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Scheven, Christina von (2010): The Anatomy and Function of the equine thoracolumbar Longissimus dorsi muscle. Dissertation, LMU München: Tierärztliche Fakultät



The aim of this thesis was to evaluate the structure and function of the largest muscle of the equine back, the Longissimus dorsi muscle (LD) and investigate the usefulness of ultrasonography in determining LD architecture in live horses. Dissection of clinically normal horse and pony cadaver backs demonstrated the complex architecture of this muscle with its regional variations in diameter, muscle fibre length and pennation angle. The observed anatomical differences corresponded to regional differences in muscle activity pattern and the intensity of muscle activity in six horses examined. Electrmyographic measurements showed significant diffeneces at different anatomical locations, gait, speed and inclines. Ultrasonography was evaluated as a tool to visualize and quantify LD architecture in live horses. In the first ultrasonographic study the ultrasonographic anatomy of the LD was determined by matching ultrasonographic images to corresponding frozen sections in a cadaver. Inter- and intra-operator repeatability of ultrasound based muscle measurements showed that muscle thickness measurements were found to be reapeatable, pennation angle was not. The presented thesis contributes to understanding the biomechanics of the equine LD by illustrating the relationship between anatomy and function through integrating cadaveric data with measurements in live horses. In the second part the use of ultrasonography in determining LD architecture and functioin in live horses as future diagnostic tool was investigated and its usefulness and limitations established.