Temporomandibular joint: characteristics, anatomy and diseases.

The temporomandibular joint is one of the most important joints in the body; let's see how it works.

The mandible is an odd, flat, symmetrical, central bone located in the lower part of the face. It may look like just another bone, but without any doubt, it is one of the most important bony structures in the human being. Thanks to the mandibular complex we are able to chew food and, in addition, we have developed a complex communication system based on it.

Without going any further, disorders in the craniomandibular joint complex not only result in difficulty in eating, but can also cause vertigo, dizziness, tinnitus, headaches, communication problems and many other events related to the head and/or ears. This type of pathology is suffered by up to 12% of the population, being much more prevalent in young people.

To understand the anatomy, functionality and possible failures of the chewing and speaking process, we must describe in depth the temporomandibular joint (TMJ), which allows this bone to move correctly. We tell you about it from both an anatomical and medical approach, since pain in the maxillofacial area is very common in the general population and deserves to be known.

What is the temporomandibular joint?

The temporomandibular joint is, as its own name indicates, the articular element that joins the temporal bone and the mandible.. It is a synovial joint (allowing movement) of the bicondylar type (when the heads of two bones fit over each other to create a joint). It is a unique type of joint in the whole body, since both components function as a unit and, in addition, it is one of the few mobile joint structures that can be found in the human head.

We can distinguish several anatomical sections in this very striking articular portion. We will tell you about its particularities in the following lines, but you cannot forget that each of them is part of a homogeneous and unitary whole at a functional level:

• Capsule: it is a thin and diffuse envelope that is inserted into the bony surfaces in the vicinity. It allows a high range of movements and biological executions.
• Articular disc: it is composed of a fibrocartilaginous tissue that is positioned between the head of the mandibular condyle and the mandibular fossa. Its diameter is 2 to 3 mm, depending on the area analyzed.
• Ligaments: There are three distinct ligaments encompassed in the temporomandibular joint (TMJ), one major and two minor.
• Nerve structures: the sensory innervation of this structure comes from the auriculotemporal and maseterine nerves, both branches of the trigeminal nerve.
• Blood supply: blood with nutrients and oxygen comes from the external carotid artery, bifurcated from the common carotid.

The aforementioned ligaments are particularly noteworthy, since it is thanks to them that the movements of the edges of the jaw are produced, i.e. those positions that can be adopted without suffering pain of a muscular nature in a normal situation. The major ligament is called the "temporomandibular ligament", while the two minor ligaments are known as the stylomandibular and sphenomandibular ligaments..

As we have summarized in previous lines, the blood supply comes from the superficial temporal artery and the maxillary artery, both being branches of the bifurcation of the external carotid artery, which in turn is a product of the bifurcation of the carotid artery itself. This artery is essential for survival in the human being since, as a whole, it is responsible for blood perfusion to a large part of the brain.

On the other hand, the auriculotemporal and maseterine nerves sensorially innervate the temporomandibular joint.. Both arise as collateral branches of the mandibular nerve (V3), the largest of the three branches that converge on the trigeminal. However, it should be noted that these nerve structures are purely sensory, since the motor fraction is taken care of by the nerves associated with the skeletal muscles surrounding the area.

Functions of this jaw joint.

When the human mouth is opened, there is a combination of movements a combination of movements: a rotational one on the part of the discomandibular space and a translational one, in the discotemporal space.. The condylar process performs rotational and translational movements (in that order) thanks to the presence of muscular and ligamentous structures associated with the articular elements.

In addition to the mechanical actions of opening and closing the mouth, these complexes allow movements of protrusion, retrusion, laterality and combinations of all of them. All these mechanical efforts and positions are linked to such basic human actions as chewing, sucking, swallowing, speaking, forming gestures, breathing, opening the mouth and maintaining the correct pressure in the middle ear. Undoubtedly, the temporomandibular joint plays an essential role in almost all typical human processes, which we perform unconsciously.

The pathologies of the temporomandibular joint

We have narrated how important this synovial joint is for our species, so you can imagine that its failures are more than evident in the day-to-day life of patients, even during the most trivial tasks. First of all, it is worth noting that up to 25% of the population experiences symptoms of temporomandibular disorders (TMD) at some point.. However, curiously, only 5-7% seek help after the onset of these complaints.

