The Role of the Lateral Pterygoid Muscle in Articular Disc Displacement: A Cross-Sectional Magnetic Resonance Imaging Study

Background: Determination of the role of the Lateral Pterygoid Muscle LPM in the articular disc displacement ADD is controversial referring to the variations in the pattern of insertion of the Superior Lateral Pterygoid Muscle SPLM. Introduction: it was well understood that the superior head of the lateral pterygoid muscle has only a single insertion pattern among individuals in which the muscle is attached to the articular disc and capsule. However, recent findings in many studies have shown a noticeable variation in the insertion pattern of the upper LPM. Method: MRI examinations were collected at King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia. Scans of 61 patients (41 females, 20 males, mean age 33 years old) with symptoms of temporomandibular dysfunction were reviewed retrospectively. The direction of their articular disc displacement was evaluated through sagittal and coronal views in both open and closed mouth positions. Results: There was no statistical significance found between the LPM attachment types and TMJ disc position. The chi-square test also showed no significant difference between the type of LPM attachment and the condylar location. Forty-five percent of the articular discs were located between the articular eminence and the glenoid fossa. The majority of the disc displacement was in the anterior direction. Conclusion: There was no statistically significant association between the type of LPM attachments and the direction of disc displacement.

Assessment of anterior positioning splint in conjunction with lateral pterygoid BTX injection to treat TMJ disc displacement with reduction — a preliminary report

Objective Treatment of temporomandibular disc displacement with reduction is controversial. This study assesses the use of an anterior positioning splint with botulinum toxin in the lateral pterygoid muscle (BTX) for such cases. Methods Twelve joints were included; groups I and II received BTX injection while group II also received an anterior positioning splint. Pain scores and clicking status were recorded at regular intervals then a postoperative MRI was done after 4 months. Results Clinical improvement was noted in both groups. Mean pain scores dropped significantly and clicks in the twelve joints disappeared in 83% of group I and 33% of group II. MRIs showed significant disc position improvement with the higher mean change (1.33 ± 0.76) in group I. Group I showed better improvement of discal position and only one joint regained a click. Patients of group II reported discomfort from the splint which may have caused psychological distress and so worst pain scores. Conclusions Group I showed slightly better results but the cost of BTX injections and the complications of the splint should be kept in mind and the decision of treatment selection made according to each condition.

Anatomical Characteristics of the Lateral Pterygoid Muscle in Mandibular Prognathism

Mandibular prognathism is one of the most concerning subjects in the oral and maxillofacial fields. In our previous studies, we attempted to clarify the etiology of mandibular prognathism. They revealed that one of the major characteristics of mandibular prognathism was the lower volume/length ratio of the mandibular condyle and body compared to normal, and the masseter muscle showed parallelism with this. This study aimed to evaluate the relationship between mandibular prognathism and the lateral pterygoid muscle by measuring the orientation and volume/length ratio of the lateral pterygoid muscle. Computed tomography was used to calculate the volume/length ratio of the lateral pterygoid muscle in 60 Korean individuals. Mimics 10.0 and Maya version 2018 were used to reconstruct the surface area and surface planes. The results showed that the prognathic group showed smaller lateral pterygoid volume/length ratios compared to the normal group (p < 0.05). In addition, the normal group displayed a larger horizontal angle (p < 0.05) to the mandibular and palatal planes than the prognathic group. This demonstrated that the mechanical drawback of the lateral pterygoid in the prognathic group is associated with mandibular prognathism.

Maxillary Artery runs medial to the mandibular nerve unilaterally: Case report and Literature Review

Background: The maxillary artery supplies the deep structures of the face and cranium. The maxillary artery and the mandibular nerve form a clinically important relation in the infratemporal fossa. Variations of the maxillary artery may complicate dental, oral, and maxillofacial surgeries in this region. Methods: During routine academic dissection of a 91-year-old Caucasian female cadaver, the pterygoid segment of the left maxillary artery was found medial to the posterior division of the mandibular nerve in the infratemporal fossa. Results: The maxillary artery coursed superior to the point of division of the mandibular nerve and remained undivided. Conclusion: This rare unilateral variation will be of interest to anatomists and clinicians, as an understanding of anatomical variations of the maxillary artery can help decrease the risk of hemorrhage and other surgical complications. KEY WORDS: Maxillary artery, Mandibular nerve, Lateral pterygoid muscle, Infratemporal Fossa.