basic anatomy of TMJ. i hope this will help everyone

1. BY – DR.DHAVAL TRIVEDI
TEMPORO-MANDIBULAR JOINT

2.  Ginglymoid joint
 Diarthrodial joint
 Formed by 2 bones
 Compound joint
 only synovial joints with an articular disc

3.  Condyles
 Articular surface of the temporal bone
 Capsule
 Articular disc
 Ligaments
 Lateral pterygoid

6. - The squamous portion of the temporal bone (
concave )
- Anterior : a convex bony prominence
( tubercle ) = articular eminence
- Posterior : squamotympanic fissure
anteromedial : petrosquamous fissure
posteromedial : petrotympanic fissure

7. The posterior roof is thin , not designed to
sustain heavy force in which condyle situated
- The articular eminence consists of thick dense
bone to tolerate such forces
- The steepness of the articular eminence
surface dictates the pathway of the condyle

8. - It is the posterior portion of the ramus
mandibula that extends upward
- Mediolateral : 15 – 20 mm
Anteroposterior : 8 – 10 mm
- Anterior view : medial and lateral poles,
the medial pole generally more prominent
- The actual articulating surface extends
anteriorly and posteriorly to the most superior
aspect ( P > A )
Lateral pole anterior to medial pole
Articular surface: anterior superior aspect

9.  Articular zone
 Proliferative zone
 Fibrocartilaginous zone
 Calcified cartilage zone
 Subarticular bone

10. The articular surface of the mandibular fossa and
condyle are lined with dense fibrous connective
tissue affords several advantages over hyaline
cartilage :
- less susceptible to the effects of aging
- less likely to break down over time
- a better ability to repair

12. The internal surface of the joint cavity are
surrounded by specialized endothelial cells that
form a synovial lining , produces synovial fluid
So TMJ - a synovial joint
The synovial fluid serves two purposes :
1. Acts as a medium for providing metabolic
requirement, since the articular surfaces of the
joint are nonvascular
2. As a lubricant during function
Two mechanisms of the lubrication :
1. Boundary lubrication
Prevents friction in the moving joint
2. Weeping lubrication
Eliminates friction in the compressed but not
moving joint

13.  The articular eminence,which is present
anterior to the glenoid fossa consists of a
descending slope, transverse ridge that is a
medial extension of the zygomatic tubercle,
and an ascending slope.
 The eminence is covered by
dense, compact, fibrous
tissue that consists primarily
of collagen with a few fine
elastic fibers.

14.  Origin: modified periosteum of intramembranous
bone, NOT endochondral origin. A consequence
of 2 embryonic tissue masses growing towards
each other, NOT a single tissue mass cleft to form
a joint articulation.
 Function:
 1) load distribution 2) synovial lubrication
 Character: NOT hyaline cartilage, but fibrous in
nature
 1) avascular 2) NOT innervated
3) resistant to shear, tension forces
4) increased remodeling potential

15.  These two bones are actually separated by
an articular disc, which divides the TMJ into
two distinct compartments. The inferior
compartment allows for rotation of the
condylar head around an instantaneous axis
of rotation, corresponding to the first 20 mm
or so of the opening of the mouth. After the
mouth is open to this extent, the mouth can
no longer open without the superior
compartment of the TMJ becoming active.

17.  Fibroelastic , highly vascular & innervated
 Attachments –
 Lateral aspect – zygomatic tubercle , lateral
rim of glenoid fossa , postglenoid tubercle
 Lateral capsule continues medially and
becomes less distinct anteriorly
 Medially – medial rim of glenoid fossa
 Close relation medially - spine of sphenoid ,
sphenomandibular ligament , middle
meningeal artery

18.  Posteriorly – petrotympanic fissure & fuses
with superior stratum of the posterior
bilaminar zone
 B/w posterior capsule and postglenoid
tubercle – vascular body present , part of
parotid gland
 Lateral capsule becomes thickened to form
TM ligament
 Inferior – periosteum of the neck of the
condyle

20. - Serves as a nonossified bone
- Composed of dense fibrous connective tissue
devoid of any blood vessels or nerve fibers
- Sagittal plane can be divided into 3 regions
according to thickness
- anterior border
- posterior border slightly thicker than
anterior border
- central area is the thinnest intermediate
zone in which condyle is located normally

21. - Anterior view - the disc is generally thicker
medially than laterally so increased space
between the condyle and the articular fossa
toward the medial of the joint
- The precise shape of the disc depend on
morphology of the condyle and mandibular
fossa
- During movement the disc is somewhat
flexible and can adapt to the functional
demands of the articular surface do not imply
that morphology of the disc is reversibly
altered during movement

