Anatomic study of the distance between the articular eminence and foramen spinosum and foramen spinosum and petrotympanic fissure

PURPOSE

The middle meningeal artery is in close proximity to the medial aspect of the temporomandibular joint (TMJ). A major potential complication of surgery in the area of the TMJ is possible severance of the middle meningeal artery. An understanding of the relationship of the middle meningeal artery to easily identifiable landmarks lateral to the TMJ can help prevent the complications associated with TMJ surgery. The aim of the present study was to define the location of the middle meningeal artery by relating the distance between the easily identifiable bony landmarks of the articular eminence, petrotympanic fissure, and foramen spinosum.

MATERIALS AND METHODS

Using a cross-sectional study design, we selected dried skulls from the Hamman-Todd skeleton collection at the Cleveland Museum of Natural History that were older than 20 years of age at death. The primary study variables were the distances between the articular eminence and foramen spinosum and the foramen spinosum and petrotympanic fissure. To appropriately analyze the variables, stratifications of age, gender, race, and anatomic location were applied. To measure the relationship between the stratifications and distances, a multivariate analysis of variance test was performed. The statistical results were deemed significant at P < .05.

RESULTS

The sample consisted of 354 skulls or a total of 708 complexes. In analyzing the data, we noted that the only stratifications that bore any statistical significance were gender, with P < .0001, and the race-distance correlation, with a P value of .0007.

CONCLUSIONS

The results of the present study suggest a definite difference in regard to gender on the distance between both sets of anatomic landmarks. Future studies could be tailored to further explore the effect of age on the distance, as a slight correlation was noted in our study.

Anatomy of the equine temporomandibular joint: study by gross dissection, vascular injection and section

REASONS FOR PERFORMING STUDY

The minute anatomy of the temporomandibular joint (TMJ) in horses is poorly documented in the literature.

OBJECTIVES

To examine in detail the anatomy of the normal equine TMJ and the relationship of the joint to adjacent structures.

METHODS

The anatomy of the TMJ was examined in 12 equidae using dissections, synovial and vascular injections and frozen and plastinated sections. Relevant structures were photographed.

RESULTS

Rostral and caudal compartments were identified in the dorsal and ventral synovial pouches of the TMJ. Lateral and caudal ligaments were identified and attachments of the masticatory muscles over the TMJ were documented. Direct relationships between the TMJ and components of the ear were found, and the vascular supply described.

CONCLUSIONS

This joint is related to some components of the ear as in man, and has its own peripheral vascular supply.

POTENTIAL RELEVANCE

A knowledge of the detailed anatomy of the equine TMJ is a prerequisite to interpreting the imaging techniques, and will enable improved diagnosis of TMJ pathologies.

Anatomy of the temporomandibular joint

The temporomandibular joint (TMJ), also known as the mandibular joint, is an ellipsoid variety of the right and left synovial joints forming a bicondylar articulation. The common features of the synovial joints exhibited by this joint include a fibrous capsule, a disk, synovial membrane, fluid, and tough adjacent ligaments. Not only is the mandible a single bone but the cranium is also mechanically a single stable component; therefore, the correct terminology for the joint is the craniomandibular articulation. The term temporomandibular joint is misleading and seems to only refer to one side when referring to joint function. Magnetic resonance imaging has been shown to accurately delineate the structures of the TMJ and is the best technique to correlate and compare the TMJ components such as bone, disk, fluid, capsule, and ligaments with autopsy specimens.

The Posterior Segment of the Temporomandibular Joint Capsule and Its Anatomic Relationship

PURPOSE

The aim of this work was to clarify the arrangement of the posterior segment of the temporomandibular joint capsule and its pertinent relationships.

MATERIALS AND METHODS

The temporomandibular region was dissected bilaterally in 20 adult cadavers. Natural stained latex was injected into 16 cadavers through the external carotid artery to facilitate the dissection of the arterial vessels.

RESULTS

The posterior segment of the joint capsule is made up of the so-called "bilaminar zone" of the articular disc. The upper internal portion of the posterior segment of the capsule was reinforced by the discomalleolar ligament. The retroarticular space was filled with loose connective tissue and the anterior branches of the anterior tympanic artery were distributed throughout the posterior segment of the joint capsule.

CONCLUSION

The posterior segment of the temporomandibular joint capsule corresponds to the bilaminar zone of the articular disc. The structures of the retroarticular space are extracapsular.

[Intracranial venous outflows associated with myofascial syndrome according to the data of computer tomography and magnetic resonance imaging]

To have a pictorial view of the extent of large paired sinuses of the posterior cranial fossa, jugular foramens, temporomandibular joints, magnetic resonance imaging and computed tomography were used to examine 1600 patients. The findings specified that the cross sizes of sinuses and jugular veins rather widely varied, their relative increase being observed with age. Furthermore, in most cases the paired sinuses of the posterior cranial fossa, internal jugular veins and jugular foramens are asymmetrically developed, the asymmetry being clearly defined only in infants aged more than 1 year. Thereafter, a group of patients with the asymmetrical structure ofjugular foramens was observed to have the signs characterizing the atypical structure or position of the heads of the mandible.

Vascular malformation of the temporomandibular joint: report of a case and review of the literature

The diagnosis and treatment of vascular anomalies is extremely challenging because of inconsistent terminology and classification systems, as well as nonspecific clinical and radiological findings. We report a vascular malformation that was treated successfully via resection, and reconstructed using a custom-made temporomandibular joint fossa and condylar prosthesis by TMJ Concepts. The available pertinent literature is also reviewed.

Normal and abnormal temporomandibular joint disc and posterior attachment as depicted by magnetic resonance imaging in symptomatic and asymptomatic subjects

PURPOSE

This investigation provides a detailed assessment of the morphologic and signal intensity changes of the temporomandibular joint disc and posterior disc attachment as depicted by magnetic resonance imaging in symptomatic versus asymptomatic subjects.

