Department of Veterinary Clinical Studies, Royal (Dick) School of Veterinary Studies, the University of Edinburgh, Easter Bush Veterinary Centre, Large Animal Hospital, Midlothian, UK.
Equine Vet J. 2010 Jul;42(5):431-7. doi: 10.1111/j.2042-3306.2010.00067.x.
Dysfunction of the muscles is implicated in the pathogenesis of intermittent dorsal displacement of the soft palate (DDSP) in exercising horses. The histological features of normal equine soft palate muscles have not been previously described.
To describe the histological and morphometric features of normal equine soft palate muscles.
The palatinus, palatopharyngeus, levator veli palatini and tensor veli palatini muscles of 6 Thoroughbred type horses were examined histologically and histochemically to assess their general morphology, fibre-type distribution and mean fibre diameter.
The muscles of all 6 specimens showed very similar characteristics, including a low proportion of type 1 muscle fibres in the 4 different muscles examined, with the 3 muscles innervated by the pharyngeal branch of the vagus (i.e. palatopharyngeus, palatinus and levator veli palatini) having significantly fewer (P<0.005) type 1 muscle fibres compared to the tensor veli palatini. The mean fibre diameters were significantly (P<0.05) smaller in type 1 than type 2 fibres in all muscles except the palatinus. Considerable variability in mean fibre size diameter was evident in all muscles examined, with type 1 fibres in the levator veli palatini and rostral fasciculus of the palatopharyngeus and both fibre types in the caudal fasciculus of the palatopharyngeus having the most marked variation, with coefficients of variation >250 and the latter also having high levels of endomysial connective tissue. The palatinus had least variation in fibre size.
Morphological characterisation of the normal soft palate muscles may provide reference values for future comparative studies with samples obtained from horses with palatal dysfunction. The palatinus appears to be the best muscle to histologically examine for evidence of muscle abnormality.
肌肉功能障碍与运动马间歇性硬软腭后移位（DDSP）的发病机制有关。正常马软腭肌肉的组织学特征以前尚未描述过。
描述正常马软腭肌肉的组织学和形态计量学特征。
对 6 匹纯血马的硬腭肌、腭咽肌、腭帆提肌和腭帆张肌进行组织学和组织化学检查，以评估其一般形态、纤维型分布和平均纤维直径。
所有 6 个标本的肌肉均表现出非常相似的特征，包括在 4 种不同肌肉中 1 型肌纤维的比例较低，3 种由迷走神经咽支（即腭咽肌、硬腭肌和腭帆提肌）支配的肌肉 1 型肌纤维的比例明显较低（P<0.005），与腭帆张肌相比。除硬腭肌外，所有肌肉的 1 型纤维的平均纤维直径均显著（P<0.05）小于 2 型纤维。所有检查的肌肉中，平均纤维大小直径都有很大的差异，腭帆提肌和腭咽肌的升支的 1 型纤维以及腭咽肌的降支的两种纤维类型的变化最为显著，变异系数>250，后者还具有高水平的肌内膜结缔组织。硬腭肌的纤维大小变化最小。
正常软腭肌肉的形态学特征可为未来与腭功能障碍马获得的样本进行比较研究提供参考值。硬腭肌似乎是最适合进行组织学检查以发现肌肉异常的肌肉。
