The medial capsule of the human temporomandibular joint

Arthroscopic osteoplasty of the medial and anteromedial wall of temporomandibular joint: surgical technique and anatomical considerations

The anterior displacement of the articular disc is the most frequent cause of pathological alterations in the TMJ. Although it is an extremely common pathology, there is no certainty about the aetiopathogenesis of this disease. The main aim of the present report is to describe new anatomical findings that could help clarifying the aetiopathogenesis of this disease and determine a typology of treatment based on the cause of the disease. All the operative records of patients who underwent arthroscopic osteoplasty of the medial TMJ wall in our centre from January 2021 to September 2021 were reviewed and analysed to identify specific anatomical features observed in every procedure. Fifty-two joints were included for analysis in this study. Twenty-two joints were classified as Wilkes stages II-III and 30 as Wilkes stages IV-V. The most common complication observed in our sample was the dysaesthesias found in the temporal and preauricular regions. Other complications observed were frontal branch paresis (n = 2), intraoperative bleeding (n = 1), and postoperative malocclusion (n = 1). The compression of the superior head of pterygoid lateral muscle (SPLM) on the medial bony wall and the consequent muscle atrophy could be key for the aetiology of the anterior TMJ disc displacement. Therapeutic actions on the osseous and muscular component in this anatomical area could improve the outcomes of patients affected by TMJ internal derangement. A meticulous dissection of the fascia of the superior fascicle of the lateral pterygoid muscle allows a remodelling of the bone surfaces with minimal complications.

Temporomandibular joint anatomy, function and clinical relevance

The articulatory system comprises the temporomandibular joints (TMJs), intra-articular discs, mandibular/jaw muscles and occlusion. In the simplest terms, the TMJ is the articulation between the upper and lower jaws. The teeth form the contacts between the upper and lower jaws and the muscles are the motors that move the mandible. This system is unique in that the TMJs are paired; any stimulus that affects one joint or any other single part of the articulatory system can have a 'knock-on effect' in the rest of the system.It is important to have a good understanding of anatomy, not only to be able to differentiate between what is physiological and what is pathological, but also to understand the objectives of some treatment options. Sound knowledge of anatomy is essential and an appreciation of the anatomical features associated with the TMJ can serve as a foundation for understanding the clinical management of temporomandibular disorders.This article reviews the functional anatomical features of the articulatory system with a look at the clinical significance of this anatomy.

[The temporo-mandibular articulation]

The standing posture of humans has created both morphological and functional adaptations in the temporo-mandibular joint and the masticatory function. This biped state is the one of the most important characteristic of human evolution. It is furthermore the agent determining most of the functional changes in the whole body. This survey will be carried out in several levels including, a descriptive anatomy, biomechanics, radiological imaging, functioning in the articulation of TMJ. The descriptive anatomic picture will be obtained by the traditional dissection techniques. 20 TMJ joints are dissected from 10 cadavers: 7 cadavers, 65-75 year old, 3 cadavers, 60-65 year old. The x-rays are lateral view and the subjects of the radiological imaging are young's, adults and olds: 1, 3 y-old Male; 1, 7 y-old Female; 1, 14 y-old Female; 10, 19-23 y-old Male; 1, 26 y-old Female; 1, 34 y-old Male; 1, 75 y-old Female. The anatomic elements in the TMJ well resembled the ones described in the literature of the capsule, the ligament, the masticator muscles (masseter, temporal, medial and lateral pterygoids). The temporo-mandibular ligament proved to be difficult to separate from the capsule in some of the specimens. Sometimes it was not always found after a dissection.

