Where is the mandibular fossa located?
This anatomical landmark is situated in the squamous part of the temporal bone (squama temporalis). Anteriorly, the fossa is located at the root of the zygomatic process (processus zygomaticus), with the articular tubercle (tuberculum articulare) positioned just anterior to it. Posteriorly, it borders the external acoustic meatus.
Structure and Topography
The structure forms an oval depression. It is crossed approximately in the middle by the petrotympanic fissure, which divides the fossa into two distinct regions:
- Anterior part (intracapsular) — located within the cavity of the temporomandibular joint.
- Posterior part (extracapsular) — located outside the joint capsule.
While the bony articular surface of the fossa is lined by a thin layer of connective tissue (fibrocartilage), this coverage extends only to the anterior portion located anterior to the petrotympanic fissure.
Role in the Temporomandibular Joint
The mandibular fossa, together with the head of the mandible (caput mandibulae) and the articular tubercle, forms the temporomandibular joint (articulatio temporomandibularis). Because the size and shape of the mandibular head and fossa do not completely match, a natural incongruency exists. This is resolved by the articular disc (discus articularis), whose superior surface conforms to the shape of the mandibular fossa.
Additionally, the superior retrodiscal laminae, containing elastic fibers, extend from the disc to the mandibular fossa, helping to retract the disc during mouth closure.
Clinical Significance
Understanding the anatomy of the fossa and adjacent structures is essential for diagnosing TMJ disorders:
- In anterior disc displacement with reduction, the disc is displaced anteriorly at rest; during mouth opening, it reduces back onto the mandibular head, often producing an audible click. When the mouth is fully open, the condyle and disc are properly aligned beneath the articular tubercle.
- In chronic dislocation, the mandibular head is excessively displaced anteriorly, moving completely past the articular tubercle of the temporal bone.
- The compartmentalization of the joint space by the articular disc provides high functional compensation capacity.