TMJ, (Tempero-Mandibular Joint) anatomy, surgical anatomy, surgical approaches with relevant anatomical diagrams and photographs

2. DEVELOPMENT, ANATOMY & SURGICAL
ANATOMY
BY : JOEL D’SILVA
PG STUDENT
DEPARTMENT OF ORAL & MAXILLOIFACIAL SURGERY

3. The most important functions of the
temporomandibular joint (TMJ) are mastication
and speech and are of great interest to dentists,
oral surgeons, orthodontists, clinicians, and
radiologists.
The TMJ is a ginglymoarthrodial joint, a term
that is derived from ginglymus, meaning a hinge
joint, allowing motion only backward and
forward in one plane, and arthrodia, meaning a
joint of which permits a gliding motion of the
surfaces.

4. The right and left TMJ form a bicondylar
articulation and ellipsoid variety of the synovial
joints similar to knee articulation.
The common features of the synovial joints
exhibited by this joint include
a) Disk
b) Bone
c) Fibrous capsule
d) Fluid
e) Synovial membrane
f) Ligaments.

5. However, the features that differentiate
and make this joint unique are:
Its articular surface covered by
fibrocartilage instead of hyaline cartilage

6. Bilateral diarthrosis – right & left function
together
Articular surface covered by fibrocartilage
instead of hyaline cartilage
Only joint in human body to have a rigid
endpoint of closure that of the teeth
making occlusal contact.

7. In contrast to other diarthrodial joints
TMJ is last joint to start develop, in about
7th week in utero.
Develops from two distinct blastema

9. Mandibular condyle
Articular surfaces of Temporal bone
Capsule
Articular disc
Ligaments
Muscular component

10. An ovoid process seated atop a
narrow mandibular neck. It’s the
articulating surface of the
mandible.
It is convex in all directions but
wider latero-medially (15 to 20
mm) than antero-posteriorly (8 to
10mm).

11. The medial pole is directed
more posteriorly.
Thus, if the long axes of two
condyles are extended
medially, they meet at
approximately the basion on
the anterior limit of the
foramen magnum, forming an
angle that opens toward the
front ranging from 145° to
160°
It has a medial and lateral pole

12. The lateral pole of the condyle is
rough, bluntly pointed, and
projects only moderately from the
plane of ramus, while the medial
pole extends sharply inward from
this plane.
The articular surface lies on its
anterosuperior aspect, thus facing
the posterior slope of the articular
eminence of the temporal bone.

14. The articular surface of the temporal
bone is situated on the inferior aspect of
temporal squama anterior to tympanic
plate.

15. ARTICULAR
EMINENCE
• This is the entire transverse bony
bar that forms the anterior root of
zygoma. This articular surface is
most heavily traveled by the condyle
and disk as they ride forward and
backward in normal jaw function.
ARTICULAR
TUBERCLE
• This is a small, raised, rough, bony
knob on the outer end of the
articular eminence.
• It projects below the level of the
articular surface and serves to attach
the lateral collateral ligament of the
joint.

16. PREGLENOID
PLANE
• This is the slightly hollowed,
almost horizontal, articular
surface continuing
anteriorly from the height of
the articular eminence

17. E: Articular eminence; enp:
entogolenoid process;
t:articular tubercle; lb: lateral
border of the mandibular
fossa; pep: preglenoid
plane; Gf: glenoid fossa

19. The articular disc is the most
important anatomic structure of the
TMJ.
It is a biconcave fibro cartilaginous
structure located between the
mandibular condyle and the
temporal bone component of the
joint.
Its functions to accommodate a
hinging action as well as the gliding
actions between the temporal and
mandibular articular bone

20. The articular disc is a roughly oval, firm, fibrous
plate.
1. anterior band = 2 mm in thickness,
2. posterior band = 3 mm thick,
3. thin in the center intermediate band of 1 mm
thickness.
More posteriorly there is a bilaminar or retrodiscal
region.

21. It is shaped like a peaked cap that divides
the joint into a larger upper compartment
and a smaller lower compartment.

22. Hinging movements take place in the
lower compartment and gliding
movements take place in the upper
compartment.
The superior surface of the disc -
saddle-shaped
to fit into the cranial
contour,
The inferior surface - concave
to fit against the mandibular
condyle.

