Two mammalian species in which the intercostal nerves innervate the serratus anterior or scalenus muscles together with the cervical nerves: an important clue to clarify the homology of cervico-thoracic trunk muscles in mammals
Two mammalian species in which the intercostal nerves innervate the serratus anterior or scalenus muscles together with the cervical nerves: an important clue to clarify the homology of cervico-thoracic trunk muscles in mammals
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DOI：
10.1007/s12565-019-00487-1
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发表时间：
2019-09-01
影响因子：
1.2
通讯作者：
Koizumi, Masahiro
中科院分区：
文献类型：
--
作者：
Koizumi, Masahiro
哺乳动物的肩胛提肌、菱形肌、前锯肌（统称为肩胛带背侧肌）和斜角肌通常受颈神经支配。然而，在无尾熊中，前锯肌还受到第一肋间神经外侧皮分支的支配。在猫中，与其他一些哺乳动物物种一样，斜角肌的一部分（长斜角肌）由肋间神经的外侧皮支支配。对这两例患者的同一节段的神经支配进行精确的比较，可以明确颈、胸干肌的同源关系。在这种情况下，本研究的目的是遵循的神经纤维包括在供应背肩带和斜角肌的神经水平的脊神经根在两只考拉和两只猫。结果表明，来自肋间神经外侧皮分支的考拉前锯肌神经和猫斜角肌神经在脊神经根中的位置与颈神经肩胛带背肌分支和胸神经肋间外肌分支相同。根据这些结果，颈胸区的轴干肌可以分为：斜角肌和背肩带肌与肋间外肌属于同一个外侧轴干肌群，并与肋间内肌和最内肌等内侧肌群有明显区别。
The levator scapulae, rhomboideus, and serratus anterior muscles (as a group referred to the dorsal shoulder girdle muscles) and the scalenus muscles in mammals are usually innervated by cervical nerves. However, in koalas, the serratus anterior is additionally innervated by the lateral cutaneous branch of the first intercostal nerve. In cats, as in some other mammalian species, a part of the scalenus muscle (scalenus longus muscle) is innervated by the lateral cutaneous branches of the intercostal nerves. A precise comparison of the innervating nerves at the same segment in these two cases could clarify the homological relationship between the cervical and thoracic trunk muscles. In this context, the aim of this study was to follow the nerve fibers included in the nerves supplying the dorsal shoulder girdle and scalenus muscles up to the level of the spinal nerve roots in two koalas and two cats. The resultant observations revealed that both of the nerves to the serratus anterior in koalas and to the scalenus muscles in cats from the lateral cutaneous branch of the intercostal nerve occupy the same position in the spinal roots as the cervical nerve branches to the dorsal shoulder girdle muscles and the thoracic nerve branches to the external intercostal muscle. Based on these results, the axial trunk muscles in the cervico-thoracic region could be classified as follows: the scalenus and dorsal shoulder girdle muscles belong to the same lateral axial trunk muscle group as the external intercostal muscle, and are clearly distinguished from the medial group, such as the internal and innermost intercostal muscle.