**2. Anatomy of the temporomandibular joint**

The temporomandibular joint is the articulation between the mandible and the cranium. The mandibular head (condyle), glenoid (mandibular) fossa, and articular eminence form the TMJ. These joints serve as one anatomic control for both mandibular movement and the occlusion, surrounded by a capsule which consists of fibrous material, and a synovial lining. The capsule is quite thin anteromedially and medially ~ 0,7 mm and thick laterally and posteriorly ~ 1,8 mm. The inner layer of the capsule or synovial membrane is highly vascularized layer of endothelial origin cells, producing synovial fluid. The capsule stretches from the edge of the mandibular fossa to the neck of the mandible, proximal to the pterygoid fovea, and envelops the articular eminence. TMJ is reinforced by the temporomandibular and sphenomandibular ligaments. The articular surface of the

Temporomandibular Joint Arthroscopy 5

Fig. 1. A sagittal section through the left temporomandibular joint .

Fig. 2. Branches of trigeminal nerve. Innervation and blood supply of temporomandibular

joint (by R.Schmelzle, 1989).

mandible is the upper and anterior surface of the condyle, lined by dense, avascular fibrous connective tissue. A layer of hyaline cartilage covers the articulating cortical bone. The adult human condyle is about 15 to 20 mm from side to side and 8 to 10 mm from front to back. The articular surface is convex when viewed from the side and less when viewed from the front. Glenoid fossa is the concavity within the temporal bone. The anterior wall is formed by the articular eminence of the temporal bone and its posterior wall by the tympanic plate, which also forms the anterior wall of the external auditory meatus. An articular disc is interposed between the temporal bone and the mandible, dividing the articular space into upper and lower compartments. The interposed fibrocartilaginous disc has a bow-tieshaped biconcave morphology. The anterior and posterior ridges of the disc are termed anterior and posterior bands and are longer in the mediolateral than in the anteroposterior dimension. The smaller anterior band attaches to the articular eminence, condylar head, and joint capsule. The posterior band blends with highly vascularized, loose connective tissue, the bilaminar zone, and the capsule, the bilaminar zone residing in the retrodiscal space in the mandibular fossa and attaching to the condyle and temporal bone. Medially and laterally, the disc is firmly attached to the capsule and the condylar neck. Anteromedially, it is attached to the superior part of the pterygoid muscle. In a physiologic joint, the disc is positioned between the mandibular head inferiorly and the articular eminence anteriorly and superiorly when the jaw is closed. The posterior band of the disc lies within 10° of the 12 o'clock position. The medial and lateral corners of the disc align with the condylar borders and do not bulge laterally or medially. When the jaw is opened, the disc slides into a position between the mandibular head and articular eminence. The loose tissue of the bilaminar zone allows the remarkable range of motion of the disc. The attachments of the disc prevent luxation during opening. A triangular lateral ligament acts as a strong lateral stabilizer and inhibits the posterior translation of the mandibular head (Fig. 1).

The muscles of mastication are responsible for the complex movement of the jaw. The temporal, medial pterygoid, and masseter muscles facilitate jaw closure. Mouth opening is effected by coordinated action of the lateral digastric, mylohyoid, and suprahyoid muscles. The lateral pterygoid muscle and part of the fibers of the masseter and medial pterygoid muscles effect the anterior translation of the mandible. The superior belly of the lateral pterygoid muscle originates from the greater sphenoid wing and inserts on the disc. Subsequently, the superior belly plays a key role in upholding the physiologic position of the disc as it pulls the disc forward when the jaw is opened, in a combined translation and rotation. The inferior head of the lateral pterygoid muscle stretches from the lateral lamina of the pterygoid process to the pterygoid fovea. The medial pterygoid muslcle originates from the pterygoid fossa and inserts near the medial aspect of the mandibular angle (Sommer et al., 2003). The blood supply to the TMJ, outer and inner ear is provided mainly by branches from the internal maxillary artery as follows: temporal superficial artery, superior auricular artery, anterior tympanic artery and pterygoid artery. Innervation is provided by the auriculotemporal nerve (sensory branch of the mandibular nerve), deep temporal nerve, masseteric nerve. Sensory cervical sympathetic ramifications are going to the disc and capsule. The auriculotemporal nerve runs medial to the joint, then runs laterally, crossing the condylar neck, where it divides into branches to innervate the capsule, disc attachments, the tympanic membrane, the anterior surface of the cochlea, the upper part of the auricle, the tragus of the ear, the skin lining the external auditory meatus, the temporal region,. Nerve receptors as Ruffin receptors, Golgi tendon organs, Vater-Pacini corpuscules free nerve endings are in the capsule and substance P nerve fibres are also available in both the auriculotemporal and masseteric nerves, and have been demonstrated in the capsule, disc attachments but they are not present in the disc (Fig. 2).

mandible is the upper and anterior surface of the condyle, lined by dense, avascular fibrous connective tissue. A layer of hyaline cartilage covers the articulating cortical bone. The adult human condyle is about 15 to 20 mm from side to side and 8 to 10 mm from front to back. The articular surface is convex when viewed from the side and less when viewed from the front. Glenoid fossa is the concavity within the temporal bone. The anterior wall is formed by the articular eminence of the temporal bone and its posterior wall by the tympanic plate, which also forms the anterior wall of the external auditory meatus. An articular disc is interposed between the temporal bone and the mandible, dividing the articular space into upper and lower compartments. The interposed fibrocartilaginous disc has a bow-tieshaped biconcave morphology. The anterior and posterior ridges of the disc are termed anterior and posterior bands and are longer in the mediolateral than in the anteroposterior dimension. The smaller anterior band attaches to the articular eminence, condylar head, and joint capsule. The posterior band blends with highly vascularized, loose connective tissue, the bilaminar zone, and the capsule, the bilaminar zone residing in the retrodiscal space in the mandibular fossa and attaching to the condyle and temporal bone. Medially and laterally, the disc is firmly attached to the capsule and the condylar neck. Anteromedially, it is attached to the superior part of the pterygoid muscle. In a physiologic joint, the disc is positioned between the mandibular head inferiorly and the articular eminence anteriorly and superiorly when the jaw is closed. The posterior band of the disc lies within 10° of the 12 o'clock position. The medial and lateral corners of the disc align with the condylar borders and do not bulge laterally or medially. When the jaw is opened, the disc slides into a position between the mandibular head and articular eminence. The loose tissue of the bilaminar zone allows the remarkable range of motion of the disc. The attachments of the disc prevent luxation during opening. A triangular lateral ligament acts as a strong lateral

