Temporomandibular joint Anatomy, Physiology, Movements, Clinical examination in children.

1. TEMPOROMANDIBULAR JOINT
Presented by:
Dr Divya Gaur

2. CONTENTS
• INTRODUCTION
• ANATOMY
• EMBRYOLOGY
• HISTOLOGY
• AGE CHANGES IN TMJ
• TMJ DISORDERS IN CHILDREN
• TMJ IMAGING
• REFERENCES

3. INTRODUCTION
• The name is derived from the two bones that form the joint:
– Upper TEMPORAL bone.
– Lower MANDIBLE
• It 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.1 It refers to its dual compartment
structure and function.
• The right and left TMJ form a bicondylar articulation and ellipsoid
variety of the synovial joints similar to knee articulation.2

4. ANATOMY
• Articular surface
• Mandibular component
• Cranial component
• Articular disc
• Articular capsule
• Ligaments
• Neurovascular components
X Alomar et al. Anatomy of Temporomandibular joint. J Sult 2007; 170-183.

5. MANDIBULAR COMPONENT
• Ovoid condylar process seated atop a narrow mandibular neck.
• 15 to 20 mm side to side.
• 8 to 10mm from front to back.
• Articular surface is covered with white fibro-cartilage.
• If long axes of both condyles are extended medially, they would meet at
approx the basion on the anterior limit of foramen magnum, forming an angle
that opens towards the front ranging from 145-160o.
X Alomar et al. Anatomy of Temporomandibular joint. J Sult 2007; 170-183.

6. MANDIBULAR COMPONENT (Contd)
• Lateral pole of condyle: rough, bluntly pointed and projects only moderately
from the plane of ramus.
• Medial pole: extends sharply inward from this plane.
• Articular surface lies on its anterosuperior aspect.
X Alomar et al. Anatomy of Temporomandibular joint. J Sult 2007; 170-183.

7. • Formed by the following parts:
– Articular eminence
– Articular tubercle
– Preglenoid plane
– Posterior articular ridge and postglenoid process
– Lateral border of mandibular fossa
– Entoglenoid process
CRANIAL COMPONENT
X Alomar et al. Anatomy of Temporomandibular joint. J Sult 2007; 170-183.

8. • Articular eminence:
– The transverse bony bar that forms
the anterior root of zygoma.
– Most heavily travelled by the condyle
and articular disc as they ride
forward and backward in normal jaw
function.
• Articular tubercle:
– Small, raised, rough bony knob on
the outer end of articular eminence.
– Serves to attach lateral collateral
ligament of the joint.
• Preglenoid plane:
– Slightly hollowed, almost horizontal,
articular surface continuing anteriorly
from the height of articular
eminence.
CRANIAL COMPONENT (Contd)
X Alomar et al. Anatomy of Temporomandibular joint. J Sult 2007; 170-183.

9. CRANIAL COMPONENT (Contd)
•Posterior articular ridge and postglenoid
process:
•Posterior part of mandibular fossa is an anterior
margin of petrosquamous suture and is elevated
to form a ridge known as post art ridge or lip.
•The ridge increases in height laterally to form a
thickened cone-shaped prominenc called post-
glenoid process.
•Lateral body of mandibular fossa:
•Usually raised to form a slight crest joining the
articular turbercle, in front, with post glenoid
process behind.
•Entoglenoid process:
•The fossa narrows on medial side and is
bounded by a bony wall.
•It passes slightly medially as the medial glenoid
plane.
X Alomar et al. Anatomy of Temporomandibular joint. J Sult 2007; 170-183.

10. ARTICULAR DISC
• Most important anatomic structure of the TMJ.
• STRUCTURE: A biconcave fibrocartilaginous
structure located between the mandibular
condyle and the temporal bone component of
the joint. Roughly oval, firm, fibrous plate with
its long axis being tranversely directed.
• SHAPE: Shaped like a peaked cap that
divides the joint into a larger upper compartment
and a smaller lower compartment.
• SURFACES: Superior surface of the disk is
said to be saddle-shaped to fit into the cranial
contour. Inferior surface is concave to fit against
the mandibular condyle.
• PARTS: Is thick, round to oval all around
its rim, divided into an anterior band of 2 mm in
thickness, a posterior band 3 mm thick, and thin
in the centre intermediate band of 1 mm
thickness. More posteriorly there is a bilaminar
or retrodiskal region.2
X Alomar et al. Anatomy of Temporomandibular joint. J Sult 2007; 170-183.

