Condylar process of the mandible

Anatomical structure and location

Superiorly, the mandibular ramus terminates in two processes separated by the mandibular notch (Incisura mandibulae):

• condylar process (Processus condylaris);
• coronoid process (Processus coronoideus), anterior and pointed.

The condylar process includes:

• head of the mandible (Caput mandibulae);
• neck of the mandible (Collum mandibulae).

On the medial surface of the neck lies the pterygoid fossa (Fovea pterygoidea).

Participation in TMJ formation

The condylar process of the mandible participates in the formation of the temporomandibular joint (articulatio temporomandibularis). TMJ articular surfaces:

• condylar process of the mandible;
• mandibular fossa and articular tubercle of the temporal bone.

• Joint type: complex, combined: the right and left sides act synchronously.
• Articular disc (discus articularis): divides the joint cavity into two compartments. Rotational movements occur in the lower compartment, while translational movements, i.e., gliding, occur in the upper compartment.
• Ligamentous apparatus: the capsule is strong, attached along the margins of the articular surfaces. TMJ ligaments: lateral ligament (lig. laterale) — the primary one, stylomandibular ligament (lig. stylomandibulare), and sphenomandibular ligament (lig. sphenomandibulare).

Biomechanics of movements

The following movements of the mandible are possible in the TMJ:

• depression and elevation;
• protrusion and retraction;
• lateral movements.

Lateral condylar path — the trajectory of movement of the condylar head in the TMJ during lateral displacement of the mandible. On the balancing, i.e., non-working side, the condylar head shifts downward, forward, and inward.

Bennett angle — the angle formed during lateral movement of the mandible on the balancing side. It is projected in the horizontal plane and formed by the sagittal plane and the actual movement trajectory of the balancing condylar head, which shifts medially.

Clinical significance and traumatology

• Palpation of the mandible: performed in a strictly sequential manner: from the condylar process down along the ramus and forward along the body of the mandible.
• Diagnosis of condylar process fracture: detection of a "bony step" upon palpation indicates a fracture and medial displacement of the end of the process.
• Palpation of the TMJ: examines the head of the condylar process and its articulation with the articular fossa.
• Radiological diagnostics: in fractures of the condylar process, anteroposterior radiographs demonstrate lateral displacement of the fragment.
• Differential diagnosis: acute TMJ arthritis must be differentiated from a fracture of the mandibular condylar process.

Joint pathologies and displacements

Alterations in the position of the condylar process and articular disc have been described in TMJ disorders:

• Chronic dislocation of the mandibular head: with the mouth open, the condylar process, i.e., the head of the mandible, shifts excessively anteriorly, moving beyond the articular tubercle of the temporal bone.
• Chronic dislocation of the mandibular head with subluxation of the articular disc: free movement of the mandibular head past the apex of the articular tubercle is observed; the process is accompanied by a characteristic "early" click within the articular fossa.
• Chronic TMJ dislocation: a click occurs at the moment the head exits the articular fossa as it moves toward the anterior slope of the articular tubercle; this click repeats upon mouth closure.
• Articular disc subluxation: anterior displacement of the articular disc occurs with reduction within the mandibular fossa. A click appears upon both mouth opening and closure; at maximum mouth opening, the mandibular head does not leave the mandibular fossa.
• Recurrent articular disc dislocation: the displaced disc acts as a mechanical obstruction blocking the movement of the mandibular head; episodes of mandibular movement blockage last from several minutes to several hours.
• Chronic articular disc dislocation: the disc assumes a permanent anteromedial position; objectively, limitation of mouth opening is noted — the distance between the incisal edges of the upper and lower incisors is less than 2.5 cm, and the mandible deviates toward the affected joint.
• Chronic articular disc dislocation and secondary osteoarthrosis: deformation of the articular disc, defects of the cartilage coating, deformation of bony structures, and osteophyte formation are described.
• Chronic posterior articular disc dislocation: at the initiation of movement, the disc becomes trapped between the condylar process and the posterior surface of the articular fossa.

Class and exam questions

What else to study on this topic

• Mandibular ramus (Ramus mandibulae)
• Temporomandibular joint (TMJ)
• Coronoid process of mandible
• Biomechanics of the masticatory apparatus

Other topics in the "Anatomical Structures" section

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