PATIENTS AND METHODS

Sixty-one asymptomatic volunteers and 58 symptomatic subjects were imaged using a 1.5 tesla magnetic resonance system utilizing bilateral high-resolution surface coils with the jaw in the closed and maximal opened position. Disc shape and signal intensity characteristics were tabulated along with a detailed assessment of the various regions of the disc posterior attachment in a blinded fashion as to symptomatology.

RESULTS

Deformity of the disc was noted in 34 of 116 (29.3%) of joints in patients and in 5 of 122 (4%) of joints of volunteers ( P < .0005; chi-square test). There was a large region of increased signal intensity in the posterior band of the disc on proton- or T1- weighted images in 13 of 116 (11.2%) joints in patients versus 1 of 122 (0.8%) joints in asymptomatic subjects ( P < .0005). In all joints with disc displacement with or without reduction, the temporal posterior attachment was visualized in only 43.5% in the closed jaw position ( P < .0005 versus all normal joints) and in 30.4% ( P < .0005 versus all normal joints) in the open jaw position.

CONCLUSION

Magnetic resonance allows an in vivo characterization of the fine structural details of the disc and the disc posterior attachment, separating normal from internal derangement temporomandibular joints.

The influence of the sagittal split osteotomy on the condylar cartilage structure and the subchondral vascularization of the temporomandibular joint: A preliminary study in goats

OBJECTIVE

The concern that a sagittal split osteotomy of the mandibular ramus could compromise the subchondral vascularization and especially the venous outflow in the condylar area, which in turn could influence the structure of the condylar cartilage, prompted this preliminary study on goats.

STUDY DESIGN

A sagittal split osteotomy was performed in the mandibular ramus at 1 side in each of 6 young adult goats. The contralateral side served as control. The animals were killed after different postoperative periods, ranging from 1 to 15 days. Histomorphometric analyses were performed after perfusion of the vascular system with India ink.

CONCLUSION

Based on the observed cartilage thickening, the sagittal split osteotomy may influence the condylar cartilage in the first days postoperatively through a disturbance of the vascular supply.

The immunohistochemical distribution of vimentin in human temporomandibular joint samples

The aim of this investigation was to evaluate the immunohistochemical distribution of vimentin in the temporomandibular joint (TMJ) and to compare it with the control specimens. Immunohistochemical distribution in the disc and synovial membrane in 30 human TMJ (internal derangement of TMJ, n = 20; and control, n = 10) was studied immunohistologically using paraffin-embedded tissue and specific anti-human vimentin monoclonal antibody. Vimentin expression was distributed in chondrocyte-like cells, synovial cells and endothelial cells. There was an obvious distinction of vimentin immunoreactivity between the control specimens and internal derangement cases, in the posterior and/or anterior loose connective tissues. In particular, intensive vimentin expression was detected in the hypertrophic synovial membrane of internal derangement cases. The findings of the present study suggest that vimentin might be an important marker of pathological hypertrophy of the synovial membrane and/or connective tissue with internal derangement of TMJ.

[An immunohistochemical study on neovascularization in TMJ during mandibular advancement]

OBJECTIVE

Neovascularization is proved to be closely correlated with ossification. This study was designed to determine the biochemical path through which the new bone formation is enhanced in TMJ during mandibular protrusion.

METHODS

SD Rats were fitted with bite-jumping appliances to allow for an adequate advancement of the mandible. The animals were sacrificed 3, 7, 14, 21 and 30 days, respectively, after placement of the appliances. Slides with TMJ tissue were prepared for biochemical procedure. Immunohistochemical approaches were adopted to examine neovascularization in TMJ by immuno-localizing the newly formed endothelial cells. Computer-assisted image analysis system was applied to quantify the positive immunoreaction.

RESULTS

Neovascularization in connective tissue close to the condyle was 200% higher in the experimental groups than that in the control, and, within the bony tissue of the condyle, neovascularization in experimental animals was found to be 103% higher than that of the control.

CONCLUSION

Increased neovascularization triggered by mandibular protrusion might intensify new bone formation in condyle and glenoid fossa and finally lead to a growth adaptation of TMJ to bite-jumping therapy.

Microvascular temporomandibular joint and mandibular ramus reconstruction in hemifacial microsomia

Microvascular temporomandibular joint (TMJ) and mandibular ramus reconstruction was performed in a 4-year-old hemifacial microsomia patient with multiple craniofacial and extracranial anomalies (Goldenhar syndrome). Her major craniofacial anomalies included bilateral cleft lip and palate, left macrostomia, left microtia, and complete absence of the left vertical mandibular ramus and TMJ. Most of her other anomalies had been corrected surgically before TMJ and vertical mandibular ramus reconstruction, which was accomplished with a metatarsophalangeal (MTP) joint transplantation. The MTP joint was placed in hyperextended position in the skull base inserting the proximal phalanx under the remnants of the zygomatic arch and replacing the vertical mandibular ramus with the metatarsal bone. Straight mouth opening, correction of the midline, and normalized lateral movements of the mandible were accomplished. The graft includes two epiphyseal plates, which should maintain growth of the transplant. During the follow-up period (16 months) the achieved results have been maintained without adverse effects. The present technique appears to be a promising alternative in the treatment of children with Pruzansky type 3 hemifacial microsomia.

