SURGICAL ANATOMY OF THE TEMPOROMANDIBULAR JOINT.pptx

temporomandibular joint

1. SURGICAL ANATOMY OF THE TEMPOROMANDIBULAR JOINT

2. Joints A junction between two or more bones or cartilages A device to permit the movements More joints in a child than in an adult

3. Classification of Joints

4. The T emporomandibular Joint The area where the mandible articulates with the temporal bone of the cranium is called the temporomandibular joint ( TMJ) O ne of the most complex joints in the body P rovides for hinging movement in one plane and therefore can be considered a ginglymoid joint A t the same time, also provides for gliding movements, which classifies it as an arthrodial joint

5. F ormed by the mandibular condyle and the mandibular / glenoid fossa of the temporal bone, into which it fits. The articular disc separates these two bones from direct articulation The TMJ is also classified as a compound joint. Functionally , the articular disc serves as a nonossified bone , which permits the complex movements of the joint .

6. The Articular Disc C omposed of dense fibrous connective tissue for the most part devoid of any blood vessels or nerve fibres. The extreme periphery of the disc is slightly innervated. In the sagittal plane it can be divided into three regions, according to thickness

7. From an anterior view, the disc is usually a little thicker medially than laterally, which corresponds to the increased space between the condyle and the articular fossa toward the medial portion of the joint . The precise shape of the disc is determined by the morphology of the condyle and mandibular fossa During movement , the disc is somewhat flexible and can adapt to the functional demands of the articular surfaces

8. The articular disc is attached posteriorly to a region of loose connective tissue known as retrodiscal tissue or posterior attachment; that is highly vascularized and innervated Superiorly , it is bordered by superior retrodiscal lamina; which contains many elastic fibres The superior retrodiscal lamina attaches the articular disc posteriorly to the tympanic plate.

9. At the lower border of the retrodiscal tissues is the inferior retrodiscal lamina, which attaches the inferior border of the posterior edge of the disc to the posterior margin of the articular surface of the condyle The inferior retrodiscal lamina is composed chiefly of collagenous fibres The remaining body of the retrodiscal tissue is attached posteriorly to a large venous plexus, which fills with blood as the condyle moves forward.

10. The superior and inferior attachments of the anterior region of the disc are to the capsular ligament, which surrounds most of the joint The superior attachment is to the anterior margin of the articular surface of the temporal bone The inferior attachment is to the anterior margin of the articular surface of the condyle.

11. The articular disc is attached to the capsular ligament not only anteriorly and posteriorly but also medially and laterally This divides the joint into two distinct joint cavities The upper or superior cavity is bordered by the mandibular fossa and the superior surface of the disc The lower or inferior cavity is bordered by the mandibular condyle and the inferior surface of the disc.

12. The internal surfaces of the cavities are surrounded by specialized endothelial cells, which form a synovial lining . This lining, along with a specialized synovial fringe located at the anterior border of the retrodiscal tissues, produces synovial fluid, which fills both joint cavities . This synovial fluid serves two purposes. Acts as a medium for providing metabolic requirements to the articular surfaces Serves as a lubricant between articular surfaces during function

13. Synovial fluid lubricates the articular surfaces by way of two mechanisms

14. Histology of the Articular Surfaces The articular surfaces of the mandibular condyle and fossa are composed of four distinct layers or zones

15. Innervation of the Temporomandibular Joint Like all joints, the TMJ is innervated by the same nerve that provides motor and sensory innervation to the muscles that control it i.e. the trigeminal nerve Branches of the mandibular nerve provide the afferent innervation Most innervation is provided by the auriculotemporal nerve as it leaves the mandibular nerve behind the joint and ascends laterally and superiorly to wrap around the posterior region of the joint Additional innervation is provided by the deep temporal and masseteric nerves .

16. Vascularization of the Temporomandibular Joint The predominant vessels are, Superficial temporal artery - Posteriorly Middle meningeal artery - Anteriorly Internal maxillary artery - Inferiorly Other important arteries are the deep auricular, anterior tympanic, and ascending pharyngeal arteries

17. The Ligaments I n any joint system, ligaments play an important role in protecting the structures. They are made up of collagenous connective tissues fibres that have particular lengths. They do not stretch; however , if extensive forces are applied to a ligament, whether suddenly or over a prolonged period of time, the ligament can be elongated. When this occurs, it compromises the function of the ligament, thereby altering joint function .

