic process
• Base is towards the lateral wall of the nose
• In articulated skull it is reduced by
Above
• Uncinate process of ethmoid
• Desending part of lacrimal bone
Below: inferior nasal concha
Behind: perpendicular plate of palatine
• It opens into the middle meatus of the nose usually by two
openings one of which is closed by mucous membrane in
living state
• Occasionally there are projections in the maxillary sinus
from roof to anterior wall

14. Processes
• Zygomatic: it is rough and pyramidal
– Front:it is contineous with the anterior surface of
body
– Behind(concave):in continuity of the posterior
surface
– Above: articulates with zygomatic bone
– Below(arched border) which anterior and
posterior surface of the body

15. • Frontal Process:
– Lateral Surface:
• Vertical ridge (Lacrimal crest)
• Groove for the lacrimal sac
– Medial surface: It is rough and uneven and
articulates with the ethmoid and also closes the
anterior ethmoidal sinus below ethmoidal crest
• Upper end: Articulates with the frontal bone
• Anterior border with the nasal bone
• Posterior border with the lacrimal bone

16. • Alveolar processes: It has thick arched border
behind and contains sockets to receive roots
of teeth which vary in size and depth
– Canine deepest
– Molar widest and subdivided into 3 minor sockets
by septae
– Incisors and premolars single
– Occasionally incisors are divided into 2 sockes

17. • Palatine Process: Thick strong horizontal
– Inferior surface is concave and presents numerous
foramina for passage of nutrient vessels and contains
depressions for lodgement of glands
– Groove for grater palatine Vessels and nerves
– Incisive fossa leads into the incisive canal
– Sometimes anterior and posterior incisive foramen for
long sphenopalatine nerve which communicates with
the greater palatine nerve
– Upper surface: forms the floor of the nasal cavity
– Lateral Border fuses with rest of the bone
– Posterior border fuses with the horizontal plate of the
palatine

18. Muscles attached to maxilla

19. Muscles of face

20. Arterial supply

21. Maxillary Artery

22. Veinous drainage

24. Nerve Supply

25. Lymphatics

26. Age changes in Maxilla

27. Mandible
• Largest and strongest bone of the face
• Curved horizontal body; convex forwards
• It has two rami which project upward from
posterior end of the body
• The body is horse shoe shaped

30. External Surface
• Faint ridge: symphisis menti
• Mental protuberance in the triangular area
below sympisis menti
• Mental tubercle on each side of mental
protruberance
• Mental foramen between premolar teeth
• Oblique line

32. Internal Surface
• Myelohyoid line
• Sub mandibular fossa
• Sub lingual fossa
• Genial tubercle
• Myelohyoid groove

33. Borders
• Upper boder:
– Sockets for the mandibular teeth are present
• Lower border(Base) presents a digastric fossa
• Ramus
– Lateral Surface
– Medial Surface
• Mandibular foramen canal
• Lingula- mylohyoid groove
• Inferior border is continuous with the angle of
mandible
• Upper Border: Mandibular Notch

34. Arterial Supply of Maxilla and
Mandible

36. Nerve supply of Mandible

38. Veinous drainage of Mandible

39. • Processes:
– Condylar
– Coronoid
• Mandibular canal

40. Age changes in mandible

41. Applied Anatomy
Muscle injuries: Its cause and effects
• Incisivus labii Superioris:
– During the exposure of
the bone of premaxilla
between the canines ,a
mucoperiosteal flap
reflection may detach
the muscle and if the
muscle gets damaged
the the drooping of the
septum and ala of the
nose may occur

42. • Mylohyoid muscle
– Surgical manupulation of the floor of the mouth may result
in edematous swelling of the sublingual space (above the
mylohyoid muscle )and submandibular space(below the
mylohyoid muscle)
– Cellulitis of this sublingual space in quiet common
however excessive bilateral cellulitis of the sublingual
spaces may push the tongue backwards and compress the
pharynx and may result in airway obstruction

43. • Genoiglossus muscle
– During the elevationof
the lingual mucosa
before making an
impression for a
subperiosteal implant a
portion of the muscle
may be reflected from te
genial tubercle, however
if the muscle is
completly detached
from the tubercle it may
lead to retrusion of the
tongue and airway
obstruction