23. The disc is attached all around the joint capsule
except for the strong straps that fix the disc directly
to the medial and lateral condylar poles, which
ensure that the disc and condyle move together in
protraction and retraction.

24. The anterior extension of the disc is attached
to a fibrous capsule superiorly and inferiorly.
In between it gives insertion to the lateral
pterygoid muscle where the fibrous capsule is
lacking and the synovial membrane is
supported only by loose areolar tissue.

25. The anterior and posterior bands have
predominantly transversal running fibers,
while the thin intermediate zone has
anteroposteriorly oriented fibers.
Posteriorly, the bilaminar region consists of
two layers of fibers separated by loose
connective tissue.

26. The upper layer or temporal lamina is composed of elastin
and is attached to the postglenoid process, medially
extended ridge, which is the true posterior boundary of
the joint. It prevents slipping of the disc while yawning.
The inferior layer of the fibers or inferior lamina curve
down behind the condyle to fuse with the capsule and
back of the condylar neck at the lowest limit of the joint
space. It prevents excessive rotation of the disc over the
condyle.

27. In between the two layers, an expansile, soft pad of
blood vessels and nerves are sandwiched and
wrapped in elastic fibers that aid in contracting
vessels and retracting disc in recoil of closing
movements
The volume of retrodiscal tissue must increase
instantaneously when the condyle translates
anteriorly.

29. Thin sleeve of tissue completely surrounding the joint.
Extends from the circumference of the cranial articular
surface to the neck of the mandible.

30. anterolaterally to the articular tubercle,
laterally to the lateral rim of the mandibular
fossa,
posterolaterally to the postglenoid process,
posteriorly to the posterior articular ridge,
medially to the medial margin of the temporal
fossa,
anteriorly it is attached to the preglenoid plane

31. MANDIBULAR NECK -
Laterally- the lateral condylar pole but
Medially - dips below the medial pole.
On the lateral part of the joint, the capsule is a
well-defined structure that functionally limits the
forward translation of the condyle.

32. This capsule is reinforced more laterally by an
external TMJ ligament, which also limits the
distraction and the posterior movement of the
condyle.
Medially and laterally- blends with the
condylodiscal ligaments.

34. Anteriorly, the capsule has an
orifice through which the lateral
pterygoid tendon passes. This area
of relative weakness in the
capsular lining becomes a source
of possible herniation of intra-
articular tissues, and this, in part,
may allow forward displacement of
the disk.

35. The synovial membrane lining the capsule covers
all the intra-articular surfaces except the pressure-
bearing fibrocartilage.
There are four capsular or synovial sulci situated
at the posterior and anterior ends of the upper and
lower compartments.
These sulci change shape during translatory
movements, which requires the synovial
membrane to be flexible.

37. The ligament on each side of the jaw is designed
in two distinct layers.
 The wide outer or superficial layer is usually fan-
shaped and arises from the outer surface of the
articular tubercle and most of the posterior part
of the zygomatic arch.
There is often a roughened, raised bony ridge of
attachment on this area.

39. The ligamentous fascicles run obliquely downward and
backward to be inserted on the back, behind, and below
the mandibular neck.
Immediately medial to this layer, a narrow ligamentous
band arises from the crest of the articular tubercle
continuously, with attachment of the outer portion at
this site.
 This narrow inner or deep band runs horizontally back
as a flap strap to the lateral pole of the condyle.
An upper part of this band continues on to attach to the
back of the disk, lateral to the condylar pole.

41. Arises from the angular
spine of the sphenoid and
petrotympanic fissure.
Runs downward and
outward.
Insert on the lingula of the
mandible.

42. 1. Laterally - lateral pterygoidmuscle.
2. posteriorly - auriculotemporal nerve.
3. anteriorly - maxillary artery.
4. Inferiorly - the inferior alveolar nerve and
vessels a lobule of the parotid gland.
5. Medially - medial pterygoid with the chorda
tympani nerve and the wall of the pharynx
with fat and the pharyngeal veins intervening.

44. The ligament is pierced by the
myelohyoid nerve and vessels.
This ligament is passive during
jaw movements, maintaining
relatively the same degree of
tension during both opening
and closing of the mouth.