stabilizer and inhibits the posterior translation of the mandibular head (Fig. 1).

in the capsule, disc attachments but they are not present in the disc (Fig. 2).

The muscles of mastication are responsible for the complex movement of the jaw. The temporal, medial pterygoid, and masseter muscles facilitate jaw closure. Mouth opening is effected by coordinated action of the lateral digastric, mylohyoid, and suprahyoid muscles. The lateral pterygoid muscle and part of the fibers of the masseter and medial pterygoid muscles effect the anterior translation of the mandible. The superior belly of the lateral pterygoid muscle originates from the greater sphenoid wing and inserts on the disc. Subsequently, the superior belly plays a key role in upholding the physiologic position of the disc as it pulls the disc forward when the jaw is opened, in a combined translation and rotation. The inferior head of the lateral pterygoid muscle stretches from the lateral lamina of the pterygoid process to the pterygoid fovea. The medial pterygoid muslcle originates from the pterygoid fossa and inserts near the medial aspect of the mandibular angle (Sommer et al., 2003). The blood supply to the TMJ, outer and inner ear is provided mainly by branches from the internal maxillary artery as follows: temporal superficial artery, superior auricular artery, anterior tympanic artery and pterygoid artery. Innervation is provided by the auriculotemporal nerve (sensory branch of the mandibular nerve), deep temporal nerve, masseteric nerve. Sensory cervical sympathetic ramifications are going to the disc and capsule. The auriculotemporal nerve runs medial to the joint, then runs laterally, crossing the condylar neck, where it divides into branches to innervate the capsule, disc attachments, the tympanic membrane, the anterior surface of the cochlea, the upper part of the auricle, the tragus of the ear, the skin lining the external auditory meatus, the temporal region,. Nerve receptors as Ruffin receptors, Golgi tendon organs, Vater-Pacini corpuscules free nerve endings are in the capsule and substance P nerve fibres are also available in both the auriculotemporal and masseteric nerves, and have been demonstrated

Fig. 1. A sagittal section through the left temporomandibular joint .

Fig. 2. Branches of trigeminal nerve. Innervation and blood supply of temporomandibular joint (by R.Schmelzle, 1989).

Temporomandibular Joint Arthroscopy 7

vasodilatation, extravasation, releasing of mediators, activation of nociceptors, release of neuropeptides as substance P (SP), neuropeptide Y (NPY), which stimulate releasing of

The most frequent complaint is pain and a decrease in the maximal interincisal opening

The following symptoms as pain (at rest, during maximum mouth opening and upon chewing), tenderness to digital palpation of the joint, sounds (clicking, crepitation), restricted mandibular mobility e.g*.* difficulty in opening the mouth, intermittent lock, closed lock, stiffness in the morning are observed. The stages of disease are usually classified according to Wilkes (1989; Table 1) by reviewing the case histories, clinical data, radiological records (computerized tomography images, magnetic resonance images, ortopantomography and/or

a. Clinical: No significant mechanical symptoms other than opening reciprocal clicking;

b. Radiologic: Slight forward displacement , good anatomic contour of the disc,

c. Pathoanatomy: Excellent anatomic form; slight anterior displacement, passive in-

a. Clinical: One or more episodes of pain: beginning major mechanical problems consisting of mid-to-late opening loud clicking; transient catching and locking b. Radiologic: Slight forward displacement; beginning disc deformity, slight thickening

c. Pathoanatomy: Anterior disc displacement; early disc deformity; good central

a. Clinical: Multiple episodes of pain; major mechanical symptoms consisting of locking

b. Radiologic: Anterior disc displacement with significant deformity or prolapse of disc (increased thickening of posterior edge), negative tomograms, no bone structure

c. Pathoanatomy: Marked anatomic disc deformity with anterior displacement; no hard

b. Radiologic: Increase in severity over intermediate stage; positive tomograms showing early-to-moderate degenerative changes - flattening of eminence,

c. Pathoanatomy: Increase in severity over intermediate stage; hard tissue degenerative remodelling of both bearing surfaces (osteophyts), multiple adhesions in anterior and

( intermittent or fully closed): restriction of motion, function difficulties

of posterior edge; negative tomograms, no bone structure changes

a. Clinical: Slight increase in severity over intermediate stage

posterior recesses; no perforation of disk or attachments

deformation of condylar head, erosions, sclerosis

histamin and serotonin from afferent nerve endings and hyperalgesia in TMJ occurs.

**5. Diagnostics of the temporomandibular disorders** 

(MIO), which normal values are between 35 - 50 mm (Fig. 3).

negative tomograms, no bone structure changes

**5.1 Clinical data** 

I. Early stage

plain radiographs by Schüller, Parma).

no pain or limitation of motion

coordination demonstrable

II. Early intermediate stage

articulating area III. Intermediate stage

changes

tissue changes IV. Late intermediate stage