[Analysis of the changes of temporomandibular joint under repeated +Gz stress]

Changes of temporomandibular joint (TMJ) under repeated +Gz stress were discussed. From the etiological point of view in TMJ, many papers in the fields of aviation medicine, microcirculation, maxillofacial surgery and bone surgery were reviewed. +Gz forces can cause inadequacy of blood of oxygen supply to TMJ area. This situation can be worsened by release of free radical agent and cellular factors, ischemia/reperfusion injury, and/or hemorrheologic changes. Furthermore, G-induced injury of cervical muscles and spine may break the maxillofacial muscle chain balance. In addition to the above factors, mental stress may do harm to TMJ. This paper introduced the researches on this area in an attempt to enlighten the concern about TMJ responses to increased +Gz acceleration forces.

Substance P and mast cells: preliminary histologic analysis of the human temporomandibular joint

PURPOSE

Neuropeptide-containing nerves can serve as a mechanism for nervous system regulation of host defense responses. Because bacteria associated with reactive arthritis have been identified in the temporomandibular joint (TMJ), this study investigates whether the presence of substance P (SP) neuropeptide-containing nerves and mast cells can be identified in the TMJ.

MATERIAL AND METHODS

Posterior bilaminar tissue removed during TMJ surgery from 9 women was evaluated for the presence of neuropeptide-containing nerves by staining with a monoclonal antibody to SP. Staining of the TMJ tissue sections with 0.5% toluidine blue was performed to identify the presence of mast cells.

RESULTS

SP-containing nerves and mast cells were identified within the posterior bilaminar tissue associated with the vasculature.

CONCLUSIONS

The presence of neuropeptide nerves and mast cells within the TMJ has been shown. Mast cell degranulation products and SP release can contribute to TMJ inflammation.

Nutrient arteries of the temporomandibular joint: an anatomical and a pathological study

We have identified an artery which is a sub-branch of the inferior alveolar artery, and propose to call it the temporomandibular branch. Mandibular bones of 36 autopsy cases (ages 23-85; 20 males and 16 females) were examined. Contrast media were injected into the inferior alveolar artery, decalcification was conducted, and photographs were taken using soft X-ray equipment (Softex: Nippon Softex, co. CSM type). Then, an examination was conducted concerning sclerosis of these arteries. Next, H.E., Azan, and Pap silver stains were used for microscopic specimens to examine arteriosclerosis of the temporomandibular joint. The artery that sub-branches toward the temporomandibular branch, branches out immediately after the inferior alveolar artery and enters the mandibular foramen, becoming the artery that supplies the temporomandibular joint. This temporomandibular branch travels slightly downward, forward of the inferior alveolar artery, and turns back toward the mandibular base. It advances to the mandibular joint almost directly. The route taken was classified into three types. Toward the head of the mandible, the temporomandibular branch, after passing over the neck of the mandible, divides into two sub-branches, anterior and posterior. In our pathological study of the temporomandibular branch, there were a small number of cases with slight intimal thickening and mild elastosis. As regards sclerotic changes, particularly in cases more than 50 years old. There were very few cases showing intimal changes. Sclerotic changes of the artery supplying the head of the mandible increase with age. The same can be said of the about the constriction rate. These findings correlated with subject age.

The structure of the bilaminar zone in the human temporomandibular joint: a light and scanning electron microscopy study in young and elderly subjects

The bilaminar zone (BZ) in the human temporomandibular joint (TMJ) of toothed adults (GI) and toothless, elderly humans (GII) were analysed using light and scanning electron microscopy (SEM). In both groups the BZ consists of an upper and a lower stratum of connective tissue separated by a vascularized middle region. The superior stratum contains bundles of collagen fibres disposed in different directions. The fibres are fairly thick and transversely oriented immediately posterior to the TMJ disc. The initial part of the inferior stratum contains curved bundles of collagen fibres oriented anterio-posteriorly. From the middle to the posterior part of the inferior stratum, the fibres are right-aligned in GI and clearly sinuous in nature in GII. In both groups, the middle and posterior portions of the middle region are distinguished by the presence of vessels and vascular spaces. Loosely arranged connective and adipose tissues are also evident. The vascular spaces are wider in GII than in GI. The predominance of type I collagen fibres is clear in all regions of the BZ in both groups. The elastic fibres lie parallel to the collagen fibres in both groups and they are thicker and more abundant in GI, apparently decreasing in GII.

Distribution of substance P-like immunoreactive fibers in feline temporomandibular joint

OBJECTIVE

To study the distribution of substance P-like immunoreactive fibers in feline temporomandibular joint.

METHODS

The immunohistochemical PAP method was used for the investigation of the distribution of substance P-like immunoreactive fibers in feline temporomandibular joint.

RESULTS

The TMJ capsule and the anterior and posterior disc attachments all contained SP-immunoreactive nerve fibers, but the medium fibers in diameter were mainly observed. The density of the distribution of SP-positive nerve fibers was the highest in the subsynovium of the TMJ capsule. The density of distribution was similar in the anterior and posterior disc attachments, but lower than in the subsynovium and the lateral joint capsule. Such fibers in the synovial membrane were sparser, and a part of the fibers were seen around the thin blood vessels in all the foregoing tissues.

CONCLUSION

These results provide the morphological data for exploring the neurobiological mechanisms of temporomandibular joint disorder and its pain.

On the formation of the temporomandibular joint cavity in the human fetus

The purpose of this study was to clarify the mechanism of articular cavity formation by means of observing the temporomandibular joint (TMJ) in human fetuses (9th-30th gestational weeks) using light microscope. In the 9th-11th week, although neither cavity had been formed, several small blood vessels running postero-anteriorly on the lower surface of the articular disk that would be the future lower cavity were recognized. However, such blood vessels were not seen in the future upper cavity beneath the glenoid fossa. In the 12th week, when the lower cavity formation commenced, the cavity was filled with blood corpuscles, and a series of apertures was observed throughout the condyle, from the posterior portion to a part of the anterior portion. Tracing posteriorly, the lower cavity diminished gradually until it had at last united to one blood vessel. On the other hand, in upper cavity formation, which was recognized only at the posterior portion of the TMJ, no blood corpuscles were seen in the upper cavity but several small clusters of collagen fibers. Blood corpuscles in the lower cavity disappeared after the formation of synovial membrane (20th week) and vascular canals in the condyle (21st week). From these findings, the mechanism of lower cavity formation appears to differ from that of upper cavity formation. Lower cavity formation involved small blood vessels running postero-anteriorly on the lower surface of the articular disk. As for upper cavitation, there was no evidence of blood vessels, which would suggest that upper cavitation depends on another mechanism of formation.