45. This is a specialized dense, local concentration of
deep cervical fascia extending from the apex and
being adjacent to the anterior aspect of the
styloid process and the stylohyoid ligament to the
mandible’s angle and posterior border.

46. This ligament then extends forward as a broad
fascial layer covering the inner surface of the
medial pterygoid muscle.
The anterior edge of the ligament is thickened
and sharply defined.

48. It is lax when the jaws are closed and slackens
noticeably when the mouth is opened because
the angle of the mandible swings up and back
while the condyle slides downward and forward.
This ligament becomes tense only in extreme
protrusive movements. Thus, it can be
considered only as an accessory ligament of
uncertain function.

49. The synovial fluid comes from two sources: first,
from plasma by dialysis, and second, by secretion
from type A and B synoviocytes with a volume of
not more than 0.05 ml.
 However, contrast radiography studies have
estimated that the upper compartment could
hold approximately 1.2 ml of fluid without undue
pressure being created, while the lower has a
capacity of approximately 0.5 ml.

50. It is clear, straw-colored viscous fluid.
It diffuses out from the rich cappillary network of
the synovial membrane.
Contains:
Hyaluronic acid which is highly viscous
May also contain some free cells mostly
macrophages.

51. Functions:
Lubricant for articulating surfaces.
Carry nutrients to the avascular tissue of the
joint.
Clear the tissue debris caused by normal wear
and tear of the articulating surfaces.

52. The way the teeth fit together may affect the TMJ
complex.
A stable occlusion with good tooth contact and
interdigitation provides maximum support to the
muscles and joint, while poor occlusion (bite
relationship) may cause the muscles to
malfunction and ultimately cause damage to the
joint itself.
Instability of the occlusion can increase the
pressure on the joint, causing damage and
degeneration.

53. Branches of External Carotid Artery
1. Superficial temporal artery
2. Deep auricular artery
3. Anterior tympanic artery
4. Ascending pharyngeal artery
5. Maxillary artery

54. The Blood supply to TMJ is only Superficial, i.e.
there is no blood supply inside the capsule
TMJ takes its nourishment from Synovial fluid

55. venous plexus
maxillary vein
Tranverse facial vein.
Superficial temporal vein.

56. Auriculotemporal
Deep temporal
Massetric nerve

58. Anteriorly - Mandibular notch
Lateral pterygoid
Masseteric nerve and artery

59. A careful dissection of 16 intact human cadaveric
head specimens revealed The location of the
masseteric artery was then determined in relation
to 3 points process:
1) the anterior-superior aspect of the condylar
neck = 10.3 mm;
2) the most inferior aspect of the articular tubercle
= 11.4 mm;
3) the inferior aspect of the sigmoid notch = 3 mm.
Journal of Oral and Maxillofacial Surgery. 2009;67 (2) : 369–371

61. Posteriorly - parotid gland
Superficial temporal vessels
Auriculotemporal nerve

62. Laterally –
Skin and fascia
Parotid gland
Temporal branches of facial nerve
Medially - Tympanic plate (separates from ICA)
spine of sphenoid
Auriculotemporal & chorda tympani nerve
middle meningeal artery
maxillary artery

64. Superiorly –
middle cranial fossa
middle meningeal vessels
Inferiorly –
maxillary artery &
vein

66. Rotational / hinge movement in first 20-25mm of
mouth opening
Translational movement after that when the
mouth is excessively opened.

67. Translatory movement – in the superior part of
the joint as the disc and the condyle traverse
anteriorly along the inclines of the anterior
tubercle to provide an anterior and inferior
movement of the mandible.

68. Hinge movement – the inferior portion of the
joint between the head of the condyle and the
lower surface of the disc to permit opening of
the mandible.

69. Depression Of
Mandible
Lateral pterygoid
Digrastric
Geniohyoid
Mylohyoid

70. Elevation of
Mandible
Temporalis
Masseter
Medial
Pterygoids

71. Protrusion of Mandible
Lateral Pterygoids
Medial Pterygoids

72. Retraction of Mandible
Posterior fibres of Temporalis

73. Mainly 4 forms are
seen-
1. Convex-58%
2. Flat- 25%
3. Pointed-12%
4. Round- 3%
( mainly in children)

74. A. Early development:
Develops relatively late compared to large joints of
extremities.
At 7th prenatal week jaw joint lacks condylar
growth cartilage joint cavities, synovial tissue &
articular capsule.

