Back to Search
Start Over
Muscle fibre composition and electromyographic features of cervical muscles following prolonged head extension in growing rats
- Source :
- The European Journal of Orthodontics. 25:21-33
- Publication Year :
- 2003
- Publisher :
- Oxford University Press (OUP), 2003.
-
Abstract
- Soft tissue stretching has been proposed as one of the control factors in craniofacial morphogenesis. However, its mechanism remains unclear. The present study investigated electromyographic (EMG) activity and muscle fibre composition of cervical muscles following prolonged head extension in growing rats. Thirty-six male Wistar rats were divided into two experimental (E1, E2) and one control (C) group at 25 days of age. To induce head extension, the experimental rats were raised in cylindrical cages, which were positioned horizontally for group E1 and tilted upward at 45 degrees for group E2. At 55 days of age, EMG activity was recorded from the anterior digastricus (AD), sternohyoideus (SH), sternomastoideus (SM), longus capitis (LC), and biventer cervicis (BC) muscles in the rest position and passive head extension. EMG activity was analysed on its integrated values (IEMG), and composition of muscle fibres was evaluated by myosin ATPase reaction and fibre cross-sectional areas were calculated. Group E1 showed a higher percentage of type I fibres and lower IEMG during passive head extension in AD. In group E2 there was a higher percentage of type I fibres, a higher IEMG at rest, and a lower IEMG during passive head extension in BC. The experimental groups demonstrated altered proportions of type IIA and IIB fibres in SM and LC. They also showed higher percentages of subtype fibres and reduced cross-section areas of type II fibres in most of the muscles investigated. These findings suggest that head extension affects fibre transition, distribution, cross-section area, and recruitment pattern in cervical muscles.
- Subjects :
- Male
Myosin ATPase
Longus capitis muscle
Muscle Fibers, Skeletal
Posture
Orthodontics
Electromyography
Myosins
Neck Muscles
Myosin
medicine
Animals
Rats, Wistar
Craniofacial
Analysis of Variance
Chi-Square Distribution
medicine.diagnostic_test
Cervical muscles
Chemistry
Soft tissue
Signal Processing, Computer-Assisted
Anatomy
Rats
Muscle Fibers, Slow-Twitch
Head Movements
Models, Animal
Muscle Fibers, Fast-Twitch
Head (vessel)
Muscle Contraction
Subjects
Details
- ISSN :
- 14602210 and 01415387
- Volume :
- 25
- Database :
- OpenAIRE
- Journal :
- The European Journal of Orthodontics
- Accession number :
- edsair.doi.dedup.....c8a6f327ffacc051ba78c739ec62bb33