11. • ATTACHMENT:
– Attached all around the joint capsule except for the strong straps that fix
the disk directly to the medial and lateral condylar poles, which ensure that
the disk and condyle move together in protraction and retraction.2
– Anterior extension of the disk is attached to a fibrous capsule superiorly
and inferiorly.
– In between it gives insertion to the lateral pterygoid muscle.
• FIBRES:
– Anterior and posterior bands have transversally running fibres.
– Thin intermediate zone has anteroposteriorly oriented fibres
– Posteriorly, bilaminar region consists of 2 layers
of fibres separated by loose connective tissue.
– Upper layer: temporal lamina is composed of
elastin and is attached to the postglenoid process.
– Inferior layer: inferior lamina curves down behind
the condyle to fuse with the capsule and back of
the condylar neck.

12. • FUNCTIONS:
– Accommodates a hinging as well as gliding actions between the temporal
and mandibular articular surfaces.
– Temporal lamina prevents slipping of the disk while yawning.
– Inferior lamina prevents excessive rotation of the disk over the condyle.
• HISTOLOGY:
– De Bont et al observed in adults, particularly in humans (ages ranging from
58 to 73 years), that the articular surface of the disc was composed of
closely packed collagen fibrils running predominantly anteroposteriorly.

13. ARTICULAR CAPSULE
• A thin sleeve of tissue completely surrounding the joint.
• Extends from the circumference of the cranial articular surface to the neck of
the mandible.
• ATTACHMENTS:3
– ANTEROLATERALLY: Articular tubercle
– LATERALLY: Lateral rim of mandibular fossa.
– POSTEROLATERALLY: Postglenoid process
– POSTERIORLY: Posterior articular ridge
– MEDIALLY: Medial margin of temporal bone at its suture with greater wing
of sphenoid.
– ANTERIORLY: Preglenoid plane
• RELATIONS:
– LATERALLY AND MEDIALLY: Capsule blends with condylodiscal ligaments.
– MORE LATERALLY: Temporomandibular ligament
– ANTERIORLY: Capsule has an orifice through which lateral pterygoid
tendon passes.
A site of possible herniation of intra-articular tissues.4

14. • Synovial membrane:
– Covers all intra-articular surfaces except the pressure bearing fibro-
cartilage.
ARTICULAR CAPSULE (contd)

15. TEMPOROMANDIBULAR LIGAMENTS
COMPLEX
TEMPOROMANDIBULAR LIGAMENT:
• Designed in two layers.
• Wide outer or superficial layer:
– Fan shaped.
– Origin: Outer surface of articular
tubercle and most of the posterior part
of zygomatic arch.
– Fibres: run obliquely downward and
backward.
– Insertion: Behind and below the
mandibular neck.
• Narrow, inner or deep layer:
– Arises from the crest of articular
tubercle.
– Runs back as flap strap to the lateral
pole of condyle.

16. SPHENOMANDIBULAR LIGAMENT:
• Origin: Angular spine of sphenoid.
• Fibres: Downward and outward
• Insertion: Lingula of the mandible.
• Relations:
– Laterally: Lateral pterygoid muscle
– Medially: Medial pterygoid muscle, chorda
tympani nerve, wall of pharynx and
pharyngeal vessels.
– Anteriorly: Maxillary artery
– Posteriorly: Auriculotemporal nerve
– Inferiorly: Inferiorly alveolar nerve and
vessels.
• Pierced by: Mylelohoid nerve and vessels
• Function: Passive during jaw movements,
maintaining same degree of tension during
opening and closing of the mouth.
TEMPOROMANDIBULAR LIGAMENTS
COMPLEX (contd)

