Temporomandibular joint: an anatomical approach method

doi:10.15406/mojap.2020.07.00310

MOJ

eISSN: 2471-139X

Anatomy & Physiology

Method Article Volume 7 Issue 6

Temporomandibular joint: an anatomical approach method

Paulo Sérgio Flores Campos,¹

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José Aderval Aragão,² Francisco Prado Reis^2,3

¹Department of Radiology, School of Dentistry, Federal University of Bahia, Brazil
²Department of Morphology, Federal University of Sergipe (UFS), Brazil
³Medical School of Tiradentes University (UNIT), Brazil

Correspondence: José Aderval Aragão, Federal University of Sergipe, Marechal Rondon Avenue, São Cristóvão, Sergipe, Brazil, Tel 55 79 991916767

Received: November 16, 2020 | Published: December 7, 2020

Citation: Campos PSF, Aragão JA, Reis FP. Temporomandibular joint: an anatomical approach method. MOJ Anat Physiol. 2020;7(6):173-174. DOI: 10.15406/mojap.2020.07.00310

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Abstract

Objective: To describe a technique for a conservative approach to anatomical study of the temporomandibular joint (TMJ); this method is designed to demonstrate the structure of the TMJ while teaching Anatomy to Dentistry and Medical students.

Methodology: We took the head of a specimen, emptied the cranial cavity and determined a point of reference, situated approximately 2cm behind the external acoustic meatus. Then we traced a line from this point up to the midpoint of the margin that separates the anterior cranial fossa from the middle cranial fossa, bilaterally. Based on these reference lines, we cut the head.

Results: Two halves of the TMJ was obtained permitting us to visualize the soft and osseous articular components. Conclusion: This technique provided good samples of both TMJs without damage to the neighboring anatomical structures.

Keywords: anatomy, temporomandibular joint, temporomandibular joint disc

Abbreviations

TMJ, temporomandibular joint

Introduction

Only a few textbooks show some anatomic samples of the TMJ because its anatomical study presents several difficulties.¹ Separation of the joint in a block results in sacrificing many structures, which is unacceptable. The challenge, therefore, is to standardize a procedure that allows one to study the TMJ components, while preserving the anatomical structures around it to the maximum extent.

Materials and methods

We took the head of a specimen, emptied the cranial cavity and determined a point of reference, situated approximately 2cm behind the external acoustic meatus (Figure 1).

Figure 1 Point of reference posterior to the external acoustic meatus.

After this, for both sides, we traced a line from this point up to the midpoint of the margin that separates the anterior cranial fossa from the middle cranial fossa; this margin being formed by the smaller wing of the sphenoid bone and by the horizontal lamina of the frontal bone (Figure 2). Based on these reference lines, we made the cuts of the part, which resulted in three segments: A central segment with a triangular shape and two lateral segments (Figure 3).

Figure 2 Guide line through the middle cranial fossa, indicating the trajectory of the cut.

Figure 3 Anatomic parts sectioned according to the pre-established guidance.

Results

After separating the segments, we perceived that the cut passed approximately through the center of the mandibular condyle, which made it possible to visualize the two halves of one and the same TMJ (Figure 4).

Figure 4 Result of the procedure showing the TMJ on the right side and on the left.

Dissociation of the structures from the lateral segments allow detailed observation of almost all the intra and extra-articular components: disc, capsule, posterior ligament of the disc (bilaminar zone) and the superior and inferior bundles of the lateral pterygoid muscle (Figure 5).

Figure 5 Showing the intra and extracapsular articular components.

Discussion

The textbooks on anatomy generally show TMJ drawings^2–5 or its ultra-structural characteristics;^6–8 other publications show its arthroscopic and imaging features.^9–13 As we said before, separation of the TMJ in a block results in sacrificing many structures, and dissecting it has been shown to be a difficult task, because in fixed specimens, it is impossible to clearly distinguish the articular capsule from other neighboring tissues, which invariably leads to its loss. A more reasonable alternative would be to evaluate the TMJ structures from the inside to the outside, which presupposes establishing a parasagittal section perpendicular to the long axis and passing through the center of the mandibular condyle. Nevertheless, another problem remains: the sacrifice of many anatomic structures.