25. - The articular disc is attached posteriorly to this region
- It is a loose connective tissue region that highly
vascularized and innervated
- Superior : superior retrodiscal lamina
( contains many elastic fibers ) bilaminary zone
It attaches the disc posteriorly to the tympanic plate
- Inferior : inferior retrodiscal lamina
( composed chiefly collagenous fibers )
It attaches the inferior border of the posterior edge of
the disc to the posterior margin of the articular surface
of the condyle
- The remaining body of the tissue is attached
posteriorly to a large venous plexus , it fills with blood
as the condyle moves forward

26.  Anterior region of the disc is attached to the
capsular ligament
- Superior : anterior margin of the articular
surface of the temporal bone
Inferior : anterior margin of the articular
surface of the condyle
- Composed of collagenous fibers
Anteriorly the disc is also attached by
tendinous fibers to the superior lateral
pterygoid muscle

28.  Disc is attached to capsular ligament
medially and laterally
 Divides the joint in 2 cavities
 Superior & inferior
 Endothelial cells that form a synovial lining
surrounds the internal surfaces of the cavities
– produces synovial fluid

29. 1) The collateral Ligaments,
(2) The capsular ligament, and
(3) The temporomandibular ligament.
(4) The sphenomandibular,
(5) Stylomandibular,
(6) Discomalleolar (Pinto's) ligament

30.  The collateral ligaments attach the medial and
lateral borders of the articular disc to the
poles of the condyle. They are commonly
called the discal ligaments
1. The medial discal ligament attaches the
medial edge of the disc to the medial
pole of the condyle.
2. The lateral discal ligament
attaches the lateral edge of
the disc to the lateral pole
of the condyle.

31.  The discal ligaments are true ligaments,
composed of collagenous connective tissue
fibers; therefore they do not stretch.
 They function to restrict movement of the
disc away from the condyle.
 In other words, they allow the disc to move
passively with the condyle as it glides
anteriorly and posteriorly on the articular
surface of the condyle.
 Thus these ligaments are responsible for the
hinging movement of the TMJ which occurs
between the condyle and the articular disc.

32.  The fibres of the capsular
ligament are attached
superiorly to the temporal
bone along the borders of the
articular surfaces of the mandibular
fossa and articular eminence.
 Inferiorly the fibres of the capsular ligament
attach to the neck of the condyle.
 The capsular ligament acts to resist any
medial, lateral or inferior forces that tend to
separate or dislocate the articular surfaces.

33.  The lateral aspect of the capsular ligament is
reinforced by strong tight fibres that make up the
lateral ligament or the TM ligament.
• An outer oblique portion Arising form outer
surface of the articular eminence and extending
backward and downward to insert into the outer
surface of the condylar neck.
• Inner horizontal portion with the same origin but
inserting into lateral pole of the condyle and
posterior part of the articular disc.
• The oblique portion of the TM ligament resists
excessive dropping of the condyle and therefore
acts to limit the extent of mouth opening

34.  Sphenomandibular ligament forms a broad
impenetrable wall medial to mandibular
foramen.
 It is one of the two TMJ accessory ligament.
 It arises from the spine of the sphenoid bone
and extends downward to a small bony
prominence on the medial surface of the
ramus of the mandible called the lingula.
 It doesn’t have any significant limiting effect
on the mandibular movement

35.  The stylomandibular ligament arrises from the
styloid process and extends downward and
forward to the angle and posterior border of
the ramus of the mandible.
 It becomes taut when the mandible is
protruded, but is more relaxed when the
mandible is opened.
 Therefore the stylomandibular ligament limits
excessive protrusive movements of the
mandible.

36. :
 The discomalleolar ligament ( Pinto's ligament)
was described by Pinto (1962) as a connection
between the malleus and the medial wall of
the joint capsule. However, a separate
ligament can be demonstrated here in only
29% of temporomandibular joints

37.  Damage to structures within the middle ear
during surgical manipulation of the
temporomandibular joint (TMJ) has been
reported.
 Two structures are proposed as possible
intermediaries in this trauma: the discomalleolar
ligament @ML), which passes from the malleus to
the medial retrodiscal tissue of the TMJ,and the
anterior malleolar ligament (AML), which
connects the malleus with the lingula of the
mandible via the sphenomandibular ligament
(SML).
 It has been hypothesized that when tension is
applied to the DML and/or AML, the resulting
movement of the malleus could cause damage to
the tympanic membrane and associated
structures.