44. • Medial pterigoid
– The medial pterigoid muscle
binds the pterigomandibular
space medially ,during
surgical procedures involving
the area of pterigomandibular
space infection may occour
and may be dangerous due to
its closed proximity to the
pharyngeal space
– Surgical exposure of the
tissue posterior to the
maxillary tubrosity may also
involve the medial pterigoid
muscle as a part of the
muscle originates from the
maxillary tubrosity

45. • Lateral pterigoid muscle
– The lateral pterigoid muscle fibres are placed in an
angulated manner and because of this there may
be pain in patients with a full arched subperiosteal
implant or prosthetic splint

46. • Mentalis muscle:
– Complete reflection of the
mentalis muscle for the
purpose of extension of a
subperiosteal implant may
result in a condition known
as witch’s chin
There is failure of the mentalis
muscle reattachment
following the implantation.
An external bandage is
applied for four days to help
in the reattachment of the
muscle

47. • Buccinator muscle:
– Myositis of the detached buccinator muscle in
patients with subperiosteal implants may cause
swelling and pain at the site of origin of the
muscle

48. Nerve injuries
• Inferior alveolar nerve:
– The nerve may be
damaged easily when
making an incision or
reflection of the
mucosa in its area
therefore position of
the inferior dental
canal in vertical and
buccolingual
dimension is of great
importance during
site preprations for
implants

49. • Lingual nerve
– The position of the
nerve is lateral to the
retromolar pad the
incision should remain
lateral to the pad and
the mucosal reflection
should be done with a
periosteal elevator in
constant contact with
the bone to prevent
injury to the nerve

50. • Nerve to mylohyoid:
– The nerve lies in closed relation to the ramus of
mandible hence it is prone to get damaged during
surgical intervention

51. • Long buccal nerve:
– When the ramus is
accessed for the
purpose of a block
graft excision great
care must be take
to protect this
nerve from injury

52. Injury to vessels
• Maxillary vessels:
– During the surgical
orthognathic
procedures the major
nutrient artery of the
maxilla are sometimes
damaged, but the
blood supply is
maintained by
anastamosis present
in the soft palate

53. The Temporomandibular joints
• It is a joint present between head of mandible
and the articular fossa and articular eminance
of the temporal bone
Type of joint: It is a condylar
variety of synovial joint
The joint cavity of TMJ is divided by fibro-
cartilagenous disc into 2 compartments

54. Bony framework of joint
• Proximal : Articular fossa and the
articular eminance of the mandible
• Distal side: Head of mandible
Articular surfaces:
• The anterior eminance is formed by the root of zygoma
and the articular surface is formed by the smooth area
of tht mandibular fossa of the temporal bone
• The distal articular surface is also a smootharea forned
by the head of the mandible.

55. The ligaments of TMJ
• True ligament
– Capsular ligament
– Temporomandibular ligament
• Accessory ligament
– Stylomandibular ligament
– Sphenomandibular ligament

56. True ligaments
• Capsular ligament: It is like a
fibrous sac over the joint
cavity. It is attached above to
the articular surface of TMJ
and on the other side to the
neck of the mandible
– It covers the joint cavity very
loosely
– It is covered by the synovial
membrane

57. • Temporomandibular ligament:
– this ligament is the thickening of the lateral part
of the capsular ligament
– It runs posterio-inferiorly and is attached above to
the articular surface and below to the ramus of
mandible and the posterio-lateral aspect of the
mandible

58. Accessory ligament
It provides additional support to the TMJ
• Stylomandibular ligament: This ligament is
formed by the thickening of the deep cervical
fascia.
– It is attached above to the styloid process and
below to the angle of mandible and lateral border
of ramus of mandible
– This ligament helps to seperate the parotid gland
and the submandibular gland

60. • Spheno-mandibular ligament; This ligament is
attached above to the spine of the sphenoid
bone and below to the lingula on the
mandible.
– This ligament is innervated by various nerves and
vessels
– Embryologically it is the un-ossified intermediate
part of the Meckel’s cartilage of the 1st branchial
arch

61. Interior of the joint
• The bones forming the joint cavity are covered
by fibrous cartilage rather than the hyaline
cartilage
• The absence of hyaline cartilage makes it an
atypical type of synovial joint

62. The articular disc
• The articular disc divides the joint into two
compartments, the upper and the lower
compartment
• Articular disc is a fibro-cartilagenous disc, it is
thickened in the periphery and thin in the
center
• The vascularity is also more in the periphery

64. Relations of the joint
• Anteriorly: fibres of the muscles of lateral
pterigoid
• Posteriorly: part of the parotid gland
• Medially: spheno mandibular ligament
• Laterally: parotid gland