75. B. Condylar cartilage development
Between 8-12 wk of I.U life cartilagenous condyles
develop anteriorly to malleus incus articulation.
Then altered by endochondral bone formation & fuses
to posterior part of bony body of mandible.
By 12th wk condyle consists of large mass of hyaline
cartilage covered by a fibrous cap.

76. C . Articular disc formation;
In 12th wk first appearance of TMJ cavity is seen
& first of 2 compartments inferior or
mandibular compartment is formed.
A split appear in synovial mesenchyme &
temporal or superior compartment is formed in
next wk.
Presence of both sup & inf compartment
develops articular disc.

77. D . Fate of meckle’s cartilage;
As mandible enlarges remnants of meckles
cartilage becomes relatively smaller.
At 18-20 i.u life it loses its function &
disappears.

78. Occurs in 14th I.U life .
Condyle grows by both interstitial & appositional
growth of condylar cartilage.
Formation of temporal fossa starts with
development of heavy spicule of temporal bone
superior to forming articular disc.
Articular disc takes its characteristic shape &
blends into articular capsule at 26th wk.

79. At 18-20 prenatal wk TMJ starts functioning.
The condylar bone increases in size & density ,
& mandible undergoes changes in shape & size
associated with differentiation & functioning of
muscles of mastication.

80. Growth continues in 2nd decade of postnatal life
a. Temporal fossa deepens as bone forms laterally &
articular tubercle enlarges.
b. Dense fibrous nature of disc & capsule becomes
apparent.
c. condyles continue endochondral like growth .
Perichondral covering of condyle consists of 2 layers.
-portion lying next to cartilage which is highly
cellular &
-outer layer which is fibrous.

81. Preauricular
Dingman’s, Blair’s, Thoma’s,Al-kayat and
Bramley’s, Popowitch’s
Postauricular .
Endaural approach
Post ramal/ Hind’s approach
Submandibular/Risdon’s approach
Hemicoronal
bicoronal

82. Basic incision given by
Dingman(1951)
Most basic & standard
approach to tmj.

83. Blair & Ivy (1936) –
“Inverted hockey stick “
incision.
Facilities exposure of
arch along with condylar
area.

84. Thoma in 1958
Angulated vertical
incision.
-carried out across
zygomatic arch infront of
ear to avoid main trunk
of facial nerve.

85. 1979.
Modified preauricular
approach.
Facial nerve divides in front of
auditory canal as near as 0.8cm
& as far as 3.5cm
Protection achieved by making
incision through temporal
fascia& periosteum down to
arch not more than 0.8cm.

86. Hoops et al (1970),
Alexander and James (1975)
Highly cosmetic incision
Disadvantage- poor access &
visibility,the risk of external
auditory meatus stenosis,
infection & deformity of the
auricle.

87. Lempart (1938)
Short facial skin incision
extending in to ext. auditory
meatus
Excellent cosmetics
Disadvantage-
Meatal stenosis or
chondritis, injury to the
branches of the facial nerve

88. Indication – surgeries of
condylar neck & ramus area.
Incision- 1cm behind ramus
of mand. and extends 1cm
below the lobe of ear.
Highly cosmetic, excellent
visibility and accessibility.
Injury may occur to posterior
facial vein and main trunk of
facial nerve.

89. Risdon (1934)
Mainly used for neck of
condyle & ramus region.
supplement to different
tmj approaches for
tunneling through the soft
tissues to place a graft

90. Hemicoronal (unilateral) or bicoronal (bilateral)
approach is used.
More extensive but versatile approach for upper
& middle regions of facial skeleton, zygomatic
arch & TMJ.
Advantage- scar is hidden in the hairline.

92. GREY`S ANATOMY (38TH EDITION)
SICHER & DUBRUL`S ORAL ANATOMY (8TH
EDITION)
ANATOMY OF HEAD & NECK BY B.D CHAURSIA
TEXTOOK OF ORAL & MAXILLOFACIAL SURGERY
BY NEELIMA MALIK.
TEXTBOOK OF TMJ DISORDERS BY EDWARD F.
WRIGHT.
TEXTBOOK OF TMJ DISORDERS BY KAPLAN &
ASSAEL