Angiogenesis in the human temporomandibular joint studied by immunohistochemistry for CD34 antigen

The CD34 antigen is a sensitive marker of vascular endothelium and angiogenesis. Thus, we examined the expression of CD34 in 20 human temporomandibular joint (TMJ) samples with internal derangement and in 10 control specimens by an immunohistological technique using paraffin-embedded tissue and specific anti-human CD34 monoclonal antibody. In the control specimens, CD34 was observed sporadically within the TMJ discs. On the other hand, in the internal derangement specimens, CD34 was found frequently in the walls of blood capillaries within the TMJ discs. In the synovial membrane, CD34 was detected frequently in the walls of many blood capillaries in both the controls and the internal derangement specimens. Indeed, CD34 expression in internal derangement specimens was more intense than in control specimens. In the posterior loose connective tissue of the bilaminar zone, and in the anterior loose connective tissue between the upper and lower lamellae of the anterior capsular wall, CD34 was detected in abundance in the walls of blood capillaries both of the controls and the internal derangement specimens. Generally, CD34 was found rarely in the walls of large blood vessels. The presence of CD34 is suggested to be correlated with the process of angiogenesis induced by internal derangement of the TMJ.

The expression of substance P in human temporomandibular joint samples: an immunohistochemical study

The expression of neuropeptide substance P was examined in 18 human temporomandibular joint (TMJ) samples with internal derangement of the TMJ, and in 10 control specimens. The examination was carried out using an immunohistological technique, using paraffin-embedded tissue and specific anti-human substance P polyclonal antibody. We noted five characteristic distribution patterns of substance P expression: at the nerves' fibre bundles in the connective tissues of the anterior and/or posterior attachment; around the blood vessels in the attachments; at the margin of the TMJ disc and synovial membrane layer; on the surface of hypertrophic synovial membranes with inflammation and proliferation; and around the newly formed capillaries in the TMJ discs. In TMJs with internal derangement associated with severe pain, we found distinct substance P expression in most of the specimens. The expression was particularly intense at the margin of the TMJ disc and synovial membrane layer, on the surface of hypertrophic synovial membranes and around the newly formed capillaries in the TMJ discs. The clinical symptoms of internal derangement of the TMJ are thought to be associated with the degree of synovitis. We conclude that the expression of substance P seems to be closely related to histopathological changes of the human TMJ with internal derangement.

The vascular relationship between the temporomandibular joint and the middle ear in the human fetus

PURPOSE

The aim of this work was to clarify the vascular relationships between the middle ear and the temporomandibular joint region during human fetal development.

MATERIALS AND METHODS

Light microscopic studies were done on 40 human fetuses from 72 mm crown-rump length (C-R) to 150 mm C-R, which were stained by various methods. Five human fetuses were dissected. Natural latex with industrial coloring was injected through the external carotid artery. All specimens were dissected bilaterally.

RESULTS

The limits of the retroarticular region and the fetal tympanosquamosal fissure are shown. The anterior tympanic artery has a variable origin. In most cases, it originates from the maxillary artery; in other cases it originates from the superficial temporal artery or the bifurcation of the external carotid artery. On its way through the retroarticular region, it gives branches to the posterior part of the temporomandibular joint. It progresses along the most lateral part of the tympanosquamosal fissure, dividing into three branches that extend throughout the middle ear. A number of venous spaces in the retroarticular region that constitute the retrodiscal venous plexus. Small venous vessels along the fetal tympanosquamosal fissure accompany the anterior tympanic artery and drain into the retrodiscal venous plexus.

CONCLUSIONS

During human fetal development, there is a wide connection across the tympanosquamosal fissure between the middle ear and the temporomandibular joint region. The anterior tympanic artery and its branches, as well as small venous vessels that are connected with the retrodiscal venous plexus, extend along the most lateral part of the fissure.

Synovial inflammation in arthroscopically obtained biopsy specimens from the temporomandibular joint: a review of the literature and a proposed histologic grading system

Data indicate that the synovial lining of the temporomandibular joint (TMJ) in some respects differs from other joints. The normal variation in morphology of the synovial lining of the TMJ is quite great, whereas the variation in pattern of pathologic changes appears to be relatively small (ie, synovial inflammation is not of the severity as that in other joints). In the current review, a system for histologic grading of synovial inflammation is proposed. The system is based on semiquantitative evaluation of the following set of parameters: 1) synovial lining cell layers; 2) vascularity (number or size of vascular profiles); and 3) Inflammatory cell infiltrate (commonly lymphocytes).

