Sokoloff A J, Deacon T W
Harvard University, Cambridge, Massachusetts 02138.
J Comp Neurol. 1992 Oct 1;324(1):81-93. doi: 10.1002/cne.903240107.
The movements of the tongue in feeding and vocalization are enabled by a complex system of interdigitated muscle fibers in the tongue body. Because of this complexity, the detailed anatomical connections between individual intrinsic tongue muscles and corresponding motoneurons in the hypoglossal nucleus have not been described for any mammal. In this study we describe the distribution of retrogradely labeled neurons in the hypoglossal nucleus, following injections of wheat-germ agglutinin-horseradish peroxidase into different regions of the tongue of 21 cynomolgus monkeys. These experiments demonstrate a spatial organization of hypoglossal motoneurons that reflects the anatomical and functional organization of tongue body muscles: motoneurons innervating the transversus and verticalis muscles are located in medial hypoglossal nucleus regions, motoneurons innervating the genioglossus are located in intermediate hypoglossal nucleus regions, motoneurons innervating the hyoglossus and inferior longitudinalis are located in ventrolateral hypoglossal nucleus regions, and motoneurons innervating the styloglossus and superior longitudinalis are located in dorsolateral hypoglossal nucleus regions. Motoneurons innervating the suprahyoid muscle, the geniohyoid, are situated in a cell column separated ventrally from the main body of the hypoglossal nucleus. Motoneurons innervating the palatoglossus are located in the nucleus ambiguus and, possibly, in dorsolateral hypoglossal nucleus regions. Motoneurons of the medial divisions of the hypoglossal nucleus innervate tongue muscles that are oriented in planes transverse to the long axis of the tongue whereas motoneurons of the lateral divisions innervate tongue muscles that are oriented parallel to this axis. These results suggest that the segregation of motoneurons corresponds to the functional distinction between tongue protrusion and retrusion.
舌体中相互交错的肌纤维组成的复杂系统，使舌头能够在进食和发声时运动。由于这种复杂性，尚未有任何哺乳动物的单个舌内肌与舌下神经核中相应运动神经元之间详细的解剖学连接被描述。在本研究中，我们将小麦胚芽凝集素 - 辣根过氧化物酶注射到21只食蟹猴舌头的不同区域，然后描述舌下神经核中逆行标记神经元的分布。这些实验证明了舌下运动神经元的空间组织反映了舌体肌肉的解剖学和功能组织：支配横肌和垂直肌的运动神经元位于舌下神经核内侧区域，支配颏舌肌的运动神经元位于舌下神经核中间区域，支配舌骨舌肌和下纵肌的运动神经元位于舌下神经核腹外侧区域，支配茎突舌肌和上纵肌的运动神经元位于舌下神经核背外侧区域。支配舌骨上肌（颏舌骨肌）的运动神经元位于一个细胞柱中，该细胞柱在腹侧与舌下神经核主体分开。支配腭舌肌的运动神经元位于疑核以及可能位于舌下神经核背外侧区域。舌下神经核内侧部的运动神经元支配与舌长轴垂直平面定向的舌肌，而外侧部的运动神经元支配与该轴平行定向的舌肌。这些结果表明，运动神经元的分离对应于舌前伸和后缩之间的功能差异。
