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Investigating the Contraction Pattern of the Zygomaticus Major Muscle and its Clinical Relevance: A Functional MRI
Daniel J Rams1, Michael Alfertshofer2, Jakub Batko1
1Department of Anatomy, Jagiellonian University Medical College, Kraków, Poland.
Aesthetic Plastic Surgery
|February 27, 2024
Summary
This study reveals the zygomaticus major muscle contracts isotonically, decreasing length and increasing width/thickness during joyful expressions. Findings aid in assessing facial muscle function and guiding clinical evaluations.
Area of Science:
- Anatomy and Physiology
- Medical Imaging
Background:
- Facial muscle contraction patterns and their presentation in clinical imaging are not well understood.
- Detailed knowledge of zygomaticus major muscle behavior is crucial for surgical planning and treatment development.
Purpose of the Study:
- To investigate the contraction patterns and dimensional changes of the zygomaticus major muscle during various facial expressions using MRI.
- To enhance understanding of facial anatomy and muscle function for clinical applications.
Main Methods:
- Magnetic resonance imaging (MRI) was used to analyze the zygomaticus major muscle in 34 healthy young adults.
- Measurements of muscle length, thickness, width, and angle were taken during five expressions: repose, anger, joy, surprise, and sadness.
Main Results:
- Joyful expressions induced isotonic contraction, reducing muscle length and increasing width and thickness.
- Other expressions (anger, surprise, sadness) generally caused muscle stretching with variable dimensional changes and altered facial angles.
Conclusions:
- The zygomaticus major muscle exhibits isotonic contraction, characterized by decreased length and increased width/thickness.
- Muscle thickness is a reliable indicator for assessing facial muscle function, providing valuable insights for practitioners.
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