18. The ligaments associated with the TMJ are, F unctional ligaments; that support the TMJ (1 ) the collateral ligaments (2 ) the capsular ligament (3 ) the temporomandibular ligament (TML). A ccessory ligaments (1) the sphenomandibular ligament (2) the stylomandibular ligament

19. The Collateral / Discal Ligaments They attach the medial and lateral borders of the articular disc to the poles of the condyle. C ommonly called the discal ligaments, and there are two . The medial discal ligament The lateral discal ligament

20. The medial discal ligament attaches the medial edge of the disc to the medial pole of the condyle . The lateral discal ligament attaches the lateral edge of the disc to the lateral pole of the condyle These ligaments are responsible for dividing the joint mediolaterally into the superior and inferior joint cavities. The discal ligaments are true ligaments, composed of collagenous connective tissue fibres; therefore they do not stretch .

21. They function to restrict movement of the disc away from the condyle. The attachments of the discal ligaments permit the disc to be rotated 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 .

22. The Capsular Ligament The entire TMJ is surrounded and encompassed by the capsular ligament 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; to the neck of the condyle.

23. The capsular ligament acts to resist any medial, lateral, or inferior forces that tend to separate or dislocate the articular surfaces . A significant function of the capsular ligament is to encompass the joint , thus retaining the synovial fluid. It is well innervated and provides proprioceptive feedback regarding position and movement of the joint.

24. The Temporomandibular Ligament The lateral aspect of the capsular ligament is reinforced by strong tight fibres, which make up the lateral ligament or the temporomandibular (TM ) ligament It is composed of two parts , an outer oblique portion and an inner horizontal portion

25. The outer oblique portion extends from the outer surface of the articular tubercle and zygomatic process postero -inferiorly to the outer surface of the condylar neck The inner horizontal portion extends from the outer surface of the articular tubercle and zygomatic process posteriorly and horizontally to the lateral pole of the condyle and posterior part of the articular disc.

26. The oblique portion of the TM ligament resists excessive dropping of the condyle, therefore limiting the extent of mouth opening . It also influences the normal opening movement of the mandible. During the initial phase of opening, the condyle can rotate around a fixed point until, as its point of insertion on the neck of the condyle is rotated posteriorly, the TM ligament becomes tight.

27. When the ligament is taut, the neck of the condyle cannot rotate further If the mouth were to be opened wider, the condyle would have to move downward and forward across the articular eminence This effect can be demonstrated clinically by closing the mouth while applying mild posterior force to the chin. If the mouth begins to open with this force applied, the jaw will easily rotate open until the anterior teeth are 20 to 25 mm apart.

28. At this point, resistance will be felt when the jaw is opened wider. If the jaw is opened still wider, a distinct change in the opening movement will occur, which represents the change from rotation of the condyle about a fixed point to movement forward and down the articular eminence. This change in opening movement is brought about by the tightening of the TM ligament.

29. This unique feature of the TM ligament, which limits rotational opening , is found only in humans. In the erect postural position and with a vertically placed vertebral column, continued rotational opening movement would cause the mandible to impinge on the vital submandibular and retromandibular structures of the neck. The outer oblique portion of the TM ligament functions to resist this impingement.

30. The inner horizontal portion of the TM ligament limits posterior movement of the condyle and disc. When force applied to the mandible displaces the condyle posteriorly, this portion of the ligament becomes tight and prevents the condyle from moving into the posterior region of the mandibular fossa. The TM ligament therefore protects the retrodiscal tissues from trauma created by the posterior displacement of the condyle.

31. The inner horizontal portion also protects the lateral pterygoid muscle from overlengthening or extension. The effectiveness of this ligament is demonstrated during cases of extreme trauma to the mandible. In such cases, the neck of the condyle will be seen to fracture before the retrodiscal tissues are severed or the condyle enters the middle cranial fossa.

32. The Sphenomandibular Ligament O ne of the two TMJ accessory ligaments 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 does not have any significant limiting effects on mandibular movement .

33. The Stylomandibular Ligament The second accessory ligament Arises 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 most relaxed when the mandible is opened.

34. The Surgical Anatomy The temporomandibular joint is situated in an area that is relatively easy to expose surgically , although the extent of exposure obtained is not much The structure that limits the extent of exposure is the branching facial nerve. Although the TMJ itself is relatively small, there are many important anatomic structures near it This region contains the parotid gland, superficial temporal vessels, and facial and auriculotemporal nerves.

