• Articular surface/Glenoid Fossa: hyaline cartilage (Type II collagen)
  • Articular Disk:
    • Fibrocartilage (Type I)
    • Avascular, Aneural, Alymphatic
  • Synovial A and B cells
    • A cells – macrophage like cells (remove debris)
    • B cells – fibroblasts (make synovial fluid and hyaluronic acid
Temporomandibular Joint Cartilage
Temporomandibular Joint Cartilage Composition

Temporomandibular Dysfunction (TMD)

  • Temporomandibular disorder (TMD) can be divided into 3 groups
    • Myofascial disorders
    • Internal derangements
    • Degenerative joint diseases

TMJ Ligaments

  • The lateral ligament, also known as the temporomandibular ligament, is a fan-shaped structure that runs obliquely in a posterior and caudal direction from the lateral aspect of the articular eminence to the posterior aspect of the mandibular condyle and lateral margin of the articular disk. The lateral ligament is composed of two elements: an outer oblique portion and an inner horizontal portion. The lateral ligament limits inferior and posterior displacement of the mandibular condyle, and to a limited extent the posterior displacement of the articular disk.
  • The capsular ligament is a relatively thin structure originating from the rim of the glenoid fossa. This structure extends inferiorly to join the periosteum of the condylar process below the condylar head. The capsular ligament encloses the joint cavity, which is divided into a superior joint space and an inferior joint space by the articular disk. The stylomandibular ligament extends from the styloid process to the angle of the mandible. The sphenomandibular ligament, a remnant of the perichondrium of Meckel’s cartilage, runs from the spine of the sphenoid bone to the mandibular lingula. The stylomandibular and sphenomandibular ligaments provide resistance to extreme anterior, lateral, and caudal displacements of the mandible, offering indirect support of the TMJ.

TMJ Disc

  • In cross section the disc has a biconcave shape. This shape enhances load distribution between the surfaces of the condyle and temporal bone. The disc is composed of fibrous connective tissue. The disc has little or no innervation.
  • Impaired disc mobility is more closely related to alterations in the internal milieu of the joint and altered joint mechanics than is disc position. Disc displacement, though a marker of internal derangement, is probably not as important as altered disc mobility

Structures Medial to TMJ

  • The mean distance from the outer aspect of the zygomatic arch to the middle meningeal artery has been reported as 31 mm (range: 21-43 mm). This vessel is located slightly forward of the center (i.e., depth) of the glenoid fossa (mean: 2.4 mm). The mean distances from the outer aspect of the zygomatic arch to the carotid artery (37.5 mm;  range: 29-48 mm), internal jugular vein (38.3 mm; range, 31-49 mm), and the third division of the trigeminal nerve (35 mm; 24-46 mm) were greater than that of the middle meningeal artery, but are nevertheless at risk for injury during TMJ surgery.
  • The middle meningeal artery is immediately medial to the temporomandibular joint. Preservation of the medial joint capsule will minimize injury to this vascular structure. Options a,b,c, are incorrect because none of these vessels course immediately adjacent to the medial portion of the TMJ.
  • The middle meningeal artery is a branch of the internal maxillary artery, coursing medially from the internal maxillary artery ascending between the sphenomandibular ligament and the lateral pterygoid muscle, passing through the foramen spinosum. The average distance from the glenoid fossa to the middle meningeal artery is 2.4 mm. The close proximity of the middle meningeal artery to the TMJ places it at risk during complex procedures that require dissection medical to the mandibular condyle.