History taking and anamnesis
The first stage of diagnosis is a thorough patient interview. It is important to remember that the absence of spontaneous complaints does not guarantee joint health, so the physician must conduct a targeted dialogue.
Chief and additional complaints Patients most frequently report pain during jaw movement, limited mouth opening, and various acoustic phenomena (crepitus or clicking). However, the clinical presentation may be complemented by atypical symptoms:
- Tenderness of the masticatory muscles (myalgia) and pain radiation along the branches of the trigeminal nerve (n. trigeminus).
- General signs: hearing loss, tinnitus, dizziness, headaches, and general irritability.
- Difficulty in chewing food.
Medical and personal history It is necessary to clearly document the chronology of symptom development. Dental interventions often serve as the triggering mechanism: recent prosthetics, tooth extraction, or simply spending a long time in the dental chair with the mouth open. Special attention is paid to systemic pathology. If a patient complains of problems with other joints (knee, elbow, or small joints of the hands), this may be a manifestation of a rheumatological disease, requiring an immediate consultation with a specialist.
Visual inspection and biomechanics assessment
Objective examination begins with assessing facial symmetry, skin condition, and identifying possible edema in the parotid region. Next, the physician proceeds to analyze the movements of the mandible.
Measurement of range of motion
- Vertical plane: at maximum mouth opening, the distance between the incisal edges of the upper and lower incisors should fall within the range of 40–55 mm.
- Transversal plane (lateral shifts): the jaw should move symmetrically to the right and left, with the average excursion value being 7 mm.
Trajectory disturbances The physician evaluates the smoothness of the mandibular motion. If a deviation from the midline is observed during lowering (curvilinear movement), this condition is called deviation. Most often, it indicates chronic dislocation of the articular heads, problems with the articular disc, or other morphological alterations.
It is also taken into account that physiological mouth opening is divided into three phases: from the rotation of the condyles in the lower compartment of the joint to their forward sliding by 12–20 mm along with the articular disc.
Joint and muscle palpation
Palpation provides crucial tactile information about the synchrony of TMJ function, the configuration of its elements, and the presence of tender points.
TMJ palpation technique The examination is performed via two approaches:
- External — through the skin anterior to the tragus of the auricle.
- Internal — through the anterior wall of the external acoustic meatus.
Assessment must be performed both in a state of physiological rest (with clenched jaws) and dynamically — with the mouth open. Practice shows that painful zones and asymmetry of condylar movements are best palpated precisely at the moment of functional activity.
The masticatory muscles are examined synchronously. Superficial and deep palpation are used to detect muscle hypertonus, spasms, and tension asymmetry, since it is the coordinated work of the muscles (under CNS control) that ensures the correct distribution of masticatory load on the teeth and periodontium, protecting the joint itself from overloads.
Intraoral examination and supplementary methods
The oral cavity is examined to identify the root causes of joint pathology. The three main causes of TMJ dysfunction:
- Occlusal disorders.
- Morphofunctional alterations of the facial muscles.
- Trauma to the dentognathic system.
The physician records dental arch defects, assesses the bite and the condition of the mucosa. For a deep analysis of occlusal contacts, impressions are often taken and plaster dental casts are studied in an articulator.
Among additional functional methods, axigraphy is used — an instrumental technique for recording individual mandibular movement trajectories, allowing for the precise localization of biomechanical disorders.
Briefly: answers to topical questions
What three phases is physiological mouth opening divided into?
Physiological mouth opening is divided into three sequential phases.
- First phase (onset of opening) — movement occurs around the frontal axis in the lower compartment of the joint, and the articular disc remains in the mandibular fossa.
- Second phase (significant lowering of the mandible) — rotation continues in the lower compartment, while translational movements occur in the upper division. The articular disc, along with the head, slides forward and downward, moving onto the articular tubercle.
- Third phase (maximum mouth opening) — movement is carried out exclusively in the lower compartment of the joint around the frontal axis, with the articular disc positioned on the articular tubercle.
Which nerve branches innervate the temporomandibular joint?
The temporomandibular joint is innervated predominantly by sensory nerve fibers from several sources.
- Auriculotemporal nerve (n. auriculotemporalis) — serves as the main source, giving off 4–7 independent permanent branches that richly innervate the adipose tissue layer behind the articular disc and the capsule surface.
- Facial nerve (n. facialis) — acts as an additional source of innervation.
- Posterior deep temporal nerve — gives off additional branches to the joint.
- Third branch of the trigeminal nerve (n. mandibularis) — is also an additional source of innervation.
Which specific masticatory muscles must be palpated when examining a patient with TMJ dysfunction?
When examining a patient with TMJ pathology, it is necessary to palpate the following muscles involved in mastication:
- Masseter muscles (m. masseter) — assessed using superficial and deep palpation methods.
- Temporal muscles (m. temporalis) — examined at rest and during function.
- Medial pterygoid muscles (m. pterygoideus medialis) — the site of their attachment at the inner angle of the mandible is palpated.
What imaging diagnostic methods are used to study TMJ structures?
The following imaging diagnostic methods are used to study the structures of the temporomandibular joint:
- Traditional radiological methods — Pordes-Parma radiography, Schüller radiography, zonography, tomography, and orthopantomography.
- Computed tomography (CT) and magnetic resonance imaging (MRI).
- MRI is used to visualize soft tissue elements, including the articular disc; dynamic MRI can be used simultaneously with recording mandibular movements.
Class and exam questions
What parameters of mandibular movements are considered normal?
Normally, vertical mouth opening (between the incisors) is 40–55 mm, and lateral excursions are symmetrical and equal to approximately 7 mm in each direction.
What is the purpose of palpation through the external acoustic meatus?
It allows palpation of the posterior surface of the condylar head, assessment of its shape, range, and synchrony of movement, as well as the identification of local tenderness.
What is mandibular deviation?
This is a pathological deviation of the jaw from the midline when opening the mouth. It indicates joint dyssynchrony, disc displacement, or condylar dislocation.
Why do clinicians ask about other joints during a TMJ examination?
TMJ symptoms can be the initial manifestation of systemic rheumatological diseases, so it is important to rule out involvement of the knee, elbow, and small joints.
What else to study on this topic
- Biomechanics of movement: planes, axes, and masticatory load distribution
- Three phases of mouth opening and the role of the articular disc
- Innervation and venous drainage of the temporomandibular joint
- Neuromuscular control and proprioceptive regulation of the TMJ
- Acute and chronic dislocations: pathogenesis and clinical presentation
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Other topics in "Chapter 13. Temporomandibular Joint Disorders (V.V. Bekreev)"
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