35. Relations of the TMJ Superficial relations skin, superficial fascia and branches of the facial nerve, The auriculo -temporal nerve passes through the fascia. The superficial temporal artery The glenoid lobe of the parotid gland

36. Superior relations The roof of the mandibular fossa separates the tm joint from the middle cranial fossa and the temporal lobe of the brain. The tympanic cavity is medio-superior and slightly posterior to the joint. The chorda tympani nerve and anterior ligament to the malleus pass through the squamotympanic fissure medio-superiorly to the joint.

37. Inferior relations The parotid gland The lower head of the lateral pterygoid. Inferior to the condylar neck there are numerous venous channels.

38. Anterior relations The lateral pterygoid. The masseteric and deep temporal nerves pass between the lateral pterygoid muscle and the inferior surface of the temporal bone.

39. Posterior relations The auriculo -temporal nerve The parotid gland lies between the cartilaginous EA canal and joint. The styloid process.

40. Medial relations The medial capsule of the joint. anterior ligament to the malleus. The spine of the sphenoid, sphenomandibular ligament. The chorda tympani nerve The auriculo -temporal nerve, middle meningeal artery. The structures of the middle, inner ear, auditor tube. Petrus temporal bone - carotid canal containing the internal carotid artery.

41. Structures from zygomatic arch Mean mediolateral Mean anteroposterior Middle meningeal artery 31mm 2.4mm Carotid artery 37mm -6.5mm Internal jugular vein 38.3mm -8.7mm Mandibular nerve (from GF) 18.7mm 9.2mm Nojan et al [OOO 1999; 88: 674-8]. Distances of important structures medial to TMJ.

42. The Parotid Gland L ies below the zygomatic arch, below and in front of the external acoustic meatus , on the masseter muscle, and behind the ramus of the mandible The superficial pole of the parotid gland lies directly on the TMJ capsule. It is enclosed within a capsule derived from the superficial layer of the deep cervical fascia, called the parotideomasseteric fascia.

43. Superficial Temporal Vessels They emerge from the superior aspect of the parotid gland and accompany the auriculotemporal nerve The superficial temporal artery rises in the parotid gland by bifurcation of the external carotid artery As it crosses superficial to the zygomatic arch, a temporal branch is given off just over the arch .

44. The superficial temporal artery divides into the frontal and parietal branches a few centimeters above the arch. The superficial temporal vein lies superficial and usually posterior to the artery The auriculotemporal nerve accompanies , and is posterior to, the superficial temporal artery.

45. Auriculotemporal Nerve It innervates parts of the auricle, the external auditory meatus, the tympanic membrane, and the skin in the temporal area It courses from the medial side of the posterior neck of the condyle and turns superiorly, running over the zygomatic root of the temporal bone

46. Just anterior to the auricle, the nerve divides into its terminal branches in the skin of the temporal area Preauricular exposure of the TMJ area almost invariably injures this nerve The damage is minimized by incising and dissecting in close apposition to the cartilaginous portion of the external auditory meatus, realizing that this structure runs somewhat anteriorly as it courses from lateral to medial.

47. Facial Nerve Shortly after the facial nerve exits the skull through the stylomastoid foramen, it enters the parotid gland At this point, the nerve usually divides into two main trunks – the temporofacial and cervicofacial The division of the facial nerve is located between 1.5 and 2.8 cm below the lowest concavity of the bony external auditory canal.

48. The terminal branches of the facial nerve emerge from the parotid gland and radiate anteriorly They are commonly classified as temporal, zygomatic, buccal , marginal mandibular , and cervical As the temporal nerve branches (frequently two) cross the lateral surface of the zygomatic arch, they course along the undersurface of the temporoparietal fascia

49. The temporal branch crosses the zygomatic arch at varying locations in different individuals, and may be located anywhere from 8 to 35 mm (20 mm average) anterior to the external auditory canal Therefore , the temporal branches of the facial nerve can be protected by incising through the superficial layer of temporalis fascia and periosteum of the zygomatic arch not more than 0.8 cm in front of the anterior border of the external auditory canal.

50. Mandibular and cervical branch Important structure during submandibular and retromandibular incision. Mandibular branch Depressor anguli oris and muscle of lower lip. “ Dingman ” - 1.8cm behind and below gonion . Cervical branch Platysma muscle. “ Ziarah ” – 2cm posterior to ramus and 4cm from inferior border of mandible. Both run deep to cervical fascia and lie superficial to deep fascia. (Anatomy of cervical branch-BJOMS,1981,19,171-179).

51. Layers of the Temporoparietal Region The temporoparietal fascia is the most superficial fascial layer beneath the subcutaneous fat It is the lateral extension of the galea and is continuous with the superficial musculoaponeurotic system (SMAS) layer It is easy to miss this layer completely when incising the skin because it is just beneath the surface.

