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Three-dimensional lateral pterygoid muscle volume: MRI analyses with insertion patterns correlation
Gabriela Sobral de Figueiredo Melke1, André Luiz Ferreira Costa1, Sérgio Lúcio Pereira de Castro Lopes2
1Department of Orthodontics, University of São Paulo City, São Paulo, São Paulo, Brazil.
Summary
The volume of the lateral pterygoid muscle changes with mouth position and is influenced by gender. A subdivided upper head attachment in the lateral pterygoid muscle correlates with increased volume.
Area of Science:
- Temporomandibular Joint (TMJ) Disorders
- Head and Neck Anatomy
- Medical Imaging (MRI)
Background:
- The lateral pterygoid muscle is crucial for temporomandibular joint function.
- Understanding its volumetric changes is important for diagnosing TMJ disorders.
- Previous research has not fully explored the muscle's volume variations in different physiological states and anatomical configurations.
Purpose of the Study:
- To evaluate the volume of the lateral pterygoid muscle in closed and open mouth positions.
- To investigate the association between muscle volume and temporomandibular joint conditions like disc displacement, effusion, and abnormal disc shape.
- To determine the influence of gender and upper head insertion type on lateral pterygoid muscle volume.
Main Methods:
- Analyzed 24 MRI scans (15 female, 9 male, aged 19-64) using 3D reformations.
- Performed segmentation and volumetric assessment of the total, upper, and lower heads of the lateral pterygoid muscle.
- Compared muscle volumes between closed and open mouth positions and correlated findings with TMJ pathologies.
Main Results:
- The upper head of the lateral pterygoid muscle consistently showed a smaller volume than the lower head in both mouth positions.
- A significantly larger upper head volume was observed in the open-mouth position for individuals with a subdivided upper head attachment compared to those with a single attachment (p=0.0130).
- Gender was found to affect muscle volume, particularly in the upper head component.
Conclusions:
- Lateral pterygoid muscle volume differs significantly between closed and open mouth positions.
- The type of upper head insertion and gender are factors that appear to influence lateral pterygoid muscle volume.
- These findings contribute to a better understanding of TMJ anatomy and potential volumetric changes associated with disc displacement and other abnormalities.
