Imaging of the temporomandibular joint: An update
Asim K Bag, Santhosh Gaddikeri, Aparna Singhal, Simms Hardin, Benson D Tran, Josue A Medina, Joel K Curé
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Abstract
Imaging of the temporomandibular joint (TMJ) is continuously evolving with advancement of imaging technologies. Many different imaging modalities are currently used to evaluate the TMJ. Magnetic resonance imaging is commonly used for evaluation of the TMJ due to its superior contrast resolution and its ability to acquire dynamic imaging for demonstration of the functionality of the joint. Computed tomography and ultrasound imaging have specific indication in imaging of the TMJ. This article focuses on state of the art imaging of the temporomandibular joint. Relevant normal anatomy and biomechanics of movement of the TMJ are discussed for better understanding of many TMJ pathologies. Imaging of internal derangements is discussed in detail. Different arthropathies and common tumors are also discussed in this article.
Key words: Temporomandibular joint; Magnetic resonance imaging; Imaging; Computed tomography; Anatomy; Pathologies
Core tip: “Imaging of the temporomandibular joint: An update” is a thorough review of the imaging techniques and imaging appearances of normal anatomy, anatomic variation and pathologies of the temporomandibular joint (TMJ). Numerous images are appropriately used for illustration of the key concepts of TMJ imaging. Nice blend of exquisite details and beautiful illustrative images is the main feature of this article. The purpose of this article is easy understanding of many difficult aspects of imaging of the TMJ.
INTRODUCTION
Pain related to the temporomandibular joint (TMJ) is common in the general population. Only about 3%-7% of the patients with pain related to TMJ seek medical attention. Although TMJ disorders or dysfunctions are the most common clinical conditions for imaging referrals, pathologies specific to the bone and the joints are also common. Different imaging modalities are available to image the TMJ, each with inherent strengths and weaknesses. Magnetic resonance imaging (MRI) is the most widely used and is diagnostic technique of choice. In this article, we review the imaging techniques, anatomy pathology involving the TMJ with special emphasis on MRI findings.
Embryology and development of TMJ
The TMJ is one of the last diarthrodial joints to appear in utero and does not emerge in the craniofacial region until the 8thweek of gestation. The maxilla, mandible, muscles of mastication, and biconcave disc develop embryologically from the first branchial arch through the 14th week of gestation. The TMJ is considerably underdeveloped at birth in comparison to other diarthrodial joints making it susceptible to perinatal and postnatal insults. The joint continues developing in the early childhood years as the jaw is utilized for sucking motions and eventually chewing.
ANATOMY OF TMJ
The TMJ is a ginglymoarthrodial synovial joint (latin: ginglymus = hinge joint) that allows both backward and forward translation as well as a gliding motion. Similar to the other synovial joints in the body, the TMJ has a disk, articular surfaces, fibrous capsule, synovial fluid, synovial membrane, and ligaments. What makes this joint unique is the articular surfaces are covered by fibrocartilage instead of hyaline cartilage. The articular surfaces of the TMJ are formed inferiorly by the mandibular condyle and superiorly by the glenoid fossa (also known as mandibular fossa) and articular eminence of the temporal bone.
Articular surfaces
The mandibular component consists of the ovoid condylar process that is 15-20 mm wide in the transverse dimension and 8-10 mm wide in the antero-posterior dimension[3]. The appearance of the mandibular condyle is extremely variable between patients and in different age groups.
The cranial component of the TMJ lies below the squamous portion of the temporal bone anterior to tympanic plate. The articular fossa is formed entirely by the