The etiology of TMD is multifactorial. Multiple theories have been proposed, such as mechanical displacement, osteoarthritis, muscle failure, physical-psychological factors, social events and various interactions between some or all of them. In any case, we can group the typologies of the disease into three possible general causes:

• Predisposing factors: these are the events that lead to the appearance of TMD or orofacial pain. These include genetic disorders, systemic problems, psychological pathologies and structural deformities.
• Initiating factors: a blow or continued overexertion of the temporomandibular joint can lead to its degradation.
• Perpetuating factors: muscular stress and certain metabolic problems can slow down the healing of the joint if it has been damaged in the past.

One of the major implicated in temporomandibular joint disorders is bruxism. This silent pathology is suffered by up to 70% of the population at any given place and time, and is defined as involuntary jaw clenching and tooth grinding, especially at night, when these movements are unconscious.

It is estimated that up to 52% of people with bruxism are positive to certain stress, anxiety and depression tests.. Whenever the wear and tear of the structures involved is accompanied by pain or sensitivity, this is considered pathological, so it is never an option to "leave it alone": if a patient ignores the wear/inflammation/injuries and other events in the temporomandibular joint, he/she may lose the ability to eat properly and require surgery.

In addition to bruxism, it should be noted that arthritis, arthralgia, synovitis, capsulitis, osteoarthrosis, systemic Arthritis and many other events can cause temporomandibular joint dysfunction.. In general, anything that damages bones, tendons, synovial fluid and muscles involved in this special gear of life can jeopardize the proper functioning of the TMJ.

A person with TMJ disorders usually perceives one or more of the following symptoms: pain in the jaw (more specifically in the area near the ear), difficulty in chewing/chewing and severe pain when trying to do sochronic discomfort inside the ear or at its borders and, finally, total blockage of the joint, which implies a total impossibility to open or close the mouth.

Summary

As you will have seen along these lines, the temporomandibular joint (TMJ) is one of the most important articular formations of the jaw. is one of the most important joint formations of the whole body, as events so essential for the life of the patient are so important.It is one of the most important articular formations of the whole body, since events as essential for life as eating, speaking or breathing are totally or partially conditioned by it. Therefore, it is necessary to take care of it and go to the doctor promptly at any sign of prolonged facial pain.

There are treatments to alleviate the discomfort of TMJ syndromes, both medical and physiotherapeutic. For example, analgesics, tricyclic antidepressants, muscle relaxants, nighttime mouth splints and sessions to learn to manage stress and other altered states can help patients with these conditions tremendously. If you know you have a problem related to the temporomandibular joint, don't let it go: your condition has a solution.

Bibliographic references:

• Temporomandibular joint (TMJ): syndrome, symptoms and treatments, Maxillofacial Institute. Retrieved March 20, from https://www.institutomaxilofacial.com/es/2018/11/04/articulacion-temporomandibular-atm-sindrome-sintomas-y-tratamientos/.
• Bordoni, B., & Varacallo, M. (2019). Anatomy, head and neck, Temporomandibular Joint. StatPearls [Internet].
• Maini, K., & Dua, A. (2020). Temporomandibular Joint Syndrome. StatPearls [Internet].
• Murphy, M. K., MacBarb, R. F., Wong, M. E., & Athanasiou, K. A. (2013). Temporomandibular joint disorders: A review of etiology, clinical management, and tissue engineering strategies. The International journal of oral & maxillofacial implants, 28(6), e393.
• Prevalence of TMJD and its Signs and Symptoms, NIH. Recogido a 20 de marzo en https://www.nidcr.nih.gov/research/data-statistics/facial-pain/prevalence#:~:text=The%20prevalence%20of%20temporomandibular%20joint,are%20higher%20among%20younger%20persons.
• Trastornos de la articulación temporomandibular, Mayo Clinic. Recogido a 20 de marzo en https://www.mayoclinic.org/es-es/diseases-conditions/tmj/symptoms-causes/syc-20350941
• Trastornos de la articulación temporomandibular, Medlineplus.gov. Picked up on March 20 at https: