TMJ Temporomandibular Joint Anatomy PDF

Temporo-mandibular Articulation Dr. Sandeep Gupta Assistant Professor  Synonyms:  JAW JOINT  MANDIBULAR JOINT  CRANIOMANDIBULAR JOINT  GINGLYMODIARTHRODIAL JOINT Definition: It is a diarthrodial freely movable articulation between the condyle of the mandible and squamous part o...

Temporo-mandibular Articulation Dr. Sandeep Gupta Assistant Professor  Synonyms:  JAW JOINT  MANDIBULAR JOINT  CRANIOMANDIBULAR JOINT  GINGLYMODIARTHRODIAL JOINT Definition: It is a diarthrodial freely movable articulation between the condyle of the mandible and squamous part of the temporal bone.  Classification of joints:  The common and basic classification includes: 3 types  Fibrous joints: Two bones are connected by fibrous tissue.  Cartilagenous joints: Two bones are connected by Cartilagenous or bone tissue.  Synovial joints: Two bones are united and surrounded by a capsule that creates a joint cavity and permits significant movement.  TMJ It is a bilateral condylar variety of synovial joint. Anatomically, it is a diarthrodial joint, which is a discontinuous articulation of two bones. Provides a hinging or rotation movement in one plane, thus can be considered as ginglymoid joint, and provides a sliding movement, thus called as arthrodial joint. Therefore it can be called as GINGLIMOARTHRODIAL joint.  Anatomy of TMJ: Gross Anatomy: a. Number: present on each side, 2 in number b. Type: synovial joint c. Bones involved:- (i) Glenoid fossa of temporal bone (ii) Condyle of the mandible  Articulatory system: 2 articular surfaces upper lower Roof: 2 parts of Floor: superior Roof: inferior Floor: temporal bone surface of disc surface of disc Articulating surface of the mandibular condyle Articular surface of Condyle temporal bone (Mandibular (Cranial component) component) 1. Articular surface of temporal bone (Cranial component) It includes three components: 1. Glenoid fossa 2. Postglenoid tubercle 3. Articular eminence Gray”s Anatomy: The anatomical basis of medicine and surgery; 38th edition, 578-582  1. The articular eminence: is a small prominence in the zygomatic arch, it is strongly convex anteroposteriorly and concave mediolaterally, is usually thick and serves as a major functional component of the TMJ.  2. The articular tubercle or post glenoid tubercle: is a nonarticulating process on the lateral aspect of the zygomatic root of the temporal bone, which serves as a point of attachment of collateral ligaments.  3. The Glenoid fossa: it has an anterior articular area formed by the inferior aspect of temporal squama.  The surface is smooth and oval. 2. Mandibular component:  The articular part of the mandible is an ovoid condylar process (head) with narrow mandibular neck.  The condyle tends to be rounded mediolaterally and convex anteroposteriorly.  Broad laterally and narrow medially.  Mediolaterally – 13-25mm  Anteroposteriorly – 5.5- 16mm 5.5-16 mm  The articular part of condyle is covered by fibrocartilage. Fibrocartilage Articular disc:  Morphology of disc  It is derived from mesoderm of 1st pharyngeal arch.  It is biconcave sagitally thicker anteriorly & thinner posteriorly, oval, avascular & non-innervated in the middle. Anatomically it can be divided into 3 general regions as viewed from the lateral perspective: 1. anterior band (2mm) 2. central intermediate zone (1mm), and 3. posterior band(3 mm).  Upper joint space is larger (1.2ml)  Lower joint space is smaller (0.9 ml) Posterior disc attachment/ Bilaminar zone Posteriorly: This area is called as the posterior bilaminar zone which has a rich neurovascular supply.  Disc divides into: Inferior lamella: Superior lamella: Function of articular disc: Condyle and the temporal bone do not fit together in the absence of the disk.  Stabilization of the temporomandibular joint:  The articular disc may reduce wear. TMJ ligaments  TMJ Ligaments Functional ligament Accessory ligament (True Ligaments) 1. Sphenomandibular 1. Collateral 2. Stylomandibular 2. Capsular 3. Mandibulo-malleolar or Pinto’s 3. Lateral ligament Major anatomic contents of the They serve as passive restraints on joint mandibular motion. Articular disc and synovial membrane are also the Ligamentous structures 1. Collateral ligament:  Attaches the disk to the lateral and medial poles of each condyle.  2. TMJ Capsule/ Capsular Ligament  Funnel shaped, fibroelastic, highly vascular and innervated dense connective tissue.  Circumferentially, it is attached to the rim of the glenoid fossa and the articular eminence of the temporal bone above and the neck of the condyle below.  3. Lateral/TMJ ligament These are single structures that function in paired fashion Consist of 2 distinct portions: 1. Outer oblique portion 2. Inner horizontal portion  Accessory Ligament 1. Sphenomandibular ligament Remnants of Meckel’s cartilage 2. Stylomandibular ligament 1 Thick band of deep cervical facia which Limits excessive 2 protrusion of the mandible Thank You