17. STYLOMANDIBULAR LIGAMENT:
• Specialized dense, local concentration of deep
cervical fascia.
• Origin: Apex and anterior aspect of Stylohyoid
process and stylohyoid ligament.
• Insertion: Angle and posteror border of
mandible.
• Then extends forward as a broad fascial layer
covering the inner surface of medial pterygoid
muscle.
• Functions:
– Lax when jaws are closed.
– Slackens noticeably when mouth is
opened.
– Tense only in extreme protrusive
movements.
TEMPOROMANDIBULAR
LIGAMENTS COMPLEX (contd)

18. NEUROVASCULAR COMPONENTS
• SENSORY INNERVATION:
– Auriculotemporal and Massetric branches of Mandibular branch of
Trigeminal nerve (V cranial nerve).
• PROPRIOCEPTION: involves 4 receptors
– Ruffini endings: static mechanoreceptors which position the mandible.
– Pacinian corpuscles: dynamic mechanoreceptors which accelerate
movement during reflexes.
– Golgi tendon organ: static mechanoreceptors for the protection of
ligaments around the temporomandibular joint.
– Free nerve endings: pain receptors for the protection of
temporomandibular joint itself.
• ARTERIAL BLOOD SUPPLY:
– Branches of external carotid artery, predominantly the Superficial temporal
branch.
– Other branches: Deep auricular artery, Anterior tympanic artery, Ascending
pharyngeal artery and maxillary artery.
Neither innervation nor vascularization within central portion of articular disc.

19. EMBRYOLOGY OF TMJ
• Early TMJ structures emerged from a block of embryonic mesenchymal cells
interposed between the developing temporal bone and mandible.
• Merida-Velasco et al confirm that the critical period of morphogenesis of TMJ
occurs between 7th and 11th week of gestation.
• PRIMARY JOINT:
– At about 7th week, Meckels cartilage extends from the midline backward
and dorsally, acting as a scaffold to the developing mandible.
– It terminates at malleus and articulates with the incal cartilage forming the
primary joint.
– Factors promoting joint formation are intrinsic and genetically determined.
– This exists for about 4 months until the cartilages ossify and become
incorporated in the middle ear.
• SECONDARY JOINT:
– At 3 months of gestation, two distinct regions of mesenchymal
condensation appear:
• TEMPORAL BLASTEMATA
• CONDYLAR BLASTEMATA

20. TEMPORAL BLASTEMA:
• Give rise to articular eminence and glenoid fossa.
• First appearance of articular fossa occurs at approx 7-7.5 weeks as a visible
condensation of deeper staining stellate cells comprising embryonic
mesenchyme.
• Spicules of primary cancellous bone appear most prominently at 10-11 weeks.
• Upto 9 weeks, shape of articular fossa is convex.
• Later, the fossa progressively takes on its definitive concave shape.
CONDYLAR BLASTEMA:
• Condensation and shaping of mandibular condyle occur at about the same time
as for the articular fossa.
• This mass is superiorly convex.
• Condylar cartilage cells appear at 9-10 weeks.
• Till 10th week, articular fossa and condyle ossify at the same rate. Later
articular fossa ossifes faster.
• Small coalesing clefts for the lower compartment of joint cavity appear at about
10 weeks, and for upper compartment at 11.5 weeks.
EMBRYOLOGY OF TMJ

21. CONDYLAR BLASTEMA (contd)
• These small clefts gradually enlarge and coalesce into larger spaces.
PHASES IN DEVELOPMENT OF TMJ
STAGES EVENTS
Blastematic stage
(7-8weeks)
Corresponds with the onset of the
organization of condyle and the articular
disc and capsule. During week 8,
intramembranous ossification of temporal
squamous bone begins.
Cavitation stage (9-11
weeks)
Corresponding to the initial formation of
inferior joint cavity (week 9) and the start
condylar chondrogenesis. Week 11 marks
the initiation of organization of superior
joint cavity.
Maturation stage After week 12 of development.