Substance P-associated increase of intra-articular temperature and pain threshold in the arthritic TMJ

Neuropeptides are considered mediators and modulators of inflammatory joint disease. Substance P (SP) has been proposed as a mediator of pain, and its vasoactive properties are well documented. In this study, the presence of SP-like immunoreactivity in the synovial fluid was correlated to intra-articular temperature (IAT) and pain from the arthritic temporomandibular joint (TMJ) 3 to 5 weeks after one intra-articular injection of glucocorticosteroids. Eighteen TMJs were investigated for IAT and the presence of SP-like immunoreactivity in the synovial fluid in 12 patients with systemic inflammatory joint disease. After arthrocentesis, the aspirates were analyzed for SP-like immunoreactivity by means of competitive radio immunoassay. A visual analogue scale and an algometer determining the pressure pain threshold and tolerance level assessed arthritic pain and hyperalgesia in the TMJ. Our results indicate that SP-like immunoreactivity is associated with IAT and that increased concentrations of joint fluid SP-like immunoreactivity correspond to increased pain threshold and tolerance and a concomitantly decreased visual analogue scale. These findings suggest that SP is implicated in the vascular and nociceptive response of the arthritic joint and that SP, possibly assisted by the antinociceptive effect of local corticosteroids, has a modulatory role in arthritic pain and hyperalgesia.

Anterior tympanic artery: course, ramification and relationship with the temporomandibular joint

The anterior tympanic artery, a branch of the maxillary artery, ascends through the retroarticular region dividing into anterior branches that spread through the posterior part of the temporomandibular joint, and posterior branches that contribute to the vascularization of the external acoustic meatus and the tympanic cavity. The arrangement of the anterior tympanic artery was studied bilaterally in 18 adult cadavers. In some cases, the anterior tympanic artery branches off from the superficial temporal artery. The relationships of the anterior tympanic artery with the posterior part of the temporomandibular joint were analyzed.

Immunohistochemical distribution of lymph capillaries and blood capillaries in the synovial membrane in cases of internal derangement of the temporomandibular joint

The distribution of lymph capillaries and blood capillaries in the synovial membrane was examined immunohistologically with anti-human collagen IV antibody and anti-human von Willebrand factor in 26 human temporomandibular joint (TMJ) samples comprising discs with adjoining synovial membrane from 10 control TMJs and from 16 TMJs with internal derangement. Three different distribution types were observed in the synovial membrane. In the control samples, the occurrence of blood capillaries and lymph capillaries was rare. In mildly hyperplastic synovitis, lymph capillaries were observed just beneath the surface of the synovial membrane, whereas blood capillaries occurred in a little deeper layer of the synovial membrane. In a severely hyperplastic synovitis, both lymph and blood capillaries were observed frequently. The present results suggest that the different distribution patterns of lymph capillaries and blood capillaries reflect the degree of synovitis but can not be attributed to specific clinical symptoms.

Microanatomy of the moose temporomandibular joint (Alces alces; Linnaeus, 1758)

Temporomandibular joint (TMJ) histology was investigated in 8 female Scandinavian moose. 5 were 1-year-old with a carcass weight (cw) of 125-140 kg, and 3 were 2-years-old (160-175 kg cw). The condylar articular surface consisted of a connective tissue lining with parallel collagen fibres. Numerous blood vessels were observed adjacent to the joint chamber. Below the fibrous layer, a proliferative cellular zone of undifferentiated mesenchymal cells was situated. These cells differentiated into chondroblasts and hypertrophied chondrocytes. Further down, an endochondral ossification process was initiated. Vertically directed invaginations were observed. A similar cellular organization was identified in the temporal component. However, the undifferentiated mesenchymal cell layer was discontinuous. The disc showed dense collagen bundles without main alignment. Vessels were identified throughout the entire disc. The results indicate that the cellular organization of the moose TMJ is similar to the TMJ histology found in other mammals but differences do occur.

Microscopic changes in the retrodiscal tissues of painful temporomandibular joints

PURPOSE

The purpose of this study was to investigate the association between temporomandibular joint (TMJ) pain and histological changes in TMJs with disc displacement.

METHOD

Samples from capsules and posterior disc attachments from 27 TMJ pain patients who underwent surgery were compared with samples from seven asymptomatic persons.

RESULTS

On logistic regression analysis, retrodiscal tissues from the painful joints demonstrated a significantly higher density of fibroblasts, presence of narrowed and obliterated arterial lumens, and a significantly lower distribution of elastic fibers.

CONCLUSION

The results indicate that there is a difference between painful and asymptomatic joints at the microscopic level.

Age-related changes of the retrodiscal tissues in the temporomandibular joint

PURPOSE

This study compares the histologic features of the lateral capsule and lateral and central posterior disc attachment of temporomandibular joints (TMJs) in young and elderly persons.

MATERIAL AND METHODS

Samples were removed from 36 joints belonging to young persons (mean age, 30 years; age range, 16 to 39 years) and 29 joints belonging to elderly persons (mean age, 69 years; age range, 58 to 78 years). Twelve joints from elderly persons had altered disc position, whereas none of the young joints had this condition. Six-micrometer-thick sections were stained with hematoxylin-eosin and the Fränkel method (for elastic fibers). Logistic regression analysis using a likelihood-ratio test was applied for comparisons between groups and to avoid the confounding effect of differences in disc position and gender.

RESULTS

A significantly lower density of fibroblasts was observed in elderly persons in all the three areas investigated. In addition, elderly persons demonstrated a significantly lower distribution of vascular tissue and a significantly higher presence of dense connective tissue in the central third of the posterior disc attachment.

CONCLUSION

This study shows that retrodiscal tissues, which may eventually function as an articular disc during altered disc position, are susceptible to age-related connective tissue changes.

The angioarchitecture of the rat mandibular joint bilaminar zone

In mammals, temporomandibular-joint articular disc attachments have a bilaminar pattern. The three-dimensional angioarchitecture of the bilaminar zone in the adult rat was described using scanning election microscopy of microvascular corrosion casts (47 specimens) and light microscopy of Indian ink-injected, cleared, thick-sectioned temporomandibular joints (6 specimens). The bilaminar zone had an axial core of feeder vessels composed primarily of flat venules which were organized in plexuses. Arterioles were few and slender. In both laminae, there were usually three branching levels until vessels approached the surface of the lamina, where a dense capillary meshwork was formed. Both laminae ended abruptly at the periphery of the avascular disc with a single, slightly undulating marginal vessel. This marginal vessel, which faced the avascular disc, was definitely larger in diameter than the other superficial capillaries and was rather a postcapillary venule than a capillary. Functionally, this marginal venule might be important in sustaining nutrition of the avascular disc centre by allowing bidirectional blood flow during jaw movements.