The anatomical relationship between the position of the auriculotemporal nerve and mandibular condyle

Head, neck, face, and ear pains are commonly associated with disorders of the temporomandibular joint (TMJ). Several theories have been proposed regarding the functional relationship of the TMJ and the associated structures, and how they might contribute to certain painful conditions. This study was conducted to determine the anatomic relationship of the auriculotemporal nerve to the middle meningeal artery and the mandibular condyle. Forty human cadaver temporomandibular joints were dissected to locate the precise position of the auriculotemporal nerve to the mandibular condyle. The study findings revealed a significant variation in the relationship of the auriculotemporal nerve to the middle meningeal artery. The auriculotemporal nerve was found to be between 10-13 mm inferior to the superior surface of the condyle and 1-2 mm posterior to the neck of the condyle. The nerve was not found to be in a position that would likely create an entrapment with adjacent tissues. These findings may assist the clinician to locate the most appropriate injection site for an auriculotemporal nerve block.

Temporomandibular joint in miniature pigs: anatomy, cell replication, and relation to loading

The mechanical environment is a regulator of growth and adaptation of the musculoskeletal system, including joints. Although pigs (Sus scrofa) are used frequently as models for temporomandibular joint (TMJ) dysfunction, no systematic description of microanatomy exists for this species. We injected the thymidine analog 5-bromo-2'-deoxyuridine (BrdU) into 10- to 11-month-old miniature pigs that were undergoing measurements of TMJ bone strain. Ten hr later, the animals were sacrificed and their heads were perfused. Histological sections were used to map the distribution of replicating cells. Additional observations were made on gross dissections of jaw joints obtained from an abattoir. The pig TMJ is better supported than that of humans laterally and medially, but more vulnerable posteriorly. The posterior attachment area of the intra-articular disc is fibro-fatty rather than vascular, as in humans. Cartilage lines the articular eminence as well as the condylar surface. At the posterosuperior region of the condyle, the cartilage ends abruptly and is replaced by an invaginating, actively replicating periosteum. Almost all of the BrdU-labeled cells resided in the prechondroblastic zones. The condyle had more replicating cells than did the eminence (P < 0.02), but lateral and medial locations did not differ in either element. In sagittal sections, the condyle had more replicating cells posteriorly (P < 0.001), but no A-P differences were seen in the eminence. Comparisons of these data with data on bone strain indicate that increased loading is negatively associated with cell replication.

Anatomy of the structures medial to the temporomandibular joint

OBJECTIVE

To define the relationship of the branches of the trigeminal nerve and the infratemporal vessels to the zygomatic arch and medial capsular ligament of the temporomandibular joint (TMJ).

MATERIAL AND METHOD

In a study of 20 cadaveric dissections of the infratemporal fossa, measurements were obtained in anterior-posterior and transverse directions to identify the relationship of the trigeminal nerve, carotid artery, internal jugular vein, and middle meningeal artery to the zygomatic arch. The distance from the lateral to the medial aspect of the glenoid fossa was measured to further delineate the proximity of these structures to the medial portion of the capsule of the TMJ.

RESULTS

The mean transverse distance from the zygomatic arch to the middle meningeal artery was 31 mm (range, 21 mm to 43 mm). The mean anterior-posterior distance from the height of the glenoid fossa to the middle meningeal artery was 2.4 mm (-2 mm to 8 mm). The transverse distance from the carotid artery to the zygomatic arch was a mean of 37.5 mm (29 mm to 48 mm) with the mean anterior-posterior distance of -6.5 mm (-21 mm to 6 mm). The mean distance from the internal jugular vein to the zygomatic arch was 38.3 mm (31 mm to 49 mm). The mean anterior-posterior distance was -8.7 mm (-20 mm to 7 mm). The transverse distance from the trigeminal nerve to the arch was a mean distance of 35 mm (24 mm to 46 mm). The mean anterior-posterior distance was 9.2 mm (1 mm to 25 mm). The mean medial to lateral width of the glenoid fossa was 18.7 mm (16 mm to 23 mm).

CONCLUSION

The arteries, nerves, and veins are close to the medial aspect of the TMJ. A knowledge of these relationships can guide the surgeon on the medial aspect of the TMJ and can help to prevent complications associated with these structures.