52. The blood vessels of the scalp, such as the superficial temporal vessels, run along the superficial aspect of the temporoparietal fascia, close to the subcutaneous fat On the other hand, the motor nerves, such as the temporal branch of the facial nerve, run on its deeper surface The subgaleal fascia in the temporoparietal region is well developed and can be dissected as a discrete fascial layer if required, but it is generally used only as a cleavage plane in the standard preauricular approach.

53. The temporalis fascia is the fascia of the temporalis muscle This thick fascia rises from the superior temporal line and fuses with the pericranium The temporalis muscle rises from the deep surface of the temporal fascia and the whole of the temporal fossa.

54. Inferiorly, at the level of the superior orbital rim, the temporal fascia splits into the superficial layer attaching to the lateral border, and the deep layer attaching to the medial border of the zygomatic arch. A small quantity of fat between the two layers is sometimes called the superficial temporal fat pad . A large vein frequently runs just deep to the superficial layer of temporalis fascia.

55. History of TM Joint Surgeries There is evidence of TMJ surgeries by humphrey in 1856 for condylotomy. 1883- reidel prformed meniscectomy. 1887- micro surgical procedure for disc repositioning by Annandale. 1920-bockenheimer used post auricular incison.

56. Complications lead to further modification by Axhausen . 1934 – Risdon preauricular incision 1936 – Blair modification (inverted L) 1968 – Dingman modification (obtuse angled incision) 1972 – Row & Killey combined endaural and preauricular.

57. 1979 – Breakthrough – Alkayat and Bramley incision with explanation of facial planes. 1986 – Ziarah – extensive study on marginal mandibular nerve and cervical branch of facial nerve. To reduce the surgical complications newer microsurgical procedures are introduced 1975 - Ohinishi – Arthroscopy

58. Approaches to the Temporomandibular Joint The temporomandibular joint and its components frequently require exposure for a myriad of procedures. Internal derangements of the TMJ, arthritis, trauma, developmental disorders , and neoplasia may all affect the TMJ and/or the skeletal and soft tissue components Several approaches to the TMJ have been proposed and used clinically. The standard and most basic approach, however, is the preauricular approach

59. Many approaches have been proposed. Can be named as follows Pre-auricular Submandibular Post auricular Endaural Retromandibular

60. Pre-auricular approach Started by Risdon in 1934, popularized by Blair (1936) – inverted L shape. Dingman used Blairs modification - obtuse angulated vertical incision. Vertical component – anterior to tragus. Superior leg – obliquely anterior to pinna. Row and Kelly – combination of preauricuar and endaural (1972).

61. 1979 - Alkayat and Bramley -modified preauricular incision, in the form of a Question mark shaped skin incision just within hairline. Vertical component as close as possible to tragus.

62. Indications When maximum exposure is required. When lateral and anterior exposure is desired. Advantage: There is minimal bleeding and less nerve damage. Fascial planes are easily identified. There is excellent visibility. The potential complications of muscle herniation and fibrosis are avoided.

63. Disadvantages: Scarring present. Threat of damage to facial nerve branches. Sensory loss over post-auricular skin. Frey syndrome. Damage to superficial temporal artery. Keith L et al, JOMS1984,58:637-646

64. Endaural approach Introduced by Shanbaugh – middle ear surgeries. Lemperts – used it for TMJ. Different from Dingman that it involved external auditory meatus to a greater depth. Davidson modification – superior preauricular component.

65. I-part Anterior endaural incision in superior meatal wall (depth-bony cartilagenous junction). Then outward incision for 3-5mm at conchal cartilage. II-part Extends from superior extent endaural incision directly upwards to a point about halfway between meatus and upper edge of the auricle.

66. III-part Continuous superiorly in the inter cartilagenous cleft and becomes the facial portion. After skin incision a similar dissection as in preauricular approach.

67. Advantages: Excellent lateral and posterior exposure. Scar exposure is less. Disadvantage: Limited anterior visibility. Demands greater skills. Tragal cartilage degeneration. Keith L et al, JOMS1984,58:637-646

68. Risdon’s approach (Submandibular) Incision about finger breadth below angle of mandible parallel to lower border. Lies between cervical branches of facial nerve, lower boundary of bony EAM at least 3cm inferior.

69. Dissection through skin fat, platysma and outer layer deep cervical fascia (facial nerve lies here). Identify the angle and body of the mandible. The masseter and periosteum are dissected out, parotid capsule turned upwards.