65. Development of TMJ
• Temporomandibular ligament developes from the
mesenchyme situated between the developing
temporal bone above and the mandibular condyl
below
• During 12 weeks of development two clefts appear
and remain separated from each other by an
intervening mesenchymal plate
– These clefts become the upper and the lower joint
cavities
– The mesenchymal plate becomes the articular disc
– Condensation of the mesenchyme around the
developing joint becomes the capsule of the joint

66. The supply of the gland
• Arterial supply
• Superficial temporal artery
• Maxillary artery
• Veinous drainage
• Superficial temporal vein
• Retromandibular vein
• Lymphatics: It drains into the superficial and
deep parotid lymph nodes and deep cervical
nodes.

68. Movements of the TMJ
• The principle movements of the joint are:
» Elevation
» Depression
» Protraction
» Retraction
» Side to side movements
Various muscles are involved in these
movements, collectively known as muscles of
mastication.

69. Elevation •Messeter
•Anterior fibres of temporalis
•Medial Pterigoid
Depression •Lateral pterigoid muscle
•Anterior belly of digastric, mylohyoid and
geniohyoid also assist
Protraction
Retraction
•Masseter, Medial pterigoid and lateral
pterigoid
•Deep fibres of masseter
•Posterior fibres of temporalis
Side to side movements •It is caused by alternate contraction and
relaxation of Medial and lateral pterigoid

70. Muscles of mastication
• There are 4 muslces involved in mastication
– Masseter
– Temporalis
– Medial pterigoid
– Lateral pterigoid

71. Masseter
• Origin: it arises from 2 heads
• Superficial hear arises from the lower border of the anterior 2/3rd
of the zygomatic arch
• Deep head arises from the whol length of the zygomatic arch and
lower border of th posterior 1/3rd of the zygomatic arch.
• Insertion: The two heads unite and gets inserted into
the whole length of the outer surface of the ramus and
angle of mandible
• N. Supply: Massetric nerve and a branch of anterior
division of the Mandibular nerve
• Actions:
• Elevation of mandible
• Protrusion of the mandible

73. Temporalis
• Origin: whole length of the temporal fossa, the fascia covering of the
temporalis and from the inferior temporal line
The anterior fibres are vertical, posterior are horizontal and middle
fibres are oblique
• Insertion: all the fibres converge to form a thick tendon which passes
deep to the zygomatic arch and is inserted into the medial surface,
the apex, the anterior and the posterior border of the coronoid
process and anterior border of ramus of mandible upto the last molar
tooth.
• Nerve supply: Deep temporal nerve which arises from the anterior
division of the mandibular nerve
• Actions:
Anterior fibres are strong elevators of the mandible
Posterior fibres retract the mandible

75. Lateral Pterigoid
• Origin: It also arises from two heads
– The upper/superior head originates on the infratemporal surface and
infratemporal crest of the greater wing of the sphenoid bone,
– lower/inferior head on the lateral surface of the lateral pterigoid plate
• Insertion: Inferior head inserts onto the neck of condyloid process
of the mandible; upper/superior head inserts onto the articular disc
and fibrous capsule of the temporomandibular joint
• N. Supply: The mandibular branch of the fifth cranial nerve, the
trigeminal nerve, specifically the lateral pterigoid nerve, innervates
the lateral pterygoid muscle.
• Actions: Unlike the other three muscles of mastication, the lateral
pterygoid is the only muscle of mastication that assists in
depressing the mandible (opening the jaw).

76. Superior head of lateral
pterigoid
Inferior head of lateral
pterigoid

77. Medial pterigoid
• Origin:
– The bulk of the muscle arises as a deep head from just above the medial
surface of the lateral pterigoid plate.
– The smaller, superficial head originates from the maxillary tuberosity and the
pyramidal process of the palatine bone.
• Insertion: Its fibers pass downward, lateral, and posterior, and are
inserted, by a strong tendinous lamina, into the lower and back part of the
medial surface of the ramus and angle of the mandible
• N. Supply: Like all other muscles of mastication the medial pterygoid is
innervated by the anterior root (motor root) of the mandibular branch of
the trigeminal nerve (V).
• Actions: It contributes to following functions:
– Elevation of the mandible (closes the jaw)
– Minor contribution to protrusion of the mandible
– Assistance in mastication
– Excursion of the mandible; contralateral excursion occurs with unilateral
contraction

78. Medial pterigoid
insertion
origin