Micro- and Nanostructural Characteristics of Rat Masseter Muscle Entheses
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- Arakawa Keitaro
- Department of Orthodontics, Tokyo Dental College Oral Health Science Center, Tokyo Dental College
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- Matsunaga Satoru
- Oral Health Science Center, Tokyo Dental College Department of Anatomy, Tokyo Dental College
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- Nojima Kunihiko
- Department of Orthodontics, Tokyo Dental College Oral Health Science Center, Tokyo Dental College
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- Nakano Takayoshi
- Division of Materials & Manufacturing Science, Graduate School of Engineering, Osaka University
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- Abe Shinichi
- Department of Anatomy, Tokyo Dental College
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- Yoshinari Masao
- Oral Health Science Center, Tokyo Dental College
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- Sueishi Kenji
- Department of Orthodontics, Tokyo Dental College Oral Health Science Center, Tokyo Dental College
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Abstract
<p>The entheses of the masticatory muscles differ slightly from those of the trunk and limb muscles. However, the bones of the skull are subject to various functional pressures, including masticatory force, resulting in a complex relationship between bone structure and muscle function that remains to be fully elucidated. The present study aimed to clarify aspects of masseter muscle-tendon-bone morphological characteristics and local load environment through quantitative analysis of biological apatite (BAp) crystallite alignment and collagen fiber orientation together with histological examination of the entheses. Result of histological observation, the present findings show that, in the entheses of the masseter muscle in the first molar region, tendon attaches to bone via unmineralized fibrocartilage, while some tendon collagen fibers insert directly into the bone, running parallel to the muscle fibers. Furthermore, BAp crystallites in the same region show uniaxial preferential alignment at an angle that matches the insertion angle of the tendon fibers. Conversely, in the entheses of the masseter muscle in the third molar region, the tendon attaches to the bone via a layer of thickened periosteum and chondrocytes. As in the first molar region, the results of bone quality analysis in the third molar region showed BAp crystallite alignment parallel to the orientation of the tendon fibers. This indicates that the local mechanical environment generates differences in enthesis morphology. The present study showed a greater degree of uniaxial BAp crystallite alignment in entheses with direct insertion rather than indirect tendon-bone attachment and the direction of alignment was parallel to the orientation of tendon fibers. These findings suggest that functional pressure from the masseter muscle greatly affects bone quality as well as the morphological characteristics of the enthesis, specifically causing micro- and nanostructural anisotropy in the direction of resistance to the applied pressure.</p>
Journal
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- Journal of Hard Tissue Biology
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Journal of Hard Tissue Biology 28 (4), 365-370, 2019
THE SOCIETY FOR HARD TISSUE REGENERATIVE BIOLOGY
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Details 詳細情報について
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- CRID
- 1390282752355063424
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- NII Article ID
- 130007738999
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- NII Book ID
- AA11074332
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- ISSN
- 1880828X
- 13417649
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- NDL BIB ID
- 030116124
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- Text Lang
- en
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- Data Source
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- JaLC
- NDL
- Crossref
- CiNii Articles
- KAKEN
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- Abstract License Flag
- Disallowed