22. AGE CHANGES IN TMJ
ARTICULAR LAYER:
• Vascular at birth and becomes progressively fibrous.
ARTICULAR DISC:
• Initially flat and highly vascular.
• With ageing, there is marked decrease in vascular supply, the disk becomes
fibrous.
• Central part thins with anterior and posterior parts becoming thicker.
• Collagen fibres become coarse and dense and get arranged in a three-
dimensional network.
After 20 yrs, superior and anterior part of condyle and posteroinferior part of
eminence retain the condylar cartilage.
Reasoning for this: adaptation to functional stress.

23. HISTOLOGY
CONDYLE:
• Cancellous bone covered by a thin layer of compact bone.
• Trabaculae radiate from the neck of mandible and rach the cortex at right
angles, giving maximal strength to the condyle.
• As age progresses, trabaculae thickens, decreasing the size of large marrow
spaces.
• Red marrow is of myeloid or cellular type which is replaced by fatty marrow in
older individuals.
ROOF OF GLENOID FOSSA:
• Thin compact layer of bone.
• Articular eminence is composed of spongy bone covered with a thin layer of
compact bone.
• Areas of chondroid bone are commonly seen in articular eminence.

24. ARTICULAR SURFACES OF MANDIBULAR CONDYLE AND FOSSA:
• Lined with dense fibrous connective tissue with some elastic fibres.
• Composed of four distinct layers/zones :
– Articular
– Prolferative
– Fibrocartilaginous
– Calcified cartilage
• ARTICULAR ZONE:
– Most superficial layer, found adjacent to the joint cavity.
– Covered with a layer of fibrous tissue.
– Tightly packed collagen bundles oriented parallel to the articular surfaces,
allowing them to withstand the forces of movement.
– Adv of fibrous cartilage: less susceptible to the effects of ageing.
• PROLIFERATIVE ZONE:
– Mainly cellular, consisting of undifferentiated mesenchymal cells, that are
responsible for the proliferation of articular cartilage in response to
functional demands.
HISTOLOGY

25. • FIBROCARTILAGINOUS ZONE:
– Collagen fibres arranged in bundles in a crossing pattern.
– Provides a 3-dimensional network that provides resistance to compressive
and lateral forces.
• CALCIFIED CARTILAGE:
– Fourth and the deepest zone.
– Made up of chondroblasts and chondrocytes distributed throughout the
articular cartilage.
– Chondrocytes become hypertrophic and die, causing their cytoplasm to be
evacuated, forming bone cells from within the medullary cavity.
HISTOLOGY

26. ARTICULAR DISC:
• Dense, collagenous fibrous pad between condylar heads and articular surfaces.
• Fibroblasts are elongated and send flat cytoplasmic processes into the
interstices between the adjacent bundles.
• Thinnest centrally, and thickens in the periphery.
• Devoid of any blood vessels and nerves , except for extreme periphery which is
slightly innervated.
• 80% type I collagen and 5% glycosaminoglycans of its dry weight.
• Of the 5% GAGs, 80% is chondroitin sulphate and 15% is dermatan sulphate.
• Small amount of type III collagen in posterior attachment region.
SYNOVIAL MEMBRANE:
• Lines the inner surface of the joint capsule.
• Folds to form synovial villi which project into the spaces.
• Made up of an intimal layer of synovial cells from 1-4 cells in depth resting over
loosely organized subintimal connective tissue layer.
• Connective tissue layer has extensive plexus of nerves and vessels and
numerous fibroblasts, mast cells and macrophages.
HISTOLOGY

27. • Synovial layer lacks a distinct basement membrane: rapid diffusion of
substances in and out of joint cavities.
• Synovial fluid: dialysate of plasma.
• Types of synovial cells:
– Type A: synthesis and transport of hyaluronodate and are involved in
active phagocytosis.
– Type B: synthesis and transport of proteins into the synovial fluid.
• Functions of synovial fluid:
– Lubrication of the joint
– Essential nutrients for chondrocytes within the cartilage matrix.
– Aid in the phagocytosis and elimination of particulate and dissolved
substances.
– Provide necessary vehicle for transport and diffusion of substances in and
out of joint cavities.
HISTOLOGY