The angioarchitecture of the rat mandibular joint synovium

The synovium (or synovial membrane) lines all intra-articular surfaces of synovial joints except for the articulating surfaces. This study describes the angioarchitecture of the synovium of the adult rat temporomandibular joint using microvascular corrosion casts and scanning electron microscopy. To corroborate findings, India ink-injected, thick-sectioned specimens (200 microns) and haematoxylin and eosin-stained tissue sections (7 microns) were analysed. Rostrally, the synovial membrane was fed by several layers of vessels branching towards the superficial lining of highly convoluted capillary loops. Arterioles were rare, and venules organized in large plexuses. The membrane thinned out in the caudal direction. Villi were present on the surface. They were flat, with a core of two parallel linear feeder vessels, one arteriole and one venule, which were interconnected by capillary loops. At the periphery of the articulating surfaces, the vessels of the synovial layer were flatter. Caudally, the synovial membrane of the richly vascularized retrodiscal pad showed many synovial folds. Feeder vessels were directed rostrally and branched in all directions. The number of subdivisions depended on the size of the synovial fold. Again, venules were organized in plexuses and lining capillaries were convoluted. The densely capillarized synovial membrane with its folds and villi is considered well adapted to serve synovial fluid production and joint dynamics.

Diagnostic accuracy of TMJ arthroscopy in correlation to histological findings

From 1987-1993, 356 arthroscopic examinations of the temporomandibular joint were performed on 295 patients. During 69 examinations, biopsies were obtained to correlate arthroscopic findings with histology. In the overall group, histology confirmed in 78.9% the arthroscopic findings. Correlation was better in joints with degenerative changes (81.5%) than in those with a synovitic/hyperaemic appearance (61.5%). Chondroid metaplasia, detritus synovitis and synovial chondromatosis were additional diagnoses given by histological examination. In 11 joints, open arthrotomy was performed after arthroscopy with biopsy was carried out. The excised tissue was also investigated microscopically and correlates to the biopsy-result. Because no different pathological changes were found, it is concluded that biopsies performed during arthroscopy of the temporomandibular joint are representative for histological investigation. An additional perforation for introducing the biopsy forceps is not necessary, because results obtained with different techniques appeared to be equally accurate.

The TMJ-ear connection

This article documents the existence of three structures that traverse through the petrotympanic fissure. These structures are the mandibular malleolar ligament, the chorda tympani nerve and the anterior tympanic artery. The mandibular malleolar ligament or the disk-malleolar ligament originates on the anterior process of the mallous. It traverses through the petro-tympanic fissure and attaches to the posterior portion of the capsule and disk of the temporomandibular joint. The chorda tympani nerve supplies sensory feeling to the posterior two thirds of the tongue. The anterior tympanic artery supplies blood to the area of the tympanic membrane. Clinical experience with implants that impinge or cover ear problems and other symptoms. Removal of these implants and placements with devices that do not cover these structures often relieve these symptoms.

A new retinacular ligament and vein of the human temporomandibular joint

In the human temporomandibular joints of 14 Japanese cadavers, we observed a new retinacular ligament that connected to the retrodiskal pad posterolaterally and was accompanied by a vein draining the retrodiskal pad. This retinacular ligament originated from lateral to posterolateral part of the joint. The origin included the articular tubercle of the zygomatic process of the temporal bone. The ligament descended along the mandibular ramus to insert into the fascia of the masseter muscle at the mandibular angle. The vein originated from the venous plexus in the retrodiskal pad and ran parallel to the retinacular ligament, giving off branches to the retromandibular, transverse facial, and superfacial temporal veins. There were no remarkable differences in the size of the retinacular ligaments among individuals as well as between the left and right sides. The retinacular ligament had firm fibrous connections with the posterolateral part of the retrodiskal pad, where the external fibrous membrane of the articular capsule was lacking. These findings suggest that the retinacular ligament and its accompanying vein function together to maintain blood circulation during jaw movement and may also be related to the development of occlusal disorders.

The fine vasculature of the rat mandibular joint

There is no detailed description of the fine vasculature of the rat mandibular joint in the literature. The gross vasculature of the cephalic area and of the mandible is known, but without particular emphasis on the joint itself. This article describes the fine vasculature of the rat mandibular joint, using transverse (coronal) and sagittal thick sections of specimens injected with India ink and analyzed with light microscopy. The main vascular supply to the joint comes from the rostral and caudal aspects. Medially, the joint is directly vascularized by vessels from the lateral pterygoid muscle. Rostrally, the synovial membrane and the bilaminar zone of the disc are supplied by articular branches from the rostral deep temporal vessels, terminal branches of the maxillary artery. Caudally, the rich synovium of the retrodiscal pad and the bilaminar zone are supplied by the articular branches of the caudal deep temporal artery, a branch of the maxillary artery. Venous return is into the short, but large retroarticular vein which empties into the maxillary vein together with the vein from the transverse sinus exiting from the postglenoid foramen. Intra-articular synovial membranes own rich venous plexuses, and are lined by a dense capillary network. The central part of the fibrous articular disc is avascular in adult rats, and is circumferentially lined by a rim of capillaries from the bilaminar zone.

