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Are muscle spindles present in human suprahyoid muscles ?
Boekbijdrage - Boekhoofdstuk Conferentiebijdrage
The fibre composition and occurrence of muscle spindles was studied in the masticatory, the suprahyoid and the infrahyoid muscles of animals. However, there is a gap of the knowledge in man. Studies on rat show that many muscle spindles, often clustered, are present in het masticatory muscles, except in the lateral pterygoid. In most of the suprahyoid muscles, these sensory structures are absent. Finally, in the infrahyoid muscles, solitary muscle spindles are found. In addition, other studies suggest that muscle spindles are absent or few in digastric and mylohyoid muscles in the cat. In humans, it seems that some unusual aspects to the internal organization of jaw muscles are present and that each muscle would be considered an entity unto itself. Thus we purpose to analyze the characteristic of the neuromuscolar fuses in human suprahyoid muscles.
This study is based on the analysis of eleven digastric muscles and six mylohyoid muscles. As control, four plantaris and one flexor digitorum brevis muscles were obtained.
This study was performed with postmortem tissue. Spindle distribution was analyzed under light microscopy, using a Leica microscope (Leica Microsystems, Milano, Italy) calibrated to a digitizing system, and Leica FireCam 1.9.2 software (Leica Microsystems, Milano, Italy). Muscle section perimeters were traced using a x4 objective and the location of all identified spindles plotted using a x10 objective for all stained sections. The distribution of muscle spindles in the plotted muscles sections was then determined using a rectangular grid positioned over each plotted section. {...} Finally, it is possible to hypothesize that during evolution muscles changed their relationship with external forces, such as gravity. In fact, in the passage from quadruped to biped standing, muscles involved in temporo-mandibular articulation movements resulted to work in gravity favour.
This study is based on the analysis of eleven digastric muscles and six mylohyoid muscles. As control, four plantaris and one flexor digitorum brevis muscles were obtained.
This study was performed with postmortem tissue. Spindle distribution was analyzed under light microscopy, using a Leica microscope (Leica Microsystems, Milano, Italy) calibrated to a digitizing system, and Leica FireCam 1.9.2 software (Leica Microsystems, Milano, Italy). Muscle section perimeters were traced using a x4 objective and the location of all identified spindles plotted using a x10 objective for all stained sections. The distribution of muscle spindles in the plotted muscles sections was then determined using a rectangular grid positioned over each plotted section. {...} Finally, it is possible to hypothesize that during evolution muscles changed their relationship with external forces, such as gravity. In fact, in the passage from quadruped to biped standing, muscles involved in temporo-mandibular articulation movements resulted to work in gravity favour.
Boek: XIXième Colloque de la Société Internationale de Biométrie Humaine
Trefwoorden:muscle spindles, human suprahyoid muscles