70. Indications Usually for subcondylar procedure Severe bony ankylosis Direct condylar fracture fixation Costochondral grafting Advantages: Less chances of facial nerve damage Disadvantages: Inadequate accessibility Increased reflection and traction of tissue

71. Developed by E.C. Hinds and W.J. Girotin (1967) Slight upward tilt of head The space between SCM and ascending ramus identified. Incision parallel and posterior to ascending ramus at distant 2cm, starting 2.5cm vertically below gonion and extending upwards along the anterior border of the SCM upto 3.5cm Retromandibular approach

72. Dissection is made through skin, fat, platysma and snipp off the investing fascia. Structures encountered Posterior part of the parotid gland with fascia, ascending ramus, deep part of angular tract, retromandibular vessels etc.

73. Indications For condylar neck fractures Condylotomy Vertical ramus osteotomies Advantages: Less chances of damage to facial nerve Disadvantages: Reduced accessibility Parasthesia of facial nerve Damage to retromandibular vessels

74. Post-auricular approach Introduced by Bockenheimer (1920) Modified by Axhausen. Surgical technique 3-4mm posterior to aurical, depth till mastoid fascia (1 st anatomical landmark ). Superior and posterior surface of the external auricular canal are freed. Exposure of cartilagenous layer – not necessary.

75. 2 nd landmark – temporalis fascia. Exposure of temporalis fascia, lateral aspect of articular eminence, root of zygomatic arch. 3 rd landmark - Zygomatic arch 4 th landmark – joint capsule

76. Advantages: Excellent accessibility especially posterior and lateral. Reduction in facial nerve damage. No excessive bleeding. Disadvantages: Limited anterior accessibility. Perforation of cartilaginous external auditory meatus. External auditory canal stenosis. Infections . Keith L et al, JOMS 1984,58:637-646

77. Incision following hair line about 4cm behind it. Depth – till subgleal loose tissue Inferior extent – continue as preauricular Blunt dissection to reflect the flap till 2cm above the infraorbital rim and superior temporal line. Pericranium is incise about 3-4cm superior to orbital rim, not to extend on superior temporal line. Incision of Alkayat and Bramley continued Bicoronal flap

78. Indication Bilateral exposure Extensive exposure required Advantages Good exposure Easy to get the facial phase Reduced risk of damage to facial nerve branches Hidden scar Disadvantages Bleeding in initial phase Extensive dissection required Not esthetic in completely bald patients

79. A variant of retromandibular approach. Incision – 1.5-2cm superior to level of Z arch in the posterior aspect of the ear. Inferiorly and blends with the preauricular incision anteriorly. Depth – skin and subcutaneous tissue Platysma is dissected with blunt scissor Expose retromandibular tissue and parotid Retract then to visualize pterygomesseter sling Incise it at the posterior border of the mandible near the angle and reflect the flap along the ramus Rhitydectomy approach

80. Indications Esthetic is a concerned and extensive exposure is required. Advantages Less conspicuous facial carve Good exposure Disadvantage Added time required

81. Management of Temporomandibular Disorders & Occlusion – Jeffrey Okeson III ed. Anatomical Atlas of the Temporomandibular joint – Ide & Nakazawa Oral Histology – A.R. Ten Cate , V ed. Temporomandibular Joint & Masticatory Muscle Disorder – Z arb , Carlsson , Sessle , Mohl , II ed. Developmental Aspects of TMJ Disorders, Craniofacial growth series, Monograph no. 16. A text book and colour atlas of temporomandibular joint – John Norman and Sir Paul Bramley References

82. Modified pre-auricular approach to the temporomandibular joint and malar arch – Adil Al-Kayat et al; BJOMS 17 (1979-80), 91-103. The surgical anatomy of the cervical distribution of the facial nerve – Haithem A. Ziarah et al; BJOMS (1981), 19, 171-179. The surgical anatomy of the mandibular distribution of the facial nerve – Haithem A. Ziarah et al; BJOMS (1981), 19, 159-170. Correlation of temporomandibular joint internal derangements via the posterior auricular approach – Paul J. Walters and Eric T. Geist; J Oral Maxillofac Surg, 41:616-618; 1983. Surgery of the temporomandibular joint I. Surgical anatomy and surgical incisions – Keith L. Kreutziger; Oral Surg 58: 637-646, 1984. Anatomy of the structures medial to the temporomandibular joint – Nojan Talebzadeh et al; Oral Surg, Oral Med Oral Pathol Oral Radiol Endod 1999; 88: 674-8.

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