28. TEMPOROMANDIBULAR JOINT
DISORDERS IN CHILDREN
• Children seldom seek treatment for TMDs but dentist’s awareness of early signs
and symptoms can facilitate quicker resolution and prevent progression.
• Clinical evaluation is important– owing to difficulty in verbalizing the precise
location and nature of orofacial pain.
• EPIDEMIOLOGY:
– The skewed age and gender distribution suggest a hormonal influence.
– Treatment seeking peaks occur during reproductive years.
– Prevalence of signs and symptoms of TMDs in children varies considerably,
due to difference in:
• Population investigated
• By examination methods
• Diagnostic criteria used
• Interindividual and intraindividual variations of examiners.
A study of 3428 consecutive patients of all ages enrolled in a health maintenance
organization who sought treatment for TMDs revealed that 85.4% were female.5

29. TEMPOROMANDIBULAR JOINT
DISORDERS IN CHILDREN
Wahlund and colleagues reported that the prevalence of TMD in children and
adolescents (12-18 yrs) was 7%.6
Nilsson found that prevalence of TMD pain in 28899 youths aged 12-19 yrs was
4.2% and was significantly higher in girls (6%) than in boys (2.7%).
ETIOLOGY:
• Historically, malocclusion has been considered a primary cause.
• However, the occurrence of malocclusion, occlusal interferences and
missing teeth is nearly equal for males and females. 7
• Predisposing factors:
•Systemic (affecting the entire body or a particular body system.)
•Psychosocial (interaction of psychological and social variables.)
•Physiologic (cellular and metabolic processes, neuromuscular.)
•Structural (dental occlusion, musculoskeletal, articular, developmental
anomalies).
•Precipitating/initiating factors: 7,8
•Trauma or overuse.
•Repetitive activities with jaw in sustained or abnormal posture:
playing wind instrument or violin or sleep posture.

30. • Prepetuating/ sustaining factors:9
– Parafunction
– Overuse
– Systemic diseases
– Occlusal factors
– Psychological distress
TEMPOROMANDIBULAR JOINT
DISORDERS IN CHILDREN

31. EXAMINATION FOR TMDs
• RANGE OF MOTION: ROM
– Simple and objective method.
– Mandibular ROM is directly related to height.
– The ability of a patient to place 3 fingers vertically in a handshake position
between the incisor teeth (the 3 finger test) approximates a normal range
of mandibular opening of 35-50mm.10
– If it is not possible to get even 2 fingers, then the reason for the limited
opening should be investigated.
– Excursive mandibular movement to each side is normally 8 to 10 mm.
– Width of a permanent maxillary central incisor is 8to 9 mm, so if a patient
can move the lower jaw sideways by the width of upper central incisor, this
should be considered normal.
– Pain, mandibular deviation, end-point deflection, catching, or locking
associated with these movements should be noted.

32. • PROVOCATION OF MASTICATORY MUSCLE PAIN:
– Firm bilateral pressure applied to temporalis and masseter muscles while
the patient is clenching will reveal tenderness and determine if there is
atrophy or hypertrophy, which may be associated with extreme bruxism.
• TMJ PALPATION AND LOAD TESTING:
– Lateral aspect of the capsule is examined by having the patient open their
mouth halfway while the clinician firmly presses the index fingers in the
depression created behind each condyle, just in front of the tragus of the
ear.
– Presence of discomfort is noted as the patient slowly opens and closes.
– Joint loading is accomplished by the clinician applying force under the
angle of the mandible, with the teeth slightly out of contact.
– Functional loading while chewing on a cotton roll or wax between the last
molars provides information about contralateral capsular pain. This
squeezing action torques the TMJ on the opposite side and can trigger the
clicking or muscle pain that the patient experiences while chewing.
– Biting on tongue blade on the side of pain may reduce the pain if it is
related to inflammation.
EXAMINATION FOR TMDs