38.  Trigeminal nerve
 Most innervation by auriculotemporal nerve
 Deep temporal
 Massetric

39.  Superficial temporal – posterior
 Middle meningeal – anterior
 Internal maxillary – inferior
 Deep auricular
 Anterior tympanic
 Ascending pharyngeal
 The condyle receives supply through its
marrow spaces by inferior alveolar artery and
feeder vessels

40.  Preauricular - Blair 1914 and
Al-Kayat,Bamley 1979
 Advantage Exposure of anterior portion of
zygomatic arch
 Complications - Facial nerve paralysis,
Paresthesia of auriculotemporal nerve,
Salivary fistula, sialocele , Scarring , Frontal
nerve injury

41.  Postauricular - Alexander 1975
 Adv- Avoid possible facial nerve injury,
salivary fistula and formation of a sialocele,
Minimal swelling ,Less discomfort
 Com - Stenosis of external auditory canal ,
Infection , Paresthesia (temporary or
permanent) of the external pinna , Deformity
of the auricle

42.  Endaural - Rogetti 1954
 Adv - Excellent access to the lateral and
posterior aspect of TMJ , Good exposure of
the anterior aspect of TMJ , Esthetics
 Com - Perichondrtis with esthetic
compromise , (loss of tragal projection)

43.  Perimeatal (preauricular + postauricular) -
Eggleston6 1978
 Adv - Access to glenoid fossa, No damage to
frontal branch of facial nerve ,Avoid stenosis
or infection of the cartilage
 Com - Poor access to the entire zygomatic
arch , Difficult to extend the incision

44.  Submandibular - Risdon 1934
 Adv - Better access and visualization
(in combination with preauricular)
 com - Possible injury to the marginal
mandibular and cervical branches of facial
nerve

45.  Bicoronal - Pogrel 1991
 Adv - Simultaneous access to both TMJs using
one incision Superior approach , Good access
, Enables harvesting of the temporalis m and
fascia , Minimal chance of facial injury
 Com - Greater area for reflection, Time-
consuming for pre-op preps , Compromised
esthetic as hair shaving required, Temporary
weakness of frontal nerve

46.  The superficial temporal artery, the transverse facial
artery, the auriculotemporal nerve, and the facial
nerve (cranial nerve VII) are intimately involved in
the surgical dissection to the TMJ.
 The superficial temporal artery, one of the terminal
branches of the external carotid, begins behind the
mandibular condylar neck deep to the parotid gland
as it emerges from behind the parotid gland.
 It crosses over the posterior root of the zygomatic
process of the temporal bone and enters the
temporal region of the scalp.

47.  The transverse facial artery arises from the base of the
superficial temporal artery and runs almost
transversely across the face, lying upon the outer
surface of the masseter muscle about 1.5 cm below the
zygomatic arch but above the parotid duct.
 The auriculotemporal nerve, a cutaneous sensory
branch of the mandibular division of the trigeminal
nerve , travels just posterior to the neck of the condyle
at the inferior level of the capsule attachment.
 It travels upward across the root of the zygomatic arch
just posterior to the superficial temporal artery, which it
accompanies into the scalp.

48.  The distance from the most anterior concavity of the bony
external auditory canal to the most posterior significant
temporal branch of the facial nerve was measured, with a
mean of 2.0 * 0.5 cm and a range of 0.8 to 3.5 cm.
 The mean distance from the bifurcation of the main trunk of
the facial nerve to the lowest concavity of the external
auditory canal was 2.3 *0.28 cm, with a range of 1.5 to 2.8
cm.
 The mean distance from the bifurcation of the facial nerve to
the postglenoid tubercle was 3.0 + 0.31 cm, with a range of
2.4 to 3.5 cm.
 Knowledge of the distances and the range of the facial
nerve branches from fixed bony landmarks within the
surgical field alerts the surgeon to the areas of highest risk.

50.  To locate the facial nerve, an incision is made just in front of
the tragus of the ear from the root of the zygoma to the angle
of the jaw. Here the incision is carried forward about one
finger breadth below the ramus of the mandible as far as is
necessary to obtain adequate exposure.
 The incision is carried down through skin and subcutaneous
tissue to the cartilage bounding the anterior extremity of the
external auditory canal. Then, with blunt dissection, the
cartilage of the external auditory canal is separated from the
capsule of the parotid gland as far & medially as is possible
or until a firm bony resistance is met.
 This is the base of the styloid process and is encountered at a
depth of about 1.5 inches (4 em.) from the skin incision. It is
important to remember to stay high just under the root of the
zygoma, so that the base of the styloid process is the first
important structure to be identified.

51.  With finger dissection and palpation, the styloid
process can next be identified immediately below
its base; a good headlight and a dry field greatly
facilitate this stage of the operation.
 With gentle traction on the capsule of the parotid
gland anteriorly, the facial nerve is brought into
view, emerging from the medial aspect of the
styloid process and coursing sharply upward and
laterally to enter immediately the capsule of the
parotid gland.
 The nerve usually is heavily invested in fascia
and a.ccompanied by the stylomastoid artery that
may prove troublesome if severed.