Angiography of the temporomandibular joint. Description of an experimental technique with initial results

The vascular supply to the temporomandibular joint is not completely understood. To form a base for advancement in this area we developed a method for experimental angiography of the temporomandibular joint that was applied to fresh temporomandibular joint autopsy specimens. Via the external carotid artery the vessels were infused with a mixture of barium and an acrylic resin. The specimens were sectioned and contact radiographs were obtained. These showed the vascularity of the joint and the surrounding structures with great detail. Most of the vascular supply appears to come from the lateral and medial aspects of the condyle head and from the anterior and posterior disk attachments. The method was applied to both normal and abnormal joints and the results suggest that this method could be used to gather further understanding of the vascularity of the temporomandibular joint relative to disease.

Effect of experimental traumatic occlusion on blood flow in the temporomandibular joint of the rat

Fluorescent microspheres (FM) were used to visualize and semi-quantify blood flow in the temporomandibular joint (TMJ) during experimental unilateral traumatic occlusion of the maxillary and mandibular molar teeth in 30 young rats. At different postoperative observation periods varying from 1 to 30 days FM were injected systemically, and the number of FM were counted in serial sections from the TMJ in a fluorescent microscope. Blood flow was related to the number of FM found in the fibrous connective tissue and bony condyle of the TMJ. A percentage increase in blood flow was found at 15 to 20 days on the experimental side, compared with the contralateral side. Furthermore, there was an increase in blood flow in both TMJs in the experimental animals compared with an unoperated control material of 10 animals. The study thus indicates that a local unilateral occlusal trauma initiates blood flow responses not only unilaterally but also in the TMJ on both sides in rats.

Anatomy of the human temporomandibular joint. An updated comprehensive review

This article is an in-depth review of the current knowledge on human temporomandibular joints (TMJ's). All aspects of joint anatomy are described with emphasis on adaptability to biochemical stimuli throughout life. Each TMJ is a pressure-bearing compound double synovial joint. TMJ's are unique in having a movement not only controlled by the morphology of the joint per se but also by the dentition at the other end of the lever system. During life the temporal, condylar and discal articular surfaces undergo remodelling. The synovium is an important joint component which contributes to nourish and lubricate the avascular surfaces and has bactericidal properties. The joint capsule has privileged relationships anteriorly with the lateral pterygoid muscle. This muscle has two heads that show functionally reciprocal activation. The exact insertion and role of the superior head of the lateral pterygoid muscle remains controversial. The disc has a very low coefficient of friction and compensates for the lack of congruence between articular surfaces. Biomechanically it is stabilized between condyle and articular eminence by its thick rim which has special viscoelastic properties. Apart from the viscoelastic deformations the other important mechanism of disc stabilization seems to be related with the structure of some of the disc attachments.

[MRI of the temporomandibular joint. Demonstrability and significance of the retro-articular vascular plexus]

The retro-articular vascular plexus of the temporomandibular joint (TMJ) is of great importance for the function of this joint. Aim of this study was to determine the amount of increase of signal intensity in the retro-articular vascular plexus after intravenous injection of contrast medium and to figure out potential advantages of this procedure. The posterior band of the articular disc--a landmark in the diagnosis of disc dislocations--becomes prominent after injection of contrast medium. Forty-five temporomandibular joints were studied before, and after intravenous injection of contrast medium with magnetic resonance imaging (MRI) using T1-weighted images in parasagittal plane. In all cases a measurable increase of signal intensity was demonstrable in healthy volunteers as well as in patients with normal or pathological TMJ findings. In 53.3% of cases the posterior band was better differentiable after administration of contrast medium. In patients with suspicion of pathological features in series without contrast medium, in 27.3% of those cases administration of contrast medium led to a more precise--"diagnostic"--evaluation of disc location. The study emphasizes the use of contrasts medium for evaluations of disc dislocation with MRI in cases of pathological or unclear findings in precontrast MRI series.

The microscopic structure and function of the vascular retrodiscal pad of the human temporomandibular joint

The highly vascular retrodiscal pad attaches the articular disc of the temporomandibular joint to osseous structures posterior to it. There is debate as to whether or not the pad includes erectile tissue. Histological examination of 11 retrodiscal pads revealed thick-walled muscular arteries, thin-walled veins and numerous vascular sinuses, which is different from the erectile tissue of the corpora cavernosa. Its histological features and position within the joint suggest that the retrodiscal pad may function differently from other human joints due to: (1) the large amount of distraction it undergoes relative to its size and (2) its location anterior to the ear.

Development of collagen fibers and vasculature of the fetal TMJ

Using 12 human fetuses, histological development and changes in connective fiber structure and fine vascular patterns have been investigated in various fetal gestational stages by light and scanning electron microscopy. The main arterial supply of the articular disc was from the bilaminar region and pterygoideus lateralis muscle. The vascular network on the disc surface was related with fluid secretion. When the bilaminar region was compressed, it caused ischemia and fibrosis as the main pathological changes in TMJ derangement. A decrease in fluid from blood vessels might occur in TMJ degeneration. Collagen fibers in the disc passed mainly anteroposteriorly. In the anterior and posterior bands, muscular tendon fibers came from the pterygoideus lateralis muscle and superior stratum of the bilaminar region. In the posterior band three-dimensional structures of collagen fibers suitable for load bearing were observed. The compass network and process on the disc showed the normal structure that is formed gradually and has functions including dispersion, pressure bearing, friction-proofing and storage of the synovial fluid. Attachments of the disc were suitable for disc function. Large elastic fibers in the posterolateral part of the superior stratum of the bilaminar region may be antagonistic to the upper head of the pterygoideus lateralis muscle fibers passing medioanteriorly, indicating that this antagonism is available for disc function.