33. • DIFFERENTIATION OF TMJ SOUNDS:
– TMJ sounds can be categorized as:
• Clicking
• Soft tissue crepitus
• Hard-tissue grating
– A stethoscope applied lightly over the joint is helpful in distinguishing the
character and intensity of sounds.
– The noise should be evaluated on opening, closing and in excursive jaw
movements.
– Applying upward pressure at the angle of mandible usually increases the
intensity of the sounds and this should be done if the patient reports a
recent history of sounds but none were detected in unloaded jaw
movements.
EXAMINATION FOR TMDs

34. TMJ IMAGING
• Recommended when there is a recent history of mandibular trauma, evidence
of developing facial asymmetry or when hard tissue grinding or crepitus is
detected.
• Age-related changes of mandibular condyle should be considered:
– As size of condyles increase, the angle decreases and therefore the
position of condyle within the fossa changes.
– The shape of mandibular condyle changes from a round to oval
configuration.
• Most commonly accomplished with a panoramic view.
– Low cost
– Widespread availability
– Minimal radiation
– Reliable for evaluating condylar head morphology and angulation and
cortex density but do not permit evaluation of joint space or condylar
motion.
– Useful for measuring vertical ramus height, which ahs been shown to be
reduced in growing children with disc displacement.11
– A steeper mandibular plane angle, increased antegonial notching and
skeletal facial asymmetry are seen more often in patients with TMD. 12

35. • Computed tomography (CT) or cone beam computed tomography (CBCT) is
indicated for detection of TMJ osseus abnormalities, fracture detection and
analusis of facial asymmetry.
• Magnetic resonance imaging produces no ionizing radiation and provides
visualization of position and contours of the TMJ disc and other soft tissues,
can detect inflammation.
TMJ IMAGING

36. REFERENCES
1. Dorland WA: medical dictionary. Philadelphia and london, saunders co.,1957.
2. Williams pl: gray’s anatomy, in skeletal system (ed38). Churchill livingstone london 1999,
pp578-582.
3. Patnaik vvg, bala s,singla rajan k: anatomy of temporomandibular joint? A review. J anat
soc india 49(2):191-197, 2000
4. Kreutziger KL, mahan PE: temporomandibular degenerative joint disease. Part II.
Diagnostic procedure and comprehensive management. Oral surg oral med oral pathol
40(3):297-319, 1975
5. Howard JA. Tempo mand joint disorders, facial pain and dental problems in performing
artists. In: sataloff RT, brandfonbrener AG, lederman RJ, editors. Performing arts
medicine. 3rd edition. Naberth (PA): science and medicine 2010.P151-96.
6. Mohlin b, axelsson s, paulin g et al. Tmd in relation to malocclusion and orthodontic
treatment. Angle orthod 2007;77(3):542-8.
7. Howard ja, lovrovich at. Wind instruments: their interplay with orofacial structures. Med
probl perform art 1989;4:59-72
8. Kovero o, konone m. Signs and symptoms of tmds and radiologically observed
abnormalities in the condyles of tmj of professional violin and viola players. Acta odontol
scand 1995;53(2):81-4
9. Rugh jd, woods bj, dahlstrom l. Temporomandibular disorders : assessment of
psychological factors. Adv dent res 1993;7(2):127-36

37. 10. Abou-atme ys, chedid n, melis m et al. Clinical measurement of normal maximum mouth
opening in children. Cranio 2008;26(3):191-6
11. Nebbe b, major pw, prasad n. Female adolescent facial pattern associated with tmj disk
displacement and reductin in disk length: part 1. Am J orthod dentofacial orthop
1999;116(2):168-76.
12. Dibbets jm, carlson ds. Implications of tm disorders for facial growth and orthodontic
treatment. Semin orthod 1995;1(4):258-72.

38. TEMPOROMANDIBULAR JOINT
Part II
Dr Divya Gaur
I yr PG
Dept of Pedodontics and Preventive Dentistry

39. CONTENTS
• APPLIED ANATOMY
• TMJ MOVEMENTS
• TMJ DISORDERS
• REFERENCES

40. TMJ MOVEMENTS