The structure and function of the temporomandibular joint

Although characterised by having a synovial membrane lining the nonarticulating surfaces within the joint capsule, in some ways the temporomandibular joint (TMJ) is an atypical joint. This paper highlights the differences between the TMJ and other movable joints with a description of the structure, innervation blood supply and musculature. Also included are details of how the TMJ moves--the effectors of movement and the various reflexes controlling movement of the joint.

Superficial vascularity of temporomandibular joint retrodiskal tissue: an element of the internal derangement process

Superficial vascular changes in the retrodiskal tissue are an aspect of the remodeling process during progressive anterior displacement of the temporomandibular joint (TMJ) disk. The salient portion of the remodeled retrodiskal tissue (RRT) is contained in a 3 x 3 grid of arthroscopic fields in the superior joint space, plus the tympanic portion of the remodeled retrodiskal tissue. A four-level vascularity classification system gives a statistically significant association between superficial avascularity of the remodeled retrodiskal tissue and progressive stages of disk derangement. In particular, simultaneous avascularity in both the tympanic remodeled retrodiskal tissue and the central arthroscopic field occurs with severe disk displacement without reduction. Analyses are based on 16 microscopic studies, 25 magnetic resonance imaging and tomographic imaging studies, and 26 arthroscopic studies.

The TMJ and the middle ear: structural and functional correlates for aural symptoms associated with temporomandibular joint dysfunction

Several anatomic relationships existing between the ear and the temporomandibular joint have been proposed to account for the presence of aural symptoms that occur in some patients with temporomandibular joint dysfunction. There are a plethora of functional hypotheses for aural symptoms relating to disturbed functions of the eustachian tube (as well as neuromuscular relationships and neurovascular functions integrating with these hypotheses). Investigators explain the presence of aural symptoms relative to the anatomic relationship of the middle ear to the TMJ as hypothetically due in part to the "tiny ligament," the sphenomandibular ligament, or the diskomalleolar ligament. This article reviews hypotheses, explanations, and current research on this controversial issue.

Microangiography of the rabbit temporomandibular joint in the open and closed jaw positions

The purpose of this investigation was to test the hypothesis that jaw position significantly affects the vascular morphology of the temporomandibular joint (TMJ). The study was performed using intravascular perfusion with 30% Micropaque and 40% gelatin. Six anesthetized New Zealand white rabbits were divided into 2 groups of three. Group 1 rabbits were perfused in the resting, closed-jaw position and group 2 rabbits were perfused while the jaw was held open. The animals were killed with an overdose of pentobarbital and frozen. The heads were hemisected, fixed, decalcified, and embedded in Cedukol. Sagittal sections were cut at the level of the meniscus and radiographed with a specimen x-ray unit on high-resolution film. The 6 rabbits (12 TMJs) demonstrated consistent microvascular differences. In 83% of the jaws in group 2 rabbits the anterior condylar vein was not seen or appeared patchy whereas the same vein was readily seen in all jaws of group 1 (P less than .01). The superior condylar vasculature was distended in 83.3% of group 2 jaws and in 16.7% of group 1 jaws (P less than .05). This study demonstrates significant changes in vascular morphology when the jaw is placed in the open position.

Fine structure of calcitonin gene-related peptide-immunoreactive nerve fibres in the rat temporomandibular joint

The distribution and fine structure of these nerve fibres was examined by immunoelectron microscopy. CGRP-immunoreactive fibres were seen in the nerve bundles, blood vessels and periosteum around the condyle as well as in the disc. These nerve fibres were unmyelinated and had diameters varying from 200 to 600 nm. They were completely or partially enclosed by Schwann cell cytoplasm and did not form synaptic contact with any cells. CGRP-immunoreactive nerve fibres may be sensory nature and this peptide could be involved in pain transmission and neurogenic inflammation.

Histologic features of the temporomandibular joint disk and posterior disk attachment: comparison of symptom-free persons with normally positioned disks and patients with internal derangement

To gain further knowledge about the differences between normal and pathologic anatomy of the temporomandibular joint disk, we examined histologically disks obtained at autopsy from 10 symptom-free persons and compared our findings with observations involving 17 surgically removed disks. The surgical patients had internal derangement and severe long-standing temporomandibular joint pain and dysfunction. The normal disks were biconcave, whereas the surgically removed disks were deformed and thicker than the normal disks. Chondrocytes (4 joints), a surface layer of proliferative connective tissue (4 joints), vessels (2 joints), and splitting (4 joints) were seen in the surgical specimens but not in the normal specimens. The surgical specimens also showed higher maximal density of fibroblasts and vessels. It was concluded that surgically removed temporomandibular joint disks demonstrated several histologic alterations that were not seen in normal disks. These characteristics may serve as the basis for development of a histologic grading of pathologic conditions of the temporomandibular joint disk and the posterior disk attachment.

Surgical repair of defects in the rabbit temporomandibular joint disc: a comparison of various techniques

A study was designed to evaluate the effects of different types of repair (suture vs. graft), donor graft tissues (dermis vs. fascia), and methods of graft fixation (sutured vs. laser-assisted) on excisional defects of the rabbit TMJ disc made anterior to the retrodiscal tissue. Groups created to compare the different variables were assessed at 30 and 90 days postoperatively by macroscopic and histologic methods, microangiography, and mechanical strength testing. Without repair, all excisional defects of the disc failed to heal. Suturing of the reapproximated margins did not appear to promote healing or provide much strength beyond the properties of the suture material. Dermal grafts, fixed by suturing, induced healing by becoming incorporated into the disc, restoring discal continuity, and approximating normal disc strength. The use of laser-assisted tissue welding for dermal graft fixation was found to be inadequate and was subsequently abandoned. Fascial grafts could be fixed into position by both suture and laser-assistance, but consistently failed to exhibit successful transplantation and promote healing at the disc site.